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First stage of labor recorded by cervical tocometry
First stage of labor recorded by cervical tocometry H. SIENER, Frankfurt
on
M.D. Main,
Germany
years, and in 1960-61 with Vossius and in cooperation with the Company Hartmann & Braun of Frankfurt on Main, was developed to its present state.l**, 21, 26
D u R I N G the first stage of labor, increasing dilatation of the cervix is the only reliable indicator of the progress of parturition. Until a few years ago, the only methods to determine the width of the external OS of the cervix were digital examination by the vagina1 or rectal route and vaginal speculum examination. There were no facilities for visualizing the dilatation and actual width of the OS continuously and there was no possibility for recording the course of the labor. Years ago some attempts were made to visualize the dilatation of the cervix during labor. In 1951, for example, WolfZ7 reported on trials to record the size of the margins of the external OS by applying small induction coils to them, but these apparently failed. Attempts by Smyth22 in 1954 were also not very successful. He tried to record the dilatation of the OS with a forceps-shaped instrument containing a strain gauge. In 1956, Friedman5 reported on an instrument which ahowed the width of the OS to be read from a scale. Independent of Friedman, I described in the same year a method by which the dilatation movements of the external cervical OS could be continually transmitted to a recording apparatus.” This method, which we refer to as Cervixwehenmessung (cervical tocometry) , was improved in the course of the following
Method Two suitably shaped clamps (modified intestinal clamps) were attached to the external OS of the cervix (Figs. 1A and IB) . For this procedure, the patient is placed in lithotomy position. The OS is exposed by plate specula and a clamp is fastened on each side (at 9 and 3 o’clock) to the internal margin of the cervical lips. The woman then returns into a normal supine position, straddling her legs somewhat. The receptor part of the instrument is slid onto the outer ends of the clamps protruding from the vaginal entrance (Fig. 1B). The receptor part is equipped with a potentiometer which with every change in the size of the OS is accordingly moved through the clamps. The resulting changes in the electrical tension of the potentiometer are transmitted to a normal continuous line recorder. The recording instrument contains several amplifier stages which allow the dilatation of the OS to be recorded in the ratios 1:1, 1:2, or 1:4. It was also of great interest during investigations to observe the relationship between uterine contractility and dilatation of the cervix. Measurements of cervical dilatation were therefore always combined with external tocography. The recently used tocograph is shown in Fig. 1C. It, too, contains
From the Department of Obstetrics and Gynecology of the University of Frankfurt. 303
304
Siener
a potentiometer and thus is based on the same principle as the cervical tocometrr. A probing “finger” projecting from the basal plate contacts the uterus through the intact abdominal wall. Its excursions are transmitted through the potentiometer to the recording apparatus. In view of its potentiometer component, this external tocograph can be considered a further development of the instruments mentioned by Rechl” in 1934 and by Siener and Vossius” in 1960. With this method ! Fig. 1D) studies were made during all stages of labor in 80 women (primiparas and srcundiparas) Roth the physiologic behavior of the cervix and that of several drugs (oxytocics, analgesics, and antispasmodics) in their effects on cervical dilatation were observed. Results
The combined external tocography and cervical tocometry proved to be a valuable method for observing the effect of each uterine contraction on the cervix and for observing the relationship over a prolonged period between uterine contractility pattern and cervical opening. It allows normal labor and abnormalities to be studied and the effect of drugs to be visualized. The knowledge of the uterine contractility and the dilatation of the cervix during the first stage
Fig. able
1A. Cervical handles.
