To review, doctors have assumed for many years that vertical (up-down) incisions would lessen the risk of infection and wound complications in very fat women by avoiding an incision in the moist area underneath the belly. This was based more on assumptions than on real evidence, but it was taught as a medical truth for many years.
However, a number of recent studies have shown poorer outcomes with vertical incisions, showing the need to re-evaluate this medical teaching. Yet some doctors still believe and promote that a vertical incision is necessary in high-BMI women.
New Study
This study reaffirms (yet again) that vertical incisions do NOT improve outcome.
It found that women who had a supraumbilical vertical incision experienced more blood loss, longer operating times, and nearly 25 times the risk of a classical cesarean, which is a far riskier uterine incision with long-lasting implications for future pregnancies.
In addition, the study showed that doing a vertical incision did NOT reduce the risk for infection or other wound complication. In fact, although the difference did not rise to statistical significance (probably because of the small sample size), there was a clear trend towards more wound complications in the group with the vertical incision (19% vs. 8% in the horizontal incision group, a 2.7x risk after adjusting for confounders).
Discussion of Cesarean Incision Research
Many providers are catching on that vertical incisions generally result in poorer outcomes, even in the most obese women. I'm happy to report that there seem to be fewer women of size being pushed into classical cesareans purely because of weight, and that more educational institutions are teaching that low transverse (side-to-side) incisions are preferable in most cases, regardless of the woman's BMI.
Sadly, though, there are still some stubborn hold outs who insist that very obese women "need" a vertical incision, and some educational institutions and materials are still promoting this approach.
And it's important to note that even though fewer providers are using vertical incisions in obese women now, about 1 in 10 to 1 in 15 obese women having a cesarean are still being subjected to a vertical incision.
This flies in the face of the fact that the vast majority of research clearly indicates that vertical incisions carry more complications and often result in the risky classical uterine incision that has tremendous short- and long-term health implications for the mother.
Furthermore, research on vertical versus horizontal incisions in non-maternity abdominal incisions confirms the general superiority of horizontal incisions.
Some recent researchers are resisting the move towards low transverse incisions in women of size. They have claimed that the evidence is not yet conclusive on whether vertical or low-transverse incisions are better. They point out that most study samples are not randomized and do not rise to the "gold standard" research that is most desirable, and that some studies have not found a statistical difference in wound complications between incision types.
While the call for gold standard research is a legitimate concern, there have been enough studies that have found worse outcomes with vertical incisions that they should be curtailed while we wait for the results of a randomized controlled study. (There is a randomized study currently being conducted but it won't be finished for several years yet; if we wait until this study is finished and published before changing policy, many more high-BMI women will likely suffer major wound complications and associated morbidity by being subjected to vertical incisions in the interim.)
It's true that a few studies (like the one discussed today) have not found a statistical difference in wound complications between vertical and low-transverse incisions. However, if you read the full studies more closely, all found a strong trend towards worse outcomes in the vertical group. These differences simply did not rise to statistical significance because of the small sample sizes involved, not because results were truly equivalent.
It's also important to point out that not a single study has found improved outcomes with vertical incisions. If vertical incisions really resulted in superior outcomes, that trend would be clear, and it most definitely has not been. Instead, the trend is markedly in the other direction and only fails to be clear because of the small sample sizes in some studies.
Clearly, more research needs to be done. But in the meantime, considering the strong trend in the existing research, vertical incisions should be reserved only for times when it is truly medically indicated (certain placental presentations, certain fetal positions, extremely emergent situations, etc.).
Bottom line, vertical incisions should NOT be done routinely simply because a woman has a high BMI.
It's time for all the educational institutions and clinicians to acknowledge this and adjust their teaching and practices accordingly.
Reference
J Pregnancy. 2013;2013:890296. doi: 10.1155/2013/890296. Epub 2013 Nov 20. The effect of cesarean delivery skin incision approach in morbidly obese women on the rate of classical hysterotomy. Brocato BE1, Thorpe EM Jr1, Gomez LM1, Wan JY2, Mari G1. PMID: 24349784 (Free full text can be found here.)
OBJECTIVE: To assess the risk of classical hysterotomy and surgical morbidity among women with a body mass index (BMI) greater than 40 kg/m(2) who underwent a supraumbilical incision at the time of cesarean delivery. METHODS: We conducted a retrospective cohort study in women having a BMI greater than 40 kg/m(2) who underwent a cesarean delivery of a live, singleton pregnancy from 2007 to 2011 at a single tertiary care institution. Intraoperative and postoperative outcomes were compared between patients undergoing supraumbilical vertical (cohort, n = 45) or Pfannenstiel (controls, n = 90) skin incisions. RESULTS: Women undergoing supraumbilical incisions had a higher risk of classical hysterotomy (OR, 24.6; 95% CI, 9.0-66.8), surgical drain placement (OR, 6.5; 95% CI, 2.6-16.2), estimated blood loss greater than 1 liter (OR, 3.4; 95% CI, 1.4-8.4), and longer operative time (97 ± 38 minutes versus 68 ± 30 minutes; P < .001) when compared to subjects with Pfannenstiel incisions (controls). There was no difference in the risk of wound complication between women undergoing supraumbilical or Pfannenstiel incisions (OR, 2.7; 95% CI, 0.9-8.0). CONCLUSION: In women with a BMI above 40 kg/m(2), supraumbilical incision at the time of cesarean delivery is associated with a greater risk of classical hysterotomy and operative morbidity.
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