This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Medical Illness Complicating Pregnancy, Subject name: Gynaecology & Obstetrics
Virus responsible for non immune hydrops fetalis is 
Select and explain. 
A. Cytomegalovirus, B. Herpes simplex virus, C. Hepatitis B virus, D. Parvovirus
D: Parvovirus
Answer: D: Parvovirus 
Explanation: Hydrops is defined as the accumulation of extracellular fluid in tissues and serous cavities. Hydrops fetalis is more common because of non-immune reasons rather than Rh isoimmunization. Most common cause of non-immune hydrops is due to congenital hea block (cardiac causes) Most common infection causing non immune hydrops- Parvovirus B19 infections