Pregnancy: How to manage placenta previa

Placenta previa may affect about 1 in 200 pregnant women in the last 12 weeks before delivery. It is a condition in pregnancy where the placenta covers the opening in the woman’s cervix.   A consultant obstetrician and gynaecologist with the Ahmadu Bello University Teaching Hospital, Zaria, Dr. Solomon Avidime, described placenta previa as a condition […]

Placenta previa may affect about 1 in 200 pregnant women in the last 12 weeks before delivery. It is a condition in pregnancy where the placenta covers the opening in the woman’s cervix.  

A consultant obstetrician and gynaecologist with the Ahmadu Bello University Teaching Hospital, Zaria, Dr. Solomon Avidime, described placenta previa as a condition where there is low implantation of the placenta on the uterus, adding that where this occurs, the placental occupation of the lower segment can either completely or partially cover the cervix.

Dr Avidime an associate professor also described the placenta as an organ that develops inside the uterus during pregnancy, connecting the developing fetus to the uterine wall to allow nutrient uptake, thermo-regulation, waste elimination, and gas exchange between the mother and the fetus. 

The placenta, he said, can implant virtually anywhere in the body of the uterus to nourish the fetus but the lower uterus segment.

According to him, problems occurring with the placenta during pregnancy are usually associated with vaginal bleeding. He said bleeding is often encountered during the second half of pregnancy at the period when the fetus is described as viable in our environment which corresponds to 28 weeks of gestational age.

 “Most often, the cause of bleeding may be indeterminate, but significant and life threatening cause of bleeding can be due to placenta previa. Other related causes are placental abruptio, vasa previa, and uterine rupture. 

“The placenta is thus located either alongside of that part of the fetus that is leading towards the cervical os or the placenta is ahead of that part of the fetus leading to the birth canal, that is, presenting part,” he explained.

 The associate professor said the four types of placenta previa are: Complete type IV, Partial III, Marginal type II and Low lying type I, which depends on the degree of the placental occupation of the lower segment of the uterus with type I having a partial occupation of the cervical os but will be displaced on cervical dilation and may allow vaginal delivery. 

Type IV placenta previa is wholly covering the cervix os and will prevent totally vaginal delivery, he said.

 He said it is characterised by painless vaginal bleeding in a pregnant woman from the 28 weeks of gestational age and the bleeding is from the placenta. “Some patients may experience slight bleeding at the initial symptom but at later stage, torrential and life threatening bleeding can occur. The early, slight bleeding is called warning bleed.”

 Placenta previa may affect about 1 in 200 pregnant women in the last 12 weeks period before delivery, he said adding that the cause of placenta previa is unknown, but among other factors, it is common with previous history of placenta previa.

 It is also found to be associated with women with previously scared uterus, such as from previous surgery including cesarean deliveries, uterine fibroid surgeries, and dilation and curettage. 

It is common in women aged 35 years and above; women carrying multi-fetal pregnancy and women who have had more than one pregnancy in the past.

 Diagnosis

 Avidime stated that the advent of ultrasound scan has provided an easy tool for making diagnosis of placenta previa; either during a routine ultrasound scanning during pregnancy or after an episode of vaginal bleeding. 

“This is a diagnosis often made in the second half of the pregnancy. Diagnosis may require that a combination of abdominal ultrasound and trans-vaginal ultrasound is done. 

“There are some categories of women that were earlier diagnosed to have placenta previa, but as the uterus grows, it might increase the distance between the cervix and the placenta margin and the uterus then will be found to have moved out of the lower segment of the uterus,” said Dr Avidime.

 However, the management options are dependent on the time of diagnosis, the amount of bleeding, maternofetal well-being and the type of placenta previa. As at the time of diagnosis, maternal anxiety will have to be allayed and given counseling about the nature and possible outcomes of placenta previa. The possibility of bleeding which can be mere spotting initially progressing to torrential and life threatening bleeding will have to be underscored.

 He said: “Bed rest and prolonged hospital admission may be prescribed depending on the amount of bleeding and the materno-fetal well-being. Heavy blood loss will require blood transfusion. Decision on the mode of delivery is dependent on the type of placenta previa. Major degree placenta previa from some variant of the Type II – IV types will require caesarean delivery.”

The expert advised pregnant women to avail themselves for antenatal care services as soon as pregnancy is suspected, saying, this allows for routine ultrasound scan that can detect placenta previa even when there are no symptoms in the earliest time possible and the appropriate management instituted. 

“However, women experiencing bleeding in pregnancy irrespective of the amount must see a doctor as soon as possible for evaluation and diagnosis of the cause of bleeding,” he advised.