This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hydramnios and Oligo Hydramnios, Subject name: Gynaecology & Obstetrics
Fetal exsanguination can occur if - 
Select and explain. 
A. Vasa previa, B. Placentaprevia, C. Polyhydramnios, D. Oligohydramnios
A: Vasa previa
Answer: A: Vasa previa 
Explanation: Ans. is 'a' i.e., Vasa previa Vasa previao In it a leash of blood vessels happens to traverse through the membranes overlying the internal os, in front of presenting part. Rupture of membranes involving the overlying vessels leads to vaginal bleeding. As it is entirely fetal blood, this may result in fetal exsanguination and even death.Placenta previao When placenta is implanted partially or completely over the lower uterine segment (over and adjacent to the internal os) it is called the placenta previa. The blood is almost is almost always maternal when bleeding occurs.