Uterine Motility in the Second Trimester

UTERINE MOTILITY IN THE SECOND TRIMESTER JoHN

V.

KELLY,

M.D.,4:-

AND NrLs PossE,

M.D.,

STOCKHOLM, SWEDEN

(From ihe Allmanna Barnbordshusei)

URING the nearly one hundred years since study of uterine motility was initiated, a number of methods for measuring and recording it have been devised. They are divided into two groups, the external and internal methods. The external hysterographic techniques have included the CrodeP tokometer, Dodek's 2 pneumatic hysterograph, Frey's 3 hysterotonograph, the Lorand4 and Reynolds 5 tokoclynamometers, and various electrohysterographic methods. 6 • 11 More investigators in this sphere include Schaeffer,' 2 Bukoemsky,'3 Riibsamen, 14 Fabrr,' 5 Embrey,'"- 17 Murphy,' 8 and others. The internal recording methods have consisted of various intrauterine balloons, bags, and catheters, uterine cavity and uterine muscle electrodes to record activity potentials, hysterosalpingography with various contrast media, microcarbon pressure receptors, transabdominal and transvaginal intra-amniotic pressure manometers, uterine intramuscular microballoons, and different types of intrauterine electrical strain gauges. Many prominent names arc included in this field. 19 - 39 Of an these methods, one of the most accmate and efficient, ancl judged by Jf'ffcoate 40 to be one of the very best, is that of Karlson. 35 This is an internal trchnique and the apparatus consist:;; of a receptor probe, the recording instruments, and electrical batteries. The receptor probe (Fig. 1) is constructed of soft steel wire 30 em. in length and 1 mm. in diameter, to which are soldered three receptor chambers, positioned on the wi1·e so that one each will be located in thr fundus, isthmus, and cervix. These chambers are composed of two copper caps on either end of a short rubber tube which contains packed ear bon powder; the chambers are cylindrical and measUl'e 12 mm. in length and 4.6 mm. in diameter. From each chamber two conducting wires pass along the receptor pro be to their respective trrminals. The three small carbon cham hers via their direct contact with the nterine walls give a recording of the extent and progress of motility in various parts of the uterus. Every increase in intrauterine pressure causes a decrease in the electrical resistance of the carbon which produces an increase in the current which is passing from batteries to three self-registering milliammeters, each one electrically connected to its respective carbon chamber in either the fundus, isthmus, or cervix. Each milliammeter is equipped with an ink recording system and registers on a graph which rotates at a speed of 6 em. per

D

•Fulbright Fellow in Obstetrics an
124

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UTERINE MOTILITY IN SECOND TRIMESTER

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minute. The sensitivity of the r eceptor chambers and the recording apparatus is such that distinct defl ections are obtained for variations in pressure of approximately 1 mm. of mercury.

Purpose of Study Knowledge of the physiology of the pregnant uterus in the first six months is scanty, primarily because research has been nearly complet ely curtailed by the possibilities of jeopardizing the fetus by the methods of internal hysterogt·aphy. External tokometry is not feasible in the first two trimesters because of the smaller size of the uterus. In Sweden, however, opportunities are available to study uterine physiology during pregnancy by utilizing for clinical research those patients admitted to the hospital for legal abortions; legal abortions here are r elatively frequent and are usually performed between the tenth and twenty-fourth weeks of pregnancy. When a patient is studied in the hospital just a few hours prior to surgical interruption, no significance is attached to inadvertent rupture of membranes, initiation of fetal distress, or induction of labor, if such does occur as a result of the investigative technique.

Fig. 1.-Receptor probe.

We considered that a study such as this could be valuable in contributing hitherto unavailable information and data to the r ealm of physiology of the p regnant uterus. Evidence concerning myometrial activity in pregnancy is of basic importance in solving clinical problems such as spontaneous abortion, habitual abortion, missed abortion, prematu re labor, and t he eventual full understanding of normal and abnormal labor.

Material J<...,rom a total of over 100 pregnant women admitted to the Allmanna Barnbordshuset (The General Maternity Hospital of Stockholm) during 1955-1956 for legal abortion, 55 whose gestations seemed normal in all r espects and who wished to cooperate in this study were selected for r ecording. The patients' ages ranged from 15 to 43. The series included 10 women pregnant for the first time and 45 women who had at least one child. The patients' pregnancies varied in time of gestation from 10 to 24 weeks; the length of each gestation was measured in weeks from the first day of the last menstrual period. Table I shows the distribution of primigravidas and multiparas and also the distribution of cases p er numb er of weeks of pregnancy. The heavy concentration of patients between the seventeenth and twentieth weeks is due to the average 6 week delay from the time of request for interruption by the patient (usually after the second missed period) to final governmental approval after clearance of the request by the various social, medical, and psychiatric bureaus.

