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The Conduct of Abnormal Labor
The Conduct of Abnormal Labor D. N. DANFORTH, M.D., PH.D., F.A.C.S.*
THE term "abnormal labor" is used to describe any labor which deviates significantly from the normal. It is evident that this is an inclusive term, and for purposes of discussion it is necessary to consider only certain of the more important abnormalities of labor. Of the lesser deviations, many are so slight that they will be unrecognized, and Nature will care for them skillfully if left to her own devices. In the major abnormalities it is essential that the obstetrician recognize them promptly, have full understanding of their possibilities, and deal with them skillfully when it is indicated. At the outset it should be mentioned that most obstetrical catastrophes result directly from intervention rather than from the lack of it. So-called aid, however skillfully performed, is inevitably worse than none at all if it is ill-timed. Bumm has said, "They are poor obstetricians who cannot await the safe processes of nature." So it is in the conduct of abnormal labor. One's effort must be first to understand thoroughly the details of the problem which is presented, and second, to avoid operative intervention unless it is specifically and clearly indicated. So long as there is any question as to whether intervention is indicated, it is best deferred until positive and unequivocal indication arises. There are three important ways in which labor may be abnormal. First, the powers, or uterine forces, may function in an abnormal manner; second, the baby may present by an abnormal or unfavorable attitude; and third, the birth canal itself may provide impediment to the passage of the baby. The second and third possibilities are interrelated. ABNORMALIty OF THE UTERINE FORCES
Under normal or favorable circumstances the uterine contractions of labor have one fundamental characteristic, namely, coordination. In From the Department of Obst~trics and Gynecology , Northwestern University M edical School, Chicago, and the Evanston Hospital, Evanston, Illinois.
* Associate Professor of Obstetrics and Gynecology, Northwestern University Medical School; Chairman, Department of Obstetrics and Gynecology, Evanston Hospital. 125
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an effective labor the contractions begin simultaneously in the uterine cornua and spread evenly over the uterus, ultimately involving the entire organ. They occur at regular, gradually diminishing intervals; they are of even, gradually increasing intensity, and are of regular, gradually increasing duration. Such contractions cause progressive dilatation of the cervix. Certain requisites are necessary in order that this highly coordinated activity may occur. First, the uterine muscle must be in this nebulous state of affairs referred to as proper nutrition. It is well known that a high proportion of prolonged labors occurs among patients whose prenatal care has been indifferent. Excessive weight gain, improper diet, and inadequate rest during pregnancy may predispose to this complication. Second, the uterine muscle must not be overstretched. Hydramnios and multiple pregnancy may predispose if uterine growth is not commensurate with the increase in bulk of the conceptus. Third, an efficient labor requires that the lower pole of the uterus be properly and evenly stimulated by the presenting part, or by an intact bag of waters. The anterior and transverse mechanisms of the occiput, with full flexion, appear to provide optimal fitting of the head to the lower pole of the uterus, while generally poor fitting occurs in the occiput posterior mechanism. In the latter case, desultory, protracted labors are common. A stellar example of improper fitting occurs when the axis of drive is not directly into the inlet, as in the pelvis which is inclined far posteriorly and the head directed against the symphysis, or when the uterus lies on one side or the other of the abdomen, perhaps being held in this position by a distended stomach or colon. A case is recorded in the literature of an air swallower who achieved enormous distention of the stomach periodically during labor. Contractions virtually ceased when the stomach became distended, to resume instantly upon release of the gas by stomach tube. The inertia was attributed to reflex inhibition by the gastric distention, but I suspect the more likely explanation to be interference with proper axis of drive by pressure upon one side of the uterus, with consequent improper fitting of the head to the lower pole of the uterus. Under such circumstances stimulation of the nerve endings in the lower uterine segment is uneven, and inefficient contractions are the result. Uterine Inertia
As for terminology, the purist suggests that one may diagnose uterine inertia only after the cervix has shown no further dilatation for eight hours in the first stage, or if in the second stage there has been no progress for two hours, and in both instances the uterus is easily indentable at the height of a contraction. These criteria are useful in precluding abuse of the term "uterine inertia" as justification for unwarranted operative
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intervention. They are less helpful in the practical management of this complication, for one's evaluation of the problem must begin long before such an inordinate length of time has passed. An eminent obstetrician of unusual skill, and virtually flawless obstetrical judgment, was once asked whether he was disturbed about a patient whose labor was inefficient. Said he, "I am always disturbed about any patient whose labor is in any way abnormal." One's observation of the parturient should be sufficiently close that deviations from the normal may be noted as they occur. It is thus apparent that uterine inertia, in its various degrees and in the different stages of labor, should be regarded as a sign and not a diagnosis. It is an indication of an underlying and often correctable defect. Evaluation of this problem should lead to an attempt to determine the defect which causes the inefficiency, and to correct it if possible. Failing this, the effort must be made to keep the patient in the best possible general condition, to apply such measures of gentle stimulation as may be consistent with safety, and, above all, to inflict no damage. MANAGEMENT OF DESULTORY LABOR FIRST STAGE
During the beginning of the first stage of labor, inefficient contractions cause no concern, for they will inevitably improve. Two circumstances particularly which predispose to a slow start, as it were, are a head which is extremely low at the onset of labor, and a cervix which is far posterior. Under these circumstances the patient must be prepared for the several hours of desultory contractions which invariably precede active labor. Stimulation must be avoided. Ambulation should be avoided, except for the patient's comfort and peace of mind; it is a dismal sight to see a patient and her husband trudging up and down the corridor in an effort to precipitate a labor which would probably start if she were to lie down. With the head already deeply engaged and the cervix far back, the upright position tends to exaggerate this defect. In the absence of factors in the first stage of labor which can be easily corrected, one is then left with certain important general principles which should be employed in the conduct of desultory, ineffective labor. Rest Periods
Although the efficiency of uterine contractions during the first stage of labor may be poor, nevertheless they are painful and, if allowed to continue indefinitely, extremely tiring to the patient. For this reason the use of morphine or Pantopon in full dose (morphine X grain or Pantopon 7~ grain) at intervals of six or eight hours may have an extremely salutary effect. With this dose the patient will obtain from one
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and one-half to three hours of sleep. She generally awakens refreshed, and in addition the uterine contractions, formerly inefficient and poorly coordinated, are often found to resume in an efficient and coordinated manner. Irrespective of the length of the first stage of a desultory labor, the timely use of opiates in full dose is considered essential. Hydration It is well known that the emptying of the stomach is greatly delayed during labor. For this reason, and also in anticipation of the possible need for general anesthesia at any time, it is unwise to require patients to take adequate amounts of fluid by mouth. Particular attention must be paid, however, to fluid balance, which is of particular importance in prolonged labor. It should be a standing rule in any maternity that the urine should be examined for acetone and diacetic acid after the first twelve hours of labor, and at four hour intervals thereafter. If these tests are positive at any time, an infusion of 5 or 10 per cent dextrose in water should be started immediately. Depending on the state of affairs, either 1000 or 1500 cc. of this fluid should be administered, and should be repeated if it is indicated by the later reappearance of acetone or diacetic acid in the urine. Ambulation It has already been mentioned that ambulation is not desirable if the head is deeply engaged in the pelvis and the cervix is situated far posteriorly. In other cases, however, it is considered desirable, especially between rest periods, for two reasons. First, a change of scene may have a beneficial psychological effect, and may tend to minimize the anxiety of the patient and her family. Second, the upright position may improve the fitting of the head to the lower pole of the uterus and consequently enhance the efficiency of the contractions. It is emphasized that an exhausted patient should not be forced to tramp the halls, for this achieves little or nothing. Rather, she should be advised that she may get up and walk about a little if she wishes, and may go out and visit with her family. She should be asked to return to bed if she becomes fatigued, or contractions are troublesome. Stimulation
Enemas. The commonest form of stimulation used in obstetrics is the soapsuds enema. Its effectiveness in desultory labor should not be overlooked, and it is permissible to give a hot soapsuds enema at intervals of twelve or fourteen hours, so timed that they will coincide with the end of a rest period.