recording:
clamps
with
detach-
Fig. IB. Clamps in situ. thr receptor the potentiometer resentation)
slid
on
p;trr (semidiagrammatic
c,,\rryirq rep-
of labor allows an exact control of this important period of parturition. Some of our observations are described below : 1. During the first stage of labor. every contraction of the corpus uteri reaching a certain strength causes a dilatation of the external OS. When the contraction subsides, the OS returns completely or partly to its previous size. In none of our cases could a uniform linear dilatation of the OS be observed; this is in contrast to the findings of Langreder’ who described it for primiparas as the “cervical opening type.” 2. As a rule, the force of corpus contraction and the degree of corresponding OS dilatation are in a definite qualitative relationship. The stronger a body contraction, the wider it dilates the cervix. 3. As labor progresses, the effect of the corpus contractions on the cervical dilatation increases. Of two equally strong contractions, that one acting on the OS in a more
Volume Number
86 3
Cervical
dilated state is more effective. The same strength of contraction produces a considerably greater dilatation of the cervix when this is already dilated to 7 cm. than when it is dilated to only 3 cm. Vice versa, a comparatively weak contraction incapable of dilating a narrow external OS causes marked dilatation of an already more dilated OS. 4. A delay between the onset of a corpus contraction and the onset of the corresponding dilatation of the external OS is usually observed. The difference diminishes as the dilatation of the cervix increases. When the cervix is already fairly dilated, the onset of a contraction is often first noticed from the beginning dilatation of the external OS. 5. By the administration of antispasmedics, the course of dilatation of the cervix was in no case definitely accelerated. 6. After administration of oxytocin (1 to 1.5 I. U. intramuscularly) a marked acceleration of the dilatation of the cervix was recorded in most cases. In relation to the increase in the force and frequency of corpus contractions, effected by the oxytocin, the single steps of dilatation of the external OS became greater and its dilatation was on the whole accelerated, as is seen from the rising of the basal line written by the recording apparatus (Figs. 2 and 5).
Fig. 1C. raphy.
Abdominal
capsule
for
external
tocog-
tocometry
305
Fig. 1D. Diagram showing the method of recording. Both the uterine contractions (external tocography) and the dilatation of the external OS are recorded simultaneously.
Comment
From the investigations carried out so far two particularly interesting results become apparent: First, it can be concluded that normally the cervix remains passive during parturition and does not exert any activity of its own, contrary to several reports.‘, ‘2 ‘, 7, ‘-*l, “8 IF. 2S Otherwise there would not be the regularly observed consistency in quality between corpus contraction and corresponding cervical dilatation. Any activity of the cervix itself would disturb this relationship in many cases. It appears that the behavior of the uterus during labor can be summarized in a simple basic scheme. On one side the progress of labor normally depends on the strength of the myometrial activity of the corpus uteri, on the other side mainly on the resistance of the cervical tissue. Both uterine contractility and cervical resistance are, of course, influenced by a number of factors which can be collectively taken as a definable factor. A measure for corpus activity is already known as the “Montevideo unit.” A method for measuring the resistance of the cervix is
306
Siener
June 1, 1963 Am. J. Obst. Rc Gym.
Fig. 2. Primipara, 18 years old. Membranes intact. The external OS dilated during the period of recording (about 2 hours) from approximately 3 cm. to 7 to 8 cm. width. The relationship between uterine contractions and behavior of the external OS, and the effect of oxytocin are notable. Descri@ion: Synchronous recording of uterine activity (external tocography) and cervical dilatation (cervical-tocometry) Upper curve: corpus contractions. Lower curve: behavior of the external OS (cf. symbols). The recording was continuous. The next dual curve is the immediate continuation of the curve above it. Time in minutes.
