Symptoms and Signs with Scar Rupture ‐ Value of Uterine Activity Measurements

S. Arulkumaran, S. Chua, S. S. Ratnam

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EDITORIAL COMMENT: This is an important study since it provides perspective on the risks of uterine rupture in patients having a trial of scar (trial of labour) after previous Caesarean section, as well as providing clinical information that may assist in early diagnosis of scar rupture. These 9 cases of uterine rupture were encountered in a series of1,081 women who had a previous Caesarean section, with 71% (722) of these women having a trial of labour with 70% (506 of 722) having a vaginal delivery. This is a very high incidence of trial of scar with a high incidence of successful vaginal delivery, these being facts of relevance when considering the rate of scar rupture. For comparison the study reported by Targett (1), comprised 4,892 women with a previous Caesarean with only 32% (1,577) having a trial of scar, although 76% of these having a trial of scar had a vaginal delivery. In Targett's series the incidence of uterine rupture was 0.82% and he excluded some cases of scar dehiscence which may have been included in the present series in which the rate of uterine rupture was 1.24%. It is rather difficult to decide when to code a case as scar dehiscence rather than a thin lower segment. At repeat Caesarean section it is common to encounter a lower uterine segment so thin that the baby's hair can be seen through the peritoneum. Presumably all these cases are incomplete ruptures with only peritoneum still intact. In most institutions these cases are probably not coded as cases of incomplete uterine rupture; the repeat Caesarean section is easy and the lower segment is repaired. It is the Editor's practice to warn such patients that it would be wise to avoid future pregnancies because of the risk of scar rupture, although this advice is often not acted upon by the patient! Unfortunately in this Singapore series we are not told the proportion of patients having trials of scar who had an oxytocin infusion. Possibly the rate was rather high since a high rate of infusion could account for the high success rate in terms of successful vaginal delivery. It seemed to our reviewer that the takeaway message from this paper was that scar rupture even when complete can be silent but that when cardiotocography shows the onset of bradycardia or loss of beat to beat variation in labour this is an indication for immediate Caesarean section. Figure 1 taken from Targett's paper illustrates such a case of a patient who had repeat Caesarean section performed when loss of beat to beat variation was noted by cardiotocography when she was in spontaneous labour without Syntocinon infusion‐augmentation. This case was coded as a scar dehiscence although the tear had extended into the uterine wall and minimal bleeding had commenced. This case illustrates the difficulty with coding of these patients and therefore the difficulty in comparing incidences of ruptured uterus in series of patients having trials of scar. The comment quoted by the authors that ‘the fetal morbidity and mortality is low in patients with rupture of a previous Caesarean section scar’ is not a statement with which the Editor would agree. It should be noted that in 1 of the 9 cases in this Singapore series the infant died from fetal hypoxia presumably as a result of the uterine rupture. Likewise in Targett's series there were 16 women who sustained a ruptured uterus and 2 of the infants died from this complication alone.

Original languageEnglish
Pages (from-to)208-212
Number of pages5
JournalAustralian and New Zealand Journal of Obstetrics and Gynaecology
Issue number3
Publication statusPublished - 1992


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