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Castor Oil. Castor oil has no place in the management of uterine inertia. Quinine. The efficacy of quinine as a stimulant to uterine contractions is questionable. The occasional report of congenital deafness following its use should outlaw this drug from obstetrics. Calcium. It has been shown both clinically and experimentally that calcium may be an effective stimulant to uterine contractions, and that in the relative absence of calcium ions uterine contractions are inefficient. For the induction of labor, we have abandoned the use of castor oil in favor of 10 cc. of calcium gluconate intravenously, and find also that the use of this drug at intervals of four to six hours may be helpful in the management of desultory labor. Ergot. Derivatives of ergot have been suggested and occasionally used in the management of uterine inertia. However, they are used but rarely for this purpose, and are not recommended for the reasons that the uterine response is relatively slow, that their effects are unpredictable and difficult to follow, and that their action is too sustained. Pituitrin. Only obstetrical Pituitrin (Pitocin) should be used for obstetrical patients. It is only rarely required in the management of desultory protracted labor. Pitocin should be given only after the cervix has reached 5 cm. dilatation and the head is fully engaged without evidence of disproportion. Also, the membranes should preferably have been ruptured, since this simple measure may make the use of Pituitrin unnecessary. Finally, the case should be one of actual uterine inertia as previously defined, in which there has been failure of progress for eight hours, and a uterus which may be easily indented at the height of a contraction. The first dose of Pitocin should not exceed 0.5 minim, for even with this small dose the uterus may react in the most violent manner. For this reason the patient must be carefully observed, and ether should be at hand so that it may be given immediately in the case of a tetanic contraction of the uterus. If within thirty minutes of this dose no effect has been observed, or if only a few desultory contractions have occurred, one may then give a dose of 1 minim of Pitocin. Two subsequent doses of 1 minim only may be given thereafter at thirty minute intervals as may be required. But this dose should not under any circumstances be exceeded in an undelivered patient. If these small doses are not effective, larger doses will in all probability be ineffective. Also, they may be extremely dangerous. Some obstetricians prefer the use of a Pitocin infusion, the· fluid being prepared by injecting 5 minims of Pitocin into 500 cc. of 5 per cent glucose solution. This may be so adjusted that 0.5 minim of Pitocin, equivalent to 50 cc. of the solution, may be run in over the course of thirty minutes. This is said to have the advantage of more intimate control of the reaction, and more sustained effect.
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Operative Intervention
Stripping of the Membranes. It is well known that stripping the membranes from the cervix and lower pole of the uterus by the finger, under sterile precautions, may have a salutary effect upon uterine contractions. This procedure therefore has some usefulness in the labor which has proceeded for six or eight hours, and in which cervical dilatation does not exceed 3 cm. If the cervix is more than 3 cm. dilated, it is considered preferable to rupture the membranes. Rupture of the Membranes. In desultory labor it is desirable to rupture the membranes artificially when the dilatation reaches 3 or 4 cm. and progress is delayed. When this is done, and amniotic fluid is allowed to escape from the uterus, the readjustment of the head to the lower pole of the uterus may allow more even fitting and improve the quality of the contractions. It is our common practice to rupture membranes with the DeLee perforator after preparation of the vulva, guiding the perforator by a finger in the rectum. In desultory inefficient labor this practice is undesirable. The vaginal fingers, in addition to guiding the perforator, may strip the membranes for a short distance and so stimulate the cervix with salutary effect. Surgical Procedures. During the first stage of labor operative procedures must not be undertaken except upon the appearance of absolute fetal or maternal indication. Procedures which are permissible during the first stage are limited, since the carrying out of intrauterine manipulations through an undilated cervix is not to be sanctioned. Efforts at this time therefore are directed only toward the achievement of full dilatation and may be undertaken only if the condition of the patient or the baby definitely demands them. MANUAL DILATATION. Manual dilatation of the cervix at 4 or 5 cm. is mentioned without enthusiasm. The lacerations which inevitably result are extremely difficult to repair properly, and serious hemorrhage may occur before delivery can be effected. This is a mutilating procedure which is best avoided. The only place manual dilatation of the cervix has in modern obstetrics is in the pushing back of a rim of cervix over the head. This should be necessary only rarely; when it is done, cervical lacerations are the rule. The cervix should always be inspected after delivery, and any lacerations which are 3 cm. long or more must be repaired. DUHRSSE~'S INCISIONS. These are an acceptable means of achieving dilatation of the cervix, but are ever so exceptionally required. Such incisions should be made with a bandage scissors, and they should be placed at lO o'clock and 1 o'clock, and occasionally also at 6 o'clock. They should be made only when the head is deeply engaged, and when the cervix itself offers the only obstacle to delivery. General anesthesia should be sufficiently deep that the incisions will not be extended by the
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patient's voluntary efforts. Even with this precaution, high upward extensions may occur; when contemplating cervical incision, one should be prepared for this contingency. VOORHEES BAG (METREURYNTER). This has no place whatever in modern obstetrics. CESAREAN SECTION. This is very exceptionally indicated in the management of uterine inertia per se. Cesarean section, when it is done in this condition, is generally indicated, not by the inertia, but rather by the condition giving rise to the inertia, as, for example, malposition of the baby or inlet disproportion. SECOND STAGE Delay in the second stage of labor may be due to failure of cooperation by the patient resulting from anxiety, excessive pain or excessive analgesia; to inefficiency of the contractions; or to pelvic arrest. One's course in the first instance is clear. In the second case the judicious use of Pitocin, after the method previously indicated, may be attempted after two hours without progress have elapsed. One should remember, however, that after two hours of efficient contractions in the second stage of labor, the labor should be terminated because of the danger of contraction ring or uterine rupture. It is only in the desultory second stage that one may disregard this two hour rule. The third possibility is considered in the following section. CEPHALOPELVIC DISPROPORTION
In the presence of adequate uterine contractions, the pelvis itself may offer resistance to the passage of the baby. This resistance may be either absolute, as in absolute cephalopelvic disproportion, or relative, due chiefly to the assumption by the baby of an attitude or position which is unfavorable for that particular pelvis. The effective evaluation and management of either absolute or relative disproportion requires an intimate knowledge of the ordinary pelvic variations and their influence upon the mechanism of labor. For this reason, it is pertinent to this subject to discuss briefly (a) the important pelvic variations which are of obstetrical significance, and (b) the influence of these individual features upon the mechanism of labor. With this information it is possible to determine with reasonable accuracy the manner in which the labor should be conducted and the method of delivery which should be used. PELVIC VARIATIONS The important pelvic variations, as defined by Caldwell and Moloy, can be summarized (Table 1).
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It is extremely unusual to find a pelvis which conforms in every detail to one of the pure types. Most pelves are mixed types which show, not only combinations of these various features, but also considerable variation in size. Although it is generally possible to obtain a good estimate of pelvic type and size by palpation, there are certain circumstances under which x-ray pelviography should be made. These include the following: (1) primipara with unengaged head at term; (2) primipara with prominent spines or forward lower sacrum by palpation; (3) multipara with history of difficult labor or delivery in previous pregnancy; (4) primiparous breech; (5) irregular presenting part; (6) serious heart disease or other debilitating systemic illness. Table 1 PELVIC VARIATIONS
a
.,...
i!i
. ., ...
.::FORE PELVIS
SIDEWALLS
ISCHIAL SPINES'
SACROSIATIC NOTCH
INCLINATION OF SACRUM
. ...., P
.
SUBPUBIC ARCH
0 0
0
BONE STBUCTUBE
Z
~
---
Gynecoid. Fig. Wide 3
(cm.)
ai
iii
II!
....
DIAG. CONJ.
