What is the precaecocolic fascia?

The precaecocolic fascia, previously known as Jackson's membrane, is a variable vascular peritoneal fold between the ascending colon and the right posterolateral abdominal wall. First described in 1913, it was originally thought to be of developmental or inflammatory origin and associated with abdominal pain. This investigation aimed to review its frequency, form and structure and look for evidence of association with malformation of the bowel, or previous inflammation. 26 dissecting room cadavers were studied to identify the precaecocolic fascia, any malrotation of the colon or signs of previous inflammation: adhesions, surgical scars, or absence of the appendix. Its structure was examined histologically and latex injections were used to trace the arteries. Membranes comparable with previous descriptions of the precaecocolic fascia occurred in 12 of 26 abdomens. They varied in form and size from long and translucent to short, thick, and opaque. In structure, the fascia resembled a fold of peritoneum containing a thickened fibrous lamina. Large thin-walled arteries in the fascia crossed the arteries in the wall of the colon at the point of attachment. No significant association with colonic malrotation or markers of previous inflammation were found. Attention should be paid to the definition of the precaecocolic fascia and "membrane" seems a more appropriate term than "fascia". It is one of a recognized group of peritoneal folds/bands, doubtful in origin but unlikely to be post-inflammatory. It may modify colonic mobility or complicate colonic operations.