Cohen vs Pfannenstiel cesarean skin incision for body mass index ≥35 kg/m2: a randomized controlled trial

BACKGROUND

Maternal obesity is recognized as a significant risk factor for adverse pregnancy outcomes, including increased cesarean delivery rates and heightened surgical complications. It is unclear whether the Cohen or Pfannenstiel skin incisions for cesarean delivery are associated with different outcomes.

OBJECTIVE

This study aimed to evaluate the effect of a Cohen or Pfannenstiel cesarean skin incision on maternal morbidity.

STUDY DESIGN

Pregnant individuals with a body mass index of ≥35 kg/m², carrying either singleton or multiple pregnancies, were consented prenatally and in labor. Eligible participants who underwent a cesarean delivery between 24 and 41 weeks of gestation were randomized to either the Pfannenstiel or Cohen skin incision group at Thomas Jefferson University Hospital from October 2016 to March 2020. This study aimed to recruit 284 participants based on a sample size calculation, assuming a 50% reduction in wound complications with Cohen vs Pfannenstiel incisions (80% power; α=.05). However, recruitment was terminated early after 72 participants were randomized. The primary outcome was a composite maternal morbidity within 6 weeks, which consisted of the following: wound infection, hematoma, seroma, separation of skin of ≥1 cm, readmission for wound complications, endometritis, and postpartum hemorrhage. Statistical analyses included bivariate tests, t tests, and nonparametric analyses.

RESULTS

Of 331 pregnant individuals who consented prenatally and in labor, 72 eventually underwent cesarean delivery and were randomized, 34 to the Cohen skin incision group and 38 to the Pfannenstiel skin incision group. The mean body mass index was >42 kg/m². Approximately two-thirds of the patients had a pannus, 56% of the patients were Black, 47% of the patients had diabetes mellitus, and 56% of the patients had hypertensive disorders. The primary outcome of composite maternal morbidity occurred in 47.1% of patients in the Cohen incision group and 36.8% of patients in the Pfannenstiel incision group (risk ratio, 1.24; 95% confidence interval, 0.71–2.08) and was similar regardless of the presence of a pannus or degree of obesity. Surgical site infection, hematoma, seroma, wound separation/dehiscence, endometritis, and postpartum hemorrhage were similar between the Cohen and Pfannenstiel groups. In addition, neonatal outcomes were similar between the Cohen and Pfannenstiel groups, except that the Cohen incision group was found to have a statistically significantly lower Apgar score at 5 minutes and a higher need for respiratory support than the Pfannenstiel incision group, possibly related to the trend for a longer time from skin incision to delivery. Physicians were found to be significantly less satisfied with the Cohen incision than the Pfannenstiel incision.

CONCLUSION

In pregnant patients with a body mass index of ≥35 kg/m², obstetrical providers can choose from either a Cohen or Pfannenstiel skin incision, as they are generally associated with similar outcomes, except for lower Apgar scores and lower physician satisfaction associated with the Cohen incision. Our findings are limited by the trial's early cessation for logistical reasons, leading to an underpowered analysis. It is crucial to acknowledge that the results must be interpreted cautiously because of the reduced sample size. Our data can inform future trial design and implementation and fuel individual patient-level meta-analyses on this topic.