Relationship between body mass index and operative time in women receiving immediate postpartum tubal ligation.

Objectives: The aim of the study was to (1) assess the relationship between body mass index (BMI) and operative time during immediate postpartum tubal ligation procedures and to (2) determine whether operative time is non-inferior in women with BMI ≥30 versus women with BMI <30 and in women with BMI ≥40 versus women with BMI <40.

Study Design: We conducted a retrospective cohort study of women who received immediate postpartum tubal ligations following vaginal delivery from 2013 to 2017 at a university hospital. We abstracted demographic information, patient and procedural characteristics, and clinical outcomes. We assessed the relationship between BMI and operative time via linear regression. We also conducted non-inferiority analysis to determine whether the mean operative time in women with BMI ≥30 was non-inferior to the mean operative time in women with BMI <30, within a non-inferiority margin of 10 min. We compared intraoperative and postoperative complications in the two groups.

Results: A total of 279 women were included for analysis, among whom N=79 (28%) had a BMI of 25-29.9 and N=171 (61%) had a BMI ≥30. Demographic characteristics were similar in both groups. We found that operative time increased by 35 s for each one-point increase in BMI (p<.01). Although mean operative time was 46.1 min (n=171; 95% CI 43.7, 48.6 min) for women with BMI ≥30 and 40.6 min (n=108; 95% CI 37.9 min, 43.4 min) for women with BMI <30, (p<.01), it was non-inferior within a 10-min margin. There was no difference in rates of intraoperative or postoperative complications, incision length, total anesthesia time, and median length of stay between women with BMI ≥30 and BMI <30.

Conclusion: There is a small increase in postpartum tubal ligation operative time with increasing BMI. However, among women who received immediate postpartum tubal ligations at our institution, women with BMI ≥30 versus BMI <30 had operative times that were non-inferior within a 10-min margin.

Implications: While increasing body mass index slightly increases the operative time for immediate postpartum tubal ligations, this increase in time does not appear to be clinically significant.