Vasa Praevia

Question 1

define vasa praevia

Answer 1

the foetal vessels are exposed and they lie across the internal os

Question 2

how do the foetal vessels come to be outside of the umbilical cord? (2)

Answer 2

either the umbilical cord has attached to the chorioamnionic membranes rather than to the placenta (velamentous umbilical cord)

or there is a succenturiate lobe of the placenta and vessels have grown between the main body of the placenta and the succenturiate lobe

Question 3

what are the foetal vessels?

Answer 3

the 2 umbilical arteries and the umbilical vein

Question 4

when is there the highest risk of a complication with vasa praevia?

what is the risk?

Answer 4

after rupture of membranes/during labour

there is a high risk of foetal death

Question 5

type 1 vasa praevia

type 2

Answer 5

type 1 is due to velamentous umbilical cord

type 2 is due to an accessory placental lobe

Question 6

3 risk factors for vasa praevia

Answer 6

IVF

multiple pregnancy

low-lying placenta (NB not placenta praevia because if the placenta is covering the os then the vessels can’t…)

Question 7

4 ways that vasa praevia may be diagnosed

Answer 7

by ultrasound, during the pregnancy (it would be unusual to diagnose it this way)

by antepartum haemorrhage (2nd/3rd trimester bleeding)

examination of the os during labour may show pulsating foetal vessels

foetal distress and the passage of dark red blood following rupture of membranes

Question 8

suggest why you may not detect vasa praevia if examining the os of a pregnant patient

Answer 8

vasa praevia with foetal distress and passage of dark red blood in labour: how bad is this?

Question 9

management of vasa praevia diagnosed early

Answer 9

(corticosteroids +) elective c-section at 34-36 weeks

Question 10

management of casa praevia diagnosed by antepartum heamorrhage

Answer 10

emergency c-section