Umbilical cord loops are not an uncommon occurrence in the foetal life due to the foetal movements and the length of the cord. The cord loops can occur around various parts of the foetus. When the umbilical cord wraps around the neck, in a complete 360o loop, it is known as a nuchal cord.
Studies have shown nuchal cord to be relatively harmless and not associated with perinatal morbidity and mortality. Although in a few cases when the cord is wrapped tightly around the neck, there may be a few adverse outcomes.
Nuchal cords have been found to be of two types according to the Giacomello classification system:
- Type A: loose and freely sliding and can often undo itself (not locked).
- Type B: more locking pattern which is difficult to undo on its own (locked).
Clinical features of Nuchal Cord
The adverse outcomes due to a tightly encircling nuchal cord are a result of the umbilical cord compression which may cause obstruction of blood flow in thin-walled umbilical vein and obstruction of blood vessels in the neck of the foetus. This results in a decreased supply of oxygen to the foetus.
- Foetal bradycardia (decreased heart rate) and variable decelerations in foetal heart rate.
- Signs which are similar to that of strangulation: duskiness of face, facial petechiae, conjunctival haemorrhage
- Low umbilical artery pH (acidosis)
- Intrauterine growth retardation (IUGR)
- Meconium stained liquor
Based on pathophysiological findings mentioned above, a developing grading system of tight nuchal cords is recommended as
- Grade 1: Conjunctival haemorrhage and petechiae.
- Grade 2: Duskiness of face, facial suffusion, and pallor.
- Grade 3 Respiratory distress, stupor, and hypotonia requiring resuscitation
Ultrasonography is the gold standard investigation for detecting nuchal cords. On USG, Divot sign is seen. It is a circular indentation on the smooth contour of the foetal nuchal (neck) skin. Other minor non-specific changes helping the diagnosis are the changes in the foetal heart rate (FHR).
The management of the nuchal cord depends upon the number of involved nuchal loops, the amniotic fluid index, the gestational age, and the foetal growth, among other factors. Considering most of the factors to be normal, the only issue to tackle is the loop during the delivery.
Proper monitoring of the vitals of the foetus and the mother are needed during the delivery. If the nuchal loop is loose enough, then it can be slid over the head. The baby can also be delivered through the loop if the sliding is not possible. If either of these is not possible then, there are a few manoeuvres which can be attempted such as the somersault manoeuvre.
In the case of unstable vitals, an emergency caesarean section (C-section) is attempted.
Patients with nuchal cord are likely to have uneventful labour and delivery as cord compression is often transient and most foetuses are able to compensate for the reduced umbilical blood flow.
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