Impact of ultrasound policies on rate of undiagnosed term breech presentations

The proportion of undiagnosed term breech presentations is reduced through a routine facility-based third-trimester ultrasound policy or point-of-care ultrasound (POCUS), according to a recent study.

Breech presentation is observed in 3% to 4% of births at term and is associated with increased risk of perinatal and maternal morbidity and perinatal mortality. Understanding of fetal presentation at term is necessary for proper care.

Fetal presentations at term are screened through either routine third-trimester ultrasound or POCUS. However, the United Kingdom National Institute for Health and Care Excellence does not recommend routine third-trimester ultrasound because of a lack of clinical evidence. Also, most data on POCUS were obtained from low-resource settings.

Investigators conducted this study to compare outcomes of routine third-trimester ultrasound or POCUS with standard antenatal care. Data was gathered from St. George’s University Hospital NHS Foundation Trust (SGH) and Norfolk and Norwich University Hospital NHS Foundation Trust (NNUH).

A routine third trimester scan cohort consisted of pregnant women who gave birth between April 4, 2016, and September 30, 2021, at SGH. Routine third-trimester ultrasound has been a policy at SGH since January 2020. Women who received a routine third-trimester scan at SGH were compared with women at SGH who received standard antenatal care.

Women from NNUH were included in a POCUS cohort, as a policy of routine POCUS was adopted at the hospital from November 2020 onward. Women receiving routine care at NNUH were compared with those receiving POCUS at a 36- to 37-week visit.

The proportion of all term breech presentations undiagnosed was the primary measure of the study. Breech presentations were considered undiagnosed if they occurred after the onset of labor or immediately before induction of labor.

Gestational age at birth, mode of birth, birth weight, emergency cesarean section incidence, and neonatal adverse outcomes were included as secondary outcomes. Women were excluded if they had congenital abnormalities, preterm birth, or multiple pregnancies.

Of the 24,128 singleton pregnancies in the SGH cohort, 16,777 births were before universal third-trimester ultrasound scanning was implemented and 7351 after. Before the implementation, women giving birth were more often younger and had similar body mass index (BMI) and multiparity rate.

The chance of delivery through elective cesarean section was much greater in pregnancies with breech presentation at birth, at 76.8% vs 60.7%. Undiagnosed breech presentations were seen in 14.2% of pregnancies prior to universal screening and 2.8% after universal screening. Vaginal breech births decreased from 29 per 10,000 births to 20 per 10,000 births.

Of the 9694 singleton births in the NNUH cohort, 5119 were before initiation of POCUS screening and 4575 after. Before the implementation, women were more often older and had a lower BMI. The percentage of all term breech presentations undiagnosed was 16.2% before implementation and 3.5% after.

Increased risk of low Apgar score, reduced hypoxic ischemic encephalopathy, and extended perinatal mortality rates were seen in pregnancies with breech presentation. These outcomes decreased alongside the percentage of all term breech presentations.

Reference

Knights S, Prasad S, Kalafat E, et al.Impact of point-of-care ultrasound and routine third trimester ultrasound on undiagnosed breech presentation and perinatal outcomes: An observational multicentre cohort study. PLOS Medicine. 2023. doi:10.1371/journal.pmed.1004192