The value of adding a universal booking scan to an existing protocol of routine mid-gestation ultrasound scan

To compare 2 routine obstetric ultrasound protocols regarding number of clinically relevant events detected and total ultrasound workload.

An interventional before-and-after study comparing 2 groups of 750 consecutive low-risk pregnant women was conducted. The 1st group was routinely offered mid-trimester ultrasound and selective ultrasound examinations for specific indications; the 2nd group was, in addition to this, offered a scan at 1st prenatal visit.

The groups were comparable at baseline, and 78% underwent booking scan. The expanded protocol showed no improvement in detection of most clinically relevant findings but did detect twins slightly earlier (P=0.3) and significantly reduced the number of presumed post-term deliveries (8.4% vs 13.1%; OR 0.61 [95% CI, 0.41-0.90]). Although more women were scanned at any point or <24 weeks (P<0.001), the increase in women receiving a properly timed fetal anomaly scan was small (60.7% vs 52.3%; P=0.003). Total ultrasound workload increased by 74%, mainly because of more follow-up scans (323 vs 122) and more women being scanned for the 1st time >24 weeks (146 vs 51; P<0.001).

The results do not support a policy of routine booking scans and revealed no significant benefit apart from a small reduction in presumed post-term pregnancies.