Histologic and immunohistochemical studies of rectus sheath in obese patients

Obesity is a well-established risk factor for incisional hernia development. The exact causative factors have not been clearly defined, and development may result from structural disruptions in the connective tissue of the fasciae. The goal of this study was to compare the content of elastin in the rectus muscle sheath of obese patients and nonobese controls.

The study group consisted of 20 patients with body mass index over 35 kg/m(2) and the control group included 19 patients with normal-range body mass index. The biopsy specimens harvested during surgery were subjected to histologic evaluation, an immunohistochemical reaction with monoclonal anti-elastin antibodies, and the DAB chromatic reaction. The photomicrographs were evaluated using ImageJ software and the percentage of the area affected by the color reaction was assessed. A statistical evaluation was performed.

The specimens harvested from persons in the control group showed in hematoxylin-eosin staining a high density of fibrous elements, arranged in regular bundles. In specimens obtained from the morbidly obese, the density of the fibers was lower and their architecture was disrupted; the bundles were thinner and less regularly arranged. Most photographs show adipose tissue infiltrating the structure of the fascia. Statistical analysis of the percentage of the area occupied by elastin showed a statistically significant difference in favor of the controls.

The quantitative and qualitative changes in the elastin content of rectus abdominis muscle sheath fascia in the obese population may indicate a possible local mechanism influencing the development of incisional hernias.