11.4Placenta praevia

StudyRef.PopulationInterventionOutcomesResultsCommentsStudy typeEL
Leerentveld et al., 1990549100 women with second or third trimester haemorrhage, suspected placenta praevia, fetal malpresentaion or nonengaged presenting part from 1988 to 1990In group with suspected placenta praevia (n = 15), transvaginal scan performed at 31 weeks (median). In the rest of the women (n = 85), transvaginal ultrasound performed at 29 weeks (median)
Findings at delivery used as gold standard
Sensitivity and specificity of transvaginal placental localisation
Cases of vaginal bleeding Sensitivity: 87.5%, 95% CI 61.7 to 98.4
Specificity: 98.8%, 95% CI 93.4 to 100
No cases of vaginal bleeding and no woman who presented with vaginal haemorrhage (n = 76) displayed aggravated bleeding after sonography.
CS3
Oppenheimer et al., 200155036 pregnant women with a placenta lying within 30mm of the internal cervical os or overlapping it at or after 26 weeksEligible women identified by transvaginal ultrasound and repeated every 4 weeks until leading edge migrated beyond 30 mm or deliveryCases of vaginal bleeding from transvaginal ultrasoundNo case of vaginal bleeding
Procedure also reported to be well tolerated by all women
CS3
Sherman et al., 199155138 women with suspected placenta praevia at 26 weeks or moreGroup 1 (n = 20): abdominal ultrasound
Group 2 (n = 18): abdominal ultrasound followed by vaginal ultrasound
All women rescanned at 4 week intervals
Diagnosis of placenta praevia
Cases of vaginal bleeding
Group 1, on initial transabdominal scan: 9 complete praevias, 3 partial praevias, 4 marginal praevias, and 4 low lying
Group 2, on initial transabdominal scan: 5 complete praevias, 5 partial praevias, 2 marginal praevias, and 6 low lying
Group 2, on transvaginal scan: 4 complete praevias, 3 partial praevias, 5 marginal praevias, and 6 low lying
In subset of women who gave birth within two weeks of last scan (n = 19), in both groups, transabdominal and transvaginal scans correctly identified all cases of complete praevia. For partial praevia, 2 women in group 1 were identified at delivery but the tranabdominal scan had identified 3 women.
In group 2, 2 women with partial praevia at delivery were identified, concording with results from the tranvaginal scan, but not with the transabdominal scan which identified only 1 woman.
No patient experienced increased vaginal bleeding within 24 hours after transvaginal scan
Method of randomisation not specifiedRCT1b
Farine et al., 199055277 women with second or third trimester bleeding or previous diagnosis of placenta praeviaTransabdominal ultrasound followed by transvaginal ultrasound within 24 hours
Findings at delivery used as ‘gold standard
Sensitivity and specificity
False positives and false negatives
Cases of vaginal bleeding
Transvaginal sensitivity and specificity: 100% and 81%
Transabdominal sensitivity and specificity: 79% and 39%
Transvaginal false positive and false negative rate: 29% and 0% (all false positive cases were marginal placenta praevia)
Transabdominal false positive and false negative rate: 62% and 20%
None had vaginal bleeding in 12 hours following scan
CS3
Taipale et al., 19975536428 women with singleton pregnancies from an obstetric clinic in Finland from 1993 to 1994Transvaginal ultrasound performed at 12 to 16 weeks. Placenta that extended over the internal cervical os was measured with electronic calipersNumber of women with placenta at or over internal cervical os at 12 to 16 weeks
Number of women with placenta praevia at birth
Sensitivity
287/6428 (4.5%) had placenta at or over internal os
10/6428 (0.16%) had placenta praevia at time of birth
8/10 women with placenta praevia were identified with transvaginal scan: sensitivity 80%, 95% CI 44 to 98
In all 8 of these women, the placenta extended 15mm or more over the internal os at 12 to 16 weeks
CH2b
Taipale et al., 19985543696 women with singleton pregnancies in Finland from 1995 to 1996Transvaginal ultrasound performed at 18 to 23 weeks.
Distance from edge of placenta to internal cervical os was measured with electronic calipers
Number of women with placenta at or over internal cervical os at 18 to 23 weeks
Number of women with placenta praevia at birth
Sensitivity and specificity
Positive predictive value (PPV) with 15-mm cutoff
57/3696 (1.5%) had placenta at or over internal os
5/3696 (0.14%) had placenta praevia at time of birth
Sensitivity: 100%, 95% CI 48 to 100
Specificity: 99.4%, 95% CI 99.1 to 99.6
In all 5 women, placenta extended 15mm or more over the internal os at 18 to 23 weeks
PPV: 19%, 95% CI 6 to 38
CH2b
Hill et al., 19955551252 pregnant women from a women’s hospital in the USATransvaginal ultrasound performed between 9 and 13 weeks of gestation. The distance from the edge of the placenta to the internal cervical os was measured with electronic calipersNumber of women with placenta at or over internal cervical os between 9 and 13 weeks
Number of women with placenta praevia at birth
77/1252 (6.2%) had placenta at or over internal os
4/1252 (0.32%) had placenta praevia at time of birth
In all 4 women, the placenta extended more than 1.6 cm over the internal os by transvaginal ultrasound at 9 to 13 weeks.
CSS3
Dasche et al., 2002556714 women with singleton pregnancies and suspected placenta praevia from 1991 to 2000Retrospective analysis of women who had transvaginal or transabdominal ultrasound between 15 and 36 weeks of gestationPersistence of placenta praevia to delivery from gestational age at detectionFrom 15 to 19 weeks: 12%
From 20 to 23 weeks: 34%
From 24 to 27 weeks: 49%
From 28 to 31 weeks: 62%
From 32 to 35 weeks: 73%
CS3

From: Evidence tables

Cover of Antenatal Care
Antenatal Care: Routine Care for the Healthy Pregnant Woman.
NICE Clinical Guidelines, No. 62.
National Collaborating Centre for Women's and Children's Health (UK).
London: RCOG Press; 2008 Mar.
Copyright © 2008, National Collaborating Centre for Women’s and Children’s Health.

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