The relevance of placental location at 20-23 gestational weeks for prediction of placenta previa at delivery: evaluation of 8650 cases

Citation
Rh. Becker et al., The relevance of placental location at 20-23 gestational weeks for prediction of placenta previa at delivery: evaluation of 8650 cases, ULTRASOUN O, 17(6), 2001, pp. 496-501
Citations number
22
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Reproductive Medicine
Journal title
ULTRASOUND IN OBSTETRICS & GYNECOLOGY
ISSN journal
0960-7692 → ACNP
Volume
17
Issue
6
Year of publication
2001
Pages
496 - 501
Database
ISI
SICI code
0960-7692(200106)17:6<496:TROPLA>2.0.ZU;2-A
Abstract
Objective To determine the correlation between placental position at 20-23 weeks and incidence of birth complications caused by placental position. Subjects and methods In an ongoing prospective study, placental position wa s determined by transabdominal sonography as part of anomaly scanning at 20 -23 gestational weeks, followed by transvaginal sonography in uncertain or suspicious situations. Examination was performed in 9532 cases: feedback te as obtained from 8650 patients (90. 7%). Results Transabdominal sonography was followed by transvaginal scan in 363 of 8650 cases (4.2%). In 8551 cases (98.9%), we found normal placental posi tion, with the placenta not reaching: the internal os and a Cesarean sectio n rate of 17.1% (1458/8551). The incidence of 'low placental position', wit h the placenta reaching the internal os was 0.66% (57/8650), with a Cesarea n section rate of 21% (12/57). In 0.49% (42/8650) of cases, the placenta ov erlapped the internal os at 20-23 weeks; Cesarean section because of placen ta previa or bleeding was performed in 28 of 8650 cases (0.32 %). Vaginal d elivery was possible in 43 % of cases (13/30), when the overlap did not exc eed 25 mm. If the overlap exceeded 25 mm (12 cases), no vaginal delivery wa s reported. There was no reported case of placenta previa missed at the 20- 23-week scan. Conclusion At 20-23 weeks, a combination of routine transabdominal and indi cation-based transvaginal location of placental position is a powerful tool in predicting placenta previa at delivery. The advantage of determining pl acental position at this stage of pregnancy is a low false-positive rate co mpared to at earlier stages of pregnancy. We conclude that an overlapping p lacenta at 20-23 weeks has the consequence of a high probability of placent a previa at delivery. An overlap of 25 mm or more at 20-23 weeks seems to b e incompatible with later vaginal delivery.