• Dr Peter Chew

Placenta previa

“You can take your baby home.” These were the magical words she was waiting anxiously to hear as the nurse from the Neonatal Intensive Care Unit (NICU) handed her the tiny baby boy which was born prematurely 6 weeks ago. D, 30, a first time mum had an emergency caesarean section because the placenta (afterbirth) had totally covered the birth passage.

D first consulted me at 10 weeks of gestation when she had bloody discharge from the vagina. The bleeding subsided with rest and injections. Her pregnancy went smoothly until 20 weeks of gestation when a routine ultrasound examination showed that the placenta was covering the cervix (neck of the womb). I explained to her that she might have further episodes of bleeding in the later part of pregnancy and she should seek medical attention at the hospital immediately if the bleeding was heavy.

“One night, I was woken up by what I thought was urine flowing down my legs. I was shocked to realise that I was bleeding heavily,” D related. She was rushed by the ambulance to the hospital. She was 30 weeks pregnant then. The bleeding stopped when she reached the emergency room. The baby’s heartbeat was normal and her haemoglobin level (the oxygen-carrying protein in the red blood cells) was also normal, indicating that she had not developed anaemia, which could occur with severe blood loss. She was observed in the hospital for two days and was given corticosteroids to speed up her baby's lung

​​development, lest it needed to be delivered early. She was sent home to rest when there was no further bleeding.

At 34 weeks gestation, D had another bout of bleeding. This time, it was accompanied

by labour pains. When she was admitted to the hospital, she was in a state of shock with a low blood pressure of 90/50mm Hg and a weak and rapid pulse rate of 100/min . The bleeding was torrential with clots. There was no sign that the bleeding would stop even when she had an emergency blood transfusion. An immediate caesarean section was done and the baby, weighing 1.7 kg, was delivered . He was put into the incubator for close monitoring.

The placenta is an organ that grows along with the baby during pregnancy. It connects the baby with the mother’s blood system through the umbilical cord and provides the baby with oxygen and nutrients.

In most pregnancies, it is attached to the top or side of the womb. But if the placenta is inserted at the lower part of the womb, it is called placenta previa. It can partially (marginal placenta previa) or totally (major placenta previa) covering the opening of the womb and cause severe bleeding before or during delivery.

​The hallmark sign of placenta previa is the painless vaginal bleeding which can be light or heavy in the second half of pregnancy. The bleeding usually stops without treatment, but can recur days or weeks later.

It is usually diagnosed during the ultrasound examination in the second trimester. If it is marginal, expansion of the womb may bring the attachment higher and the condition may improve. But if it is a major one, it is unlikely to resolve with time, as in D’s case.

Placenta previa is more common in women who

· Had previous surgery in the womb such as caesarean section or fibroid removal

· Are expecting more than one baby, e.g. twin, triplet pregnancies, with a large placenta

· Had placenta previa in a previous pregnancy

· Are 35 or older

Treatment for placenta previa depends on the following factors:

· The severity of the bleeding

· Whether the bleeding has stopped

· The gestation period of the pregnancy

· Mother’s and baby’s condition

"Masterly inactivity” is the key in the management. In most cases of placenta previa, bleeding usually stops after a while. A conservative approach, ensuring the mother’s haemoglobin levels and vital signs are stabilised is ​the treatment of choice. This is to allow the baby to grow to maturity where it can survive with the neonatal care and support. A planned caesarean section is usually performed after 36 weeks of gestation.

However, in cases where the bleeding is severe and the maternal condition remains unstable, even with resuscitation, emergency caesarean section may have to be done to save the mother’s life even if the baby is premature.

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