The accuracy of catheter-tip pressure transducers for the measurement of intrauterine pressure in labour

Abstract

Objective: To assess the reliability of intrauterine pressure measurements in labour with transducer tipped catheters. Design: Prospective clinical study. Setting: Delivery ward, National University Hospital, Singapore. Subjects: 20 women admitted in early labour were randomly allocated to two groups. Interventions: Women in the first group had two catheters that had been tied together introduced transcervically into the same amniotic fluid pocket. The second group had two catheters introduced in different directions so that each catheter tip was in a different pocket of amniotic fluid. Main outcome measure: The contraction to contraction pressure difference recorded by the two catheters in the same uterus. In addition, the cumulative uterine active pressure generated by one catheter was compared with that of the other. Results: There were differences in peak pressure of up to 4-5.3 kPa (30-40 mmHg) during some contractions. The difference in pressure recordings between the two catheters could not be explained by effects of loculation of amniotic fluid. However, the pressures recorded were not systematically higher in one catheter than in the other. Cumulative uterine activity was very similar when assessed by each catheter in the same uterus. Conclusion: Intrauterine pressure measurements using transducer tipped catheters provide reliable information on the cumulative pressure wherever the catheter tip was sited in the uterus, but there are variations in pressures recorded during individual contractions.