Peritoneal inclusion cyst presenting as a rectocele after sacrohysteropexy: A case report

A 40-year-old Iranian Kurdish woman, who was nulliparous and a farmer, had been experiencing progressive left lower quadrant (LLQ) pain and vaginal bulge for four months. The pain was colicky, radiated to the back, and was rated 4/10 in severity. It was constant, non-positional, and unrelated to meals or defecation. She reported no gastrointestinal or urinary symptoms, spotting, or weight loss during this period. Two years earlier, she had presented with stage IV pelvic organ prolapse (POP-Q) without any known risk factors. Considering the patient's desire for uterine preservation and future fertility, open sacrohysteropexy using knitted macroporous polypropylene monofilament mesh (Sacromesh) was performed. Her past medical, surgical, and family histories were otherwise unremarkable, and she was not on any medications. On examination, her vital signs were stable (pulse rate 84/min; respiratory rate 14/min; blood pressure 110/80 mmHg; temperature 36.4 °C). She appeared well. Abdominal examination revealed mild distension and a non-tender palpable mass in the LLQ without guarding or rebound tenderness. Vaginal examination demonstrated no apical or anterior prolapse (POP-Q stage 0), but a reducible stage III posterior bulge ( Fig. 1 ). Bimanual vaginal examination revealed a soft, mobile mass extending to the level of the umbilicus. Digital rectal examination was normal, but a soft mass was palpable in the rectovaginal septum. Fig. 1 The reducible bulge. Fig. 1 The reducible bulge. Prior to referral, pelvic ultrasound demonstrated a large cystic lesion in the left adnexa measuring 72 × 127 × 130 mm, with hyperechoic septa and vascularized solid components. Computed tomography (CT) revealed extension into the LLQ and retroperitoneal space. The left ovary was separately visualized within the lesion, which displaced adjacent intestinal loops without invasion. Pelvic magnetic resonance imaging (MRI) confirmed a fluid-signal multilocular cyst enveloping the left ovary ( Fig. 2 ), extending into the rectovaginal septum with a narrow communication ( Fig. 3 ). Serum tumor markers (LDH, CA19–9, CA125) were within normal limits, reducing the likelihood of ovarian malignancy. The main differential diagnoses included peritoneal inclusion cyst (PIC) and lymphangioma; however, given her surgical history and MRI findings, a PIC was favored. Fig. 2 Pelvic magnetic resonance image (apical view) revealing a multilocular cyst enveloping the left ovary. Green arrow, the left ovary; pink arrow, the loop of intestine; blue arrows, the peritoneal inclusion cyst. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) Fig. 2 Fig. 3 Pelvic magnetic resonance image (sagittal view) revealing the extension of the cyst to the rectovaginal septum with a narrow communication. Green arrow, the mesh from the cervix to the promontorium of the sacrum; pink arrow, the communication of the cyst; blue arrow, the bulge in the perineum. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) Fig. 3 Pelvic magnetic resonance image (apical view) revealing a multilocular cyst enveloping the left ovary. Green arrow, the left ovary; pink arrow, the loop of intestine; blue arrows, the peritoneal inclusion cyst. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) Pelvic magnetic resonance image (sagittal view) revealing the extension of the cyst to the rectovaginal septum with a narrow communication. Green arrow, the mesh from the cervix to the promontorium of the sacrum; pink arrow, the communication of the cyst; blue arrow, the bulge in the perineum. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) The cyst was retroperitoneal, located over the major vessels, and situated between the left ureter and the sigmoid colon, with intestinal loops and mesh anteriorly. To minimize the risk of injury to adjacent organs and mesh complication, a vaginal approach was chosen as a minimally invasive alternative to abdominal surgery. Under spinal anesthesia, a vertical vaginal incision was made at the point of maximal bulging. During surgery, the entire cyst along with the extra epithelium of the posterior wall extending to the cul-de-sac was excised. This was done under rectal guidance with care to preserve the integrity of the mesh. Approximately 300 mL of serous fluid was drained. The posterior wall was closed and the cyst edges were marsupialized to the vaginal mucosa at cul-de-sac using interrupted 2–0 Vicryl sutures, promoting continuous drainage and reducing the risk of recurrence. The procedure was completed without intraoperative or postoperative complications. A small remnant measuring approximately 12 × 4 cm was seen posterior to the mesh on post-operation sonography. Histopathological examination confirmed a benign mesothelial-lined cyst without atypia, consistent with a PIC. The remnant of the cyst did not increase in size postoperatively and was not associated with any symptoms or clinical signs during follow-up. The patient experienced vaginal secretion and fluid drainage for approximately three months following the marsupialization procedure. At one-year follow-up, pelvic examination (POP-Q stage 0) and sonography showed no recurrence. The patient remained asymptomatic, reported a good quality of life, and experienced no adverse or unanticipated events.

