OP14.04: Retro‐rectal cystic lesions depicted during transvaginal ultrasound examination: a case series

The retro-rectal space (RRS) is not routinely assessed during routine transvaginal ultrasound examination. Various benign and malignant lesions of different etiologies can develop in this space. Although these lesions are rare, they are more prevalent in women (female:male ratio of 5:1). Retro-rectal lesions (RRL) can be asymptomatic, usually detected incidentally while evaluating other complaints. They can also present with pain, constipation, dyschezia and dyspareunia. Complications include rupture, infection with fistula formation and malignant transformation. Thus, surgical removal of the lesion with clean margins is recommended in all cases. No additional therapy is needed. The high rate of asymptomatic cases, together with their unique anatomic location, pose a great diagnostic challenge. Reviewing the literature, we found only a few case reports of retro-rectal masses initially depicted on trans vaginal ultrasound. The predominance in women, the vicinity to the reproductive organs and the potential for malignant transformation, call for raising the attention to these lesions while performing a routine transvaginal ultrasound examination. We report 5 cases of RRL that were depicted by scanning the RRS during routine transvaginal ultrasound examinations. All lesions were depicted as multi-locular cystic lesions with no solid tissue or vascularity. All lesions were further confirmed by MRI. Four patients underwent operation and pathologic examination: three tailgut cysts and one epidermoid cyst were reported. One patient is awaiting operation. Detecting the lesion in an asymptomatic 74 y.o. woman raises the possibility of trans vaginal ultrasonographic follow-up in asymptomatic cases showing no suggestive features of malignancy. Further studies on larger numbers are needed to confirm the safety of follow up. Scanning the RRS can be performed during routine transvaginal examination. This can contribute to the diagnosis of rare, but potentially serious conditions.