The study’s primary outcome measure was a composite of wound complications seen within 6 weeks of delivery, including surgical site infection, whether superficial, deep, or involving an organ or tissue space; cellulitis; seroma or hematoma; and wound separation. Other maternal outcomes tracked in the study included postoperative length of stay, transfusion requirement, sepsis, readmission, and death.
Cesarean-specific secondary outcomes included operative time and time from skin incision to delivery, estimated blood loss, and any incidence of hysterectomy through a low transverse incision. Neonatal outcomes included a 5-minute Apgar score of less than 7, umbilical cord pH of less than 7, and neonatal ICU admissions.
Dr. Mars said that the goal enrollment for the study was 300 patients, to ensure adequate statistical power. However, they found enrollment a challenge, with low consent rates during the defined time period from October 2013 to May 2017. They shifted their statistical technique to a Bayesian analysis, taking into account the estimated probability of treatment benefit.
Using this approach, they found a 59% probability that a Pfannenstiel incision would lead to a lower primary outcome rate – a better result – than would a vertical incision. This result just missed the predetermined threshold of 60%, said Dr. Marrs.