This work did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Written informed consent was obtained from the patient for publication of this case report and accompanying images.

PICs are benign, fluid-filled lesions lined by cuboidal mesothelial cells. They typically occur in women of reproductive age and are recognized as non-ovarian causes of cystic pelvic masses [ 1 ]. Their pathogenesis is thought to involve peritoneal fluid accumulation within adhesions following pelvic or abdominal injury [ 6 ]. While PICs are usually confined to the pelvis, they may occasionally extend into the upper abdomen or retroperitoneal space [ 7 ]. The present patient, consistent with this profile, developed a large retroperitoneal cyst after open sacrohysteropexy. The diagnosis of PIC is often challenging due to its rarity, the variety of presentations, and the broad spectrum of differential diagnoses, which include lymphangiomas [ 8 ], mesenteric cysts, pseudomyxoma peritonei, malignant mesothelioma, and adnexal pathologies [ 1 , 9 , 10 ]. Careful imaging and identification of normal ovaries can help exclude ovarian malignancy [ 11 ]. In the present case, CT and MRI were crucial in demonstrating the cystic nature of the lesion and its relationship to adjacent organs. Importantly, this case highlights a particularly rare clinical presentation of PIC as a rectocele, a finding that can easily be mistaken for recurrent pelvic organ prolapse [ 12 ]. This diagnostic challenge highlights the importance of considering alternative etiologies when evaluating patients with a new or recurrent vaginal bulge after prolapse surgery. Management of PICs is complex and depends on the lesion's size, location, recurrence risk, and proximity to vital structures [ 1 ]. In this patient, the cyst was retroperitoneal, closely associated with the bowel, major vessels, ureter, and surgical mesh. An abdominal approach carried a significant risk of visceral injury and mesh erosion; therefore, a minimally invasive vaginal approach was selected. Marsupialization of the cyst wall to the vaginal mucosa allowed continuous drainage, minimizing the risk of recurrence. The patient remained recurrence-free and asymptomatic at one-year follow-up, highlighting the effectiveness and safety of this tailored approach. Only one case report of PIC after sacrocolpopexy could be found in the literature [ 13 ], and the present report is the first of PIC following sacrohysteropexy with the unique presentation of rectocele. This emphasizes the rarity of this complication and the importance of considering PIC in the differential diagnosis of patients presenting with a vaginal mass after pelvic reconstructive surgery. This case also emphasizes the importance of thorough preoperative counseling for patients undergoing pelvic organ prolapse surgery. Clinicians should discuss the risk, however small, of PIC formation as a delayed complication. In summary, this case adds to the very few reports of PIC after prolapse surgery and shows that management must be tailored to each patient. Clinicians should keep PICs in mind when evaluating postoperative pelvic or vaginal masses, especially cystic ones, to avoid misdiagnosis. More research is needed to identify risk factors and to guide prevention, early recognition, and treatment.

This article was not commissioned and was peer reviewed.

As native Persian speakers, we used generative AI to edit grammar and enhance the readability of the manuscript; however, this technology was applied with human oversight and control, and we carefully reviewed and edited the output, recognizing that AI can produce authoritative-sounding content that may be incorrect, incomplete, or biased. The authors remain fully responsible and accountable for the final work, and generative AI was used solely to improve the language and clarity of scientific writing.

Kasra Akbari contributed to the conception of the case report, acquiring the data, drafting the manuscript, and undertaking the literature review. Mansooreh Yaraghi contributed to patient care, conception of the case report, acquiring and interpreting the data, drafting the manuscript, undertaking the literature review, and revising the article critically for important intellectual content. Both authors approved the final submitted manuscript.

Peritoneal inclusion cysts (PICs) are benign multilocular cystic lesions formed by fluid accumulation between intraperitoneal adhesions [ 1 ]. They are most frequently encountered in women of reproductive age, particularly in the third and fourth decades of life [ 2 ], often following prior pelvic or abdominal surgery, sometimes occurring months to even 20 years later. PICS are exceedingly rare, and very few cases have been documented in the literature since their first description in 1979 [ 3 ]. The diagnosis of PICs can be challenging, as they may mimic malignant or other cystic lesions [ 1 ], and their occurrence is particularly rare following gynecologic procedures such as sacrohysteropexy. Even more unusual is their clinical manifestation as a rectocele-like vaginal bulge, which can mislead both patients and clinicians. This uncommon presentation further complicates both diagnosis and management, as clinicians must balance the need to exclude malignancy with the uncertainty surrounding optimal treatment strategies [ 4 ]. This report presents the case of a premenopausal woman with a large retroperitoneal PIC after sacrohysteropexy, which uniquely presented as a rectocele. The diagnostic difficulties and therapeutic considerations associated with this rare case are reviewed. This report is written in accordance with the CARE guidelines [ 5 ].

The authors declare that they have no competing interest regarding the publication of this case report.