Abstract
Objective
First-trimester transabdominal ultrasound (TAUS) is sometimes used to diagnose placenta
previa and counsel patients accordingly. We aimed to determine the predictive capacity
of a first-trimester transabdominal ultrasonographic placenta previa diagnosis for
persistence to the second trimester.
Study Design
Retrospective cohort study of patients with singleton pregnancies and first-trimester
transabdominal ultrasonographic placenta previa diagnoses from January to December
2022. The primary outcome was the predictive capacity of a first-trimester TAUS diagnosis
of placenta previa for placenta previa persistence into the second trimester. Secondary
outcomes included the predictive capacity of a first-trimester TAUS for placenta previa
persistence to delivery and risk factors associated with placenta previa persistence.
Chi-square and student's t-test were used to determine statistical significance, and a multivariable logistic
regression determined the strength of associations.
Results
Of the 185 patients with a first-trimester TAUS diagnosis of placenta previa, 159
(86.0%) resolved by the second-trimester resulting in a predictive capacity for persistence
to the second-trimester of 14.0%. Moreover, 182 (98.4%) were resolved by delivery,
resulting in a predictive capacity for persistence to delivery of 1.6%. Among the
27 patients with a prior cesarean delivery, the predictive capacity of a first-trimester
placenta previa diagnosis for persistence to the second-trimester was 22.2% and to
delivery was 7.4%. Advanced maternal age and posterior placenta in the first trimester
were risk factors for previa persistence to the second trimester, while prior cesarean
delivery and reproductive assistance were not.
Conclusion
First-trimester transabdominal ultrasonographic placenta previa diagnosis has a poor
predictive capacity for placenta previa persistence to the second trimester and even
lower for persistence to delivery. Counseling patients regarding placenta previa diagnosis
in the first trimester may result in unnecessary patient anxiety and activity restrictions.
Key Points
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First-trimester transabdominal placenta previa diagnosis has poor predictive capacity.
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Counseling regarding first-trimester placenta previa may result in unnecessary patient
anxiety.
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Studies are needed to see whether patients prefer placenta previa disclosure in the
first trimester.
Keywords
first-trimester ultrasound - transabdominal ultrasound - placenta previa - prenatal
diagnosis
