A beltless tocodynamometer—a preliminary report

The clinical usefulness of a newly developed beltless external tocodynamometer system was evaluated in a group of 56 patients in active, early, premature, or false labor. The uterine activity records so obtained were compared with those made in the same patients using the tocodynamometer with belt (49 patients) and the intrauterine pressure catheter (seven patients). The records were classified as “usable” if the baseline was above zero and the peak of the recorded contraction was at least 15 mmHg above the baseline. Both systems were studied under similar clinical conditions. Overall, of the 7434 minutes of recordings in 49 patients using the beltless system, 7008 minutes (94%) were usable. In contrast, only 2515 out of 5667 minutes (45%) of recordings made with the belted system were usable (P < .001). Seven additional patients were monitored simultaneously with the beltless tocodynamometer and the intrauterine pressure catheter systems. Of the 1367 minutesʼ total monitoring time, the recovery rates of usable data for the beltless and intrauterine pressure catheter systems were 85 and 87%, respectively (P = not significant). These preliminary results indicate that the beltless system is a convenient, simple-to-use external tocodynamometric system that assesses uterine activity more efficiently than the belted system.