Relevant Anatomy

The abdominal wall is composed of many layers including the skin, the fat below the skin and, finally, the abdominal muscles. The fatty layer is subdivided into two layers by a thin but very strong layer of tissue called a fascia. This fascia layer is used to tighten the skin without putting undue tension on the scar itself.

The rectus abdominis muscles (“six-pack”) run side-by-side vertically in the midline. The tummy button, or umbilicus, can be traced back from the skin surface down to the midline between the two rectus abdominis muscles.

With pregnancy and/or excessive weight gain, a number of anatomical changes occur. The two midline abdominal muscles separate from each other, reducing the efficiency of the abdominal muscular system, and causing decreased definition of the abdomen. In extreme cases, the abdominal contents can cause a bulge between these two muscles through the stretched region.

The skin, which is also stretched with weight gain, has a limited ability to retract back again to its original size. Stretch marks are an indication that the skin has been either over-stretched or stretched too rapidly. The presence of extensive stretch marks indicates the skin in unlikely to ever retract back to its normal shape and size.