Question

A neonate has cyanosis, pulmonary oligemia, and a normal cardiac shadow. What could be the diagnosis?

• A. Tetralogy of Fallot
• B. Pulmonary atresia
• C. Transposition of great vessels
• D. Ebstein's anomaly

Hint:

Cyanosis appearing right at birth is most often transposition of the great vessels, the top cause of day-one cyanotic heart disease.

Answer 1

The Correct Option is C

Step 1: List the three clues.
The baby is cyanosed right from the neonatal period, the chest x-ray shows pulmonary oligemia, meaning reduced lung vascular markings, and the heart size is normal.

Step 2: Think about timing first.
Cyanosis that is already obvious in the neonatal period, meaning the first days of life, is most often caused by transposition of the great vessels. It is the single most common cause of cyanotic congenital heart disease presenting within the first day or two of birth, because the two circulations run in parallel and mixing depends only on a patent foramen ovale, a ductus, or a small VSD.

Step 3: Explain the normal heart size and oligemia.
Early in transposition, before volume overload builds up, the heart can still look close to normal on x-ray, the classic egg on a string cardiomegaly usually develops over the following days as pulmonary flow increases. When transposition is accompanied by some narrowing of the pulmonary outflow, pulmonary blood flow is further limited, which shows up as oligemia rather than the plethora usually taught for simple transposition.

Step 4: Rule out the other options.
Tetralogy of Fallot does classically give a normal-sized, boot-shaped heart with oligemia, but its cyanosis usually becomes obvious gradually over weeks to months as infundibular narrowing worsens, making it a less common cause of cyanosis noticed right in the neonatal period compared with transposition. Pulmonary atresia typically causes a prominent right atrium, so the heart is usually enlarged, not normal sized. Ebstein's anomaly is known for a massively enlarged, wall to wall cardiac silhouette, which does not match a normal cardiac shadow.

Final Answer:
The combination of neonatal cyanosis, pulmonary oligemia, and a normal cardiac shadow points to transposition of the great vessels.