126

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Am. J. Obst. & Gynec. July, 1957

Technique The patient was usually studied on the second hospital day, a few hours before surgical interruption of the pregnancy was eontemplated. After catheterization, a careful abdominal and pelvic examination was done and if no abnormalities were detected, the procedure was begun. A speculum was inserted in the vagina, the cervix grasped with a tenaculum, and a sterilized, calibrated receptor probe passed gently upward between the membranes and the uterine wall until the graduated scale ~n the receptor probe indicated that the carbon chambers were located at the fundus, isthmus, and cervix, respectively. Dilatation of the cervix was never required and no premedication, analgesia, or anesthesia was ever necessary for this procedure. Before insertion of the receptor probe, each carbon chamber was calibrated for sensitivity in the apparatus described by Karlson 3 ' in his original paper. The patient lay quietly and comfortably in the supine position during the study period (at least two hours). One of us was in constant attendance on the patient to note motility patterns and any artifacts produced by her movements. There were no complications in any of the 55 cases. In no patient were the membranes ruptured, bleeding induced, or fetal distress encountered; no uteri were perforated, labor was not initiated, and no infertions developed as a result of these intrauterine investigations. TABLE

I.

DISTRIBUTION OF GRAVIDITY AND MOTILITY PATTERNS PER WEEK OF GESTATION WEEKS PREGNANT

Motility Pattern No. 26 patients

1.~

I 10

11

12

13

Primigravidas Multiparas

Motility Pattern No. 15 patients

H

15

1

1

1

2

16

19

17

18

3 6

1

2

2

1 1

2

20

21

22

:J

2

2

1

1 1

1

2 9

4

23

2.~

Primigravidas Multiparas

1

1

2

1

No Motility Ob.scrvcd.~ 14 patiPnts

Total

Primigravidas Multiparas 5.5 patients

1

1 1

1

1

2

l 4

1

1

4

3

4

12

10

1 2

1

----~~-

Findings The findings in these recordings are artificial to a certain degree since the receptor probe is inside the uterine cavity throughout the 2 hour study period, but are as nearly physiologic as can be attained with the methods of investigation available today. All artifacts (from the patient's movements, palpation of the abdomen, auscultation of the fetal heart, etc.) were excluded in the interpretation of the registrations. The motility recorded during the first 15 minutes was disregarded, for in all cases it required approximately 5 to 10 minutes for the "irritation motility" initiated by insertion of the receptor probe to subside. No myometrial activity was evident in 25 per cent of the patients investigated (14- of 55 women). ·rn these cases the quiescence was practically complete except for an occasional small contraction in one of the three regions of the uterus. During the 2 hour study periods of these inactive uteri, no abnormalities were detected in the recording apparatus; the possibility of insensitive or malpositioned receptor chambers was excluded in each case by

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UTERiliE lvfOTILITY I:tf

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127

giVmg a minute dose of an oxytocic drug just prior to termination of each study, to stimulate uterine activity and, by recording this drug-induced motility, to demonstrate that the receptor chambers could function adequately (Fig. 2). A majority of the patients studied (41 of 55 women) showed definite uterine motility. Nevertheless, in these cases it was not uncommon for periods of activity to be interspersed by intervals of very little motility or actual quiescence. Two different types of myometrial contraction patterns were observed. One motility pattern was observed in 15 patients and is demonstrated in Fig. 3. These patterns consisted of high tonus with superimposed contractions of small amplitude and short duration (2 to 4 seconds) and a frequency of one every 3 to 6 seconds; they were very similar in both fundus and isthmus. Cervical activity was negligible in these women. 'rhe n1ore frequent of these patterns ';t;1as noted in 26 "\VOinen and is demonstrated in Fig. 4. These recordings exhibited synchronous fundal and isthmic contractions of approximately 30 to 60 seconds, occurring every 2 to 3 minutes, and possessing an average amplitude in the fundus of 12 1\fa. of current which is comparable to approximately 100 mm. of mercury.* Tonus was usually absent, and if present was usually slight in both the fundus and isthmus. Uttle cervical activity was ever noted. In both the active and inactive groups there was very rarely noted an isolated, spontaneous contraction, synchronous in fundus and isthmus and lasting 40 to 60 seconds. These were identified as Braxton Hicks contractions which Kaiser 41 reported were present in 75 per cent of patients who were at least :!.7 weeks pregnant. Fetal movements were frequently recorded and appeared as typical short (one second) deflections of large amplitude; they were corroborated by the patient at the times of their appearance. In both patterns cervical activity was usually slight if present, and was comprised of small deflections vvith no pattern and no relationship to fundal or isthmal motility. Analysis of the cases in the active and inactive groups discloses no relationship of motility to parity, age, or number of weeks of pregnancy (Table I).

