Neonatal Polycythemia Revealing Congenital Pulmonary Stenosis in a Macrosomic Newborn: A Case Report and Diagnostic Teaching Point

Abstract

Neonatal polycythemia is a common hematological finding that may lead to hyperviscosity syndrome, particularly in macrosomic infants. We report the case of a term female neonate, born after an uncomplicated vaginal delivery with a birth weight of 4700 g, who was admitted to the Neonatal Intensive Care Unit (NICU) of Mohammed VI University Hospital, Tangier, for early-onset respiratory distress. Clinical examination revealed generalized plethora and reddish skin discoloration. Laboratory investigations confirmed neonatal polycythemia, with a hemoglobin level of 24.8 g/dL and a venous hematocrit of 69%. Echocardiography identified moderate pulmonary valve stenosis associated with moderate biventricular hypertrophy and mild subaortic obstruction, consistent with an underlying congenital cardiac contribution to chronic intrauterine hypoxia and secondary erythrocytosis. The infant was managed with ventilatory support, intravenous fluids and partial exchange transfusion, with favorable clinical evolution and discharge on day 11. This case illustrates the interplay between macrosomia, neonatal polycythemia and congenital heart disease and underscores the importance of a thorough cardiac evaluation in neonates presenting with unexplained polycythemia and respiratory distress.