The management of nuchal cord in third-trimester pregnancy and labour has been debated for many years. The concern that entanglement could cause cord compression leading to intrapartum complications dates back to Hippocrates, who had already made reference to the nuchal and chest coiling of the umbilical cord in De Octimestri Partu and regarded it as "one of the dangers of the eighth month."

The presence of a single loop nuchal cord occurs in one-fourth of pregnancies but generally has no major clinical significance. It's estimated that nuchal entanglement occurs in 6% of pregnancies at 20 weeks and then increases linearly to 29% at 42 weeks. The presence of >/= 2 loops is estimated at 0.2-8.3%. For diagnostic imaging, colour Doppler sonography is a sensitive and specific method, with assessment best in the axial plane. The technique will also identify multiple loops, but their number can only be accurately counted in the sagittal plane. Cases of >/= 4 nuchal loops are at high risk for developing complications in labour and delivery, including variable fetal heart rate, decreased fetal movement, umbilical arterial metabolic academia, neonatal anemia and, in extreme situations, intrauterine fetal demise. As such, these cases demand extra care, including regular biophysical profiles, non-stress tests and Doppler assessment of the umbilical artery. When episodes of cord compression are sufficiently spaced, the fetus can clear the increased CO₂ and maintain the oxygenation by using its oxygen reserve. If there are signs of fetal discomfort or distress, however, like decreased fetal movement, or persistent fetal heart variable decelerations, or repeated late decelerations, operative intervention is recommended.

Most studies suggest that a single loop nuchal cord at term is not associated with adverse perinatal outcome, and that ultrasound for nuchal cord assessment isn't required at the time of admission for delivery. For women late in pregnancy with the fetus in breech position, though, if they're considering the option of external cephalic version, ultrasound assessment is recommended to rule out multiple loops. Nuchal cord has also been associated with induction of labour, slow progress of labour and shoulder dystocia (especially for multiple or tight nuchal loops).

In summary, the presence of a single loop nuchal cord may be associated with variable fetal heart rate decelerations but generally doesn't compromise fetal well-being, so it doesn't alter standard management. Multiple wrapping, especially >/= 4 loops, demands special care due to the risk of intermittent cord compression. If signs of fetal stress are superimposed, a C-section may be required. MM

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