Volume Number
86 3
not yet available, but trials to develop one (cervical dynamometry) are in progress.lg With a method to measure the resistance of the cervix in addition, an approximate calculation of the course of labor from both fundal activity and cervical resistance will probably be possible in the .early stage of labor. Present knowledge of the relationship between the two factors means only that for labor to proceed normally corpus activity must exceed the resistance of the cervix. There is no doubt that during the first stage of labor, resistance of the cervix (cervical factor) has at least the same importance as corpus activity. If the resistance is low, subnormal corpus activity suffices for a normal progress of labor, while greater resistance requires greater corpus activity. With increasing dilatation of the cervix in the course of labor, the resistance of the cervical tissue probably decreases. This may be the main reason why with increasing cervical dilatation the single steps of dilatation of the external OS become greater, and weaker corpus contractions which would not have a noticeable effect on a narrow OS markedly dilates a more dilated OS. The second important result of our investigations appears to be the failure of antispasmodics to effect a noticeable acceleration of the dilatation of the cervix.* This is contradictory to widespread opinions of the value of antispasmodic therapy during labor. The ineffectiveness of antispasmodics in parturition is not surprising when it is realized that all available drugs act on smooth muscle; the cervix, however, consists mainly of connective tissue.3p 4p 14v23, 24 The problem of obstetric antispasmodics was recently dealt with in detail elsewhere.*O Antispasmodics are often given in European obstetric centers. The observation that “We have tested the following drugs on their antispasmodic effect: meperidine, meperidine combined with promethazine, morphine, Buscopan (hyoscin-N-butylbromid) , Efosin (diphenylpiperidinopropanhydrochlorid plus diphenylpiperidinoaethylacetamidhydrochlorid) , Erantin (D-propoxyphenhydrochlorid) , Monzal (l,-(3, 4dimetboxyphenyl)-ldimethylamino-4-phenylbutanhydrochlorid) , and other new drugs which are still in the stage of evaluation.
Cervical
tocometry
307
they are apparently ineffective and do not facilitate parturition may suggest that they should be replaced with suitable analgesics. Oxytocin, in contrast to antispasmodics, in most cases markedly accelerated the dilatation of the cervix (Figs. 2 and 5). This effect was usually related to the degree of the dilatation of the cervix and was especially evident the more the cervix was dilated at the time of administration of oxytocin. It was of course particularly impressive in cases in which uterine contractility had been insufficient prior to the injection (Fig. 5). It appears noteworthy that a few cases in which no effect was observed after intramuscular injection of 1 I.U. oxytocin, the subsequent (20 to 30 minutes later) intramuscular injection of 1.5 units essentially accelerated cervical dilatation. Occasionally we observed after intramuscular administration of 1.5 units oxytocin distinct signs of overdosage in the form of transient tetanic contractions. It appears inadvisable to give more than 1 unit oxytocin intramuscularly without tocographic control. Intravenous drip infusions of oxytocin are increasingly used. They appear particularly indicated in severe forms of hypotonic inertia of labor. The regulation of the flow per minute, preferably on the basis of tocographic recordings, allows the activity of the corpus uteri to be accurately controlled. In suitable cases the rate of flow can be increased to achieve the individually possible maximal activity of the corpus uteri. Of the two factors, corpus activity and resistance of the cervix, on which the course of labor mainly depends, at the present time only the uterine contractility can be reliably influenced. In most cases the uterine activity can be readily amplified, a fact of great importance in regulating the course of labor. Accurate control, especially by oxytocin drip infusion, and regular observation, preferably by tocography, are at present the most valuable obstetric aids during labor when, due to functional disturbances, this cannot proceed fully spontaneously.
308
Siener
Fig. 3. Primipara, 30 years old. Membranes ruptured. The about 35 minutes from approximately 3 cm. to approximately of the cervix. For the description of the graph see Fig. 2.
Fig. 4. Secundipara, 19 years old. Membranes recording (about 75 minutes) from approximately clear-cut effect of pethidine and promethazine.
OS dilated during recording for 8 cm. Note the rapid dilatation
intact. Thr oc opened 4 cm. to approximately
during
the period 9 cm. width.
of No
Fig. 5. Secundipara, 13 years old. Membranes intact. The OS opened during the recording for about 55 minutes from approximately 4 cm. to approximately 7 cm. width. The effect of oxytocin was very marked. After its administration, uterine contractility was distinctly improved (cf. upper curve: external tocography) . As a result cervical dilatation rapidly progresses.
