Chapter 33 Midwifery and obstetric emergencies Vasa praevia

• Chapter 33 : Midwifery and obstetric emergencies. • Vasa praevia • -The term vasa praevia is used when a fetal blood vessel lies over the os, in front of the presenting part. • - This occurs when fetal vessels from a velamentous insertion of the cord or to a succenturiate lobe cross the area of the internal os to the placenta.

• The fetus is in jeopardy, owing to the risk of rupture of the vessels, which could lead to exsanguination. • - Good outcome depends on antenatal diagnosis and delivery by caesarean section before the membranes rupture • -Vasa praevia may be diagnosed antenatally using ultrasound. Sometimes, vasa praevia will be palpated on vaginal examination when the membranes are still intact.

• - If it is suspected a speculum examination should be made. • Ruptured vasa praevia • -When the membranes rupture in a case of vasa praevia, a fetal vessel may also rupture. • - This leads to exsanguination of the fetus unless birth occurs within minutes.

Diagnosis • Fresh vaginal bleeding, particularly if it commences at the same time as rupture of the membranes, may be due to ruptured vasa praevia. • -Fetal distress disproportionate to blood loss may be suggestive of vasa praevia.

Management • The midwife should call for urgent medical assistance. The fetal heart rate should be monitored. If the mother is in the first stage of labour and the fetus is still alive, an emergency caesarean section is carried out. • -If in the second stage of labour, delivery should be expedited and a vaginal birth may be achieved.

• - Caesarean section may be carried out but mode of birth will be dependent on parity and fetal condition. • -There is a high fetal mortality associated with this emergency and a paediatrician should therefore be present for the birth. • -If the baby is born alive, resuscitation, haemoglobin estimation and a blood transfusion will be necessary.

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