VAGINAL DELIVERY AFTER CAESAREAN SECTION Rupture of the Lower Segment Scar

JAMES BAXTER, M.D. Rankin Maternity Hospital, Greenock

BY

THE problem of vaginal delivery after Caesarean section has been the subject of many recent contributions to obstetrical literature. So far as the writer knows it has not been recorded that the transverse scar in the lower segment, resulting from a previous Caesarean section, may rupture silently and harmlessly during labour, and that this rupture will be missed unless a routine search is made for it. Birnbaum (1956), in an interesting paper dealing with this subject, refers briefly to the possibility of such an accident. He states “many of the so-called ‘ruptures’ of uterine scars are really asymptom- atic ‘peritoneal windows’ in the noncontractile lower uterine segment”. The ruptures described below were by no means “so-called” and, as the fingers gauged their extent, a feeling of alarm was raised until it was discovered that the utero-vesical peritoneal reflection was intact.

For many years the writer has practised exploration of the uterus immediately following vaginal delivery after a previous Caesarean section. Unfortunately this routine has not always been observed and accurate figures are not available. Nevertheless the following cases serve to demonstrate the importance of this routine examination.

Case I . Mrs. C.G., a primigravida, 36-weeks pregnant, was admitted to hospital on 9th September, 1955, as a case of ante-partum haemorrhage. Examination revealed a type 2 placenta praevia and she was delivered by lower segment Caesarean section. The placenta was located on the posterior wall of the uterus. The puerperium was uneventful and she was dis- charged on the twelfth day. She attended the antenatal clinic during her second pregnancy and was admitted to hospital, in labour, on 19th

September, 1956. She delivered herself of an infant weighing 7 pounds 1 ounce (3,203 g.). Following delivery of the placenta there was profuse vaginal bleeding. She was transfused and the uterus explored. The cavity contained a large quantity of blood clot and the scar in the lower segment was found ruptured along its entire length. The utero-vesical reflection of peritoneum was intact and there was no com- munication with the abdominal cavity. Removal of the clot followed by 0.5 mg. ergometrine, given intravenously, controlled haemorrhage which was thought to come from the placental site and not from the ruptured scar. There had been no sign of bleeding until the third stage of labour. However, to keep on the safe side, the vagina was tightly packed so that the lower segment was compressed against the upper segment. The pack was removed in 24 hours. She was discharged well on the tenth day of the puerperium.

Case 2. Mrs. M.R., a primigravida, was delivered by lower segment Caesarean section on 28th January, 1955, the indication being severe pre-eclamptic toxaemia. She was then 36-weeks pregnant. There was a mild degree of pyrexia in the early days of the puerperium thought to be due to an abscess in her buttock resulting from injection of magnesium sulphate. In her second pregnancy she was admitted to hospital because of recurrent toxaemia on 27th September, 1956, and went into labour soon after admission. She was then @-weeks preg- nant. When she was fully dilated and the head well down in the pelvis, pudendal nerve block was performed and delivery completed by low forceps. The infant weighed 6) pounds (2,948 g.). Following delivery of the placenta and before repair of the episiotomy, a hand was introduced

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are more likely to produce ischaemia in the wound area and to cause poor healing. Perhaps the most important advantage is derived from dividing the utero-vesical peritoneal reflection along its firm line of attachment to the uterus when exposing the lower segment, and re- suturing it as far as possible above the suture line in the lower segment. Experience with repeated lower segment operations suggests that when this technique is followed the peritoneal reflection does not readily become adherent to the scar and is easily stripped down even at a fourth operation. It is possible that, following operation, the distending bladder tends to raise the utero-vesical reflection and so prevents intimate adhesion to the lower segment. When the suture lines lie opposite each other they probably become closely adherent, and if rupture should occur both are involved and the rupture is complete-into the abdominal cavity. So long as the peritoneal reflection remains intact there would appear to be no immediate danger and no treatment is necessary unless there is haemorrhage. It seems reasonable to suppose that rupture is more likely when Caesarean section has been performed on a primigravida some weeks before term, the lower segment being ill-defined and not thinned out.

The recognition of this silent rupture of the lower segment scar may be of little consequence at the time, but the obstetrician should know that it has occurred, and it should be recorded in the history of the patient’s labour, since it may influence the management of a future pregnancy and labour.

to explore the lower segment and the old scar was found ruptured along its entire length. The utero-vesical reflection of peritoneum was intact and there was no access to the abdominal cavity. As there was no bleeding and no apparent disturbance resulting from the rupture it was left untreated. The puerperium was uneventful and she was discharged on the tenth day. There had been no signs or symptoms during labour to suggest rupture of this scar and it would have gone undetected had routine examination been neglected.

Accurate figures have not been kept over the years, but these two cases of rupture of a lower segment scar during vaginal delivery after a previous Caesarean section operation, are the only cases of rupture observed by the writer in a series of about 80 cases, and they would have been missed had not the uterus been explored immediately after delivery. These patients undergoing labour after a previous Caesarean section were kept under careful observation and at no time did they complain of pain in the lower abdomen or over the symphysis; palpation in this region did not elicit tenderness, and there was no bulging of the membranes to simulate a full bladder. It is probable that rupture occurred during the 2nd stage otherwise full dilatation of the 0s could scarcely have been accomplished but there was never any diminution in force or frequency of uterine contraction to suggest rupture. Rupture of the scar may lead to profuse haemorrhage but one would expect to see vaginal bleeding at the time of the rupture, and a bleeding which begins during the third stage is very likely to be from the placental site.

Lower segment Caesarean section on the two cases described above was performed by the writer, who uses a more-or-less standard technique. The curved incision in the lower segment is closed with two layers of catgut sutures. Where there is no great urgency some advantage may be gained by using separate rather than continuous sutures, since the latter

SUMMARY Vaginal delivery after Caesarean section may

cause silent and harmless rupture of the lower segment scar and such a rupture will be missed unless the uterus is explored immediately after delivery.

REFERENCE Birnbaum, S . J. (1956): Obstef. Gynec., 7, 611.