Volume
86
Number
3
Summary By cervical tocometry the behavior of the external OS in the first stage of labor was studied. Combined cervical tocometry and external tocography allowed us to observe both the effect of each contraction of the corpus uteri on the OS and the relationship between uterine contractility and cervical dilatation in a prolonged period. Some of the results obtained so far are reported and the most important of them dealt with in more detail. It is noteworthy that the cervix apparently remains completely passive during the first stage of labor. In normal cases the speed of the dilatation of
REFERENCES
1.
Bayer, R., and Hoff, F.: Wien. klin. Wchnschr. 63: 275, 1951. 3-. Bayer, R., and Hoff, F.: Ztschr. Geburtsh. u. GynPk. 153: 105, 1959. 3. Danforth, D. N.: AM. J. OBST. & GYNEC. 53: 541, 1947. 4. Danforth, D. N.: AM. J. OBST. & GYNEC. 68: 1261, 1954. 5. Friedmann, E. A.: AM. J. OBST. & GYNEC. 71: 1189, 1956. 6. Karlson, S.: Acta obst. et gynec. scandinav. 28: 209, 1949. 7. Kreis, J.: J. Obst. & Gynaec. Brit. Emp. 41: 955, 1934. 8. Langreder, W.: Bibl. gynaec. 20: 9, 1959. (SUPPl.) 9. Lox-and,. S.: Acta med. Hungaria. 2: 2, 1950. 10. Nixon. W. C. W.: AM. YT. OBST. & GYNEC. 62: 964, 1951. 11. Nixon, W. C. W., and Smyth, C. N.: J. Obst. & Gynaec. Brit. Emp. 64:. 35, 1957. 12. Noack. H.. and Siener. ’ H.: Zentralbl. Gvnak. , 78: 2Ci69> ‘1956. 157: 458, 1934. 13. Rech, W.: Arch. Gynak. 14. Runge, H., and Riehm, H.: Arch Gynik. 181: 400, 1952.
Cervical
tocometry
309
the cervix therefore depends on the one hand on the quality of the uterine contractility and on the other hand mainly on the intensity of the resistance of the cervical tissue. Another important observation was that all tested obstetric antispasmodics failed to accelerate the dilatation of the cervix. Marked acceleration of the dilatation of the cervix, resulting from improved uterine activity, was achieved in many cases with the administration of oxytocin. Of the two factors governing the first stage of labor, at present the only factor which can be reliably influenced is the corpus activity.
15.
Schickele, G.: Gynec. et obst. 17: 406, 1928; Ber. ges. Gynlk. 14: 772, 1928. 16. Schild, H. O., Fitzpatrick, R. J., and Nixon, W. C. W.: Lancet 1: 250, 1951. Gynak. 78: 2069, 1956. 17. Siener, H.: Zentralbl. H.: Geburtsh. u. Frauenh. 19: 140, 18. Siener, 1959. 18a. Siener, H.: Arch. Gynak. 196: 395, 1961. 19. Siener, H.: 34. Tag. Dtsch. Gesellsch. GynHk., Hamburg, 1962, Scientific exhibition. H.: Geburtsh. u. Frauenheilk. 22: 20. Siener, 1400, 1962. 21. Siener, H., and Vossius, G.: 33. Tag. Dtsch. Gesellsch. Gynlk., Miinchen, 1960, Scientific exhibition. 22. Smyth, C. N.: Congr. internat. GynCcol. et d’ Obstttr. GenCve 1954, S. A. Georg, p. 1030. 23. Stieve, H.: Ztschr. Mikroskop. Anatom. Forsch. 11: 291, 1927. 24. Stieve, H.: Ztschr. Mikroskop. Anatom. Forsch. 14: 549, 1928. 25. Sureau, C.: Therapie 15: 393, 1960; Ber. ces. Gvnak. 73: 89. 1961. 26. Vossius, G.: Ztscdr. ges. exper. Med. 134: 506, 1961. 27. Wolf, W.: Arch. GynIk. 180: 178, 1951.
