Endometriosis is defined as the growth of endometrial glands and stroma outside the uterine cavity [1]. Pelvic endometriosis is commonly found at pelvic peritoneum, on the surface of the uterus, adnexa and also intestinal serosa [2,3].

The most common site of extrapelvic endometriosis is intestine. Most of these lesions are asymptomatic and often diagnosed at operative time [4,5]. Sometimes, patients with intestinal endometriosis might present with non specific symptoms such as colicky pain, nausea, vomiting, constipation and gut obstruction [6]. Classically, the symptoms get worse during menses.

Intestinal endometriosis occurs in 5-15% of endometriosis patients [1,7,8]. The common sites of intestinal endometriosis are rectosigmoid area (72%), rectovaginal septum (13%), small intestine (7%), caecum (3.6%) and appendix (3%) [9,10].

Many of intestinal endometriosis patients present with gastrointestinal symptoms; therefore, radiological examination and endoscopic examination of the intestinal tract are usually performed as the initial investigation [11]. The results often lead to misdiagnosis as various inflammatory lesions or tumor of intestine [11,12,13].

If intestinal endometriosis is identified, complete excision of the lesion offers good long term symptomatic relief. In some cases, segmental resection of the intestine might be performed for complete removal of all lesions [4].

A 36 years old woman presented with difficult defecation for a year. She neither had hematochezia nor other gastrointestinal symptoms. She had regular menstruation without dysmenorrhea. Her past history revealed an uncomplicated cesarean section 15 years ago. She neither used hormonal contraception nor other medications. After completion of history taking and physical examination, colonoscopy was performed by a colorectal surgeon. The result of colonoscopy suspected intramural mass at sigmoid colon and biopsy was performed. The histopathological result of the biopsy specimen showed nonspecific change (Figure 1). Therefore, the whole abdominal CT scan was performed and heterogeneous enhancing mass at anterior wall of sigmoid colon and focal eccentric wall thickening at distal sigmoid colon were identified. Moreover, multiloculated cystic lesions in both adnexa and multiple small round shape hypodensity lesions (less than 1.5 cm) in both lobes of liver were identified.

Figure 1: Histopathology of colonic biopsy shows normal-appearing colonic mucosa with non-specific change. (Hematoxylin and Eosin stain x 100).

The patient was counseled for surgical intervention because the sigmoid colon cancer was suspected. Hand assisted laparoscopic sigmoidectomy was performed and a gynecologist was consulted for evaluation and management of the adnexal mass in the same operation. Operative finding revealed an intramural sigmoid colon mass which was 3 x 4 cm in diameter. The uterus was globular shaped and enlarged 10 week size. There was a right ovarian cyst 5 centimeter in diameter contained chocolate colored content. Cul-de-sac was obliterated and multiple brown spots were scattered on pelvic peritoneum. Uneventfully, total hysterectomy with bilateral salpingo-oophorectomy was performed by the gynecologist and sigmoidectomy with end to end anastomosis was performed by the colorectal surgeon in the same operative session. The histopathological study showed adenomyosis of the uterus, pelvic endometriosis, a right ovarian endometriotic cyst, and endometriosis of the sigmoid colon. The endometriotic foci involved nearly entire wall of the sigmoid colon except for colonic mucosa (Figure 2A and 2B). The endometrial stroma within the endometriotic foci was highlighted by immunostaining for CD10 (Figure 3A and 3B).

Figure 2a: Intramural thickening of the sigmoid colon (Gross).

Figure 2b: The endometriotic foci involving nearly entire thickness of the colonic wall with sparing colonic mucosa (Hematoxylin and Eosin stain x 20).

Figure 3a: The presence of benign endometrial glands and the stroma within submucosa (Hematoxylin and Eosin stain x 100).

Figure 3b: The endometrial stroma within submucosa is demonstrated by specific monoclonal antibody of CD10 (CD10 immunohistochemical stain x 100).

There was no serious post-operative complication. During the follow up visit, the patient’s symptom showed satisfactory relief. She received post operative hormonal suppression with GnRH agonist for 6 months and adds back therapy. There was no evidence of recurrence until her recent visit.

Endometriosis is a common gynecological disorder with a multiple etiologies. Sampson theory and coelomic metaplasia are the most common etiologies to be considered. Endometriotic implants are most commonly found in the pelvis [14-16]. The gastrointestinal endometriosis is found 5-15% in women undergone laparotomy or laparoscopy for endometriosis related symptoms. The common site of involvement is the serosa or muscular layer of the gastrointestinal tract but the mucosa is rarely involved [17]. The symptoms of intestinal endometriosis include abdominal pain, bloating, gut obstruction and rectal bleeding [18]. Symptoms are cyclical in approximately 40% of the patients and usually aggravate during menses [19]. This patient had difficulty in defecation which was one of the intestinal endometriosis symptoms but she did not have dysmenorrhea and her defecation problem was not aggravated by menstruation.

The preoperative diagnosis of intestinal endometriosis is not easy to be performed because its manifestation can be confused with other inflammatory diseases or tumor. An endoscopic biopsy has limited role because the mucosal layer is rarely affected by endometriosis [20]. Other diagnostic examinations such as CT scan, MRI and Barium enema have inconclusive benefits [21,22]. As in this patient, the investigations could not reveal the intestinal endometriosis and misled to sigmoid colon cancer.

Treatments of intestinal endometriosis depend on the clinical symptoms and operative findings. Resection of the affected intestine is needed for endometriosis related intestinal obstruction. After excision deeply infiltrated endometriosis lesions, 60-100% of patients have been reported an improvement in endometriosis related pain. Recently, there had been reports of successful laparoscopic management of intestinal endometriosis and deep infiltrated endometriosis. Non penetrating lesions can be excised and followed by estrogen suppression such as GnRH agonist or aromatase inhibitor [23,24], but the efficacy for treatment of intestinal endometriosis is unclear. In general, the definite treatment of endometriosis is removal of both ovaries and other affected lesions. The disease can recur, especially in those treated with cyclic hormonal replacement therapy [25]. In addition, the presence of malignancy should be ruled out from those lesions on affected organs [20]. Women who have severe or intestinal endometriosis should be treated in a center with expertise in this field [26].

 In this case, the operative findings revealed adenomyosis, ovarian endometriotic cyst and the lesion in the sigmoid colon involved entire muscular layer except mucosa. Those finding was most likely intestinal endometriosis. The histopathological examination was used to confirm the diagnosis. Sigmoidectomy and end to end anastomosis with total hysterectomy and bilateral salpingo-oophorectomy were performed as definite treatment for endometriosis. After the operation, the patient received GnRH agonist for 6 months with adds back therapy and no evidence of recurrence until report time (8 months).

Intestinal endometriosis should be considered for the differential diagnosis in reproductive age women with gastrointestinal symptoms. It may aggravate by menstruation. Some investigations and imaging for diagnosis of intestinal endometriosis still have inconclusive benefit. Multidisciplinary team approach is important for management intestinal endometriosis patients. Post-operative hormonal suppression may be required in some occasions.