Conservative Management of a Massive Retroperitoneal Cyst in Pregnancy: A Case Report.

Asymptomatic or benign retroperitoneal cysts are typically subjected to observational management. Although rare, cases during pregnancy may present with symptoms such as abdominal pain and distension, or require diagnostic intervention, frequently necessitating surgical procedures. Notably, in pregnant women with cysts exceeding 20 cm, surgical or aspiration procedures are implemented, even if asymptomatic. This report presents a case in which a large retroperitoneal cyst complicating pregnancy was monitored over time using magnetic resonance imaging (MRI), with the patient proceeding to term without symptoms. A 38-year-old primigravid woman was diagnosed with a uniocular pelvic cyst measuring 20 × 15 × 7 cm by a previous physician, initially suspected to be a para-tubal cyst, which was planned for removal. Intraoperative findings revealed the cyst was of retroperitoneal origin, making it inoperable due to potential intestinal resection. Despite considerations for curative surgery before pregnancy, the patient opted for observational management due to the absence of symptoms and lack of consent. Eight months post-operation, she conceived naturally and consulted our department. Given the cyst's location in the extrapelvic retroperitoneum, it was considered unlikely to obstruct delivery, and conservative management was chosen with surgical intervention as a contingency for symptomatic episodes. Regular MRI evaluations assessed the characteristics and size, which, despite uterine enlargement, were displaced to the right upper abdomen without causing respiratory distress, remained elastic, and showed no signs of rupture or growth. The patient underwent a successful vaginal delivery at 39 weeks of gestation. In pregnancies complicated by large retroperitoneal cysts, surgical intervention is often considered due to concerns regarding cyst rupture and delivery disorders. However, our case, being benign and asymptomatic, was managed with observation as the definitive surgery would necessitate intestinal resection. This case suggests that retroperitoneal cysts can flexibly adapt to the upper abdomen depending on the site of origin, indicating a low risk of parturition disorders and rupture. This clinical course implies that conservative treatment can be attempted after a thorough assessment of the location and characteristics of the cyst.