on
M.D. Main,
Germany
years, and in 1960-61 with Vossius and in cooperation with the Company Hartmann & Braun of Frankfurt on Main, was developed to its present state.l**, 21, 26
D u R I N G the first stage of labor, increasing dilatation of the cervix is the only reliable indicator of the progress of parturition. Until a few years ago, the only methods to determine the width of the external OS of the cervix were digital examination by the vagina1 or rectal route and vaginal speculum examination. There were no facilities for visualizing the dilatation and actual width of the OS continuously and there was no possibility for recording the course of the labor. Years ago some attempts were made to visualize the dilatation of the cervix during labor. In 1951, for example, WolfZ7 reported on trials to record the size of the margins of the external OS by applying small induction coils to them, but these apparently failed. Attempts by Smyth22 in 1954 were also not very successful. He tried to record the dilatation of the OS with a forceps-shaped instrument containing a strain gauge. In 1956, Friedman5 reported on an instrument which ahowed the width of the OS to be read from a scale. Independent of Friedman, I described in the same year a method by which the dilatation movements of the external cervical OS could be continually transmitted to a recording apparatus.” This method, which we refer to as Cervixwehenmessung (cervical tocometry) , was improved in the course of the following
Method Two suitably shaped clamps (modified intestinal clamps) were attached to the external OS of the cervix (Figs. 1A and IB) . For this procedure, the patient is placed in lithotomy position. The OS is exposed by plate specula and a clamp is fastened on each side (at 9 and 3 o’clock) to the internal margin of the cervical lips. The woman then returns into a normal supine position, straddling her legs somewhat. The receptor part of the instrument is slid onto the outer ends of the clamps protruding from the vaginal entrance (Fig. 1B). The receptor part is equipped with a potentiometer which with every change in the size of the OS is accordingly moved through the clamps. The resulting changes in the electrical tension of the potentiometer are transmitted to a normal continuous line recorder. The recording instrument contains several amplifier stages which allow the dilatation of the OS to be recorded in the ratios 1:1, 1:2, or 1:4. It was also of great interest during investigations to observe the relationship between uterine contractility and dilatation of the cervix. Measurements of cervical dilatation were therefore always combined with external tocography. The recently used tocograph is shown in Fig. 1C. It, too, contains
From the Department of Obstetrics and Gynecology of the University of Frankfurt. 303
304
Siener
a potentiometer and thus is based on the same principle as the cervical tocometrr. A probing “finger” projecting from the basal plate contacts the uterus through the intact abdominal wall. Its excursions are transmitted through the potentiometer to the recording apparatus. In view of its potentiometer component, this external tocograph can be considered a further development of the instruments mentioned by Rechl” in 1934 and by Siener and Vossius” in 1960. With this method ! Fig. 1D) studies were made during all stages of labor in 80 women (primiparas and srcundiparas) Roth the physiologic behavior of the cervix and that of several drugs (oxytocics, analgesics, and antispasmodics) in their effects on cervical dilatation were observed. Results
The combined external tocography and cervical tocometry proved to be a valuable method for observing the effect of each uterine contraction on the cervix and for observing the relationship over a prolonged period between uterine contractility pattern and cervical opening. It allows normal labor and abnormalities to be studied and the effect of drugs to be visualized. The knowledge of the uterine contractility and the dilatation of the cervix during the first stage
Fig. able
1A. Cervical handles.
