Pneumatosis cystoides intestinalis: an unusual complication of jejunoileal bypass.

A case of pneumatosis cytoides intestinalis associated with jejunoileal bypass is reported. The association of increased colonic gas, secondary to fermentation of undigested lactose in the colon, and the reflux of the excessive gas into the excluded segment of small bowel and dissection of the gas into the bowel wall and mesentery are postulated as the causes of pneumatosis cystoides intestinalis in patients with jejunoileal bypass.