A newborn baby presents cyanosed with no murmur and oligaemic lung fields. What is the likely diagnosis?

The presentation of a newborn with cyanosis, absence of a murmur, and oligemic lung fields strongly suggests pulmonary atresia as the likely diagnosis.

Pulmonary atresia is a congenital heart defect where the pulmonary valve is not formed properly, preventing blood from flowing from the right ventricle to the lungs. This results in inadequate oxygenation of the blood, leading to cyanosis, which is the bluish discoloration of the skin due to lack of oxygen. The absence of a murmur can be explained by the limited blood flow to the lungs, which may not create the usual sounds associated with heart defects.

The oligemic lung fields observed on a chest X-ray indicate that there is a reduced blood flow to the lungs, consistent with pulmonary atresia where blood bypasses the lungs due to the ineffective valve. This finding would reflect that the lungs are not adequately perfused with blood, and hence, they appear less dense on the X-ray.

Looking at other conditions: Tetralogy of Fallot typically presents with both cyanosis and a characteristic heart murmur due to turbulent blood flow from the right ventricle; in cases of ventricular septal defect, one would also expect a murmur due to left-to-right sh