Vasa Praevia

Vasa Praevia

Dr Fatima Z Ashrafi DGO (Dub), FRCS (Edin), MRCOG (Lon), FRANZCOG

Gisborne Hospital, New Zealand

Vasa Praevia ■ ■

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Rare - 1 in 3000 Fetal vessels run in the membrane below the presenting fetal part, unsupported by placental tissue or umbilical cord Spontaneous or artificial rupture of membranes rupture these vessels - fetal exsanguination. Hypoxia if the vessels are compressed between baby & birth canal. Fetal mortality 33-100%, if not diagnosed prenatally.

Pathology Unknown cause. ■ Trophotropism - tendency of a plant to lean towards sun to get light to survive. Lower segment not nourishing - placenta grows upwards to reach more nourishing tissue. ■ Risk factors Low lining placenta bilobed or succenturiate placenta Velamentous insertion of cord Multple pregnancies IVF pregnancies ■

Velamentous insertion of cord ■

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1% - singleton pregnancies, 8.7% - twin pregnancies, higher in early pregnancy & spontaneous abortion. Umbilical cord usually inserts on placental mass 99% cases. Velamentous - cord inserted on chorioamniotic membrane. Variable amount of cord unprotected by Wharton’s jelly. Vasa praevia coexisting in 6% singleton pregnancies with velamentous insertion.

Velamentous insertion of cord

Twin Placenta with a succenturiate lobe

Circumvallate Placenta.

Symptoms ■

Asymptomatic

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sudden onset of painless bleeding in 2nd or 3rd trimester or at ARM/SRM.

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Heavy or small amount of bleeding. No sign symptom of Placenta praevia or abruption.

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IUGR/ Congenital malformation

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Maternal risk: bleeding

Antenatal Diagnosis ■ ■

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An avoidable tragedy. Changing ultrasound protocol for checking placental cord connection. Can be diagnosed as early as 16 weeks . All suspected cases should be checked for vasa praevia Level 2 scan of LUS and/or transvaginal scan with color doppler.

Doppler scan to detect Vasa praevia - 1

Doppler scan to detect Vasa praevia - 2

Management If diagnosed prenatally tocolytics, bedrest no vaginal exams avoid heavy lifting, straining during bowel movement regular scans ■ Planned cesarean section can circumvent fetal risks. ■ Delivery can be planned early enough to avoid emergency, but late enough to avoid prematurity ■ Baby requires aggressive resuscitation & blood transfusion ■

Management ■

If PV bleeding intrapartum

Speculum - fetal vessels. Investigate for the source of bleeding Apt test - fetal hemoglobin is alkali resistant. Wright stain of blood smear. If fetal bleeding confirmed, immediate cesarean section.