Every second, somewhere in the world, a baby is born by cesarean section, and a few quick stitches help decide that mother’s reproductive future. In a new review in the American Journal of Obstetrics and Gynecology, obstetricians Emmanuel Bujold of Université Laval and Roberto Romero of the U.S. National Institutes of Health argue that the most widely used technique for closing the uterus after cesarean delivery is biologically unsound and should be reconsidered in favor of a method that respects uterine anatomy.
Drawing on more than a century of experimental work, imaging studies, and modern clinical trials, the authors link common closure practices to a long list of downstream problems. After cesarean delivery, women face elevated risks of placenta attaching abnormally to the scar (up to about 6 percent in some groups), uterine rupture in later labors (up to roughly 3 percent), spontaneous preterm birth (up to 28 percent), pelvic pain, abnormal postmenstrual bleeding, and endometriosis or adenomyosis near the scar. The review’s central message is stark but simple: how surgeons close the uterus today can shape a patient’s pain, fertility, and pregnancy risk for years to come.
A Quick Closure With Lasting Consequences
For roughly 50 years, the dominant technique has been a single, continuous layer of sutures that runs through the full thickness of the uterine wall, including the endometrium, the inner lining of the uterus. Surgeons embraced it because it is fast, technically straightforward, and helps limit bleeding in the operating room. But histology, imaging, and biomechanical testing now show that this shortcut often produces a thin, fibrous scar that does not faithfully rebuild the layered structure of the uterine wall.
“Our position is that meticulous and adequate restoration of the uterine structure is more important than the speed of the procedure.”
When the endometrium is caught in the suture line, fragments of lining tissue can be driven into the muscle layer, where they may behave like misplaced islands of endometriosis. The scar can collapse inward into a niche, sometimes called an isthmocele, that traps menstrual blood and disrupts normal cycles. Over time, these defects have been tied to chronic pelvic pain, persistent spotting after menstruation, impaired fertility, and higher risks of placenta accreta spectrum disorders in later pregnancies, when the placenta invades deeply into or even through the scar. Large trials comparing single layer and double layer closures have often reported similar short term outcomes, but once researchers separate out the details of technique, a pattern emerges: scars are stronger and thicker when the endometrium is excluded from the first layer of sutures.
Rebuilding The Uterus Layer By Layer
Bujold and Romero synthesize this body of evidence into a clear set of surgical principles and a concrete alternative. Optimal closure, they argue, should imitate what is standard in bowel or stomach surgery, where the mucosal lining is kept out of the muscular suture line to prevent weak scars and fistulas. In the uterus, that translates into a three step repair. The first step approximates the junction between the lining and the muscle without actually catching the surface endometrium. The second step brings the bulk of the myometrium together, restoring wall thickness and distributing mechanical stress evenly along the scar. The third step reapproximates the superficial myometrium and serosa, smoothing the outer surface and limiting adhesions to surrounding organs like the bladder.
“Given the high frequency of cesarean and their long-term health consequences for women, finding solutions should be considered a public health priority.”
Evidence from animal models and human trials supports the logic of this layered repair. Experimental work has shown that muscle to muscle closure without endometrial inclusion produces fewer defects and thicker residual myometrium, while randomized studies report lower rates of scar niches and greater scar thickness when the first layer avoids the uterine lining. The proposed three step method is designed for cesareans performed before or in early labor, when the lower uterine segment is still thick enough for the layers to be distinguished. In very thin, stretched tissue, the authors suggest combining the first two steps into a single layer and then adding a superficial reinforcing layer to restore the surface.
The tradeoff is time. The standard single layer closure typically takes two to three minutes; the three step repair can take five to eight minutes, with only marginal additional blood loss. The authors argue that in an era when most cesareans are performed under regional anesthesia, those extra minutes are a small price to pay for a scar that is more likely to protect a woman’s future pregnancies, rather than endanger them. They call for new trials that focus not just on operative efficiency, but on what matters most to patients, including pain, bleeding, fertility, and serious complications like uterine rupture and abnormal placentation. With one in four births in Canada and roughly one in three births in many countries now occurring by cesarean, they conclude, improving uterine closure is not merely a technical debate inside the operating room; it is an urgent public health question.
American Journal of Obstetrics and Gynecology: 10.1016/j.ajog.2025.10.007
ScienceBlog.com has no paywalls, no sponsored content, and no agenda beyond getting the science right. Every story here is written to inform, not to impress an advertiser or push a point of view.
Good science journalism takes time — reading the papers, checking the claims, finding researchers who can put findings in context. We do that work because we think it matters.
If you find this site useful, consider supporting it with a donation. Even a few dollars a month helps keep the coverage independent and free for everyone.