Incidental Diagnosis of Heterotaxy Syndrome With Left Isomerism in a Postpartum Woman Presenting With Dyspnea and Cyanosis

Heterotaxy syndrome (situs ambiguus) is a rare congenital disorder characterized by abnormal thoracoabdominal organ positioning.Left isomerism (polysplenia syndrome) is a subtype associated with bilateral left-sided morphology, multiple spleens, and complex cardiovascular anomalies.Most cases present in childhood, but adults may rarely remain undiagnosed until acute illness unmasks the condition.Timely recognition through cross-sectional imaging is critical, as delayed diagnosis in adulthood is associated with high morbidity and mortality, particularly during physiological stress, such as pregnancy and the postpartum period.We present a case of a 25-year-old postpartum woman who presented with shortness of breath, cough, and cyanosis seven days after delivery.Evaluation revealed an oxygen saturation of 70% on room air and a markedly elevated D-dimer level.Contrast-enhanced CT of the chest and abdomen demonstrated left atrial isomerism, double superior vena cava, interrupted infrahepatic inferior vena cava with azygos continuation, polysplenia, a midline liver, a right-sided stomach, dorsal pancreatic agenesis, and bilateral bilobed lungs.Cardiac anomalies included an atrial septal defect, a ventricular septal defect, discordant ventriculoarterial connections, and pulmonary arterial hypertension.This case highlights that heterotaxy with left isomerism may first present in adulthood during physiological stress, such as pregnancy and the postpartum period, and that CT plays a crucial role in defining the full spectrum of anomalies.