Embryology USMLE Step 1 Practice Question
An autopsy is performed on a man who died of an unknown cause. The pathologist discovers that the deceased has a small atrial septal defect. The defect is seen in the portion of the atrial septum near the upper border of the fossa ovalis. Which of the following was the likely functional manifestation of this defect during life?
Answer choices
- APrenatal cyanosis due to a shunt of blood from the left atrium to the right atrium
- BPostnatal cyanosis due to a shunt of blood from the right atrium to the left atrium
- CPrenatal cyanosis due to a shunt of blood from the right atrium to the left atrium
- DPostnatal cyanosis due to a shunt of blood from the left atrium to the right atrium
- ENo cyanosis occurred prenatally or postnatallyCorrect answer
- FPrenatal cyanosis due to increased pulmonary vascular resistance causing right-to-left shunting across the defect
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