recording:
clamps
with
detach-
Fig. IB. Clamps in situ. thr receptor the potentiometer resentation)
slid
on
p;trr (semidiagrammatic
c,,\rryirq rep-
of labor allows an exact control of this important period of parturition. Some of our observations are described below : 1. During the first stage of labor. every contraction of the corpus uteri reaching a certain strength causes a dilatation of the external OS. When the contraction subsides, the OS returns completely or partly to its previous size. In none of our cases could a uniform linear dilatation of the OS be observed; this is in contrast to the findings of Langreder’ who described it for primiparas as the “cervical opening type.” 2. As a rule, the force of corpus contraction and the degree of corresponding OS dilatation are in a definite qualitative relationship. The stronger a body contraction, the wider it dilates the cervix. 3. As labor progresses, the effect of the corpus contractions on the cervical dilatation increases. Of two equally strong contractions, that one acting on the OS in a more
Volume Number
86 3
Cervical
dilated state is more effective. The same strength of contraction produces a considerably greater dilatation of the cervix when this is already dilated to 7 cm. than when it is dilated to only 3 cm. Vice versa, a comparatively weak contraction incapable of dilating a narrow external OS causes marked dilatation of an already more dilated OS. 4. A delay between the onset of a corpus contraction and the onset of the corresponding dilatation of the external OS is usually observed. The difference diminishes as the dilatation of the cervix increases. When the cervix is already fairly dilated, the onset of a contraction is often first noticed from the beginning dilatation of the external OS. 5. By the administration of antispasmedics, the course of dilatation of the cervix was in no case definitely accelerated. 6. After administration of oxytocin (1 to 1.5 I. U. intramuscularly) a marked acceleration of the dilatation of the cervix was recorded in most cases. In relation to the increase in the force and frequency of corpus contractions, effected by the oxytocin, the single steps of dilatation of the external OS became greater and its dilatation was on the whole accelerated, as is seen from the rising of the basal line written by the recording apparatus (Figs. 2 and 5).
Fig. 1C. raphy.
Abdominal
capsule
for
external
tocog-
tocometry
305
Fig. 1D. Diagram showing the method of recording. Both the uterine contractions (external tocography) and the dilatation of the external OS are recorded simultaneously.
Comment
From the investigations carried out so far two particularly interesting results become apparent: First, it can be concluded that normally the cervix remains passive during parturition and does not exert any activity of its own, contrary to several reports.‘, ‘2 ‘, 7, ‘-*l, “8 IF. 2S Otherwise there would not be the regularly observed consistency in quality between corpus contraction and corresponding cervical dilatation. Any activity of the cervix itself would disturb this relationship in many cases. It appears that the behavior of the uterus during labor can be summarized in a simple basic scheme. On one side the progress of labor normally depends on the strength of the myometrial activity of the corpus uteri, on the other side mainly on the resistance of the cervical tissue. Both uterine contractility and cervical resistance are, of course, influenced by a number of factors which can be collectively taken as a definable factor. A measure for corpus activity is already known as the “Montevideo unit.” A method for measuring the resistance of the cervix is
306
Siener
June 1, 1963 Am. J. Obst. Rc Gym.
Fig. 2. Primipara, 18 years old. Membranes intact. The external OS dilated during the period of recording (about 2 hours) from approximately 3 cm. to 7 to 8 cm. width. The relationship between uterine contractions and behavior of the external OS, and the effect of oxytocin are notable. Descri@ion: Synchronous recording of uterine activity (external tocography) and cervical dilatation (cervical-tocometry) Upper curve: corpus contractions. Lower curve: behavior of the external OS (cf. symbols). The recording was continuous. The next dual curve is the immediate continuation of the curve above it. Time in minutes.