---
Straight
Not prom- Medium inent
Medium
Wide
-
10
-- --12.5 Delicate or medium 12.5 Heavy
Android .. Fig. Narrow Converg- Prominent Narrow Forward Narrow <10 gent 4 Anthropoid .... Fig. Wide Divergent Not prom- Wide Backward Wide 10 >12.5 Medium inent 5 Flat ...... Fig. Wide Straight Not prom- Medium Forward Wide 10 <12 or narMedium inent 6 row
Many technics for x-ray visualization of the pelvis have been described. The technic which in our hands gives the greatest amount of information and is technically simplest consists of three films: (1) Standing lateral taken at 36 inches. A 10 cm. rod is placed between the buttocks. This may be directly interpolated to give the anteroposterior diameter of the inlet. (2) A Thoms inlet view. (3) A subpubic arch film. The details of these films and their interpretation are considered in detail in the author's article dealing with this subject.l Predictions concerning the proper mechanism of labor for any given pelvis are based upon two dicta which are regarded as axiomatic. These are the following: (a) The biparietal diameter of the fetal head is the shortest diameter, and must therefore go through the narrowest diameter of the pelvis at any given level. (b) The occiput generally tends to rotate to the widest portion of the pelvis at any given level.
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With precise knowledge of the various features of-a given pelvis and with the aid of these two dicta it should be possible to predict with accuracy the mechanism which should obtain if all the available space is used: Inlet. From the foregoing, it is evident that in a flat pelvis, with anteroposterior narrowing, engagement will occur in the transverse position. In the anthropoid pelvis which is long anteroposteriorly, engagement Fig. 3.
Fig. 4.
Fig. 5.
Fig. 6.
Fig. 3. Typical gynecoid pelvis: inlet view. Fig. 4. Typical android pelvis; inlet view. Fig. 5. Typical anthropoid pelvis; inlet view. Fig. 6. Typical platypelloid (flat) pelvis; inlet view. (Moloy, H. C., Clinical and Roentgenologic Evaluation of the Pelvis in Obstetrics, W. B. Saunders Co.)
will occur with the sagittal suture in the sagittal plane of the pelvis. Since, however, in the anthropoid pelvis the forepelvis is narrow, the occiput will tend to rotate away from this narrowed area into the ample posterior segment, and engagement occurs in the direct occiput posterior. This mechanism is typified by the monkey and anthropoid ape, of which the anthropoid pelvis is characteristic, and in which the posterior mechanism is the rule. At the level of the mid-pelvis the features which determine mechanism are (1) the prominence of the spines, which determines the presence or
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absence of transverse narrowing in the mid-pelvis; (2) the position of the sacrum, whether forward or backward or in the normal middle position, which determines the presence or absence of anteroposterior narrowing in the mid-pelvis; and (3) the foreplevis, which plays a role in midpelvic mechanism by influencing the space available in the anteroposterior diameter. Thus, with prominent spines and a sacrum which is situated posteriorly, one would expect the head to descend with the sagittal suture in the sagittal plane of the pelvis. Conversely, with forward sacrum and spines which are not prominent, one would expect the head to traverse this plane in the transverse position. At the plane of the outlet, the transverse capacity is determined by the transverse of the outlet, or bi-ischial diameter, and the anteroposterior capacity by the width of the subpubic arch and the position of the sacrococcygeal articulation. Thus, when the transverse of the outlet is narrowed, and the sacrococcygeal articulation far posterior, the head should traverse this diameter with the sagittal suture in the sagittal plane of the pelvis. Conversely, when the lower sacrum is forward and the transverse of the outlet wide, the head should traverse this diameter in the transverse or oblique position. Inlet Arrest or Inlet Disproportion
Evaluation of inlet capacity in the final analysis is based only upon whether the patient is capable of causing the head to engage. In the presence therefore of efficient uterine contractions, an unengaged head, and an inlet which by roentgenogram is shown to be the only real obstacle to the passage of the head, one may merely wait to see whether engagement occurs as the labor progresses. However, before one may diagnose inlet disproportion with finality, the membranes must be ruptured, which should be done artificially at about 5 to 6 cm. dilatation, and the second stage must have progressed for at least one hour. Effective uterine contractions and good moulding of the head will often overcome high degrees of disproportion at this level. Frequently, however, the head which is held at a high level by narrowing at the plane of the inlet may fit poorly in the lower uterine segment, and consequently the uterine contractions may never become sufficiently strong to cause engagement. In this ease, many hours of ineffective uterine contractions may ensue, and one's clinical judgment may be taxed to the utmost. Here it is necessary to determine as carefully as possible, by x-ray examination, the precise shape and measurements of the inlet and to make a conclusion as to (a) whether it is likely that with effective pains a head of average size could traverse this inlet, and (b) the probability that effective contractions will occur. As a general rule, after five or six hours of observation it ·should be possible to make at
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least a preliminary judgment. If the contractions continue to be desultory after this length of time and if little or no advancement has occurred, the probability that the patient will develop an effective labor is extremely small, and one's thoughts should be directed toward consideration of cesarean section with the presumptive diagnosis of inlet disproportion and secondary uterine inertia. If, on the other hand, contractions become effective and the head begins advancement into the pelvis, one may safely wait to observe whether engagement will occur. If it does not after one hour of full dilatation with ruptured membranes, cesarean section should be done. Under no circumstances should forceps be applied to an unengaged head. The informed obstetrician has long since relegated to oblivion the operation of high forceps. The operation of internal podalic version has virtually no place in the management of inlet disproportion and indeed is but rarely performed in present day obstetrics. Mid-pelvic Arrest; Mid-pelvic Disproportion
In the conduct of labor in mid-pelvic contracture, it is extremely difficult to determine in advance whether the head can pass this plane with safety except in the most obvious cases of pelvic distortion at this level. Accordingly, the management of this circumstance requires that Nature be allowed to accomplish all that she safely can before intervention. A full second stage of labor with two hours of effective contractions and proper voluntary effort by the patient are necessary. Some of the most formidable mid-forceps deliveries could have been entirely avoided if another fifteen or twenty minutes had elapsed before intervention. Good voluntary effort by the patient is an essential part of the management of the second stage. This requires a patient who is not too deeply narcotized by analgesics, an obstetrical table with properly situated bars which the patient may pull upon for counter-traction, the proper administration of an analgesic mixture of nitrous oxide during the contractions and, of very great importance, thoughtful encouragement by the obstetrician himself. Intervention before two hours of an effective second stage have elapsed is only rarely necessary, and it is permissible only upon the most rigid maternal or fetal indication. When intervening on fetal indication, one should remember that the hazard of a mid-forceps extraction may far outweigh the danger of awaiting further descent and further moulding. The two hour rule referred to has been set arbitrarily because of danger after this time of the development of a contraction ring, or uterine rupture, which are complications of the first order. This refers, however, only to an effective, active second stage. If the contractions are inefficient, the second stage may; be allowed to progress for as long as four
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hours, although one would probably have elected before this time to administer a small dose of Pitocin, preferably ~4 minim and not to exceed ~~ minim, in an attempt to increase efficiency of the contractions. In considering the management of mid-pelvic arrest it is essential that the various mechanical factors outlined be given full consideration. One must determine as precisely as possible the planes of greatest narrowing both in the mid-pelvis and at the outlet, and, having determined these, must effect delivery in such a way that the biparietal diameter will be brought through them. This is true irrespective of the position of the head at the time arrest occurs. The following examples will illustrate this concept. Mid-pelvic Arrest, Occiput Anterior (OA) Position. In the great majority of such cases, delivery may be safely accomplished by the accurate application of classical forceps to the occiput anterior, and extraction in this position. Occasionally occiput anterior arrest may occur in the presence of normal pelvic features except for a forward lower sacrum; here the result is anteroposterior narrowing at the outlet, and the indication, if extraction cannot be readily effected in the occiput anterior, is for rotation to the transverse so that the biparietal may be brought through this narrow diameter. If, in addition to the forward lower sacrum, the ischial spines are prominent, thus giving rise to transverse narrowing, it is sometimes necessary to make gentle traction first to the occiput anterior, and second in the oblique and finally in the transverse in order to determine in which pelvic diameter advancement occurs most readily. Mid-pelvic Arrest, Occiput Posterior (OP) Position. Mid-pelvic arrest in the direct occiput posterior position occurs most generally in the anthropoid pelvis with wide posterior segment in the mid-plane, and some transverse narrowing by reason of convergent sidewalls or prominent spines. The latter pelvic feature prevents spontaneous rotation, and if the lower sacrum is forward, advancement in the occiput posterior is prevented. In this circumstance delivery may be accomplished only by elevation of the biparietal diameter above the level of the spines, and rotation to the direct anterior. The procedure for accomplishing rotation from the occiput posterior which most of the men on our service prefer is the manual rotation, which was described by W. C. Danforth. In this technic the right hand only is used, the fingers being widely spread. The head is grasped, elevated slightly and rotated to the anterior with a sweeping movement. Either an assistant or the operator's left hand moves the anterior shoulder across the lower abdomen (Figs. 7 and 8). My personal preference is for a technic of forceps rotation in which Tucker McLane forceps are applied directly to the occiput posterior. The head is elevated and rotated intermittently through short arcs, ultimately reaching the anterior position. The for-
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ceps are replaced with Simpson forceps, which are then used for delivery. The details of both these rotations have been presented elsewhere2 , 3 and need not be considered here. Suffice it to say that an essential to the proper execution of any rotation is deep anesthesia, preferably with ether. An easy rotation will be relatively easy under any type of anesthesia; but a difficult rotation may be rendered impossible if uterine relaxation is not adequate. For this reason, spinal anesthesia is considered to have no place in the routine management of occiput posterior. Mid-pelvic Arrest, Occiput Transverse (OT) Position. Transverse ar-
Fig. 7.
