Anesthetic management of congenital methemoglobinemia in emergency caesarean delivery: a case report.

Congenital methemoglobinemia is a rare hemoglobinopathy characterized by impaired oxygen delivery and increased risk of maternal and fetal hypoxia during pregnancy. In this report, the management of an emergency cesarean section in a patient with congenital methemoglobinemia is described. At 38 weeks and 4 days of gestation, she presented with severe dyspnea, cyanosis, and an oxygen saturation of 70% on pulse oximetry. Venous blood gas revealed a methemoglobin level of 16.9%. Urgent cesarean delivery was indicated due to fetal heart rate decelerations. Spinal anesthesia was performed following preoperative administration of 1 g intravenous ascorbic acid, with methylene blue kept available as rescue therapy. Near-infrared spectroscopy was used for cerebral oxygenation monitoring, and values increased in parallel with clinical improvement. A healthy neonate was delivered with Apgar scores of 7 and 9 at 1 and 5 minutes, respectively. Postoperatively, the mother's symptoms regressed, and she was discharged together with her infant on postpartum day 3 without complications. This case highlights the challenges of anesthetic management in parturients with congenital methemoglobinemia. Regional anesthesia with meticulous monitoring and supportive therapy can allow safe delivery, while methylene blue should be reserved for life-threatening situations after careful risk-benefit assessment.