Vasa praevia: diagnosis and management

Abstract

Key content:• Vasa praevia occurs when unprotected fetal vessels cross the cervix beneath the presenting part.• It occurs in approximately 1 in 3000-6000 births.• Rapid fetal haemorrhage can result.• A high index of suspicion and appropriate use of prenatal ultrasonography may prevent perinatal death. Learning objectives:• To recognise the risk factors and diagnostic criteria.• To review the role of expert ultrasonography.• To recognise the need for prompt action and a clear care plan. Ethical issues:• Should prenatal detection of vasa praevia be a routine component of antenatal care?• Should resource constraints influence the availability of prenatal diagnostic testing?

Vasa previa: a case report

“…Whenever associated fetal heart abnormalities are there, one should have a suspicion of vasa previa.6 Vessel compression may result because of labour, digital pressure or pressure of presenting part which can lead to severe Cardiotocography (CTG) abnormalities like fetal heart decelerations, bradycardia, and sinusoidal heart rate pattern usually signifying fetal hemorrhage which may result in fetal demise. 8,9 As the fetal blood volume is only 250 ml at term, a loss of 60 ml or more is sufficient to cause fetal exsanguination and demise. 10 Prenatal diagnosis allow us to monitor bleeding symptoms closely and facilitates elective caesarian section under more controlled circumstances and rapid volume replacement of the exsanguinated fetus.…”

“…10 Prenatal diagnosis allow us to monitor bleeding symptoms closely and facilitates elective caesarian section under more controlled circumstances and rapid volume replacement of the exsanguinated fetus. 9 A prenatal diagnosis also implicates prolonged in-patient hospital admissions in the hope of optimizing fetal outcome. The correct time of admission should be well planned.…”

“…It is recommended that women should be offered elective delivery at 35weeks or earlier after administration of corticosteroids for fetal lung maturity. 9 In one series, 28% of elective admissions had emergency CS indicated for bleeding, rupture of membranes or labour. 11 These authors believe that the mild risk associated with prematurity at 35 weeks is outweighed by risk of miserable outcome if membranes rupture, as in 8% of women membranes rupture before labour.…”

“…Once the diagnosis of vasa previa is made, the patient should be under continuous surveillance and admitted electively at 34 weeks. 9 Cases should not be managed expectantly with labour occurring as these vessels may undergo compression by the presenting part during labour or may tear when membranes rupture leading to fetal exsanguination and death.…”

“…14 However, evidence to support the introduction of routine screening for vasa previa is currently limited. 9 The outcome in cases which are diagnosed early in pregnancy is excellent. There is a higher chance of resolution when the condition is diagnosed before 24 weeks of gestation.…”