Impact of Universal Vasa Previa Screening With Color Doppler During the OB Ultrasound Anatomy Scan

Abstract

ObjectivesOur institution introduced universal vasa previa (VP) screening utilizing transabdominal ultrasound with color Doppler for all pregnancies at the second trimester anatomy scan. Our study sought to describe the clinical impact of this intervention.MethodsRadiology records from the 12 months pre‐ and post‐intervention were queried for “vasa previa.” Records included for analysis were those with a first‐time diagnosis or discussion of VP at the anatomy scan. Cases were categorized by outcome: (Group 1) True VP, with subgroups A, unresolved by time of delivery and B, resolved by delivery; (Group 2) False positives; (Group 3) Possible VP without definitive diagnosis; and (Group 4) VP ruled out, for example, “no features of VP.” Group size was expressed as a percentage of total anatomy scans during pre‐ or post‐intervention periods respectively. Absolute and relative percent change were calculated for each group.ResultsIn the pre‐intervention period, 1 case (0.36% of total scans) was categorized in Group 1A, 1 case (0.36%) in Group 3, and 7 cases (2.53%) in Group 4. In the post‐intervention period, 2 cases (0.30%) were in Group 1A, 4 cases (0.61%) in Group 1B, 2 cases (0.30%) in Group 2, 1 case (0.15%) in Group 3, and 7 cases (1.06%) in Group 4. There was a +153% relative change in true positives, from 0.36 to 0.91%.ConclusionsUniversal color Doppler screening may have increased detection (sensitivity) while simultaneously increasing false positives (decreased specificity). While decreasing sensitivity is not ideal, this is acceptable given the potential catastrophic outcome of a missed VP.

Prenatal Diagnosis of Vasa Previa in the Second Trimester of Pregnancy Based on Non-typical Ultrasound Findings: A Case Report and Mini-Review of the Literature

“…Additionally, screening for increased vascularization above the cervix should be repeated using transvaginal Doppler ultrasound at 32 gestational weeks. It has been noted that the diagnostic accuracy of vasa previa significantly improves in pregnant women diagnosed with placenta previa in the second trimester of gestation [1,15]. In our patient, a thorough examination of the cervix using transvaginal color Doppler ultrasound in the second and third trimesters of pregnancy did not reveal the typical presence of linear or circular vascular structures close to the inner cervical os of the uterus.…”