Fig. 8.
Fig. 7. Manual rotation. Head grasped by whole hand (right) and rotated to anterior position. The left hand (upper arrow) pushes the shoulder toward the woman's left, aiding the rotation. Fig. 8. Anterior rotation complete. Right hand maintains head in anterior position while left blade of forceps is applied. (Danforth, W. C., in American Journal of Obstetrics and Gynecology, Published by the C. V. Mosby Co.)
rest, due either to failure of the powers or to borderline disproportion, occurs most frequently in the following situations: ENROUTE TO AN OCCIPUT ANTERIOR POSITION FROM A PRIMARY TRANS-
In this case the anteroposterior diameters of the pelvis are generally about normal, the tendency to anterior rotation consisting in impingement of the occipitobregmatic diameter upon rather prominent spines. Here the head must rotate either anteriorly or posteriorly in order that the biparietal diameter may descend through the narrowed transverse diameter. Posterior rotation is impossible because of inadequacy of the posterior segment at this level. Anterior rotation should therefore occur. This is the mechanism which one should follow in delivering such patients by mid-forceps.
VERSE MECHANISM.
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ENROUTE TO AN OCCIPUT ANTERIOR POSITION FROM A PRIMARY POS-
The posterior mechanism in which artificial anterior rotation is necessary has been considered. If the spines are not prominent, which will allow the longer suboccipitobregmatic diameter to traverse this plane, spontaneous rotation to the occiput anterior will generally occur. Rotation, if it ceases, generally does so because of failure of the powers. In this case completion of the rotation to the occiput anterior is the mechanism which should be followed. TERIOR MECHANISM.
AS A PART OF A TRANSVERSE MECHANISM, IN WHICH ADVANCEMENT, IF IT COULD OCCUR, WOULD CONTINUE TO THE PELVIC FLOOR IN THE TRANS-
The pelvis in which this mechanism obtains is one with wide transverse diameters at all levels, and narrowed anteroposterior diameters, particularly with forward sacrum throughout. In this case the head descends in the direct occiput transverse without tendency to anterior rotation, so that the biparietal diameter may pass through the narrow pelvic diameters at all levels. Barton or Kielland forceps should be used, preferably the former, in order to effect advancement in the transverse position. Rotation here generally occurs only as the head is crowning. It is apparent that in such a pelvis, rotation to the anterior and traction in this position would bring the longer suboccipitopregmatic diameter through the narrow anteroposterior diameter of the pelvis. It is inescapable that traction to the occiput anterior in such a pelvis will inevitably give rise to cases of intracranial injury and separation of the symphysis which could have been avoided by proper attention to pelvic diameters. VERSE POSITION.
OTHER ABNORMAL PRESENTATIONS
Face
Face presentation is generally first suspected by irregularity of the presenting part. This should be confirmed by roentgenogram, which in addition to defining the attitude of the baby, will also provide important data concerning the pelvic features. In face presentation the optimum mechanism is determined precisely as outlined for occipital presentations, except that the chin tends to rotate to the widest diameters rather than the occiput. Thus, the same pelvic features which determine occipital mechanism are also responsible for face mechanism, and should be interpreted and managed in the same manner. The important exception to this rule is in the posterior mechanism. In occiput posterior, where the sacrum is situated far posteriorly, delivery as in occiput posterior may sometimes occur. This is extremely unusual in face presentation, and in the case of posterior chin, rotation to the mental anterior position is almost invariably necessary before delivery may occur. This rotation may sometimes be accomplished manually or by forceps, as outlined under the management of posterior. In selected
Conduct of Abnormal Labor cases, cesarean section is entirely permissible this complication.
139 III
the management of
Brow
In the presence of an average-sized baby, presentation by the brow is incompatible with advancement through the pelvis. Conversion to either an occipital presentation or to a face presentation must occur before the head can engage. Brow presentation is generally suspected first by the presence of an unengaged head, and irregularity of the presenting part. This should be confirmed by roentgenogram for reasons already outlined. It is particularly important here to make an early appraisal of pelvic capacity in an effort to determine the probability of disporportion. If the pelvis is considered to be adequate, one may in early labor attempt to effect conversion to face or occipital presentation by abdominal manipulation or by combined abdominal and vaginal manipulation. Failing this, and only if the labor is of average or less than average intensity, one may wait to see whether spontaneous conversion will occur. If this does not occur within a reasonably short period, and if attempts at artificial conversion fail, 'Or if the labor is a particularly violent one, cesarean section is indicated. In brow presentation which is neglected, the bizarre molding of the head which inevitably occurs may cause such distortion that, even though conversion may later be effected, vaginal delivery is no longer possiblp. Transverse Presentation
Transverse presentation is one of the most formidable complications encountered in obstetrics. The mere presence of such a presentation immediately imposes the hazard of a fetal mortality which has been estimated as high as 50 per cent, and a maternal mortality which in one report was of the order of 10 per cent. For this reason, when this presentation is established in early labor, it is entirely permissible to proceed immediately to delivery by cesarean section. There is but one circumstance under which one might elect to deliver vaginally. This is in the multipara who has previously delivered large babies vaginally, who falls into labor prematurely with a relatively small baby. Even in this case, one must not be deluded into believing that he is dealing with anything but a complication of the first order of magnitude. If one elects to deliver from below, the following course should be adopted: The patient should be placed upon the delivery table, prepared, and draped, with an anesthetist at hand. The obstetrician should be scrubbed, and should note the cervical dilatation from time to time. When the cervix becomes sufficiently dilated that the hand can be introduced into the uterus, the patient should be anesthetized deeply.
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The membranes should now be ruptured and internal podalic version performed, bringing down both legs. No attempt at delivery may be made at this time. Rather, the patient should be allowed to recover from anesthesia and the labor should be allowed to progress normally thereafter. Delivery should be effected only at the completion of cervical dilatation. If the membranes rupture spontaneously during the period of observation, the patient should be placed in the Trendelenburg posture to minimize the possibility of cord prolapse, and anesthetized deeply. If uterine relaxation can be obtained, and version performed at this time, it should be done, bringing down one or both feet into the vagina. If version is not feasible, one should proceed immediately to cesarean section. REFERENCES 1. Danforth, D. N.: Quart. Bull. Northwestern Univ. M. School 22: 223,1948. 2. Danforth, W. C.: Am. J. Obst. & Gynec. 23: 360, 1932. 3. Danforth, D. N.: Am. J. Obst. & Gynec. To be published.
