Variation in the Use of Routine Third-Trimester Ultrasound Among Canadian Maternity Care Providers

To evaluate Canadian clinical practice regarding utilization of routine third-trimester ultrasound in low-risk pregnancies and assess provider expectations regarding components of such scans.

A cross-sectional online survey was distributed to Canadian antenatal providers through the Society of Obstetricians and Gynaecologists of Canada. Information regarding provider characteristics, years in practice and routine use of third-trimester ultrasound in low-risk pregnancies, preferred timing, and expectations regarding performance of biophysical profile (BPP) scoring and fetal Doppler was collected.

A total of 765 responses were obtained, including 309 family physicians, 171 midwives, 272 obstetricians and gynecologists (OBG), and 13 OBG residents. Preference for routine third-trimester ultrasound assessment was reported by 41-63% of OBG, 50-62% of residents, 13-20% of family physicians and 2-15% of midwives. Most common timing was a single scan at 30-32 weeks or two scans at 32 and 36 weeks. Even in absence of fetal growth abnormality or other risk factor, BPP scoring was expected to be included in such scan by 27-67% of family physicians, 36-46% of midwives, 39-60% of OBG, and 25-75% of residents. Fetal Doppler was expected by 12-21% of family physicians, 6-14% of midwives, 5-17% of OBG, and around 25% of residents.

Substantial variation exists among Canadian antenatal care providers regarding routine use of third-trimester ultrasound in low-risk pregnancies. Differences are also evident in expectations regarding additional fetal surveillance measures. These findings highlight the need for greater awareness of current evidence and clinical guidelines to promote more standardized and evidence-based use of third trimester ultrasound.