Bowel obstruction and pelvic mass

After reviewing the pathology findings (Figure 2), we diagnosed (d) deeply infiltrating gastroin- testinal endo metriosis. Foci of endometriosis were also identified in mesenteric lymph nodes (Figure 3). Endometriosis is characterized by the pres- ence of functional endometrial glands and stroma outside of the uterus. This common con- dition affects up to 10% of women of reproduc- tive age, most often involving the ovaries and utero sacral ligaments. Gastrointestinal involve- ment occurs in up to 34% of women with pelvic endometriosis. 2 The diagnosis of gastrointestinal endometriosis may be difficult to establish be - cause its symptoms are relatively nonspecific. Patients may present with abdominal pain, bloat- ing, tenesmus, dyschezia (painful bowel move- ments), rectal bleeding, diarrhea, constipation or obstruction. 3 The differential diagnosis is often broad; the main considerations include appen- dicitis, diverticulitis, inflammatory bowel dis- ease, irritable bowel syndrome and malignant disease. The incidence of endometriosis causing bowel obstruction is unknown, although com- plete obstruction occurs in less than 1% of pa - tients with gastrointestinal endometriosis. 4 The symptoms associated with gastrointesti- nal endo metriosis vary according to the depth and site of involvement. Disease of the small intestine usually manifests as abdominal pain, bloating and obstruction, whereas patients with colonic endometriosis are more likely to present with altered bowel habits (decreased stool cali- bre, diarrhea, constipation, hematochezia) and an abdominal mass. 5 Early in the disease process, symptoms may be associated with menses, with cyclical episodes present in 40% of patients with gastro intestinal involvement.6 Often, however, symptoms become continuous as the lesions infiltrate the bowel wall and lead to localized fibrosis, smooth muscle hypertrophy and luminal stenosis. Adding to the challenge of diagnosing gas- trointestinal endometriosis is the often false- negative result of endoscopic biopsies. The biop- sies tend to be superficial and miss the foci of endometriosis that are located in the deeper bowel layers. When deeply infiltrating gastroin- testinal endometriosis is suspected clinically, trans vaginal ultrasonography and MRI may prove valuable in reaching the diagnosis. With a sensitivity of 91% and a specificity of 97%, transvaginal ultrasonography is the first-line imaging modality for such patients. 7,8 Likewise, MRI detects invasive intestinal endometriosis Figure 2: Specimen from colon resection. Endo metriotic glands (arrows), stroma and accompanying hemorrhage (H) caused marked thickening of the bowel wall and luminal narrowing (hematoxalin–eosin stain, original magnification × 20). Figure 3: Mesenteric lymph node from colon resection showing foci of endo - metriosis (arrows) and hemorrhage (H) (hematoxalin– eosin stain, original mag- nification × 20). what-sobel_Layout 1 16/03/11 10:57 AM Page 687 Practice 688 CMAJ, April 5, 2011, 183(6) with a sensitivity of 88% and a specificity of 93%, and it may be useful when the results of ultrasonography are equivocal. 9 Although CA- 125 levels may be elevated in endometriosis, the test is primarily used as a tumour marker, with a sensitivity of 80% for advanced ovarian cancer. However, it has poor specificity and may be ele- vated in several benign and malignant conditions, including endometriosis and colon cancer. 10 Colonic masses with obstruction A clinical presentation of an abdominal mass and bowel obstruction in the context of worsen- ing gastrointestinal symptoms and equivocal diagnostic tests frequently raises the sus picion of gastrointestinal cancer. Negative findings on colonoscopy do not necessarily rule out malig- nant disease, because primary extraluminal neo- plasms and neoplastic changes arising from endometriosis (endometrioid adenocarcinoma and clear-cell adenocarcinoma) frequently involve only the outermost layers of the colon. The differential diagnosis of intramural gastroin- testinal lesions causing large bowel obstruction is shown in Table 1. 8,11,12 Although primary col- orectal lymphoma may also present as an extra- luminal mass, mucosal involvement often can be seen with colonoscopy.11 The presence of a colonic mass with intact mucosa can also indicate sigmoid phlegmon, the most common complication of diverticular dis- ease.11 Patients with acute diverticulitis tend to present with pain in the left lower quadrant of the abdomen, altered bowel habits, low-grade fever and mild leukocytosis. On pelvirectal examination, a tender mass may be palpable. Computed tomography is the diagnostic test of choice for acute diverticulitis. 11 In our patient, phlegmon was unlikely because of the absence of both colonic diverticula and signs of inflam- mation of the bowel wall on imaging. Management Endometriosis can be managed both medically and surgically. In its clinical practice guidelines on the treatment of endo metriosis, the Society of Obstetricians and Gynaecologists of Canada rec- ommends combined estrogen–progestin hor- monal contraceptives or progestin alone as first- line medical therapy. Gonadotropin-releasing hormone agonists and the levo norgestrel- releasing intrauterine device should be consid- ered second-line therapeutic options. Non - steroidal anti- inflammatory drugs and opioids may provide effective analgesia while awaiting symptom resolution from hormonal therapy. Surgery is generally reserved for refractory symp toms, severe invasive disease, infertility, pelvic mass or diagnostic uncertainty. 13 Management of gastrointestinal endometrio- sis depends on the extent of disease. The Ameri- can Congress of Obstetricians and Gynecologists Table 1: Differential diagnosis of intramural gastrointestinal lesions causing obstruction of the large bowel Condition Characteristics Deeply infiltrating endometriosis • Patients present with dysmenorrhea, chronic pelvic pain, deep dyspareunia and dyschezia • Symptoms are initially cyclical but may become continuous as the disease progresses • Diagnosis can be aided by transvaginal ultrasonography and MRI 8 Diverticulitis with sigmoid phlegmon • This condition is a complication of acute diverticulitis • Patients present with pain in the left lower quadrant, altered bowel habits and low-grade fever • In the acute phase, CT is often diagnostic, showing an inflamed soft-tissue mass 11 Gastrointestinal mesenchymal neoplasm* • Patients with this rare type of neoplasm present with nonspecific gastrointestinal symptoms (bloating, early satiety), bleeding, pain and symptoms of bowel obstruction • CT is the imaging modality of choice, showing a smoothly contoured mass 11 Colorectal lymphoma • Patients present with pain, weight loss and symptoms of an abdominal mass • Colonoscopy is often diagnostic, showing diffuse mucosal nodularity, induration, ulceration and a mass 11 Note: CT = computed tomography, MRI = magnetic resonance imaging. *Includes gastrointestinal stromal tumour, leiomyoma, leiomyosarcoma, lipoma, liposarcoma and schwannoma. what-sobel_Layout 1 16/03/11 10:57 AM Page 688 Practice CMAJ, April 5, 2011, 183(6) 689 recommend suppression of ovarian function with a gonadotropin-releasing hormone agonist as first-line medical treatment of extrapelvic endo - metriosis. For patients presenting with bowel obstruction or those with severely advanced intestinal disease, surgical resection is the treat- ment of choice. 7 Although there is no evidence supporting the use of preoperative medical sup- pressive therapy, a postoperative course of hor- monal therapy (three months or longer) is often prescribed for patients with residual disease or persistent pain, or to extend the pain-free interval after surgery. 7 We prescribed a gonadotropin- releasing hormone agonist for our patient. At the last follow-up visit, she was awaiting the rever- sal of her colostomy.

