Acute Exacerbation of Anemia with Parvovirus B19 Infection One Year after Sleeve Gastrectomy for Severe Obesity.

Pancytopenia due to malnutrition sometimes occurs after gastric bypass but is rare after sleeve gastrectomy. A 35-year-old patient underwent sleeve gastrectomy for severe obesity. Twelve months after the operation, rapid progression of macrocytic anemia with leukopenia and thrombocytopenia occurred, and a decrease in some vitamins and trace elements due to an insufficient food intake was also detected. Haptoglobin decreased, suggesting the presence of hemolysis. In addition, IgM antibody against parvovirus B19 was detected, followed by IgG antibody. Parvovirus B19 infection was suggested to be involved in the rapid progression of anemia in this malnourished patient after bariatric surgery.