Comment and Conclusions The comparison of uterine activity in animals and that in humans is interesting. Recording of myometrial motility during early phases of pregnancy has been done in rabbits. The uterus duplex of a rabbit shows irregular contractions, segmental in various parts of the uterus, during the first week. 42 Thirty-two days is the normal length of gestation. From the tenth to the twenty-third day there is practically no uterine motility in the rabbit. 43 This corresponds to the second trimester in women, in whom we have found no uterine motility in only 25 per cent. From the twenty-fourth day on, the uterus of the pregnant rabbit shows increasingly vigorous contractions, eventually merging into coordinated labor 44 similar to the process in women as 1·epo~ted byDelson and associates. 45 The few reports in the literature on human uterine motility in the second trimester contribute only scanty information. In 1944 Malpas, 46 during laparotomies for therapeutic abortions, visualized and described uterine motility •The calibration of each of the receptor chambers both prior to and after the recording in a patient gives a quantitative determination of the intrauterine pressure as expressed In

miliiampe:res per millimeter of mercury.

Wiih carbon, however, the curve of pressure rise

with time and the curve of electrical conductance increase are not superimposed on one another, so that only an approximate relationship can be drawn between the amplitude of the contractions as measured in milliamperes of current and the millimeters of mercury pressure correspondent to that current as determined in the calibration apparatus. Furthermore, exact quantitative recordings are precluded because the area of contact of the receptor chambers with the uterine walls in the fundus, Isthmus, and cervix is not known.

128

KELLY AND P OSSE

Am. ] . Obs t. & Gynec. July, 1957

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Volume 74 :-.lumber I

UTERINE MOTILITY IN SECOND TRIMESTER

131

patterns in 18 patients; he attributed this contractility to the spinal anesthesia which these patients had received. 'l'he same year Moir 32 inserted an intrauterine condom in 6 patients who had had premedication for therapeutic abortion via hysterotomy and noted feeble contractions which disappeared when the cyclopropane anesthesia was initiated. -In 1947 Murphy18 from studies with the Lorand tokograph reported that, in 19 women investigated between the sixteenth and twenty-fifth weeks of pregnancy, he found only one case which exhibited uterine contractility. The high degree of insensitivity of external tokography before the twenty-fourth. week of pregnancy casts doubt upon this report. Alvarez and Caldeyro-Barcia47 in 1950 inserted transabdominal catheters into the amniotic fluid and recorded uterine motility in a few cases in the second trimester. They reported that these cases showed the same findings as their cases studied in the last trimester (up to the thirty-eighth week), namely, continuous rhythmical contractions appearing without any intervals of rest, a frequency of one to three per minute, and an intensity of only 5 to 40 mm. of vvater plus moderate tonus of from 40 to 100 mm. of vvater (13 rnm. H 2 0 == 1 mm. Hg). Their findings are subject to question because of their slow recording speed (0.5 ern. per minute), the errors always associated with very sensitive methods (contractions of 5 mrn. of water), the inability to record rapid contractions due to the inertia associated with fluid manometers, and the inability to record activity in different parts of the same uterus. F'urthermore, we doubt that any physiologic activity such as uterine motility will show no degree of variation throughout a 30 week period as is asserted by these authors. 47 Schild and associates 38 in 1951 studied 24 patients (with premedication for abortion by hysterotomy) with triple intrauterine balloons and noted occasional spontaneous contractions in both the fundus and cervix which were out of phase with one another; no additional information on the contractility was reported. The results of our studies show that the majority of uteri in the second trimester exhibit definitive patterns of motility. It is unlikely that the contractility patterns are a manifestation of "foreign-body reaction" for the irritability deflections were typical in appearance with very high tonus, and disappeared in all cases within 10 minutes from the beginning of the registration. The motility patterns were not persistent in each patient as there were frequent intervals of inactivity and quiescence. As far as could be ascertained, when the contractions occurred they were not related to or associated with fetal movements, changes in patient or receptor probe position, abdominal pain, urge to void or defecate, hunger, weariness, or other symptoms. Interpretation of the two motility patterns is difficult and one can only conjecture as to what may be the significance of an active uterus during the second trimester; furthermore, the fact that one of every 4 patients exhibited absolutely no evidence of myometrial activity during the study period is unexplained. Caution is necessary in drawing conclusions from observations of a pregnant uterus during a single selected 2 hour period from an entire 3 months of gestational life, under the artificial conditions set up for recording uterine motility. We think it significant, however, that there is a marked similarity between the t'\vo types of contraction patterns \Ve have found in these patients and the t\vo types of motility curves as demonstrated by several workers 34 ' •s-so and ourselves51 in the normal menstrual cycle (one pattern found in the proliferative

