Randomised trial of amnioinfusion during labour with meconium stained amniotic fluid

Abstract

Objective To assess the effect of amnioinfusion during labour with meconium stained amniotic fluid on caesarean section rate and perinatal outcome. Design Prospective randomised controlled study.Setting A tertiary care teaching hospital in India.Population Women in labour at term with meconium stained amniotic fluid.Methods Two hundred women in labour with 37 weeks gestation, single cephalic presentation with moderate or thick meconium were randomised to control and amnioinfusion groups at a 1:1 ratio. Amnioinfusion was performed using 500mL of normal saline over a period of 30 minutes in a study group. The control group received routine care. Both groups had intermittent auscultation of fetal heart rate during labour. Main outcome measures The primary outcome measure was caesarean section rate. Secondary outcome measures were meconium aspiration syndrome, 1 minute and 5 minute apgar < 7, hypoxic ischaemic encephalopathy, neonatal intensive care unit admission, meconium at the level of vocal cords. Results The caesarean section rate in the amnioinfusion group was less than the control group (RR 0.47; 95% CI 0.24 -0.93). Amnioinfusion was associated with a significant decrease in the incidence of meconium at the vocal cords ( P ¼ 0.001); improvement in 1 minute apgar scores ( P < 0.05), respiratory distress ( P ¼ 0.002) and fewer admissions to nursery compared with the controls. This sample size was inadequate to study the impact on meconium aspiration syndrome. Conclusion Amnioinfusion in an under resourced labour ward decreases caesarean section rates and fetal morbidity.

Intrapartum transcervical amnioinfusion for meconium-stained amniotic fluid

“…In this study no major maternal or fetal complications related to amnioinfusion were encountered, which is consistent with earlier reports [6–12]. The procedure is easy to perform even with minimal training, and can be carried out in all labor wards without additional resources.…”

“…Transcervical intrapartum amnioinfusion has been proposed as a method for reducing the risk of MAS in widely varying obstetric and neonatal settings [2,6–13]. By increasing amniotic fluid volume, amnioinfusion cushions the umbilical cord and dilutes the meconium, thereby probably improving variable deceleration [13,14] and reducing the risk of mechanical obstruction of the bronchioles and chemical pneumonitis [2,13].…”

Meconium

“…Smaller randomized trials in some settings have shown benefit in terms of MAS, NICU admission, and neonatal hypoxic-ischemic encephalopathy (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18), though a landmark, well-powered study failed to demonstrate a benefit (19). The most recent meta-analysis includes 15 total RCTs (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). Results are reported separately for sites with standard versus those with limited perinatal surveillance.…”

“…Under standard perinatal surveillance, compared with no amnioinfusion, amnioinfusion for MSAF (usually thick) is associated with significant reductions in MAS (47% reduction: RR 0.53, 95% CI 0.29-0.98) (23,24); heavy meconium staining of the liquor (97% reduction); variable fetal heart rate deceleration (33%); and CD for fetal distress (18%), as well as trends to reduction in overall CD rate (RR 0.78, 95% CI 0.60-1.02), NICU admission (55%), and pH < 7.20 (38%) (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24). There were no statistically significant differences in the rates of 5-minute Apgar <7 and perinatal death.…”

“…There is no difference seen in the rates of maternal endometritis, and the trials reviewed are too small to address the possibility of rare but serious maternal adverse effects of amnioinfusion. (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22).…”