The predictive value of ultrasound assessment of amniotic fluid index, biophysical profile score, nonstress test and foetal movement chart for meconium-stained amniotic fluid in prolonged pregnancies.

OBJECTIVE To evaluate the value of non-stress test (NST), biophysical profile score (BPS), amniotic fluid index (AFI) and foetal movement charted (FMC) by mother in the prediction of meconium passage in post-date pregnancies. METHODS In a cross-sectional study performed from 2003 to 2005, in the Ali-Ebne-Abitaleb Hospital, all post-date singleton pregnant women were included and evaluated a few hours before delivery for AFI, NST, BPS and FMC. Based on the results of the mentioned tests the occurrence of foetal distress was foreseen and the judgments were compared with the results of evaluation of the amniotic fluid after amniotomy during labour. Our judgment of occurrence of foetal distress was based on meconium staining of amniotic fluid (MSAF) as the gold standard. RESULTS In this study 250 women were included. The sensitivity and specificity of these tests respectively were: 62% and 42% for NST, 66% and 56% for BPS, 38% and 83% for AFI and 44% and 64% for FMC. The highest positive predictive value was recorded respectively for AFI (52%) and negative predictive value was recorded for NST (94%). There was a significant association between MSAF and BPS. In univariate analyses, there was a significant association between MSAF and BPS (P = 0.010 for linear by linear association, exact method). Also there was a significant association between MSAF and AFI < 5 cm. (OR = 2.99, 95% CI, 1.57-5.74). CONCLUSION Although BPS and AFI had the highest level of prediction, they are of limited usefulness in prediction of foetal distress. The reactive NST is more conclusive.