Endometriosis of the appendix causing small bowel obstruction in a virgin abdomen

Abstract

A 29-year-old, otherwise well, nulligravid woman presented to the emergency department with 1-day history of generalised abdominal pain and vomiting. She had similar symptoms 6 months prior following recent menstruations, which resolved conservatively. She had no prior history of abdominal surgery or endometriosis. CT scan demonstrated distal small bowel obstruction. A congenital band adhesion was suspected, and she underwent prompt surgical intervention. During laparoscopy, a thickened appendix was adhered to a segment of distal ileum. There was blood in the pelvis. Laparoscopic adhesiolysis and appendicectomy were performed. Histopathology demonstrated multiple foci of endometriosis of the appendix with endometrial glands surrounded by endometrial stroma. Oestrogen receptor and CD10 immunostains highlighted the endometriotic foci. The patient made a good recovery and was referred to a gynaecologist for further management.

Background

Endometriosis is characterised by the presence of ectopic endometrial-like tissue or glands outside the uterine cavity. Commonly, endometriosis is associated with dyspareunia, menstrual pain, infertility and pelvic pain. However, it can also be asymptomatic, thus can be missed frequently as a diagnosis. Its prevalence is between 5% and 10% in premenopausal women and can reach as high as 35% in women suffering from subfertility.¹ Although endometriosis is most commonly found within the pelvis, it is known to involve bowel in 3%–37% of cases.² Of these, 85% involve the sigmoid colon and rectum, 7% affect the small bowel, 3.6% involve the caecum and 3% the appendix.^2–4 Clinically, the symptoms of bowel endometriosis are numerous and non-specific, including abdominal pain, abdominal distension, rectal pain, per rectal bleeding, tenesmus and constipation.⁵ These symptoms are generally worse during menstruation; however, this may not always be the case, making the condition challenging to diagnose. Although small bowel obstruction is a common presentation representing 20% of all surgical admissions for acute abdominal pain,⁶ endometriosis-related small bowel obstruction is extremely rare. The authors present an unusual case of small bowel obstruction secondary to endometriosis affecting the appendix, treated with laparoscopic adhesiolysis, and appendicectomy.

Case presentation

A 29-year-old, otherwise well female of Indian descent presented with 1-day history of generalised, crampy abdominal pain, associated with vomiting. She had opened her bowels normally the day prior and had been passing flatus since. She presented to another institution with similar symptoms 6 months ago following recent menstruation, which had resolved conservatively. She denied any previous intra-abdominal operations or any history of endometriosis. She was not on regular medications. On examination, her observations were normal and afebrile. Her abdomen was distended, with mild generalised tenderness, with a positive percussion sign.

Investigations

Her white cell count was 14.3×10⁹/L (reference: 4.0–11.0), a neutrophil count of 11.4×10⁹/L (reference: 2.0–8.0),and C-reactive protein was 1.2 mg/L (reference <3). Her serum electrolytes and renal function were within normal range. CT portal vein phase was suggestive of a distal small bowel obstruction, with a transition point in the distal ileum, without a distinct mass lesion (figure 1). There was faecalisation proximally, with distended small bowel loops up to 30 mm in diameter. There were no features to suggest a closed loop obstruction, nor viscus perforation. The appendix was not visualised, and there were no adnexal or uterine lesions.

Figure 1.

CT abdomen/pelvis demonstrating distal small bowel obstruction with faecalisation and proximal dilation.

Differential diagnosis

Given she had no past medical history of intra-abdominal operations, the authors were suspecting a congenital band adhesion contributing to the patients’ distal small bowel obstruction. Other differential diagnoses include terminal ileitis secondary to inflammatory bowel disease (such as Crohn’s disease), ileocolic intussusception, ileocaecal mass causing distal small bowel obstruction and appendicitis causing secondary small bowel obstruction.

Treatment

Immediate operative intervention was sought following insertion of a nasogastric tube. During laparoscopy, there were adhesions between a segment of distal ileum to a thickened appendix (figure 2). There were no congenital band adhesions in the small bowel. Laparoscopic adhesiolysis and appendicectomy (figure 3) were performed without complications. The pelvis contained blood; otherwise, the ovaries and uterus appeared macroscopically normal.

Figure 2.

Laparoscopic view of the appendix (arrow), which was adhered onto distal ileum, correlating to the transition point.

Figure 3.

Appendicectomy specimen with multiple foci of endometriosis on the serosal surface.

Outcome and follow-up

Histopathology of the appendix demonstrated multiple foci of endometriosis with endometrial glands surrounded by endometrial stroma. Positive ER and CD10 immunostains confirmed the endometriotic foci. There were no features of appendicitis, dysplasia or malignancy. She made an uneventful postoperative recovery and was discharged 3 days later with simple analgesia. She was subsequently referred to a gynaecologist who had commenced her on Rumigest (progestin) with good symptom control.

