A Case of Wernicke's Encephalopathy in the Second Trimester of a Woman With Super-Super Obesity and a Monochorionic Diamniotic Twin Pregnancy.

Super super obesity increases perinatal risk, and monochorionic diamniotic twin gestation is uncommon. Although Wernicke's encephalopathy is linked to hyperemesis gravidarum in underweight women, severe obesity does not preclude micronutrient depletion. A woman with body mass index 65 kg/m2 carrying monochorionic diamniotic twins developed Wernicke's encephalopathy at 25 weeks after prolonged poor diet with restrictions and persistent nausea and vomiting. Severe obesity may create a false impression of nutritional adequacy. Furthermore, twin pregnancy increases metabolic demand and complicates interpretation of weight changes. Serum thiamine was low-normal; magnetic resonance imaging showed a splenial corpus callosum lesion. Empiric high-dose intravenous thiamine rapidly improved symptoms. A central venous port was required for difficult access but complicated by a catheter-related bloodstream infection. Preterm membrane rupture at 31 weeks necessitated cesarean delivery for a nonvertex second twin; mother and twins survived. Reduced intake, frequent vomiting, and weight loss should trigger prompt thiamine treatment even with near-normal levels.