Placental abruption and placenta praevia

Abstract

Antepartum haemorrhage is defined as bleeding from the genital tract from 24 weeks of gestation onwards. The incidence is around 2–5% of all pregnancies progressing beyond 24 weeks. Placenta praevia and placental abruption are of great clinical importance as causes of antepartum haemorrhage. Placenta praevia occurs when the placenta is totally or partly inserted in the lower uterine segment. The aetiology of placenta praevia may merely represent an accident of nature but is associated with advanced maternal age, multiparity and previous uterine damage such as in a previous caesarean section. Usually, the initial bleed is painless and mild, but it may be severe. Screening and diagnosis are normally by ultrasound. A dilemma exists as to whether hospitalisation should be offered to women with an asymptomatic placenta praevia. Caesarean section is the recommended mode of delivery for major placenta praevia. Haemorrhage arising from premature separation of a normally situated placenta is known as abruptio placentae. Risk factors include placental abruption in a previous pregnancy, pre-eclampsia, cigarette smoking, and trauma. The patient typically develops pain over the uterus, and this may not be associated with apparent bleeding at first. The diagnosis is mainly clinical and confirmed by the demonstration of a retroplacental clot after delivery. In the obvious case of abruption, early delivery is of crucial importance. If the baby is still alive and the gestation compatible with survival upon delivery, it is recommended that urgent caesarean section should be performed. However, if the fetus is dead, one should expedite vaginal delivery. Complications of antepartum haemorrhage include maternal shock, especially due to the increased risk of postpartum bleeding. There is a greater risk of premature delivery, fetal hypoxia and sudden fetal death.