Intrapartum Amnioinfusion in Meconium Stained Amniotic Fluid: An Update

The presence of meconium is associated with a higher incidence of abnormal labor, fetal distress, low apgar scores and delivery by cesarean section.1 It has been estimated that as many as 8 to 16% of pregnancies may be complicated by the presence of meconium in amniotic fluid.2 Meconium aspiration may occur antepartum or intrapartum. Meconium aspiration syndrome develops when there is mechanical obstruction and chemical inflammation as a result of aspiration of meconium into the lower respiratory tract of the fetus or neonate. It is a lifethreatening respiratory disorder, defined as respiratory distress in a neonate with meconium aspiration. It has been estimated to have a mortality rate of 25%. Some studies have demonstrated that presence of thick rather than thin meconium in amniotic fluid is associated with adverse perinatal outcome.3,4 Various methods such as intrapartum amnioinfusion, splinting the chest of the baby till suctioning is started at birth and proper tracheoesophageal suctioning have been employed to decrease the risk of meconium aspiration. Intrapartum amnioinfusion was initially proposed by Wenstrom and Parsons, as a method of diluting meconium to decrease the incidence of MAS.5 The instillation of normal saline into the uterus was theorized to reduce meconium concentration and thereby the effect of aspiration. Similar results have been recorded in other studies.6 It has also been observed that women with oligohydramnios have higher degree of meconium staining. This has been attributed to dilution of the same amount of meconium when liquor is normal, as a result of which meconium appears thin. Amnioinfusion may, therefore, not only dilute meconium but also correct oligohydramnios and, thus relieve umbilical cord compression. Various techniques of amnioinfusion have been described. Studies done in resource limited settings have employed the use of nasogastric tube of FG 8, inserted transcervically into the uterine cavity just above the head. 500 ml of normal saline, brought to room temperature, is infused over 30 minutes, followed by a further 500 ml at the rate of 3 ml/min.7,8 The use of a maximum one liter of saline has been generally considered in centers where continuous electronic fetal monitoring is not available. The women are monitored by fetal heart auscultation every 15 minutes and uterine activity is assessed every half hour by palpation. Rathore AM et al found the cesarean section rate to be significantly lower in women administered amnioinfusion (21%) as compared to the control group (36%). Importantly the cesareans done for fetal distress were lower in the study group (12%) as compared to control group (26%). Amnioinfusion was associated with a significant decrease in the incidence of meconium at the vocal cords, improvement in one minute apgar scores, respiratory distress and fewer admissions to NICU as compared with the controls.9 A prospective observational study was conducted in the Department of Obstetrics and Gynecology, JN Medical College, AMU, between January and December 2009. The aim of the study was to study the effect of intrapartum intracervical amnioinfusion on the perinatal outcome. A total of 50 patients were recruited to the study. Inclusion criteria were a period of Abstract