In vitro myometrial contractility reflects indication for caesarean section

Abstract

Objective: To assess the extent to which in vitro measurements of myometrial contractility reflect the clinical indication for caesarean section.

Design: A prospective, observational hypothesis-generating study.

Setting: Women were recruited from Liverpool Women's NHS Foundation Trust and experiments were performed in the Physiology Department at the University of Liverpool.

Population: Myometrial samples were taken from women undergoing a caesarean section during labour (n = 50) or from women having a repeat nonlabouring caesarean section (n = 70).

Methods: The demographic characteristics of the women and indications for current and previous caesarean sections were recorded. The force, frequency and duration of spontaneous contractions of myometrial strips, and changes in the intracellular calcium concentration of the strips, were measured. Kruskall-Wallis and post hoc tests were used to assess the significance of differences between groups.

Results: Samples from women whose caesarean section was for fetal distress/acidosis (scalp pH <7.2) contracted with more force than those from women whose caesarean section was for delay in the first stage of labour (P < 0.001). For repeat, nonlabouring caesarean sections, samples from women whose first caesarean section was for fetal distress/acidosis also contracted with more force than did samples from women whose first caesarean section was for delay in the first stage of labour (P = 0.03).

Conclusions: These findings suggest that the myometrium contracts with greater force in women who have a caesarean section for fetal distress.