THE term "abnormal labor" is used to describe any labor which deviates significantly from the normal. It is evident that this is an inclusive term, and for purposes of discussion it is necessary to consider only certain of the more important abnormalities of labor. Of the lesser deviations, many are so slight that they will be unrecognized, and Nature will care for them skillfully if left to her own devices. In the major abnormalities it is essential that the obstetrician recognize them promptly, have full understanding of their possibilities, and deal with them skillfully when it is indicated. At the outset it should be mentioned that most obstetrical catastrophes result directly from intervention rather than from the lack of it. So-called aid, however skillfully performed, is inevitably worse than none at all if it is ill-timed. Bumm has said, "They are poor obstetricians who cannot await the safe processes of nature." So it is in the conduct of abnormal labor. One's effort must be first to understand thoroughly the details of the problem which is presented, and second, to avoid operative intervention unless it is specifically and clearly indicated. So long as there is any question as to whether intervention is indicated, it is best deferred until positive and unequivocal indication arises. There are three important ways in which labor may be abnormal. First, the powers, or uterine forces, may function in an abnormal manner; second, the baby may present by an abnormal or unfavorable attitude; and third, the birth canal itself may provide impediment to the passage of the baby. The second and third possibilities are interrelated. ABNORMALIty OF THE UTERINE FORCES
Under normal or favorable circumstances the uterine contractions of labor have one fundamental characteristic, namely, coordination. In From the Department of Obst~trics and Gynecology , Northwestern University M edical School, Chicago, and the Evanston Hospital, Evanston, Illinois.
* Associate Professor of Obstetrics and Gynecology, Northwestern University Medical School; Chairman, Department of Obstetrics and Gynecology, Evanston Hospital. 125
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an effective labor the contractions begin simultaneously in the uterine cornua and spread evenly over the uterus, ultimately involving the entire organ. They occur at regular, gradually diminishing intervals; they are of even, gradually increasing intensity, and are of regular, gradually increasing duration. Such contractions cause progressive dilatation of the cervix. Certain requisites are necessary in order that this highly coordinated activity may occur. First, the uterine muscle must be in this nebulous state of affairs referred to as proper nutrition. It is well known that a high proportion of prolonged labors occurs among patients whose prenatal care has been indifferent. Excessive weight gain, improper diet, and inadequate rest during pregnancy may predispose to this complication. Second, the uterine muscle must not be overstretched. Hydramnios and multiple pregnancy may predispose if uterine growth is not commensurate with the increase in bulk of the conceptus. Third, an efficient labor requires that the lower pole of the uterus be properly and evenly stimulated by the presenting part, or by an intact bag of waters. The anterior and transverse mechanisms of the occiput, with full flexion, appear to provide optimal fitting of the head to the lower pole of the uterus, while generally poor fitting occurs in the occiput posterior mechanism. In the latter case, desultory, protracted labors are common. A stellar example of improper fitting occurs when the axis of drive is not directly into the inlet, as in the pelvis which is inclined far posteriorly and the head directed against the symphysis, or when the uterus lies on one side or the other of the abdomen, perhaps being held in this position by a distended stomach or colon. A case is recorded in the literature of an air swallower who achieved enormous distention of the stomach periodically during labor. Contractions virtually ceased when the stomach became distended, to resume instantly upon release of the gas by stomach tube. The inertia was attributed to reflex inhibition by the gastric distention, but I suspect the more likely explanation to be interference with proper axis of drive by pressure upon one side of the uterus, with consequent improper fitting of the head to the lower pole of the uterus. Under such circumstances stimulation of the nerve endings in the lower uterine segment is uneven, and inefficient contractions are the result. Uterine Inertia
As for terminology, the purist suggests that one may diagnose uterine inertia only after the cervix has shown no further dilatation for eight hours in the first stage, or if in the second stage there has been no progress for two hours, and in both instances the uterus is easily indentable at the height of a contraction. These criteria are useful in precluding abuse of the term "uterine inertia" as justification for unwarranted operative
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intervention. They are less helpful in the practical management of this complication, for one's evaluation of the problem must begin long before such an inordinate length of time has passed. An eminent obstetrician of unusual skill, and virtually flawless obstetrical judgment, was once asked whether he was disturbed about a patient whose labor was inefficient. Said he, "I am always disturbed about any patient whose labor is in any way abnormal." One's observation of the parturient should be sufficiently close that deviations from the normal may be noted as they occur. It is thus apparent that uterine inertia, in its various degrees and in the different stages of labor, should be regarded as a sign and not a diagnosis. It is an indication of an underlying and often correctable defect. Evaluation of this problem should lead to an attempt to determine the defect which causes the inefficiency, and to correct it if possible. Failing this, the effort must be made to keep the patient in the best possible general condition, to apply such measures of gentle stimulation as may be consistent with safety, and, above all, to inflict no damage. MANAGEMENT OF DESULTORY LABOR FIRST STAGE
During the beginning of the first stage of labor, inefficient contractions cause no concern, for they will inevitably improve. Two circumstances particularly which predispose to a slow start, as it were, are a head which is extremely low at the onset of labor, and a cervix which is far posterior. Under these circumstances the patient must be prepared for the several hours of desultory contractions which invariably precede active labor. Stimulation must be avoided. Ambulation should be avoided, except for the patient's comfort and peace of mind; it is a dismal sight to see a patient and her husband trudging up and down the corridor in an effort to precipitate a labor which would probably start if she were to lie down. With the head already deeply engaged and the cervix far back, the upright position tends to exaggerate this defect. In the absence of factors in the first stage of labor which can be easily corrected, one is then left with certain important general principles which should be employed in the conduct of desultory, ineffective labor. Rest Periods
Although the efficiency of uterine contractions during the first stage of labor may be poor, nevertheless they are painful and, if allowed to continue indefinitely, extremely tiring to the patient. For this reason the use of morphine or Pantopon in full dose (morphine X grain or Pantopon 7~ grain) at intervals of six or eight hours may have an extremely salutary effect. With this dose the patient will obtain from one
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and one-half to three hours of sleep. She generally awakens refreshed, and in addition the uterine contractions, formerly inefficient and poorly coordinated, are often found to resume in an efficient and coordinated manner. Irrespective of the length of the first stage of a desultory labor, the timely use of opiates in full dose is considered essential. Hydration It is well known that the emptying of the stomach is greatly delayed during labor. For this reason, and also in anticipation of the possible need for general anesthesia at any time, it is unwise to require patients to take adequate amounts of fluid by mouth. Particular attention must be paid, however, to fluid balance, which is of particular importance in prolonged labor. It should be a standing rule in any maternity that the urine should be examined for acetone and diacetic acid after the first twelve hours of labor, and at four hour intervals thereafter. If these tests are positive at any time, an infusion of 5 or 10 per cent dextrose in water should be started immediately. Depending on the state of affairs, either 1000 or 1500 cc. of this fluid should be administered, and should be repeated if it is indicated by the later reappearance of acetone or diacetic acid in the urine. Ambulation It has already been mentioned that ambulation is not desirable if the head is deeply engaged in the pelvis and the cervix is situated far posteriorly. In other cases, however, it is considered desirable, especially between rest periods, for two reasons. First, a change of scene may have a beneficial psychological effect, and may tend to minimize the anxiety of the patient and her family. Second, the upright position may improve the fitting of the head to the lower pole of the uterus and consequently enhance the efficiency of the contractions. It is emphasized that an exhausted patient should not be forced to tramp the halls, for this achieves little or nothing. Rather, she should be advised that she may get up and walk about a little if she wishes, and may go out and visit with her family. She should be asked to return to bed if she becomes fatigued, or contractions are troublesome. Stimulation
Enemas. The commonest form of stimulation used in obstetrics is the soapsuds enema. Its effectiveness in desultory labor should not be overlooked, and it is permissible to give a hot soapsuds enema at intervals of twelve or fourteen hours, so timed that they will coincide with the end of a rest period.
