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Background and Aims Non-obstetric surgeries during pregnancy are rare (2%), presenting anesthetic challenges. Retroperitoneal cysts during pregnancy are extremely uncommon, with only seven cases reported between 1955 and 2008.

Methods Description of the anesthetic approach to a large intra-abdominal mass in the third trimester of pregnancy. Informed consent was obtained.

Results A 34-year-old woman, 2G1P at 28 weeks gestation, ASA-II, presented with a right adnexal mass detected at 19 weeks gestation via ultrasound (120x60mm). A MRI at 26 weeks described a large cystic formation (150x83x76mm) in the right adnexal region with slight compression of the uterus and right colon. Despite being asymptomatic, midline infraumbilical exploratory laparotomy was suggested due to rapid mass growth and considerable size. Preoperatively, fetal lung maturation protocol and tocolysis were administered. Standard ASA monitoring and oxygen supplementation were ensured. A combined spinal-epidural anesthesia was performed using a needle-through-needle technique at the L3-L4 level, with intrathecal administration of 8mg bupivacaine and 2.5mcg sufentanil. Sensory level reached T4. During the surgery, the patient remained cooperative and hemodynamically stable without epidural reinforcement or sedation. Intraoperatively, cystic lesion was found in the retroperitoneum; due to the gravid uterus challenges, excision was deferred. Cardiotocography before and after surgery showed no abnormalities. Postoperative period uneventful, discharged after 2 days. A conservative approach with thorough clinical monitoring was adopted, with scheduled retroperitoneal mass removal after delivery.

Conclusions Besides the rarity of retroperitoneal cysts during pregnancy, very few cases of awake laparotomy for non-obstetric surgeries in pregnant women are described in the literature.