Assessing the Risks of Meconium-Stained Liquor
Published: 17 January 2023
Published: 17 January 2023
The appearance of meconium-stained liquor (MSL) during labour is generally considered to be a sign of hypoxia and a predictor of poor fetal outcome. But is this always true?
Meconium-stained amniotic fluid is present in approximately 15% of live births (SCV 2021). Traditionally, MSL has been considered a sign of fetal distress due to hypoxia. However, it can also simply be a physiological response to a normally maturing gastrointestinal tract, causing no ill effects on the fetus at all (Skelly et al. 2022).
Reed (2023) suggests that there are five reasons why the fetus may pass meconium before birth:
It’s worth pointing out that fetal distress can be present without the presence of meconium, and meconium can be present without fetal distress (Reed 2023).
Addisu et al. (2018) state that there are two classifications of MSL: non-significant and significant.
Additional indicators of a potentially adverse neonatal outcome include MSL associated with an abnormal cardiotocograph (CTG), which is more likely to result in a caesarean birth and potential neonatal complications (Priyadharshini 2013).
That said, it’s always important to consider the whole clinical picture before deciding if the presence of meconium is a significant finding or not.
Whilst it’s true that the presence of meconium in the amniotic fluid can be a potentially serious sign of fetal compromise associated with poor perinatal outcome (Vaghela et al. 2014), it’s also true that most babies who are born in poor condition do not have meconium-stained liquor and most babies with meconium-stained liquor are born in good condition (Reed 2023).
In a global sense, MSL is still considered to be a marker for adverse perinatal outcomes. Whilst the passage of meconium alone is rarely a sign of significant fetal hypoxia or acidosis, meconium in the presence of an abnormal fetal heart rate (FHR) pattern should always be investigated further.
As Qadir et al. (2016) suggest, the presence of thick meconium is associated with an increase in perinatal morbidity and mortality, and its presence should never be overlooked.
Meconium aspiration syndrome (MAS) is a potentially-fatal condition that can occur when the infant accidentally inhales meconium during delivery (Skelly et al. 2022).
MAS is estimated to occur in 5% of births where meconium-sained liquor is present (SCV 2021).
Overall, MAS is known to have a higher incidence with:
(Hirani et al. 2015)
Whilst each hospital will have its own documented policies on the management of meconium-stained liquor, Reed (2023) urges all practitioners to consider the holistic picture and suggests the following practical steps that might help lower the risk of meconium aspiration syndrome:
Safer Care Victoria (2021) also comment on the following areas of uncertainty in clinical practice, suggesting that:
Following birth, infants born through MSL may require ongoing care.
(SCV 2021)