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Castor Oil. Castor oil has no place in the management of uterine inertia. Quinine. The efficacy of quinine as a stimulant to uterine contractions is questionable. The occasional report of congenital deafness following its use should outlaw this drug from obstetrics. Calcium. It has been shown both clinically and experimentally that calcium may be an effective stimulant to uterine contractions, and that in the relative absence of calcium ions uterine contractions are inefficient. For the induction of labor, we have abandoned the use of castor oil in favor of 10 cc. of calcium gluconate intravenously, and find also that the use of this drug at intervals of four to six hours may be helpful in the management of desultory labor. Ergot. Derivatives of ergot have been suggested and occasionally used in the management of uterine inertia. However, they are used but rarely for this purpose, and are not recommended for the reasons that the uterine response is relatively slow, that their effects are unpredictable and difficult to follow, and that their action is too sustained. Pituitrin. Only obstetrical Pituitrin (Pitocin) should be used for obstetrical patients. It is only rarely required in the management of desultory protracted labor. Pitocin should be given only after the cervix has reached 5 cm. dilatation and the head is fully engaged without evidence of disproportion. Also, the membranes should preferably have been ruptured, since this simple measure may make the use of Pituitrin unnecessary. Finally, the case should be one of actual uterine inertia as previously defined, in which there has been failure of progress for eight hours, and a uterus which may be easily indented at the height of a contraction. The first dose of Pitocin should not exceed 0.5 minim, for even with this small dose the uterus may react in the most violent manner. For this reason the patient must be carefully observed, and ether should be at hand so that it may be given immediately in the case of a tetanic contraction of the uterus. If within thirty minutes of this dose no effect has been observed, or if only a few desultory contractions have occurred, one may then give a dose of 1 minim of Pitocin. Two subsequent doses of 1 minim only may be given thereafter at thirty minute intervals as may be required. But this dose should not under any circumstances be exceeded in an undelivered patient. If these small doses are not effective, larger doses will in all probability be ineffective. Also, they may be extremely dangerous. Some obstetricians prefer the use of a Pitocin infusion, the· fluid being prepared by injecting 5 minims of Pitocin into 500 cc. of 5 per cent glucose solution. This may be so adjusted that 0.5 minim of Pitocin, equivalent to 50 cc. of the solution, may be run in over the course of thirty minutes. This is said to have the advantage of more intimate control of the reaction, and more sustained effect.
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Operative Intervention
Stripping of the Membranes. It is well known that stripping the membranes from the cervix and lower pole of the uterus by the finger, under sterile precautions, may have a salutary effect upon uterine contractions. This procedure therefore has some usefulness in the labor which has proceeded for six or eight hours, and in which cervical dilatation does not exceed 3 cm. If the cervix is more than 3 cm. dilated, it is considered preferable to rupture the membranes. Rupture of the Membranes. In desultory labor it is desirable to rupture the membranes artificially when the dilatation reaches 3 or 4 cm. and progress is delayed. When this is done, and amniotic fluid is allowed to escape from the uterus, the readjustment of the head to the lower pole of the uterus may allow more even fitting and improve the quality of the contractions. It is our common practice to rupture membranes with the DeLee perforator after preparation of the vulva, guiding the perforator by a finger in the rectum. In desultory inefficient labor this practice is undesirable. The vaginal fingers, in addition to guiding the perforator, may strip the membranes for a short distance and so stimulate the cervix with salutary effect. Surgical Procedures. During the first stage of labor operative procedures must not be undertaken except upon the appearance of absolute fetal or maternal indication. Procedures which are permissible during the first stage are limited, since the carrying out of intrauterine manipulations through an undilated cervix is not to be sanctioned. Efforts at this time therefore are directed only toward the achievement of full dilatation and may be undertaken only if the condition of the patient or the baby definitely demands them. MANUAL DILATATION. Manual dilatation of the cervix at 4 or 5 cm. is mentioned without enthusiasm. The lacerations which inevitably result are extremely difficult to repair properly, and serious hemorrhage may occur before delivery can be effected. This is a mutilating procedure which is best avoided. The only place manual dilatation of the cervix has in modern obstetrics is in the pushing back of a rim of cervix over the head. This should be necessary only rarely; when it is done, cervical lacerations are the rule. The cervix should always be inspected after delivery, and any lacerations which are 3 cm. long or more must be repaired. DUHRSSE~'S INCISIONS. These are an acceptable means of achieving dilatation of the cervix, but are ever so exceptionally required. Such incisions should be made with a bandage scissors, and they should be placed at lO o'clock and 1 o'clock, and occasionally also at 6 o'clock. They should be made only when the head is deeply engaged, and when the cervix itself offers the only obstacle to delivery. General anesthesia should be sufficiently deep that the incisions will not be extended by the
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patient's voluntary efforts. Even with this precaution, high upward extensions may occur; when contemplating cervical incision, one should be prepared for this contingency. VOORHEES BAG (METREURYNTER). This has no place whatever in modern obstetrics. CESAREAN SECTION. This is very exceptionally indicated in the management of uterine inertia per se. Cesarean section, when it is done in this condition, is generally indicated, not by the inertia, but rather by the condition giving rise to the inertia, as, for example, malposition of the baby or inlet disproportion. SECOND STAGE Delay in the second stage of labor may be due to failure of cooperation by the patient resulting from anxiety, excessive pain or excessive analgesia; to inefficiency of the contractions; or to pelvic arrest. One's course in the first instance is clear. In the second case the judicious use of Pitocin, after the method previously indicated, may be attempted after two hours without progress have elapsed. One should remember, however, that after two hours of efficient contractions in the second stage of labor, the labor should be terminated because of the danger of contraction ring or uterine rupture. It is only in the desultory second stage that one may disregard this two hour rule. The third possibility is considered in the following section. CEPHALOPELVIC DISPROPORTION
In the presence of adequate uterine contractions, the pelvis itself may offer resistance to the passage of the baby. This resistance may be either absolute, as in absolute cephalopelvic disproportion, or relative, due chiefly to the assumption by the baby of an attitude or position which is unfavorable for that particular pelvis. The effective evaluation and management of either absolute or relative disproportion requires an intimate knowledge of the ordinary pelvic variations and their influence upon the mechanism of labor. For this reason, it is pertinent to this subject to discuss briefly (a) the important pelvic variations which are of obstetrical significance, and (b) the influence of these individual features upon the mechanism of labor. With this information it is possible to determine with reasonable accuracy the manner in which the labor should be conducted and the method of delivery which should be used. PELVIC VARIATIONS The important pelvic variations, as defined by Caldwell and Moloy, can be summarized (Table 1).
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It is extremely unusual to find a pelvis which conforms in every detail to one of the pure types. Most pelves are mixed types which show, not only combinations of these various features, but also considerable variation in size. Although it is generally possible to obtain a good estimate of pelvic type and size by palpation, there are certain circumstances under which x-ray pelviography should be made. These include the following: (1) primipara with unengaged head at term; (2) primipara with prominent spines or forward lower sacrum by palpation; (3) multipara with history of difficult labor or delivery in previous pregnancy; (4) primiparous breech; (5) irregular presenting part; (6) serious heart disease or other debilitating systemic illness. Table 1 PELVIC VARIATIONS
a
.,...
i!i
. ., ...
.::FORE PELVIS
SIDEWALLS
ISCHIAL SPINES'
SACROSIATIC NOTCH
INCLINATION OF SACRUM
. ...., P
.
SUBPUBIC ARCH
0 0
0
BONE STBUCTUBE
Z
~
---
Gynecoid. Fig. Wide 3
(cm.)
ai
iii
II!
....
DIAG. CONJ.
