Methemoglobinemia in Pregnancy: A Case Report and Comprehensive Review of the Literature

Methemoglobinemia causes hypoxia and can be congenital or acquired through chemical or drug exposure. Standard therapy for non-pregnant symptomatic cases is methylene blue, which poses potential fetal risks in pregnancy. We report a case of a pregnant patient with methemoglobinemia who presented with dyspnea at 18 weeks of gestation. Intravenous ascorbic acid was administered with resolution of dyspnea, and the patient was started on daily oral ascorbic acid upon discharge. With avoidance of potentially inciting agents, the patient proceeded to have a full-term, uncomplicated spontaneous vaginal delivery of a viable female neonate. This report analyzes previously reported cases of methemoglobinemia in pregnancy, its pathophysiology, diagnostic workup, and suggested management. Daily ascorbic acid may be a feasible alternative to methylene blue for the management of symptomatic methemoglobinemia in pregnancy.