Fetal Vessel Rupture

Question 1

Velamentous cord insertion

Answer 1

blood vessels insert between amnion and chorion away from placenta instead of directly into chorionic plate

Question 2

Vasa previa

Answer 2

unprotected blood vessels crossing over internal cervical os and vulnerable to compression by fetal presenting part or being torn

Question 3

% of perinatal mortality in vasa previa

Answer 3

40-60%

Question 4

Why is vasa previa important?

Answer 4

When membranes rupture, fetal vessels running through membrane have a high risk of concomitant rupture, resulting in fetal exsanguination/death.

Question 5

What is fetal blood volume?

Answer 5

80-100 ml/kg

Question 6

Epidemiology of vasa previa

Answer 6

1:2500 to 1:5000 pregnancies

Question 7

Risk factors for fetal vessel rupture

Answer 7

abdominal placentation leading to succenturiate lobe

multiple gestations

Question 8

Clinical manifestations of vasa previa

Answer 8

vaginal bleeding assoc. w/ sinusoidal FHR (fetal anemia), bradycardia, or assoc. fetal heart rate decels
palpable fetal vessels

Question 9

Diagnosis of vasa previa

Answer 9

US to check for velamentous insertion
Color Doppler
Apt test (dx. at the time of vaginal bleeding)

Question 10

What is the Apt test? How is it performed?

Answer 10

Examination of blood for nucleated fetal RBCs

diluting blood with H2O, collecting supernatant, combining with 1% NaOH

pink: fetal blood.
yellow brown: maternal blood

Question 11

Treatment of vasa previa

Answer 11

Emergent Caesarian section

Immediate transfusion