This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Gynaecology & Obstetrics
Which of the following is true about vasa pre except? 
Select and explain. 
A. Incidence is 1:1500, B. Moality rate of 20% with undiagnosed case, C. Associated with low lying placenta, D. Cesarean section is indicated
B: Moality rate of 20% with undiagnosed case
Answer: B: Moality rate of 20% with undiagnosed case 
Explanation: When the fetal vessels in the membrane cross the region of internal os and are ahead of the presenting pa,the condition is called vasa prae.An Apt test or Singer&;s alkali denaturation test can be performed to confirm a fetal bleed and thereby vasa prae (refer pgno:138 sheila textbook of obstetrics 2 nd edition)