Meconium liquor

Question 1

What are the potential reasons for a baby passing mec before birth?

Answer 1

1. Their digestive system has reached maturity and the intestine has begun working and moving the meconium out. This is the most common reason found in 15-20% of term babies and 30-40% of post-term babies.
2. Their cord or head is being compressed during labour causing a vagally mediated gastrointestinal peristalsis, the same reflex which causes variable heart rate decelerations. This may be why a lot of babies pass meconium as their head is compressed during the last minutes of birth.
3. Fetal distress resulting in hypoxia. Although the exact relationship between fetal distress and meconium-stained liquor is uncertain, it’s thought that lack of oxygen and intestinal ischaemia relaxes the anal sphincter and increases gastrointestinal peristalsis resulting in the passage of meconium.

Question 2

Thick versus light mec?

Answer 2

Thick mec thought to represent decreased amniotic fluid and therefore reflect placental insufficiency

Question 3

Factors associated with high risks of fetal harm?

Answer 3

• The presence of particulate or thick meconium.
• Abnormal fetal heart rate patterns, especially tachycardia.
• Absence of fetal heart rate accelerations and or, late decelerations.
• Umbilical artery pH of less than 7.15.
• Apgar score of less than 7 at 5 minutes.
• Meconium found in the trachea.
• Oligohydramnios.

Question 4

Assessment of women with mec liquor?

Answer 4

• Other risk factors present? e.g. FHR abnormality
• Does it fit clinical context? Re if not post dates then need to consider why mec liqour
• Thick vs thin mec?

Question 5

Risk of meconium liquor?

Answer 5

Increased perinatal morbidity
May indicate fetal distress
Increased CS rate
Meconium aspiration syndrome for neonate