Objective: To compare the rate of extramembranous placement between 2 types of intrauterine pressure catheter.
Study design: Women were randomized to a transducer-tipped intrauterine pressure catheter or an air-coupled intrauterine pressure catheter from October 1998 to August 1999. Women were eligible for the study if their attending physicians decided to place an intrauterine pressure catheter. Our primary outcome variable was extramembranous placement. The intrauterine pressure catheter was left in place during cesarean delivery, and the position was documented.
Results: A total of 257 women entered the trial. Eight were excluded due to removal of the catheter before cesarean delivery, leaving 249 evaluable patients. Of those 249, 105 (44.3%) received cesarean delivery, with 41 in the air-coupled group and 64 in the transducer-tipped group. There were no significant differences in maternal age, gestational age, gravidity, duration of membrane rupture, birth weight, pharmaceutical drug use, cocaine use, oxytocin use or catheter removal due to poor function. The transducer-tipped catheter was placed outside the membranes significantly more frequently than was the air-coupled catheter (12.5% vs. 2.4%, p = 0.02).
Conclusion: Transducer-tipped catheters were significantly more likely to be placed in the extramembranous space than were air-coupled catheters.