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Transvaginal ultrasonography at 18–23 weeks in predicting placenta previa at delivery
Author(s) -
Taipale P.,
Hiilesmaa V.,
Ylöstalo P.
Publication year - 1998
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1046/j.1469-0705.1998.12060422.x
Subject(s) - medicine , placenta previa , obstetrics , transvaginal ultrasonography , gynecology , gestation , ultrasonography , placenta , pregnancy , obstetrics and gynaecology , fetus , radiology , genetics , biology
Objective To evaluate whether transvaginal ultrasonography at 18–23 weeks' gestation is useful in predicting placenta previa at delivery. Design We performed transvaginal ultrasonography in addition to routine transabdominal ultrasonography in 3696 consecutive non‐selected pregnant women with singleton fetuses and measured the distance from the placental edge to the internal cervical os. Results In 57 of 3696 patients (1.5%), the placental edge extended to or over the internal cervical os. In 27 patients (0.7%), the placenta extended ≥ 15 mm over the internal cervical os; in these cases the positive predictive value of placenta previa at delivery was 19% (95% CI, 6–38%) with 100% (95% CI, 48–100%) sensitivity. With ≥ 25 mm used as the cut‐off point, ten cases (0.3%) were screen‐positive and the positive predictive value for previa at delivery was 40% (95% CI, 12–74%) and sensitivity was 80% (95% CI, 28–100%). The frequency of placenta previa at delivery in this population was five of 3696 (0.14%, 95% CI, 0.04–0.31%). Conclusions We recommend confirmatory transvaginal ultrasonography if placenta previa is suspected at transabdominal ultrasonography in mid‐pregnancy, and reexamination at 26–30 weeks if the placental edge covers the internal cervical os by 15 mm or more. Copyright © 1998 International Society of Ultrasound in Obstetrics and Gynecology