132

KELLY AND POSSE

Am. T.

Oh~t. &

Gynec. July, 1957

phase and one pattern characteristically found in the secretory phase) (Figs. G and 6. Compare Figs. 3 and 4 with li'igs. 5 and 6). Since the types of contractions in a normal menstrual cycle are thought to be due to estrogen (for the proliferative pattern) and to progesterone (for the secretor:r.. pattern)~ it seen1s logical to assume that the particular contractility pattern exhibited by a patient pregnant in the seeond trimester reflects a predominance of ('ither estrogen or progesterone in the blood, depending on which type of pattem is found. It might also be theorized that cases which showed no uterine motility had a predominance of neither estrogen nor progesterone, but a neutralizing ha lance between the two. Unfortunately, no facilities were available fu1· measuring serum or urine estrogen o1· progesterone values in these patients tu ~·ontirm or negate these condusions. Studies correlating urinary estrogen-prrguandiol excretion with uterine motility in the last trimester have been revortecl rrcently52• 53 ; however, until more satisfactory laboratory methods for determinations of ovarian steriod analyses are intt·o
UTERINE MOTILITY IN SECOND TRIMESTER

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133

We are indebted to Dr. Stig Karlson, Chief of the Allmauna Barnbordshuset, for his constant encouragement and invaluable advice in this study.

