Wound complications frequency similar in different incisions of cesarean surgery in morbidly obese women

The type of skin incision most frequently used at the time of cesarean delivery is a Pfannenstiel skin incision; however, a different type of incision may be used due to surgeon preference, surgical history or previous alternative type of abdominal incision used, abdominal habitus, and gestational age.

Pfannenstiel skin incision poses challenges to the surgeon when the patient is obese. First, the pannus likely hangs over the lower abdomen and suprapubic area. This can cause difficulty during the cesarean delivery due to inadequate exposure, and it may create a moist, warm environment that promotes bacterial proliferation in the postoperative period. Second, excess subcutaneous tissue beneath the skin incision has altered blood flow and immune response, in addition to harboring a potential dead space that promotes development of seromas and hematomas; these can be a source of infection. Third, obese patients are more likely to have metabolic disorders such as diabetes, prediabetes, and metabolic syndrome, which can affect wound healing and increase the risk of infection.

Alternative skin incisions that are most commonly used include infraumbilical vertical and supraumbilical vertical skin incisions. A vertical skin incision is less cosmetic than a Pfannenstiel skin incision and may be more painful in the immediate postoperative recovery period, but the data are conflicting as to whether wound complication rates are higher in obese patients who undergo cesarean delivery using a Pfannenstiel skin incision or vertical skin incision. Martin et al conducted a study in morbidly obese women undergoing cesarean delivery to compare outcomes until 42 days postpartum. Authors hypothesized that Pfannenstiel skin incision would incur more postoperative wound complications when compared with vertical skin incision, and supraumbilical vertical skin incision would result in the lowest frequency of complications.

They assembled a retrospective cohort of patients with body mass index (BMI) of 40 or higher who delivered by cesarean between July 2012 and May 2019. The primary outcome was a composite wound morbidity (until 42 days postpartum) including wound separation, infection, and dehiscence. Secondary outcomes included individual composite components plus select maternal and neonatal outcomes.

A total of 3,901 patients were included. To account for imbalances in demographics between exposure groups, vertical and Pfannenstiel skin incision patients were matched in a 1:4 fashion for age, BMI, smoking status, and diabetes.

The frequency of wound morbidity was 13.2% overall. There was no difference in the primary outcome when comparing Pfannenstiel with vertical skin incision (adjusted odds ratio [aOR] 1.5, 95% CI 0.8–2.8).

Patients with a vertical skin incision weremore likely to undergo vertical hysterotomy (aOR 138.7, 95% CI 46.9–410) and transfusion (aOR 5.4, 95% CI 1.8–16.5).

When vertical skin incision was classified into supraumbilical and infraumbilical, and compared with Pfannenstiel skin incision, infraumbilical vertical skin incision was associated with increased wound morbidity (odds ratio [OR] 2.46, 95% CI 1.4–4.5) and wound infection (OR 2.5, 95% CI 1.4–4.6) compared with Pfannenstiel.

Both types of vertical skin incision were associated with increased odds of vertical hysterotomy and transfusion when compared with Pfannenstiel.

In this study, frequency of postoperative wound complications was not increased according to type of skin incision, when comparing Pfannenstiel with vertical skin incision, in morbidly obese women undergoing cesarean delivery. When vertical skin incision was subclassified into two strata according to incision location above or below the umbilicus, increased risk of postoperative wound morbidity was noted only in patients who had an infraumbilical vertical skin incision and not in those who underwent supraumbilical vertical skin incision. This finding could be due to lack of power from a small sample size undergoing each type of vertical skin incision; however, it could also suggest that conclusions should not be drawn regarding type of skin incision when all vertical skin incisions are considered together, but rather should be considered separately according to their location above or below the umbilicus.

Vertical hysterotomy was more likely in patients undergoing vertical skin incision, especially supraumbilical vertical skin incision. Although this could be a function of gestational age—gestational ages were lower in the vertical skin incision group of this study, and vertical hysterotomy is typically used more frequently at earlier gestational ages—this finding could also be explained by the fact that it is technically difficult to perform a low transverse hysterotomy after supraumbilical skin incision due to the distance between the skin incision and the lower uterine segment. Regardless, the potential benefit gained from fewer wound complications after supraumbilical vertical skin incision may come at the expense of increased odds of vertical hysterotomy and the implications on future childbearing should be considered.

This study is unique in the methods because outcomes were followed for 42 days postpartum, which is clinically important because postoperative wound complications are most likely to arise after discharge from delivery admission until 6 weeks after delivery.

"In summary, in our retrospective cohort, frequency of postoperative wound complications was not associated with type of skin incision in morbidly obese women undergoing cesarean delivery. Relatively few women in the cohort underwent vertical skin incision and this limited our statistical power to demonstrate a statistically significant difference in outcomes between groups. This is reflected in the imprecision of our estimates, for example, the 95% CI surrounding the adjusted odds ratio suggests that patients who have a vertical skin incision may have a 20% decrease to a 280% increase in the primary outcome. Thus, large, high-quality randomized trials are needed to definitively answer the question of the optimal incision type in obese parturients."

Source: Martin et al; Cesarean Delivery Skin Incision in Obese Patients; (Obstet Gynecol 2022;139:14–20), American College of Obstetricians and Gynecologist

DOI: 10.1097/AOG.0000000000004630