Endometriosis is an estrogen-dependent disease characterized by its high replicative and expansive capacity within the abdominal cavity. The pathophysiology of endometriosis arises from the presence of endometrial-like tissue and/or stroma outside the uterine cavity, typically resulting in inflammation of the affected tissue. This inflammatory response is accompanied by increased cytokine and growth factor secretion, stimulation of angiogenesis, nerve involvement, and anatomical distortion [1] . Common sites of endometriosis include the ovaries, fallopian tubes, pelvic peritoneum, and uterosacral ligaments, whereas atypical sites may involve the gastrointestinal tract, urinary tract, soft tissues, and thoracic cavity [1] [2] .

Abrão et al. [3] describe that women with deep endometriotic lesions may also experience appendicular endometriosis (AE) with associated intestinal symptoms. Clinical manifestations of AE in affected women may include acute or chronic pelvic pain, fever, intussusception, or lower gastrointestinal bleeding, which often worsens during menstruation [2] [4] [5] . Although AE incidence remains low, its potential for mimicking acute appendicitis necessitates a prepared clinical approach to differentiate it from acute appendicitis and may require surgical intervention in elective cases [6] .

Laparoscopic examination of the affected appendix often reveals signs such as edema, rigidity, hyperemia, and congestion; however, a definitive diagnosis of AE can only be confirmed through resection and histopathological analysis [2] [3] [7] . Appendectomy during endometriosis surgery can potentially alleviate chronic pelvic pain, reduce future appendectomy risk, prevent appendicitis in endometriosis patients, and thereby reduce associated healthcare costs [2] [8] [9] . This study aims to evaluate the prevalence of AE in surgical procedures performed between February 2018 and February 2023 in symptomatic women with endometriosis and to examine potential complications associated with this condition.

This retrospective cross-sectional study included 133 patients who underwent surgery for endometriosis performed by the same surgical team, with an analysis of cases in which appendectomy was conducted for specific clinical indications. All patients had a history of chronic abdominal pain, either intermittent or continuous, lasting six months or more, and had been using contraceptives and analgesics chronically to manage symptoms ( Table 1 ).

All procedures were performed via video laparoscopy by the same team, primarily for endometriosis treatment due to either pain or infertility. Appendectomy was performed by the co-author when indicated intraoperatively, based on abnormal appendiceal findings such as visible AE lesions, adhesions, rigidity, congestion, hyperemia, and color changes.

The appendectomy technique involved ligation of the appendicular artery, mobilization of the appendix, closure of the stump with non-invaginated sutures, and cold scissor resection. The specimen was extracted through the laparoscopic trocar and preserved in formalin for histopathological analysis. Hemostasis of operative fields was verified following excision.

Preoperative investigations included transvaginal ultrasound, computed tomography, magnetic resonance imaging, and/or colonoscopy. All exams were realized with intestinal preparation.

Between February 2018 and February 2023, 133 patients were included in the study. The mean patient age was 39 years (range: 22 - 53 years). Surgical indications included complaints of pelvic and abdominal pain, either chronic, intermittent, or continuous for six months or more, in association with endometriosis ( Table 1 ).

The appendectomy procedure was performed in 26 patients (19.5%), over the 132 patients that showed bowel endometriosis. Other treatments included 55 shaving resections (38.8%), 43 segmental resections (30.3%) and 36 discoid resections of the rectal anterior wall (25.3%). Additional procedures are detailed in Figure 1 .

Histopathological analysis confirmed endometriosis in 13 of the 26 appendectomy specimens (50%), representing 10% of the total sample. No postoperative complications related to appendectomy were observed. Documented intestinal complications included six cases (4.5%) of constipation, small bowel obstruction, rectal granulomas, fistula formation, late bleeding, and hematomas ( Table 2 ).

The presence of appendicular endometriosis (AE) was initially described in 1860 by the Austrian pathologist Karl von Rokitansky [8] . In 1955, Collins D.C. [9] identified AE in 0.054% of cases within a study of 50,000 appendix specimens. Subsequently, Feldhaus et al. [4] , reported AE in less than 1% of women on post-appendectomy pathological analysis.

AE manifestations range from asymptomatic presentations to acute appendicitis-like symptoms, lower gastrointestinal bleeding, perforation, or intestinal obstruction due to intussusception [2] [6] [7] . The clinical signs often mimic gastrointestinal diseases, with symptoms such as abdominal pain, diarrhea, constipation, bloating, flatulence, nausea, and vomiting [2] [6] [10] - [14] . Melena [2] [6] [9] , proctalgia [15] , and gut microbiota alterations [13] have also been documented. Symptoms resembling appendicitis, particularly in young women with a history of infertility and pelvic endometriosis, may prompt suspicion of AE [2] [4] [6] [7] [15] .

In two-thirds of AE cases, histopathological involvement extends to muscular and seromuscular layers, with one-third involving only the serosal surface [7] . AE may exhibit mucosal or submucosal infiltration, leading to symptoms similar to inflammatory diseases like Crohn’s disease, enteritis, and ischemic colitis [7] [14] .

Due to endometriosis’ diverse manifestations and nonspecific indications, accurate preoperative AE diagnosis is challenging [14] . Transvaginal ultrasonography, MRI, and Doppler ultrasound are not definitively diagnostic for AE, though Luzier J. et al. [15] reported the “doughnut sign” on ultrasound as indicative of AE with intussusception. Serum CA125 levels may be elevated but tend to normalize postoperatively [14] .

Laparoscopy, confirmed through histopathology, remains the most effective diagnostic tool. Appendectomy is recommended for pain resolution and visibly abnormal appendices [2] [4] [7] [16] . Abrão MS et al. [16] adds that in laparoscopy, it is impossible to state that a normal-appearing appendix is truly free of disease, however, they believe this to be clinically irrelevant as they also imply that it would be unethical to perform an appendectomy on an appendix laparoscopically normal. Mabrouk M. et al. [12] emphasize that patients with endometriosis undergoing surgery should be counseled on the potential for appendectomy.

In this study, histopathological abnormalities were confirmed in 13 of the 26 resected appendices. Abnormal findings during laparoscopy, such as intussusception, edema, adhesion, or nearby endometriosis, were reliable indicators for AE, though only half were histologically confirmed.

Appendicular endometriosis is an important but relatively uncommon finding. Surgical assessment of the appendix during endometriosis procedures is critical. While clinical symptoms and imaging may suggest AE, definitive diagnosis relies on histopathological evaluation. Appendectomy is warranted when laparoscopy identifies abnormalities; however, there is no consensus on removal in cases with a macroscopically normal appendix. Patients should receive appropriate counseling prior to surgery, and further prospective, randomized studies are necessary to establish a standard recommendation for appendectomy in women with endometriosis.