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

Peritoneal inclusion cysts (PICs) are mesothelial-lined cystic lesions that usually arise in reproductive-aged women after prior pelvic or abdominal surgery. Their diagnosis is often difficult, as they can mimic ovarian tumors or malignant pelvic masses. There are very few reports of PICs following pelvic reconstructive surgery. This report concerns the case of a 40-year-old nulliparous woman with a history of open sacrohysteropexy for stage IV pelvic organ prolapse who presented with progressive left lower quadrant pain and a vaginal bulge. Imaging revealed a large multilocular retroperitoneal cyst enveloping the left ovary and extending into the rectovaginal septum. Tumor markers were within normal limits. Due to the cyst's proximity to the bowel, ureter, and major vessels, and to avoid mesh erosion, a vaginal surgical approach was selected. Approximately 300 mL of serous fluid was drained, the cyst wall was excised under rectal guidance, and marsupialization was performed to the vaginal mucosa. Histopathology confirmed a benign mesothelial-lined cyst. At one-year follow-up, the patient remained asymptomatic with no recurrence evident on imaging. This is seemingly the first reported case of a retroperitoneal PIC following sacrohysteropexy. The case underscores the diagnostic challenges posed by PICs and highlights the role of individualized, minimally invasive management. Clinicians should maintain a high index of suspicion for PICs when evaluating postoperative pelvic or vaginal masses, particularly when imaging suggests a cystic lesion.