Cesarean section prior to 28 weeks' gestation: which type of uterine incision is optimal?

Objective: The purpose of this study was to determine the factors that influence physician preference for type of hysterotomy incisions in gravidas with a singleton or twin pregnancy undergoing cesarean section under 28 weeks, and to assess factors that result in delivery complications, defined as either intraoperative dystocia or hysterotomy extension. We hypothesized that compared to those with non-cephalic presentations, gravidas with a presenting fetus in cephalic presentation would have higher rates of low-transverse cesarean section, and reduced rates of delivery complications with low-transverse hysterotomy.
Methods: This was a retrospective cohort chart analysis of 128 gravidas between 23 0/7 and 27 6/7 weeks undergoing cesarean section at a single academic institution between August 2010 and December 2022. Data was abstracted for factors that might influence the decision for hysterotomy incision type, as well as for documentation of difficulty with delivery of the fetus or need for hysterotomy extension to affect delivery.
Results: There was a total of 128 subjects, 113 with a singleton gestation and 15 with twins. The presenting fetus was in cephalic presentation in 43 (33.6%), breech presentation in 71 (55.5%), transverse/oblique lie in 13 (10.2%), and not documented in 1 (0.8%). Sixty-eight (53.1%) had a low-transverse cesarean section (LTCS), 53 (41.4%) had a Classical, 5 (3.9%) had a low-vertical hysterotomy and 2 (1.6%) had a mid-transverse incision. There was a significantly higher rate of LTCS among gravidas with the presenting fetus in cephalic presentation (30/43, 69.8%) compared to those with breech (31/71, 43.7%) or transverse/oblique presentations (7/13, 53.8%), p = .03. No other significant associations were related to hysterotomy incision, including nulliparity, racially or ethnically minoritized status, plurality, indication for cesarean delivery, or pre-cesarean labor. Twenty (15.6%) subjects experienced either an intraoperative dystocia or hysterotomy extension. For the entire cohort, there was a greater median cervical dilatation in those with delivery complications (4.0 cm, IQR .5 - 10 cm) compared to those without complications (1.5, IQR 0 - 4.0), p = .03, but no significant association between delivery complications and fetal presentation, hysterotomy type, plurality, or other demographic/obstetrical factors. However, among gravidas undergoing low-transverse cesarean section, only 2/30 (6.7%) with cephalic presentations had a delivery complication, compared to 9/31 (29.0%) with breech presentations and 3/7 (42.9%) with a transverse/oblique lie, p = .03.
Conclusion: In pregnancies under 28 weeks, the performance of a low-transverse cesarean section was significantly associated only with presentation of the presenting fetus. Among those with cephalic presentations, the rate of intrapartum dystocia or hysterotomy extension was low after a low-transverse hysterotomy, suggesting that in this subgroup, a low-transverse cesarean section should be considered.