<prompt> Which of the following is true about vasa previa except?Incidence is 1 :1500Mortality rate of 20 with undiagnosed caseAssociated with low lying placentaCesarean section is indicated  <response>: Ans. is b, i.e. Mortality rate of 20 with undiagnosed caseRef Williams Obs 23e, p 583-584, High risk pregnancy Fernando Anas 3e p 348, progress in Obs. and Gynae- John Studd vol. 17e p 209Vasa previa: It is a condition in which the fetal blood vessels unsupported by either umbical cord or placental tissue, overlies the internal os and is vulnerable to rupture when supporting membrane rupture.Thus bleeding in case of vasa previa is of fetal origin and not maternal origin unlike placenta previa and abruptioIt is rare condition and occurs in 1 in 2000 - 3000 deliveries i.e. option ais correct.Vasa previa should be suspected if any of the following condition exists-Velamentous cord insertion-Bilobed placenta-Succenturiate lobed placenta-Placenta previalow lying placenta in second trimester option c is correct-Pregnancy resulting from IVF-Multiple pregnanciesVasa previa is associated with high fetal mortality - 75-100 because---Whartons jelly is absent around the fetal vessels, hence they can be easily lacerated at the time of rupture of membranes leading to severe fetal bleeding.-Vessels can be easily compressed by the fetal presenting part during uterine contractions leading to fetal exsanguination.This explains that option b i.e. mortality rate is 20 in undiagnosed case is incorrect mortality is 75-100Maternal mortality is not increasedDiagnosis of vasa previa - In all cases of antepartum and intrapartum hemorrhage, the possibility of vasa previa should be kept in mind and blood should be tested for fetal hemoglobin characterized by resistance to denaturation by alkaline reagent Singer alkali denaturation testApt testDoppler examination can also reveal fetal blood vessels traversing below the presenting partManagement: In a diagnosed case of vasa previa elective cesarean section should be done or emergency LSCS should be done if it is diagnosed intrapartum. 