References 1. Crodel, W.: Ztschr. Geburtsh. u. Gynak. 97: 138, 1930. 2. Dodek, S. M.: Surg., Gynec. & Obst. 55: 45, 1932. 3. Frey, E.: Zentralbl. Gynak. 57: 545, 1933. 4. Lorand, S.: Zentralbl. Gynak. 57: 554, 1933. 5. Reynolds, S. R. M., Heard, 0. 0., Bruns, P., and Hellman, L. M.: Bull. Johns Hopkins IIosp. 82: 446, 1948. 6. Bode, 0.: Arch. Gynak. 146: 123, 1931. 7. Dill, L. V., and Maiden, R. M.: AM. J. OBST. & GYNEC. 56: 213, 1948. 8. Steer, C. M., and Hertsch, G. J.: AM. J. OBST. & GYNEC. 59: 25, 1950. 9. Halliday, E. C., and Heyns, 0. S.: J. Obst. & Gynaec. Brit. Emp. 59: 309, 1952. 10. Fenning, C., Davis, M. E., and Adair, F. L.: AM. J. 0BST. & GYNEC. 38: 670, 1939. 11. Levy·Sulal, E., Morin, P., and ZacouLo, F.: Presse med. 10: 1335, 1952. 12. Schaeffer, 0.: Experimentelle Untersuchungen tiber die Wehenthatigkeit des mensch· lichen Uterus, ausgefiihrt mittelst einer neuen Pelotte und eines neuen Kymo· graphion, Doctor's Thesis. Heidelberg, 1896. 13. Bukoemsky, F. W.: Monatschr. Geburtsh. u. Gynak. 3: 197, 1896. 14. Riibsamen, W.: Miinchen. med. Wchnschr. 7: 627, 1913. 15. Fabre, M.: Bull. Soc. d'obst. et de gynec., Paris 16: 68, 1913. 16. Embrey, M.P.: J. Obst. & Gynaec. Brit. Emp. 47: 371, 1940. 17. Embrey, M.P.: J. Obst. & Gynaec. Brit. Emp. 62: 11 1955. 18. ::1-furphy, D. P.: Uterine Contractility in Pregnancy, Philadelphia, 1947, J. B. Lippin· cott Company. HJ. Schatz, F.: Arch. Gynak. 3: 58, 1872. ~0. Poullet, R.: Arch. physiol. 12: 1, 1880. ~1. Heinricius, G.: Finska lak.·sallsk. hand!. 31: 349, 1889. ~2. Westermark, F.: Scandinav. arch. physiol. 4: 331, 1893. 23. Bourne, A. W., and Burn, J. H.: J. Obst. & Gynaec. Brit. Emp. 34: 2491 1927. 24. Bakke, S. N.: Med. Rev., Bergen 45: 369, 1928. 25. Knau~, H.: Zentralbl. Gyniik. 57: 3685, l!.l33. 26. Schultze, G. K. F.: Ztschr. Geburtsh. u. Gynak. 97: 351, 1930. 27. Falk, H., and Nahon, R.: AM. J. 0BST. & GYNEC. 30: 403, 1935. 28. Woodbury, R. A., Hamilton, \V. F., and Torpin, R.: Am. J. Physiol. 121: 640, 1938. 29. Jacobson, E., Lackner, J. E., and Sinykin, M. B.: AM. J. 0BST. & GYNEC. 38: 1008, 1939. 30. Wolf, W.: Zentralbl. Gynak. 64: 311, 1940. 31. Wilson, L., and Kurzrok, R.: Rndocrinology 23: 79, 1938. 33. Moir, C.: J. Obst. & Gynaec. Brit. Emp. 51: 181, 1944. 33. Bickers, W., and Main, R. J.: .T. Clin. Endocrinol. 1: 992, 1941. 34. Bickers, W.: Fertil. & Steril. 7: 268, 1956. 35. Karlson, S.: Acta obst. et gynec. scandinav. 24: Suppl. 4, 1944. :36. Ah·arez, H., and Caldeyro, H.: Arch. ginec. l\Iontevideo 7: 79, 1948. :37. Ingelman-Sundberg, A., and Lindgren, L.: Forh. Nord. Foren. Obst. & Gynak. 5: 183, 1U50.

:38. Schild, H. 0., Fitzpatrick, R. J., and Nixon, W. W.: Lancet 1: 250, 1951. 39. Williams, E. A., and Stallworthy, J. A.: Lancet 1: 330, 1952. 40. Jeffcoate, T. N. A.: in Holland, P., and Bourne, A. W.: British Gynecological and Obstetrical Practice, London, 1955, William Heinemann, Ltd., chap. 4, p. 98. 41. :r~aiser, I. H.: Bull. Univ. lvfinnesota. Hosp. & 1vfinn. 1vL Foundation 22: 482, 1951. 42. Robson, .J. M.: J. Physiol. 78: 309, 1933. 43. Ludwig, F., and Lenz, E.: Ztschr. Geburtsh. u. Gynak. 86: 589, 1923. 44. Knaus, H. H.: Arch. exper. Path. u. Pharmakol. 124: 152, 1927. 45. Delson, B., Lubin, S., and Reynolds, S. R. M.: AM. J. OBST. & GYNEC. 59: 795, 1950. 46. Malpas, P.: J. Obst. & Gynaec. Brit. Emp. 51: 112, 1944. 47. Alvarez, H., and Caldeyro-Barcia, R.: Surg., Gynec. & Obst. 91: 1, 1950. 48. Moir, C.: Edinburgh M. J. 41: 93, 1934. 49. Robertson, E. M.: Edinburgh M. J-. 44: 20, 1937. 50. Kurzrok, R.: Endocrines in Obstetrics and Gynecology, Baltimore, 1937, The Williams & Wilkins Company. 51. Kelly, J. V., and Posse, N.: Surg., Gynec. & Obst. 103: 687, 1956. 52. Taylor, E. S., Bruns, P. D., Anker, R. M., and Drose, V. E.: AM. J. OBST. & GYNEC. 70: 894, 1955. 53. Bruns, P. D., Taylor, E. S., Anker, R. M., and Drose, V. E.: AM. J. OBST. & GYNEC. 73: 579, 1957.