Amnioinfusion for the Prevention of Meconium Aspiration During Labour
Authors: Rogers M.S. , Lau T.K. , Wang C.C. , Yu K.M. 
Published: February 2008

EDITORIAL COMMENT: We accepted this paper for publication to appear in the same issue of the Journal as Risk Factors for Meconium‐Aspiration Syndrome (A) because this Hong Kong study has the considerable advantage for readers in that it gives the results obtained in a modern obstetric hospital with implementation of the regimen of amnioinfusion in patients with meconium‐stained liquor when delivery is not imminent and there is no indication for immediate Caesarean section. This carefully written study also is, as the authors indicate, a warning for those who are doing clinical trials. Although the patients were matched with a control series, these women were not appropriate controls because they tended to deliver soon after the observation of meconium‐stained liquor and hence the different outcomes in the 2 groups are probably explained by factors other than whether amnioinfusion was used. However, this series does indicate that amnioinfusion is associated with a reduced incidence of meconium‐aspiration syndrome in comparison with the previous incidence in the institution prior to the initiation of this technique. As the authors state in their conclusion, the incidence of cardiotocographic abnormalities and need for Caesarean section in these patients indicate that amnioinfusion is no guarantee that labour will proceed uneventfully or safely. We leave it for readers to decide whether we have reached the stage that amnioinfusion can be recommended in patients with meconium‐stained liquor where it is thought safe to allow labour to proceed or whether there should be a further, larger, controlled trial of patients with meconium‐stained liquor to see whether amnioinfusion is as valuable as this paper suggests may be the case. Our reviewer's literature search revealed that amnioinfusion has been evaluated when there is umbilical cord compression (potential, or diagnosed by variable fetal heart rate decelerations during labour) or when there is intrapartum evidence of oligohydramnios as well as when there is meconium‐stained liquor. It may be noted that amniotic fluid embolism has been reported after saline amnioinfusion (B). A review of practice in the United States representing 644,910 deliveries and 22,833 amnioinfusions concluded that the procedure is performed nationwide with neither the method employed nor the number of infusions performed having a significantly increased risk of having a complication (C).

Summary: The aim of this observational study is to review the outcome of prophylactic intrapartum amnioinfusion (AI) in pregnancies complicated by moderate to thick meconium‐stained liquor (MSL). The labour and neonatal outcome of all 298 AIs performed over a 3‐year period were compared to a matched‐control group of patients whose labour was complicated by moderate or thick MSL but without AI. The incidence of moderate or thick meconium below the vocal cords of the neonate were significantly lower in the AI group (6.4% and 3.4%) compared with the control group (15.4% and 6.7%). The incidence of meconium aspiration syndrome in the AI group was half (1.7%) that of the control group (3.7%), although the difference did not reach statistical significance. There was a significant higher incidence of cardiotocographic abnormalities in the AI group (30.5% versus 14.7%), with higher incidences of Caesarean section and operative vaginal deliveries. The reduction in the incidence and thickness of meconium after AI was not accompanied by any statistically significant reduction in adverse fetal outcomes such as low Apgar scores, cord pH values, admissions to and duration of admission to the neonatal unit, or the incidence of meeonium‐aspiration syndrome.