Objective: To evaluate transcervical amnioinfusion for meconium stained amniotic fluid during labout.
Design: Multicentre randomised controlled trial.
Setting: Four urban academic hospitals in South Africa. Obstetric surveillance included the use of electronic fetal heart rate monitoring in most cases.
Participants: Women in labour at term with moderate or thick meconium staining of the amniotic fluid.
Interventions: Transcervical amnioinfusion of 800 mL saline at 15 mL per minute, followed by a maintenance infusion at 3 mL per minute. The control group received routine care. Blinding of the intervention was not possible.
Main outcome measures: Caesarean section, meconium aspiration syndrome and perinatal mortality.
Results: Caesarean section rates were similar (amnioinfusion group 70/167 vs control group 68/159; RR 0.98, 95% CI 0.76-1.26). The incidence of meconium aspiration syndrome was lower than expected on the basis of previous studies (4/162 vs 6/163; RR 0.67, 95% CI 0.19-2.33). There were no perinatal deaths. There were no significant differences between any of the subsidiary outcomes.
Conclusions: This study concurred with three previous trials which found no effect of amnioinfusion for meconium-stained amniotic fluid on caesarean section rate, though the pooled data from all identified trials to date show a significant reduction. The findings with respect to meconium aspiration syndrome were inconclusive in this study alone because of the small number of babies affected, but the point estimate of the relative risk was consistent with the finding of a significant reduction in previous studies and with the Zimbabwe arm (CRAMP 2) of this study. Pooled data clearly support the use of amnioinfusion for meconium stained amniotic fluid to reduce the incidence of meconium aspiration syndrome.
PIP: Numerous clinical trials have indicated that amnioinfusion for potential or suspected umbilical cord compression reduces the frequency of fetal heart rate decelerations and cesarean section. The present study, conducted at four urban teaching hospitals in South Africa, further evaluated the benefits of transcervical amnioinfusion for meconium-stained amniotic fluid during labor on perinatal outcome. In the intervention group (n = 176), 800 ml of saline was amnioinfused at 15 ml/minute, followed by a maintenance dose of 3 ml/minute for the duration of labor. The control group (n = 176) received routine obstetric care. There were 70 cesarean sections in the amnioinfusion group and 68 in the control group (relative risk (RR), 0.98; 95% confidence interval (CI), 0.76-1.26). The prevalence of meconium aspiration syndrome was unexpectedly low: 4 cases in the intervention group and 6 cases in the control group (RR, 0.67; 95% CI, 0.19-2.33). There were no perinatal deaths in either group. Subsidiary outcomes (e.g., Apgar score, assisted delivery, cord pH, neonatal ventilation) did not differ between groups. These findings provide preliminary support for use of amnioinfusion in women whose fetuses are considered at risk of meconium aspiration syndrome. A similar study conducted in Zimbabwe demonstrated larger effects of amnioinfusion on reductions in cesarean section, meconium aspiration syndrome, and perinatal mortality.