The usefulness of ultrasound assessment of amniotic fluid in predicting adverse outcome in prolonged pregnancy: a prospective blinded observational study.

Journal article

OBJECTIVE: To determine whether a single ultrasound scan at or beyond 40 weeks of gestation to detect a single deepest pool of amniotic fluid <2 cm and amniotic fluid index (AFI) <5 cm is clinically useful in the prediction of subsequent adverse pregnancy outcome. DESIGN: A prospective double blind cohort study. SETTING: A university teaching hospital delivering approximately 6000 women annually. POPULATION: One thousand and five hundred and eighty-four pregnant women at or beyond 40 weeks of gestation. METHODS: Ultrasound assessment of liquor to detect the single deepest pool of amniotic fluid and derive the AFI at or after 40 weeks of gestation. MAIN OUTCOME MEASURES: Perinatal death, meconium aspiration, birth asphyxia, intervention in labour for fetal distress, a cord arterial pH <7 and admission to the neonatal unit. RESULTS: An AFI <5 cm but not a single deepest pool <2 cm was significantly associated with birth asphyxia or meconium aspiration. An AFI <5 cm was also significantly associated with caesarean section for fetal distress in labour, a cord arterial pH <7 at delivery and low Apgar scores. Despite there being a statistically significant association with adverse outcomes the sensitivity of AFI was low at 28.6%, 12% and 11.5% for major adverse outcome, fetal distress in labour or admission to the neonatal unit, respectively. CONCLUSIONS: The AFI is superior to a measure of the single deepest pool as an assessment of the fetus at or after 40 weeks but has a poor sensitivity for adverse pregnancy outcome. Routine use is likely to lead to increased obstetric intervention without improvement in perinatal outcomes.

Authors: Morris, J; Thompson, K; Smithey, J; Gaffney, G; Cooke, I

• Publication status: Published
• Journal: BJOG : an international journal of obstetrics and gynaecology
• Volume: 110
• Issue: 11
• Pages: 989-994
• Publication date: 2003-11-01
• DOI: 10.1016/s1470-0328(03)02917-3
• EISSN: 1471-0528
• ISSN: 1470-0328
• Language: English
• Keywords: Pregnancy; Pregnancy Outcome; Female; Humans; Amniotic Fluid; Risk Factors; Pregnancy, Prolonged; Cohort Studies; Hydrogen-Ion Concentration; Adult; Prospective Studies; Fetal Blood; Meconium Aspiration Syndrome; Infant, Newborn; Obstetric Labor Complications; Ultrasonography, Prenatal; Intensive Care, Neonatal; Fetal Distress; Sensitivity and Specificity; Asphyxia Neonatorum; Double-Blind Method