Large bowel obstruction secondary to endometriosis

I Singh, G Trotter, M Shahabdeen FRCS, J B Schofield

Key words: Endometriosis, bowel obstruction.

Abstract

Endometriosis is a common benign condition, which does not commonly cause large bowel obstruction. We present two patients with endometriosis who had cyclical pelvic pain and subsequently developed intestinal obstruction requiring surgical intervention. We found that MRI was helpful in making the diagnosis.

INTRODUCTION

Endometriosis is a benign gynaecological condition, which usually causes relatively mild symptoms. We present two patients with endometriosis who had cyclical pelvic pain and subsequently developed intestinal obstruction requiring surgical intervention.

CASE 1

A 31 yr old female presented with a history of cyclical premenstrual lower abdominal pain, vomiting and diarrhoea. On this occasion the pain was more severe and there were clinical features of large bowel obstruction. A gastrograffin enema confirmed the presence of obstruction at the rectosigmoid junction and an ultrasound scan demonstrated the presence of left hydro-uretero-nephrosis.

A Hartmann's procedure was carried out and the left ureteric stricture was initially stented followed by reimplantation of the ureter into the bladder. Colonic continuity was subsequently established.

The histology showed a cystic deposit of endometriosis within the bowel wall at the recto-sigmoid junction. The patient was later treated with the LHRH analogue Goserelin, followed by Danazol with symptomatic improvement.

CASE 2

A 34 year old lady first presented with abdominal pain in 1998, when a clinical diagnosis of 'non-specific' abdominal pain was made. As the pain did not settle she underwent laparoscopy and a left ovarian cystectomy. Subsequently, a laparotomy was performed for recurrent abdominal pain, where only fibrous adhesions were found. In 1999 she suffered further attacks of abdominal pain and dysmenorrhoea and underwent transabdominal hysterectomy and bilateral salpingo-oophorectomy. Histology showed parametrial endometriosis and she was treated with Zoladex and HRT. Over the next two years the patient experienced further attacks of intermittent colicky, lower abdominal pain associated with bloating and fresh rectal bleeding. A provisional diagnosis of inflammatory bowel disease was made. At colonoscopy a rectal stricture was seen, confirmed by CT and MRI (Fig 1).

Figure 1 MRI of the pelvis showing a mixed signal (MS) within the wall of the recto-sigmoid colon.

This was thought to be suspicious of malignancy, but colonoscopic biopsies were normal. Diagnostic laparotomy was performed and frozen section confirmed endometriosis. At this stage a defunctioning colostomy was performed. Colonic continuity was subsequently re-established with a low anterior resection. The left ureteric stricture was treated by temporary stenting at this stage. The operation was technically difficult due to extensive pelvic fibrosis. Histological evaluation of the anterior resection specimen confirmed endometriosis within the rectal wall with extensive mesorectal involvement (Fig 2).

Figure 2 H & E sections of normal endometrium (A) and bowel wall (B) showing islands of endometriosis within the muscularis propria

DISCUSSION

Large bowel obstruction most commonly occurs secondary to neoplasm or diverticulitis. Other causes include sigmoid volvulus, pseudo-obstruction, colonic intussusception, hernia and strictures due to radiation, inflammation or ischaemia. Endometriosis is an uncommon cause of large bowel obstruction.

Endometriosis is a common benign condition affecting 10-25% of women presenting with gynaecological symptoms. It is defined as the presence of functioning endometrial tissue outside the uterine cavity (1). This "ectopic" endometrial tissue continues to respond to ovarian hormones and undergo cyclical changes similar to that in the uterine endometrium. Cyclical bleeding from the endometriotic deposits often causes a local inflammatory reaction and fibrous adhesion formation (2). This fibrosis of the peritoneum, bowel wall and surrounding tissues can make surgery challenging.

Pelvic endometriosis can be found in the uterus, ovaries, fallopian tubes, pelvic peritoneum, bladder and bowel (3,4). Involvement of the colon has been reported in about 25% of patients with endometriosis (5,6). Other intestinal sites including appendix, small intestine and rectum (7,8) are less commonly affected. Clinical manifestations include bowel obstruction (9,10,11), rectal bleeding and abdominal pain. Females presenting with cyclical bowel dysfunction, rectal bleeding or abdominal pain should raise the suspicion of colorectal endometriosis, although a colonic neoplasm needs to be excluded. Malignant change in endometriosis is rare (12).

A thorough history is vital to help make the diagnosis. Colonoscopic biopsies are not always helpful as the endometriotic deposits are usually on the serosal surface or within the bowel wall and rarely involve the mucosa. MRI may be helpful in supporting the diagnosis as it generally demonstrates a mixed signal with thickened areas in the colonic wall but distinction from carcinoma is often difficult (13).

Treatment of endometriosis is generally medical (eg with Danazol). Surgery may be necessary after failed medical therapy, where there is a risk of bowel obstruction or suspicion of malignancy.

CONCLUSION

It is important that endometriosis is not overlooked in the differential diagnosis of large bowel obstruction.

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