1. Le T, Giede C, Salem S, et al. Initial evaluation and referral guidelines for the management of pelvic/ovarian masses. J Obstet Gynaecol Can2009;31:668-73. 2. Kratzer GL, Salvati EP. Collective review of endometriosis of the colon. Am J Surg 1955;90:866-9. 3. De Ceglie A, Bilardi C, Blanchi S, et al. Acute small bowel obstruction caused by endometriosis: a case report and review of the literature. World J Gastroenterol2008;14:3430-4. 4. de Bree E, Schoretsanitis G, Melissas J, et al. Acute intestinal obstruction caused by endometriosis mimicking sigmoid carci- noma. Acta Gastroenterol Belg1998; 61: 376-8. 5. Yantiss RK, Clement PB, Young RH. Endometriosis of the intestinal tract: a study of 44 cases of a disease that may cause diverse challenges in clinical and pathologic evaluation. Am J Surg Pathol 2001;25:445-54. 6. Jubanyik KJ, Comite F. Extrapelvic endometriosis. Obstet Gynecol Clin North Am1997;24:411-40. 7. Practice bulletin no. 114: management of endometriosis. Obstet Gynecol 2010;116: 223-36. 8. Piketty M, Choplin N, Dousset B, et al. Preoperative work-up for patients with deeply infiltrating endometriosis: transvaginal ultrasonography must definitely be the first-line imaging exami- nation. Hum Reprod 2009;24:602-7. 9. Bazot M, Bornier C, Dubernard G, et al. Accuracy of magnetic resonance imaging and rectal endoscopic sonography for the prediction of location of deep pelvic endometriosis. Hum Reprod 2007;22:1457-63. 10. Clarke-Pearson DL. Screening for ovarian cancer. N Engl J Med 2009; 361:170-7. 11. Corman ML, editor. Colon and rectal surgery. 5th ed. Philadel- phia (PA): Lippincott Williams & Wilkins; 2005. 12. Yantiss RK, Clement PB, Young RH. Neoplastic and pre-neo- plastic changes in gastrointestinal endometriosis: a study of 17 cases. Am J Surg Pathol2000;24:513-24. 13. Leyland NA, Casper R, Laberge P, et al. Society of Obstetri- cians and Gynaecologists of Canada clinical practice guideline. Endometriosis: diagnosis and management. J Obstet Gynaecol Can 2010;7(2 Suppl):S1-S32. Affiliations: From the Department of Obstetrics and Gyne- cology, University of Toronto, Toronto, Ont. Contributors: Both authors contributed substantially to writing the manuscript and revising it for important intellec- tual content and approved the final version submitted for publication.

The authors thank Dr. Maja Barnard for help with the histological images and Dr. Caroline Chan and Mr. Ashish Papneja for help with the clinical images, details of the case and the initial literature review. The authors also thank these people, and Dr. Paul Shuen, the clin- ical physician who supervised the case, for their help in reviewing the manuscript. Resources • Society of Obstetricians and Gynaecologists of Canada: Clinical practice guidelines on the diagnosis and management of endometriosis (www.sogc.org/guidelines /documents /gui244CPG1007E .pdf) • Practice bulletin no. 114: management of endometriosis. Obstet Gynecol2010;116: 223-36. Summary available through the National Guideline Clearinghouse at www .guideline .gov. We have partnered with Sheridan Press! To purchase commercial article reprints and e-prints or to request a quote, please contact: Matt Neiderer Content Sales Sheridan Content Services JANUARY 11, 2011, VOL. 183(1) CMAJ.CA CMAJ turns 100 RESEARCH Renal function and initiation of dialysis ANALYSIS An argument for very low starting doses PRACTICE Personal fertility monitors for contraception medical knowledge that matters CMAJ•JAMC REPRINTS 800 635-7181 x6265 [email protected] CMAJ_Filler_3rdH_03_Layout 1 11/03/11 10:53 AM Page 1 what-sobel_Layout 1 16/03/11 10:57 AM Page 689