The Natural History of Placenta Praevia in a Nigerian Population

Abstract

Context: Placenta praevia is a major cause of antepartum haemorrhage. The introduction of real time ultrasound scan has made early detection of placenta praevia possible. However, the determination of which placenta will consistently remain praevia throughout pregnancy is uncertain.

Objective: To determine the natural history of placenta praevia detected by transabdominal ultrasound scan at 12-14 weeks gestation till delivery.

Study Design: A prospective longitudinal study of antenatal women with placenta praevia detected by transabdominal ultrasound scan at 12-14 weeks gestation at the antenatal clinic of the University of Maiduguri Teaching Hospital. The subjects were followed up by serial ultrasound scan until delivery.

Result: Out of 895 consecutive pregnant women scanned in early pregnancy, 14.6% had placenta praevia at 12-14 weeks gestation. Longitudinal follow-up of those with placenta praevia showed that 85% had normally situated placenta at term. Among those with partial or total placenta praevia at 30 weeks gestation, 60% and 75% respectively persisted as major placenta praevia at term. A total of 45% of those with placenta praevia at recruitment had threatened abortion while 15.7% of them had anepartum haemorrhage. Caesarean section rate was as high as 25% among the study population when compared with 8.4% among the general population (p< 0.005).

Conclusion: Placenta praevia in the first trimester becomes normally situated at term in about 85% of cases. However, partial and total placenta praevia at 30 weeks gestation are likely to persist to term in 60% and 75% of cases respectively; these categories of patients should be closely followed-up to term.

Key Words: Placenta Praevia,Ultrasonography, Antepartum Haemorrhage

[Trop J Obstet Gynaecol, 2004;21:128-130]