Volume Number
86 3
not yet available, but trials to develop one (cervical dynamometry) are in progress.lg With a method to measure the resistance of the cervix in addition, an approximate calculation of the course of labor from both fundal activity and cervical resistance will probably be possible in the .early stage of labor. Present knowledge of the relationship between the two factors means only that for labor to proceed normally corpus activity must exceed the resistance of the cervix. There is no doubt that during the first stage of labor, resistance of the cervix (cervical factor) has at least the same importance as corpus activity. If the resistance is low, subnormal corpus activity suffices for a normal progress of labor, while greater resistance requires greater corpus activity. With increasing dilatation of the cervix in the course of labor, the resistance of the cervical tissue probably decreases. This may be the main reason why with increasing cervical dilatation the single steps of dilatation of the external OS become greater, and weaker corpus contractions which would not have a noticeable effect on a narrow OS markedly dilates a more dilated OS. The second important result of our investigations appears to be the failure of antispasmodics to effect a noticeable acceleration of the dilatation of the cervix.* This is contradictory to widespread opinions of the value of antispasmodic therapy during labor. The ineffectiveness of antispasmodics in parturition is not surprising when it is realized that all available drugs act on smooth muscle; the cervix, however, consists mainly of connective tissue.3p 4p 14v23, 24 The problem of obstetric antispasmodics was recently dealt with in detail elsewhere.*O Antispasmodics are often given in European obstetric centers. The observation that “We have tested the following drugs on their antispasmodic effect: meperidine, meperidine combined with promethazine, morphine, Buscopan (hyoscin-N-butylbromid) , Efosin (diphenylpiperidinopropanhydrochlorid plus diphenylpiperidinoaethylacetamidhydrochlorid) , Erantin (D-propoxyphenhydrochlorid) , Monzal (l,-(3, 4dimetboxyphenyl)-ldimethylamino-4-phenylbutanhydrochlorid) , and other new drugs which are still in the stage of evaluation.
Cervical
tocometry
307
they are apparently ineffective and do not facilitate parturition may suggest that they should be replaced with suitable analgesics. Oxytocin, in contrast to antispasmodics, in most cases markedly accelerated the dilatation of the cervix (Figs. 2 and 5). This effect was usually related to the degree of the dilatation of the cervix and was especially evident the more the cervix was dilated at the time of administration of oxytocin. It was of course particularly impressive in cases in which uterine contractility had been insufficient prior to the injection (Fig. 5). It appears noteworthy that a few cases in which no effect was observed after intramuscular injection of 1 I.U. oxytocin, the subsequent (20 to 30 minutes later) intramuscular injection of 1.5 units essentially accelerated cervical dilatation. Occasionally we observed after intramuscular administration of 1.5 units oxytocin distinct signs of overdosage in the form of transient tetanic contractions. It appears inadvisable to give more than 1 unit oxytocin intramuscularly without tocographic control. Intravenous drip infusions of oxytocin are increasingly used. They appear particularly indicated in severe forms of hypotonic inertia of labor. The regulation of the flow per minute, preferably on the basis of tocographic recordings, allows the activity of the corpus uteri to be accurately controlled. In suitable cases the rate of flow can be increased to achieve the individually possible maximal activity of the corpus uteri. Of the two factors, corpus activity and resistance of the cervix, on which the course of labor mainly depends, at the present time only the uterine contractility can be reliably influenced. In most cases the uterine activity can be readily amplified, a fact of great importance in regulating the course of labor. Accurate control, especially by oxytocin drip infusion, and regular observation, preferably by tocography, are at present the most valuable obstetric aids during labor when, due to functional disturbances, this cannot proceed fully spontaneously.
308
Siener
Fig. 3. Primipara, 30 years old. Membranes ruptured. The about 35 minutes from approximately 3 cm. to approximately of the cervix. For the description of the graph see Fig. 2.
Fig. 4. Secundipara, 19 years old. Membranes recording (about 75 minutes) from approximately clear-cut effect of pethidine and promethazine.
OS dilated during recording for 8 cm. Note the rapid dilatation
intact. Thr oc opened 4 cm. to approximately
during
the period 9 cm. width.
of No
Fig. 5. Secundipara, 13 years old. Membranes intact. The OS opened during the recording for about 55 minutes from approximately 4 cm. to approximately 7 cm. width. The effect of oxytocin was very marked. After its administration, uterine contractility was distinctly improved (cf. upper curve: external tocography) . As a result cervical dilatation rapidly progresses.
