7 Assessment and management of uterine contractions

Abstract

The last decade has seen a marked rise in Caesarean section (CS) rates and a steady decline in perinatal mortality rates (PNMR), with limited evidence to suggest a causal relationship (O'Driscoll and Folley, 1983; Shearer, 1983). More recently, there has been a smaller decline in perinatal mortality rates, despite the continuing trend of rising CS rates both in the developed (Maternity Alliance, 1983; National Institute of Health (NIH) consensus statement, 1981) and developing countries (Arulkumaran et al, 1985a). Such a trend has been attributed to the obstetrician's concern to reduce perinatal morbidity, but parents' attitudes to a small family size, privatization of health care, and concern over litigation, have also contributed to increasing numbers of Caesarean births. The NIH consensus report from the USA and recent reports from the UK (Yudkin and Redman, 1986), have highlighted dystocia and previous CS as major contributory factors, fetal distress and breech presentation playing a more minor role in this increasing trend. The uterus, whilst contracting to effect delivery of the fetus, reduces the utero-placental blood supply intermittently resulting, at times, in fetal hypoxia necessitating an abdominal delivery. This complication is more likely when oxytocin is used injudiciously to augment weak uterine contractions. Hyperstimulation of the uterus, and its consequences, has become the commonest cause of litigation in obstetric practice in the USA (Fuchs, 1985). Owing to concern over this, or due to lack of understanding of augmentation of labour, oxytocin is not used, or is misused, in the management of abnormal labour, resulting in prolonged labour and probable CS for dystocia. These patients are subjected to repeat CS in their next pregnancy, thus increasing the CS rate further. Despite adequate evidence of uncomplicated vaginal deliveries in cases with previous CS, many centres practise routine repeat CS. Some permit labour in cases with previous lower segment CS if in spontaneous labour with normal progress, but are reluctant to augment abnormal labour. These attitudes are related to the difficulty in predicting and diagnosing scar dehiscence. In such situations, assessing levels of uterine activity and limiting excessive activity may be of value. The three management of problems of dystocia, fetal distress and previous CS are related to uterine contractions. A