Professional and Linguistic Assessments Board (PLAB) Practice Exam

What are the four main causes of cyanosis in a newborn?

1. 4 T's

2. 5 H's

3. 3 D's

4. 2 P's

The correct answer is: 4 T's

The four main causes of cyanosis in a newborn are typically represented by the "4 T's," which refer to four critical conditions that can lead to this clinical sign. These are: 1. **Tetralogy of Fallot** - A congenital heart defect that involves four anatomical abnormalities affecting the heart, leading to reduced blood flow and oxygenation. 2. **Transposition of the Great Vessels** - Another congenital heart defect where the two main arteries that carry blood away from the heart are switched, disrupting normal oxygenation of blood. 3. **Truncus Arteriosus** - A congenital heart defect where a single vessel comes out of the heart instead of the usual two, leading to poorly organized blood flow and subsequent cyanosis. 4. **Total Anomalous Pulmonary Venous Return (TAPVR)** - A condition where the pulmonary veins that normally carry oxygen-rich blood from the lungs to the heart are connected to the right side of the heart instead, leading to oxygen-poor blood being circulated. These conditions are critical to recognize as they can lead to significant morbidity and mortality if not promptly diagnosed and treated. The other choices, such as "5 H's", "3 D's", and "2 P's