Endometrioma Causing Near-Complete Obstruction of the Sigmoid Colon

Endometriosis is characterized by extra-uterine endometrial gland and stroma implantation. Intestinal endometriosis is believed to affect about one-third of patients with endometriosis ⁴ ; 72-95% of patients experience recto-sigmoid involvement.^2,3 Occasionally, endometriotic lesions precipitate mass effect or infiltrate the bowel wall, mimicking a neoplasm. In the index case, we evaluated a G0P0 41-year-old perimenopausal female with near obstructing sigmoid endometrioma, clinically presented, investigated, and managed in the lines of sigmoid colon carcinoma. Computed Tomography revealed marked distention of the distal descending and proximal sigmoid colon to the level of a [possible] intraluminal mass. CA-125 was 247.4. Transvaginal ultrasound revealed a heterogeneous irregularity adjacent the left adnexa. Flexible sigmoidoscopy to 12-15 cm was unable to pass liquid or visualize the lumen secondary to extrinsic colonic obstruction. She underwent exploratory laparotomy with sigmoidectomy, oversew of rectal stump, and descending colostomy. Left fallopian tube and ovary were adherent to sigmoid mass, therefore, removed en-bloc. Histopathological report revealed extensive endometriosis involving the muscularis propria and serosal surface of colon and ovary, with fibrinous serosal adhesions of the sigmoid colon. While inconsistent clinical presentation, similar radiographic features, and colonoscopy with other inflammatory or malignant lesions of the bowel makes the preoperative diagnosis challenging, colonic endometriosis is to always be considered as one of the differential diagnoses in reproductive age women with patterned, cyclic gastrointestinal symptoms, and intestinal masses of uncertain etiology or diagnosis.