Objective measurement of uterine tone using a handheld hardness meter during cesarean delivery: comparison with manual palpation.

To ensure adequate uterine contractions, oxytocin is routinely administered after fetal delivery during cesarean delivery and additional dosing is typically guided by palpation-based assessment. However, manual palpation is subjective and has limited reproducibility and interobserver consistency. The PEK-MP® is a handheld device that quantifies tissue hardness and may provide an objective intraoperative assessment of uterine contraction. This study aimed to examine the relationship between PEK-MP measurements and palpation-defined uterine tone (sufficient vs. insufficient). In this secondary analysis of a randomized controlled trial, 63 paired data points from 21 patients who underwent elective cesarean delivery were analyzed. Uterine fundal hardness was measured at 3, 5, and 9 min after oxytocin administration by obstetrician-performed palpation. In the primary linear mixed-effects model adjusted for measurement timepoint, the estimated difference in PEK-MP values between the palpation-defined groups (sufficient minus insufficient) was 6.3 (95% CI - 1.0 to 13.6; p = 0.094). The measurement timepoint was significantly associated with PEK-MP values, with lower values observed at later assessments. These findings suggest that quantitative hardness measurements may be subject to temporal variation and that the timing of assessment should, therefore, be taken into account when interpreting these values.