---
Straight
Not prom- Medium inent
Medium
Wide
-
10
-- --12.5 Delicate or medium 12.5 Heavy
Android .. Fig. Narrow Converg- Prominent Narrow Forward Narrow <10 gent 4 Anthropoid .... Fig. Wide Divergent Not prom- Wide Backward Wide 10 >12.5 Medium inent 5 Flat ...... Fig. Wide Straight Not prom- Medium Forward Wide 10 <12 or narMedium inent 6 row
Many technics for x-ray visualization of the pelvis have been described. The technic which in our hands gives the greatest amount of information and is technically simplest consists of three films: (1) Standing lateral taken at 36 inches. A 10 cm. rod is placed between the buttocks. This may be directly interpolated to give the anteroposterior diameter of the inlet. (2) A Thoms inlet view. (3) A subpubic arch film. The details of these films and their interpretation are considered in detail in the author's article dealing with this subject.l Predictions concerning the proper mechanism of labor for any given pelvis are based upon two dicta which are regarded as axiomatic. These are the following: (a) The biparietal diameter of the fetal head is the shortest diameter, and must therefore go through the narrowest diameter of the pelvis at any given level. (b) The occiput generally tends to rotate to the widest portion of the pelvis at any given level.
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With precise knowledge of the various features of-a given pelvis and with the aid of these two dicta it should be possible to predict with accuracy the mechanism which should obtain if all the available space is used: Inlet. From the foregoing, it is evident that in a flat pelvis, with anteroposterior narrowing, engagement will occur in the transverse position. In the anthropoid pelvis which is long anteroposteriorly, engagement Fig. 3.
Fig. 4.
Fig. 5.
Fig. 6.
Fig. 3. Typical gynecoid pelvis: inlet view. Fig. 4. Typical android pelvis; inlet view. Fig. 5. Typical anthropoid pelvis; inlet view. Fig. 6. Typical platypelloid (flat) pelvis; inlet view. (Moloy, H. C., Clinical and Roentgenologic Evaluation of the Pelvis in Obstetrics, W. B. Saunders Co.)
will occur with the sagittal suture in the sagittal plane of the pelvis. Since, however, in the anthropoid pelvis the forepelvis is narrow, the occiput will tend to rotate away from this narrowed area into the ample posterior segment, and engagement occurs in the direct occiput posterior. This mechanism is typified by the monkey and anthropoid ape, of which the anthropoid pelvis is characteristic, and in which the posterior mechanism is the rule. At the level of the mid-pelvis the features which determine mechanism are (1) the prominence of the spines, which determines the presence or
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absence of transverse narrowing in the mid-pelvis; (2) the position of the sacrum, whether forward or backward or in the normal middle position, which determines the presence or absence of anteroposterior narrowing in the mid-pelvis; and (3) the foreplevis, which plays a role in midpelvic mechanism by influencing the space available in the anteroposterior diameter. Thus, with prominent spines and a sacrum which is situated posteriorly, one would expect the head to descend with the sagittal suture in the sagittal plane of the pelvis. Conversely, with forward sacrum and spines which are not prominent, one would expect the head to traverse this plane in the transverse position. At the plane of the outlet, the transverse capacity is determined by the transverse of the outlet, or bi-ischial diameter, and the anteroposterior capacity by the width of the subpubic arch and the position of the sacrococcygeal articulation. Thus, when the transverse of the outlet is narrowed, and the sacrococcygeal articulation far posterior, the head should traverse this diameter with the sagittal suture in the sagittal plane of the pelvis. Conversely, when the lower sacrum is forward and the transverse of the outlet wide, the head should traverse this diameter in the transverse or oblique position. Inlet Arrest or Inlet Disproportion
Evaluation of inlet capacity in the final analysis is based only upon whether the patient is capable of causing the head to engage. In the presence therefore of efficient uterine contractions, an unengaged head, and an inlet which by roentgenogram is shown to be the only real obstacle to the passage of the head, one may merely wait to see whether engagement occurs as the labor progresses. However, before one may diagnose inlet disproportion with finality, the membranes must be ruptured, which should be done artificially at about 5 to 6 cm. dilatation, and the second stage must have progressed for at least one hour. Effective uterine contractions and good moulding of the head will often overcome high degrees of disproportion at this level. Frequently, however, the head which is held at a high level by narrowing at the plane of the inlet may fit poorly in the lower uterine segment, and consequently the uterine contractions may never become sufficiently strong to cause engagement. In this ease, many hours of ineffective uterine contractions may ensue, and one's clinical judgment may be taxed to the utmost. Here it is necessary to determine as carefully as possible, by x-ray examination, the precise shape and measurements of the inlet and to make a conclusion as to (a) whether it is likely that with effective pains a head of average size could traverse this inlet, and (b) the probability that effective contractions will occur. As a general rule, after five or six hours of observation it ·should be possible to make at
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least a preliminary judgment. If the contractions continue to be desultory after this length of time and if little or no advancement has occurred, the probability that the patient will develop an effective labor is extremely small, and one's thoughts should be directed toward consideration of cesarean section with the presumptive diagnosis of inlet disproportion and secondary uterine inertia. If, on the other hand, contractions become effective and the head begins advancement into the pelvis, one may safely wait to observe whether engagement will occur. If it does not after one hour of full dilatation with ruptured membranes, cesarean section should be done. Under no circumstances should forceps be applied to an unengaged head. The informed obstetrician has long since relegated to oblivion the operation of high forceps. The operation of internal podalic version has virtually no place in the management of inlet disproportion and indeed is but rarely performed in present day obstetrics. Mid-pelvic Arrest; Mid-pelvic Disproportion
In the conduct of labor in mid-pelvic contracture, it is extremely difficult to determine in advance whether the head can pass this plane with safety except in the most obvious cases of pelvic distortion at this level. Accordingly, the management of this circumstance requires that Nature be allowed to accomplish all that she safely can before intervention. A full second stage of labor with two hours of effective contractions and proper voluntary effort by the patient are necessary. Some of the most formidable mid-forceps deliveries could have been entirely avoided if another fifteen or twenty minutes had elapsed before intervention. Good voluntary effort by the patient is an essential part of the management of the second stage. This requires a patient who is not too deeply narcotized by analgesics, an obstetrical table with properly situated bars which the patient may pull upon for counter-traction, the proper administration of an analgesic mixture of nitrous oxide during the contractions and, of very great importance, thoughtful encouragement by the obstetrician himself. Intervention before two hours of an effective second stage have elapsed is only rarely necessary, and it is permissible only upon the most rigid maternal or fetal indication. When intervening on fetal indication, one should remember that the hazard of a mid-forceps extraction may far outweigh the danger of awaiting further descent and further moulding. The two hour rule referred to has been set arbitrarily because of danger after this time of the development of a contraction ring, or uterine rupture, which are complications of the first order. This refers, however, only to an effective, active second stage. If the contractions are inefficient, the second stage may; be allowed to progress for as long as four
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hours, although one would probably have elected before this time to administer a small dose of Pitocin, preferably ~4 minim and not to exceed ~~ minim, in an attempt to increase efficiency of the contractions. In considering the management of mid-pelvic arrest it is essential that the various mechanical factors outlined be given full consideration. One must determine as precisely as possible the planes of greatest narrowing both in the mid-pelvis and at the outlet, and, having determined these, must effect delivery in such a way that the biparietal diameter will be brought through them. This is true irrespective of the position of the head at the time arrest occurs. The following examples will illustrate this concept. Mid-pelvic Arrest, Occiput Anterior (OA) Position. In the great majority of such cases, delivery may be safely accomplished by the accurate application of classical forceps to the occiput anterior, and extraction in this position. Occasionally occiput anterior arrest may occur in the presence of normal pelvic features except for a forward lower sacrum; here the result is anteroposterior narrowing at the outlet, and the indication, if extraction cannot be readily effected in the occiput anterior, is for rotation to the transverse so that the biparietal may be brought through this narrow diameter. If, in addition to the forward lower sacrum, the ischial spines are prominent, thus giving rise to transverse narrowing, it is sometimes necessary to make gentle traction first to the occiput anterior, and second in the oblique and finally in the transverse in order to determine in which pelvic diameter advancement occurs most readily. Mid-pelvic Arrest, Occiput Posterior (OP) Position. Mid-pelvic arrest in the direct occiput posterior position occurs most generally in the anthropoid pelvis with wide posterior segment in the mid-plane, and some transverse narrowing by reason of convergent sidewalls or prominent spines. The latter pelvic feature prevents spontaneous rotation, and if the lower sacrum is forward, advancement in the occiput posterior is prevented. In this circumstance delivery may be accomplished only by elevation of the biparietal diameter above the level of the spines, and rotation to the direct anterior. The procedure for accomplishing rotation from the occiput posterior which most of the men on our service prefer is the manual rotation, which was described by W. C. Danforth. In this technic the right hand only is used, the fingers being widely spread. The head is grasped, elevated slightly and rotated to the anterior with a sweeping movement. Either an assistant or the operator's left hand moves the anterior shoulder across the lower abdomen (Figs. 7 and 8). My personal preference is for a technic of forceps rotation in which Tucker McLane forceps are applied directly to the occiput posterior. The head is elevated and rotated intermittently through short arcs, ultimately reaching the anterior position. The for-
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Conduct of Abnormal Labor
ceps are replaced with Simpson forceps, which are then used for delivery. The details of both these rotations have been presented elsewhere2 , 3 and need not be considered here. Suffice it to say that an essential to the proper execution of any rotation is deep anesthesia, preferably with ether. An easy rotation will be relatively easy under any type of anesthesia; but a difficult rotation may be rendered impossible if uterine relaxation is not adequate. For this reason, spinal anesthesia is considered to have no place in the routine management of occiput posterior. Mid-pelvic Arrest, Occiput Transverse (OT) Position. Transverse ar-
Fig. 7.
