Introduction: Congenital diaphragmatic hernia (CDH) is a rare anomaly characterised by a diaphragmatic defect allowing abdominal organ herniation into the thoracic cavity, resulting in pulmonary hypoplasia and hypertension. Although most cases are detected antenatally, delayed presentation occurs in approximately 5-25% of cases.

Case Report: A male term newborn with normal prenatal imaging and genetic evaluation developed mild respiratory symptoms within the first hours of life, initially attributed to early-onset sepsis. On day three, acute respiratory deterioration with asymmetric chest expansion and absent left-sided breath sounds prompted urgent chest radiography, confirming leftsided CDH. Surgical repair on day five revealed herniation of the transverse colon, omentum, and spleen, with primary closure of a 3-4 cm defect. The postoperative course was uneventful.

Conclusion: This case highlights the diagnostic challenges of late-presenting CDH, underscoring the importance of maintaining a broad differential diagnosis in neonates with sudden respiratory deterioration, even following reassuring prenatal evaluation.