Meconium - Stained Amniotic Fluid in Labour – its Significance and Correlation to Early Maternal and Neonatal Outcome – A Prospective Case Control Study in A Tertiary Care Center

Abstract

Background: Meconium-stained amniotic fluid (MSAF) is a well-known factor which associated with significant adverse pregnancy outcomes. Meconium Aspiration Syndrome (MAS) occurs in about 5% of deliveries with MSAF and death occurs in about 12% of infants with MAS. The significance of meconium claimed to be varied from being entirely physiological, which exhibits sign of fetal maturity, to a sign of fetal distress as a response to hypoxic insult to the foetus. This study was carried out in a tertiary care centre; with the aim of detecting the significance of MSAF. Additionally, this study compares the fetal and maternal outcome in deliveries complicated by meconium-stained amniotic fluid and critically evaluates the associated predisposing maternal and fetal factors for MSAF. Method: This prospective case-control study was carried out in Colombo South Teaching Hospital (University Professorial Obstetrics Unit), Sri Lanka. Women who presented to the unit with pre-defined selection protocol were recruited to the study until the sample size (n = 216 in each arm) is achieved. The Sample was categorized in to two groups depend on the presence or absence of Meconium-stained amniotic fluid. Mean, standard deviation, median and 95% confidence interval are computed for quantitative variables. Chi-square test is applied for calculating the statistical significance of variables such as grades of meconium and Apgar score at 95% confidence interval. The p-value <0.05 and 95% confident interval was utilised to assess the statistical significance. Results: Presence of diabetes in current pregnancy was a significant risk factor for meconium-stained amniotic fluid at delivery with odd ratio of 2.397 (95% Confident Interval 1.203 - 3.568) and p value of <0.00.1. There is a statistically significant association between the mode of delivery and the nature of meconium with odd ratio of 3.029 (95% Confident Interval 1.887 – 3.136) and p value < 0.001, when its moderate to thick meconium staining. Presence of moderate to thick meconium increase the risk of neonatal respiratory morbidity with increased NICU admissions, which is both statistically and clinically significant with odd ratio of 2.412 (95% Confident Interval 1.674 - 3.199) and p value 0.005 when compared with thin meconium staining. Overall, there is a 2-fold rise in operative vaginal deliveries and EM-LSCS (Emergency Lower Segment Caesarean Section) in the presence of MSAF which accountable for 67.3% of the deliveries compared to 37.2% in the clear liquor group. The follow up of neonates at one month and three months of life, revealed no statistically significant concerns on the development of these babies in either arm of the study population. Conclusion: Presence of meconium-stained amniotic fluid is one of the common indications for caesarean delivery. Therefore, the results of this study may help to reduce the number caesarean sections carried out when the meconium is detected during labour. Presence of thin MSAF can be physiological following gut maturation of term foetuses, thus utilization of continuous electronic fetal monitoring can reliably cut down the caesarean section rates without adding numbers to the adverse perinatal outcomes. On the other hand, timely interventions upon detection of abnormal Cardiotocography (CTG), such as operative vaginal delivery or EM-LSCS, can significantly minimise these adverse neonatal outcomes. Abnormal CTG in a clinical background of moderate to thick meconium is more alarming, which warrant urgent interventions compared to the presence of thin / lightly stained meconium.