Fig. 8.
Fig. 7. Manual rotation. Head grasped by whole hand (right) and rotated to anterior position. The left hand (upper arrow) pushes the shoulder toward the woman's left, aiding the rotation. Fig. 8. Anterior rotation complete. Right hand maintains head in anterior position while left blade of forceps is applied. (Danforth, W. C., in American Journal of Obstetrics and Gynecology, Published by the C. V. Mosby Co.)
rest, due either to failure of the powers or to borderline disproportion, occurs most frequently in the following situations: ENROUTE TO AN OCCIPUT ANTERIOR POSITION FROM A PRIMARY TRANS-
In this case the anteroposterior diameters of the pelvis are generally about normal, the tendency to anterior rotation consisting in impingement of the occipitobregmatic diameter upon rather prominent spines. Here the head must rotate either anteriorly or posteriorly in order that the biparietal diameter may descend through the narrowed transverse diameter. Posterior rotation is impossible because of inadequacy of the posterior segment at this level. Anterior rotation should therefore occur. This is the mechanism which one should follow in delivering such patients by mid-forceps.
VERSE MECHANISM.
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138
ENROUTE TO AN OCCIPUT ANTERIOR POSITION FROM A PRIMARY POS-
The posterior mechanism in which artificial anterior rotation is necessary has been considered. If the spines are not prominent, which will allow the longer suboccipitobregmatic diameter to traverse this plane, spontaneous rotation to the occiput anterior will generally occur. Rotation, if it ceases, generally does so because of failure of the powers. In this case completion of the rotation to the occiput anterior is the mechanism which should be followed. TERIOR MECHANISM.
AS A PART OF A TRANSVERSE MECHANISM, IN WHICH ADVANCEMENT, IF IT COULD OCCUR, WOULD CONTINUE TO THE PELVIC FLOOR IN THE TRANS-
The pelvis in which this mechanism obtains is one with wide transverse diameters at all levels, and narrowed anteroposterior diameters, particularly with forward sacrum throughout. In this case the head descends in the direct occiput transverse without tendency to anterior rotation, so that the biparietal diameter may pass through the narrow pelvic diameters at all levels. Barton or Kielland forceps should be used, preferably the former, in order to effect advancement in the transverse position. Rotation here generally occurs only as the head is crowning. It is apparent that in such a pelvis, rotation to the anterior and traction in this position would bring the longer suboccipitopregmatic diameter through the narrow anteroposterior diameter of the pelvis. It is inescapable that traction to the occiput anterior in such a pelvis will inevitably give rise to cases of intracranial injury and separation of the symphysis which could have been avoided by proper attention to pelvic diameters. VERSE POSITION.
OTHER ABNORMAL PRESENTATIONS
Face
Face presentation is generally first suspected by irregularity of the presenting part. This should be confirmed by roentgenogram, which in addition to defining the attitude of the baby, will also provide important data concerning the pelvic features. In face presentation the optimum mechanism is determined precisely as outlined for occipital presentations, except that the chin tends to rotate to the widest diameters rather than the occiput. Thus, the same pelvic features which determine occipital mechanism are also responsible for face mechanism, and should be interpreted and managed in the same manner. The important exception to this rule is in the posterior mechanism. In occiput posterior, where the sacrum is situated far posteriorly, delivery as in occiput posterior may sometimes occur. This is extremely unusual in face presentation, and in the case of posterior chin, rotation to the mental anterior position is almost invariably necessary before delivery may occur. This rotation may sometimes be accomplished manually or by forceps, as outlined under the management of posterior. In selected
Conduct of Abnormal Labor cases, cesarean section is entirely permissible this complication.
139 III
the management of
Brow
In the presence of an average-sized baby, presentation by the brow is incompatible with advancement through the pelvis. Conversion to either an occipital presentation or to a face presentation must occur before the head can engage. Brow presentation is generally suspected first by the presence of an unengaged head, and irregularity of the presenting part. This should be confirmed by roentgenogram for reasons already outlined. It is particularly important here to make an early appraisal of pelvic capacity in an effort to determine the probability of disporportion. If the pelvis is considered to be adequate, one may in early labor attempt to effect conversion to face or occipital presentation by abdominal manipulation or by combined abdominal and vaginal manipulation. Failing this, and only if the labor is of average or less than average intensity, one may wait to see whether spontaneous conversion will occur. If this does not occur within a reasonably short period, and if attempts at artificial conversion fail, 'Or if the labor is a particularly violent one, cesarean section is indicated. In brow presentation which is neglected, the bizarre molding of the head which inevitably occurs may cause such distortion that, even though conversion may later be effected, vaginal delivery is no longer possiblp. Transverse Presentation
Transverse presentation is one of the most formidable complications encountered in obstetrics. The mere presence of such a presentation immediately imposes the hazard of a fetal mortality which has been estimated as high as 50 per cent, and a maternal mortality which in one report was of the order of 10 per cent. For this reason, when this presentation is established in early labor, it is entirely permissible to proceed immediately to delivery by cesarean section. There is but one circumstance under which one might elect to deliver vaginally. This is in the multipara who has previously delivered large babies vaginally, who falls into labor prematurely with a relatively small baby. Even in this case, one must not be deluded into believing that he is dealing with anything but a complication of the first order of magnitude. If one elects to deliver from below, the following course should be adopted: The patient should be placed upon the delivery table, prepared, and draped, with an anesthetist at hand. The obstetrician should be scrubbed, and should note the cervical dilatation from time to time. When the cervix becomes sufficiently dilated that the hand can be introduced into the uterus, the patient should be anesthetized deeply.
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The membranes should now be ruptured and internal podalic version performed, bringing down both legs. No attempt at delivery may be made at this time. Rather, the patient should be allowed to recover from anesthesia and the labor should be allowed to progress normally thereafter. Delivery should be effected only at the completion of cervical dilatation. If the membranes rupture spontaneously during the period of observation, the patient should be placed in the Trendelenburg posture to minimize the possibility of cord prolapse, and anesthetized deeply. If uterine relaxation can be obtained, and version performed at this time, it should be done, bringing down one or both feet into the vagina. If version is not feasible, one should proceed immediately to cesarean section. REFERENCES 1. Danforth, D. N.: Quart. Bull. Northwestern Univ. M. School 22: 223,1948. 2. Danforth, W. C.: Am. J. Obst. & Gynec. 23: 360, 1932. 3. Danforth, D. N.: Am. J. Obst. & Gynec. To be published.