Discussion

Although it is well known for endometriosis to affect the gastrointestinal tract, it is extremely rare to be associated with acute small bowel obstruction.⁷ It is estimated that less than 1% of intestinal endometriosis leads to an obstruction, most commonly in the rectosigmoid colon.^{5 8 9} The pathophysiology of endometriosis remains unclear, with a variety of genetic and environmental factors thought to contribute. There appears to be three main theories: (1) retrograde menstruation causing implantation and growth of endometrial cells in the surrounding organs; (2) metaplastic transformation of pleuripotent peritoneal mesothelium; and (3) endometrial lesions that infiltrate the large bowel along the nerves distant from the primary lesion.^10–12 Gastrointestinal endometriosis generally tends to only affect the bowel serosa, appearing macroscopically as ‘grey glistening in appearance’.^{5 7 11} Although generally asymptomatic, they can lead to local inflammation, resulting in fibrosis and the formation of adhesions.^{5 13}

Preoperative radiological imaging in the acute setting has little or no role for diagnosing gastrointestinal endometriosis specifically, as was in our case. CT scan is useful in demonstrating focal or constricting bowel lesions in general. In the elective setting, MRI may be helpful to characterise enteric endometriosis, with a sensitivity of 77%–93%.^{5 8 14} Intraoperative findings of endometriotic foci is considered the primary diagnostic modality, with definitive confirmation only on histopathology with immunostaining.¹⁵ In addition to H&E analysis, immunostains CD10, ER, progesterone receptor, cytokeratin-7 and, to a lesser extent, cancer antigen 125 are positive in endometriosis deposits.¹⁶ In a study of 70 specimens judged negative for endometriosis initially by H&E analysis alone, the addition of CD10 immunostaining was associated with greater detection of endometriosis lesions (45%) than H&E analysis alone (35%).¹⁷

Immediate operative management was undertaken for the index patient, as she had small bowel obstruction, in the context of a virgin abdomen. Initially, a congenital band adhesion was thought to be the likely aetiology of her presentation. Intraoperatively, the authors did not operate beyond an adhesiolysis and appendicectomy, as the affected terminal ileum did not appear compromised, nor were there any serosal deposits. In hindsight, the blood that was found in the pelvis was likely related to menstruation from endometriosis. Slesser et al reported a 33-year-old female with acute small bowel obstruction secondary to extensive endometriosis of the appendix and ileocaecal junction.⁵ They proceeded with an open right hemicolectomy, as there was a constricting lesion affecting the ileocaecal junction arising from the base of the appendix.⁵ Orbuch et al described a 38-year-old nulligravid female with previous history of multiple partial small bowel obstructions who had endometriosis-related three small bowel strictures: 20, 40and 100 cm proximal from the ileocaecal valve.³ The stricture at 100 cm was a contiguous stretch of endometriosis and corresponded to the site of small bowel obstruction on imaging.³ She also had significant endometriosis encasing the appendix. This was treated with laparoscopic appendicectomy and laparoscopic-assisted resection of 11 cm of bowel at the 100 cm stricture, with primary anastomosis.³ The serosa of the two distal segments were laparoscopically dissected free of endometriosis.³ There have been other reports of small bowel obstruction due to endometriotic ileal stricture requiring operative management.^{6 10} Interestingly but unrelated to the index patients’ presentation, there have been few reports of intussusception of the vermiform appendix secondary to appendiceal endometriosis.^{18 19} This outlines that endometriosis affecting the intestines can have a variety of presentations.

To the authors’ best knowledge, this is the first case report of small bowel obstruction secondary to endometriosis affecting the appendix, successfully managed laparoscopically. The preoperative diagnosis is challenging. Endometriosis-related bowel obstruction should be suspected in women of reproductive age, particularly if there is onset of abdominal pain after recent menses, serosal deposits found on the bowel or blood found in the pelvis intraoperatively. Appropriate follow-up with a gynaecologist is recommended.

Learning points.

• Endometriosis affecting the appendix is an uncommon entity. Small bowel obstruction secondary to this is unusual and extremely rare.

• Radiological investigation is useful to diagnose small bowel obstruction; however, it has little or no role in the acute setting to define intestinal endometriosis as the primary pathology.

• Intraoperative findings of endometriotic foci are considered the primary diagnostic modality, with definitive confirmation only on histopathology with immunostaining.

• A diagnosis of small bowel obstruction in an otherwise well female of childbearing age, with intraoperative findings of blood in the pelvis, and no ovarian pathology may prompt the surgeon towards endometriosis-related obstruction.