Congenital right ventricular diverticulum formed by pulmonary regurgitative jet flow in a fetus with tetralogy of Fallot and absent pulmonary valve

Congenital ventricular diverticulum is a rare anomaly with an unclear pathology. Here, we report a male fetus at 24 weeks of gestation, diagnosed with right ventricular diverticulum associated with tetralogy of Fallot and absent pulmonary valve. The diverticulum was located at the anterosuperior wall of the right ventricle and faced into the massive pulmonary regurgitation flow jet. Intrauterine fetal death from heart failure resulted at 26 weeks of gestation. An autopsy revealed significant subendocardial fibrosis in the diverticular wall without inflammatory cell infiltration. Clinical and pathologic features suggested that the regurgitative blood flow contributed to the formation of the right ventricular diverticulum.