John M. Thorp Jr, MD, McAllister Distinguished Professor, Division Director, General Obstetrics and Gynecology, Vice Chair of Research, Department of Ob-Gyn, University of North Carolina Schools of Medicine and Public Health, Chapel Hill.
Five years ago one of our interns operating with the director of labor and delivery challenged him as to why we were not using evidenced-based surgical techniques for cesarean delivery. Bruised by the formidable (and at times misleading) club of “evidence-based medicine” that is held as sacrosanct by the modern obstetrician, the director responded to the charge by researching a systematic review on abdominal delivery that amalgamated studies of poor quality with precious few trials. He unilaterally decided that we needed an opening in the transparent portion of the drape overlying the incision site so that we might use “evidence” to prevent operative site infection. The end result: No change in the incidence of wound infections, and adhesive drapes that did not adhere well, thereby displacing the effluent of amniotic fluid and blood that are part of a cesarean delivery back into the first assistant’s socks, shoes, and clothing. It was as if the clock had been turned back to my early years as an attending when we had cloth drapes. So much for having an evidence-based protocol. I was thus elated at reading the results of the CORONIS trial.
Details of the study
The CORONIS trial, in which investigators randomly assigned almost 16,000 women from 7 countries (Argentina, Chile, Ghana, India, Kenya, Pakistan, and Sudan), used a sophisticated factorial design and followed up 13,153 (84%) of the women for 3 years. The investigators tested an array of technical questions about 5 intervention pairs used during abdominal delivery and reported the main outcomes of interest for each intervention, including:
- blunt versus sharp abdominal entry—no evidence of a difference in risk of abdominal hernias (adjusted risk ratio [RR], 0.66; 95% confidence interval [CI], 0.39–1.11)
- exteriorization of the uterus versus intra-abdominal repair—no evidence of a difference in risk of infertility (RR, 0.91; 95% CI, 0.71–1.18) or of ectopic pregnancy (RR, 0.50; CI, 0.15–1.66)
- single- versus double-layer closure of the uterus—no evidence of a difference in maternal death (RR, 0.78; 95% CI, 0.46–1.32) or a composite of pregnancy complications (RR, 1.20; 95% CI, 0.75–1.90)
- closure versus nonclosure of the peritoneum—no evidence of a difference in any outcomes relating to symptoms associated with pelvic adhesions, such as infertility (RR, 0.8; 95% CI, 0.61–1.06)
- chromic catgut versus polyglactin-910 sutures—no evidence of a difference in the main comparisons for adverse pregnancy outcomes in a subsequent pregnancy, such as uterine rupture (RR, 3.05; 95% CI, 0.32–29.29).
Strengths and limitations. The CORONIS trial included a large number of participants and had comprehensive follow-up, a rigorous data collection process, and the participation of many countries. The trial’s participating centers, however, were mostly large referral hospitals with high research interest; adverse outcomes might have been higher in other settings. As well, a lower incidence of subsequent pregnancy among participants limited the study’s power to detect differences in outcomes between the intervention pairs.
Conclusions. None of the alternative techniques produced any real benefits despite syntheses-suggested benefit reported in systematic reviews. Surgeon preference for cesarean delivery techniques likely will continue to guide clinical practice along with economic and institution factors.
A word to the wise: Evidence is not created equally, and pushing it into lumps does not increase its value.
--John M. Thorp Jr, MD
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