Volume
86
Number
3
Summary By cervical tocometry the behavior of the external OS in the first stage of labor was studied. Combined cervical tocometry and external tocography allowed us to observe both the effect of each contraction of the corpus uteri on the OS and the relationship between uterine contractility and cervical dilatation in a prolonged period. Some of the results obtained so far are reported and the most important of them dealt with in more detail. It is noteworthy that the cervix apparently remains completely passive during the first stage of labor. In normal cases the speed of the dilatation of
REFERENCES
1.
Bayer, R., and Hoff, F.: Wien. klin. Wchnschr. 63: 275, 1951. 3-. Bayer, R., and Hoff, F.: Ztschr. Geburtsh. u. GynPk. 153: 105, 1959. 3. Danforth, D. N.: AM. J. OBST. & GYNEC. 53: 541, 1947. 4. Danforth, D. N.: AM. J. OBST. & GYNEC. 68: 1261, 1954. 5. Friedmann, E. A.: AM. J. OBST. & GYNEC. 71: 1189, 1956. 6. Karlson, S.: Acta obst. et gynec. scandinav. 28: 209, 1949. 7. Kreis, J.: J. Obst. & Gynaec. Brit. Emp. 41: 955, 1934. 8. Langreder, W.: Bibl. gynaec. 20: 9, 1959. (SUPPl.) 9. Lox-and,. S.: Acta med. Hungaria. 2: 2, 1950. 10. Nixon. W. C. W.: AM. YT. OBST. & GYNEC. 62: 964, 1951. 11. Nixon, W. C. W., and Smyth, C. N.: J. Obst. & Gynaec. Brit. Emp. 64:. 35, 1957. 12. Noack. H.. and Siener. ’ H.: Zentralbl. Gvnak. , 78: 2Ci69> ‘1956. 157: 458, 1934. 13. Rech, W.: Arch. Gynak. 14. Runge, H., and Riehm, H.: Arch Gynik. 181: 400, 1952.
Cervical
tocometry
309
the cervix therefore depends on the one hand on the quality of the uterine contractility and on the other hand mainly on the intensity of the resistance of the cervical tissue. Another important observation was that all tested obstetric antispasmodics failed to accelerate the dilatation of the cervix. Marked acceleration of the dilatation of the cervix, resulting from improved uterine activity, was achieved in many cases with the administration of oxytocin. Of the two factors governing the first stage of labor, at present the only factor which can be reliably influenced is the corpus activity.
15.
Schickele, G.: Gynec. et obst. 17: 406, 1928; Ber. ges. Gynlk. 14: 772, 1928. 16. Schild, H. O., Fitzpatrick, R. J., and Nixon, W. C. W.: Lancet 1: 250, 1951. Gynak. 78: 2069, 1956. 17. Siener, H.: Zentralbl. H.: Geburtsh. u. Frauenh. 19: 140, 18. Siener, 1959. 18a. Siener, H.: Arch. Gynak. 196: 395, 1961. 19. Siener, H.: 34. Tag. Dtsch. Gesellsch. GynHk., Hamburg, 1962, Scientific exhibition. H.: Geburtsh. u. Frauenheilk. 22: 20. Siener, 1400, 1962. 21. Siener, H., and Vossius, G.: 33. Tag. Dtsch. Gesellsch. Gynlk., Miinchen, 1960, Scientific exhibition. 22. Smyth, C. N.: Congr. internat. GynCcol. et d’ Obstttr. GenCve 1954, S. A. Georg, p. 1030. 23. Stieve, H.: Ztschr. Mikroskop. Anatom. Forsch. 11: 291, 1927. 24. Stieve, H.: Ztschr. Mikroskop. Anatom. Forsch. 14: 549, 1928. 25. Sureau, C.: Therapie 15: 393, 1960; Ber. ces. Gvnak. 73: 89. 1961. 26. Vossius, G.: Ztscdr. ges. exper. Med. 134: 506, 1961. 27. Wolf, W.: Arch. GynIk. 180: 178, 1951.