Antepartum haemorrhages are identified as bleeding in pregnancy occurring after the 20th week of pregnancy. They are associated with major risks to mother and baby’s health.
Most antepartum haemorrhages (APH) usually occur because of either:
- Placental Abruption. (Separation of part of the placenta from the uterine wall).
- Low Lying Placenta (Placenta Praevia).
Vaginal bleeding can be mild or severe. Sometimes it can be revealed but occasionally there may also be concealed internal bleeding.
When these episodes of bleeding are minor they may only require close supervision. Usually they will necessitate admission to hospital to monitor both mother and baby. Occasionally the bleeding will be severe and the baby may develop severe distress and mother may also require resuscitation. In these cases the baby is at major risk will need to be delivered prematurely and usually by caesarean section. The mother may require significant resuscitation as well.
Placental abruption results from bleeding following partial separation of a placenta, which is in a normal position inside the uterus. It can cause an isolated episode of bleeding which usually does not recur.
Half of all cases are small abruptions but 25% can be moderate or severe.
Placental abruption can increase perinatal morbidity and mortality.
The risk of placental abruption increases in women with:
- Intrauterine growth restriction
- Multiple pregnancies
- Polyhydramnios (too much liquor)
- Advanced age
- Smoking and illicit drug intake
- Prolonged premature rupture of membranes
- Chorioamnionitis (infection)
- Accidents (falls & motor car accidents)
- ECV (turning babies in breech presentation around)
In mild abruptions the pregnancy is clinically unaffected, however close supervision of mother and baby are still required. If the placental abruption is small it may have no apparent effect on the fetus but can subsequently be associated with fetal growth restriction.
In cases of severe placental abruption it can cause severe fetal distress or death and immediate delivery of the baby will be necessary. It is believed that caesarean section is usually the best method of delivery given that uterine contractions may potentially cause more shearing forces and make placental separation worse.
Placental abruption can also cause serious and life threatening problems for the mother as well through:
- Haemorrhage and Hypotension (low blood pressure)
- Poor blood flow to vital organs such as kidneys resulting in organ damage.
- DIC (coagulation problems resulting from consumption of blood clotting factors).
A low-lying placenta is commonly found at the time of the 20-week ultrasound scan. In many cases the placenta will migrate upwards later in the pregnancy and will cause no problems. From the 26th week of pregnancy the Lower Segment of the uterus will have formed and any placenta, which remains low and encroaches the lower segment will be called a Placenta Praevia.
Placenta Praevias are divided into four categories (Grade I – IV).
With grades I & II the placenta will enter the lower segment and can reach the cervical opening but will not cover the cervix. In grade III & IV the placenta will cover the cervix asymmetrically or cover it centrally.
Grade I & II will often move out of the way by the third trimester and cause no trouble. Grade III & IV will usually stay low and in these cases the baby will need to be born by caesarean section.