Prenatal detection of placenta previa and placenta accreta spectrum: Evaluation of the routine mid-pregnancy obstetric ultrasound screening between 2013 and 2017.

OBJECTIVE

To examine the detection rate of placenta previa and placenta accreta spectrum (PAS) by routine mid-pregnancy obstetric ultrasound and to estimate risk factors and prevalence within this cohort.

METHODS

This was an observational cohort study with prospectively collected data. Women attending routine mid-pregnancy obstetric ultrasound at the Sahlgrenska University Hospital with a suspected cup-shaped placenta (cohort 1, n = 339) and women diagnosed with placenta previa or PAS (cohort 2, n = 227) were analyzed according to detection rate, risk factors, and prevalence.

RESULTS

The detection rates of placenta previa and PAS were 49% (98) and 25% (14), respectively. However, 216 (99%) women with placenta previa were diagnosed prenatally, as were 14 (50%) women with PAS. In vitro fertilization was identified as the strongest independent risk factor for placenta previa (odds ratio 6.96; 95% confidence interval 4.77-10.16, P < 0.001). Risk factors were present for all women with PAS. The prevalence of placenta previa was 44/10 000 deliveries, and for PAS, 5.6/10 000 deliveries.

CONCLUSION

The existing routine mid-pregnancy obstetric ultrasound screening showed low detection rate for placenta previa and PAS. Adding risk factors could improve the detection rate.