Every few months, a patient comes to see me with concern about a bulge in the middle of their belly that typically occurs only when they're sitting up or doing something else that puts pressure on the abdomen. They are often worried about cancer, a muscle tear, or a hernia. Fortunately, it is usually none of these.
The condition I'm describing, called diastasis recti, is surprisingly common, and carries absolutely no health risks whatsoever. Let's go over some definitions and learn a little anatomy, to help you understand this phenomenon better.
The word diastasis refers to a split or widening between two body parts that are normally attached to each other. Recti refers to the rectus abdominus muscles, which are the "six-pack" muscles that run down the middle of our bellies. Their main job is to help us sit up from a lying-down position and to perform any other tasks that require curling the abdomen forward.
The rectus abdominus muscles are fused in the midline by a band of connective tissue, called the linea alba (literally "white line"). You can find images of these structures here.
In diastasis recti, the linea alba gets stretched, allowing the two sides of the rectus abdominus muscles to separate from each other. This spreading apart of the rectus muscles typically isn't much of a problem. The muscles can usually still do the job of helping us sit up without difficulty. However, the widening and weakness of the linea alba between these muscles allows the intestines inside the abdomen to bulge out a little bit (sometimes a lot), especially when there is more pressure on the belly.
The bulge looks somewhat like a football, narrower at the top and bottom. The location is always in the exact midline of the belly, usually starting at or above the belly button and extending as high up as the breast bone. The size of the bulge depends upon how wide and how long the stretch is between the two sides of the rectus muscles. Sitting up, doing crunches, blowing a horn, straining to pass a bowel movement, or anything else that increases abdominal pressure might make the bulge appear. It disappears again as soon as the pressure is released.
The description above of intestines bulging may sound to many people like a hernia. Hernias, however, occur when an organ (in this case, the intestine) actually pokes through a hole or opening in its usual lining. The critical distinction between a hernia and diastasis recti is that diastasis involves stretching of the linea alba, not tearing or making an actual hole.
Hernias can cause a variety of uncomfortable symptoms by inhibiting normal function and by pressing on other body parts. The most worrisome possible complication of an intestinal hernia is strangulation, when a segment of the bowel gets twisted around in the hernia sac, cutting off its own blood supply and requiring emergency surgery.
Since diastasis recti involves no opening in the abdominal wall, there is no possibility of strangulation. And since the bulge occurs towards the outside of the body, it doesn't press on any other organ, and therefore doesn't cause any symptoms.
Diastasis recti occasionally occurs in newborn babies, who typically outgrow it without any problem. Adults get this condition when the abdomen has been under significant strain or pressure. The most common causes are pregnancy (with especially large babies or twins), obesity, and aggressive weight-lifting regimens. Losing weight and reducing activities that involve abdominal straining can decrease the degree of bulging, but they are unlikely to correct the underlying problem.
Some people recommend exercises to try to move the rectus abdominus muscles back into their normal midline position. Those are certainly safe to try, but I am not convinced that they actually accomplish their stated goal. Surgery can be performed to bring the muscles back to the midline; however, surgery always involves some risks and costs, which are hard to justify if a significant medical problem is absent.
Diastasis recti can be very scary when first discovered, but it is usually nothing more than a cosmetic concern, and I am always happy to reassure my patients that no treatment is required.
