A 25 year-old woman with a 15 year history of refractory ulcerative colitis on maintenance azathioprine, and mesalazine, presented with several months of increasing colicky abdominal pain and distension, bloody diarrhea and malaise. Symptoms failed to respond to repeated courses of steroids and were worse around her period. On physical exam, her abdomen was mildly distended with tenderness to deep palpation in the left lower quadrant with normal bowel sounds.
Colonoscopy revealed florid changes of ulcerative colitis in the rectum with mucosal hemorrhage and colonic stricturing at the recto-sigmoid junction preventing full colonoscopy (Figure 1). Histology of biopsy specimens taken from the area of stricture showed areas of ulceration with underlying inflamed granulation tissue consistent with ulcerative colitis. There were no granulomata, dysplasia or malignancy. Laboratory analysis revealed mild neutrophilia and mild elevation of inflammatory markers.
As her abdominal pain, distension and bleeding became increasingly severe, she was referred to a colorectal surgeon who performed laparoscopy which revealed extensive pelvic endometriosis that had obliterated the Pouch of Douglas and fused the rectum to the back of the uterus. A laparoscopic-assisted proctocolectomy and W pouch with ileostomy and radical excision of pelvic endometriosis including Pouch of Douglas was performed. Histology of the resection specimen showed severe chronic ulcerative proctocolitis involving the rectum and sigmoid colon with moderate stricture formation with proximal colon dilatation, negative for malignancy. Extensive endometriosis was seen infiltrating the rectal wall (Figure 2) as well as the subserosal muscularis of the appendix.
This case illustrates that intestinal endometriosis can mimic and co-exist with other intestina diseases, producing similar clinical symptoms and similar pathological changes. Intestinal endometriosis has previously been reported to cause proctitis with mucosal ulceration, rectal masses, colonic obstruction and strictures. In this case, this young woman had dual pathology and her endometriosis diagnosis was masked by the long standing diagnosis of ulcerative colitis. Indeed it was not suspected as both conditions can produce exacerbations around menstruation. Intestinal endometriosis is potentially missed with endoscopic biopsies as they usually involved the serosa and muscularis propria, sparing the mucosa and the majority of cases are diagnosed only after colectomy. Surgical intervention in this particular case has benefited in management of symptoms in both conditions. It is therefore important to consider a differential diagnosis of intestinal endometriosis, especially in a young female who has distal, refractory inflammatory bowel disease.