The prediction of “controlled” uterine rupture by the use of intrauterine pressure catheters

Objective: To determine whether uterine activity, assessed by either fluid-filled or solid pressure catheters, changes with uterine incision at cesarean delivery. Methods: Uterine activity was recorded continuously during low transverse cesarean delivery in ten parturients using fluid-filled pressure catheters and in ten women with solid pressure catheters. Visual analyses were performed of the last 30 minutes of uterine recording before uterine incision and of the period after incision; the analyses were then compared within and between the catheter groups for mean uterine tone and contraction amplitude, frequency, and duration. Oxytocin use, anesthesia method, mean gestational age, birth weight, length of labor, duration of monitoring, and uterine incision-to-delivery time were compared between the groups. Results: All obstetric end points were similar in both catheter groups except for a higher mean birth weight in the solid-catheter group. The mean (± standard deviation) duration of post-incision monitoring was 4.7 ± 0.94 minutes. After uterine incision, mean tone and contraction amplitude were unchanged, whereas mean contraction frequency and duration decreased significantly. Conclusions: Though intrauterine monitoring was brief, this model allows a unique view of “controlled” uterine rupture. Spontaneous uterine rupture may evolve more gradually; however, neither catheter type would be likely to aid its early recognition.