How can I differentiate between cord prolapse and other causes of fetal heart rate deceleration?

To differentiate umbilical cord prolapse from other causes of fetal heart rate (FHR) deceleration, consider the following clinical and CTG features:

• Umbilical cord prolapse typically presents with sudden, profound, and prolonged variable decelerations on the CTG trace, often associated with a change in fetal heart rate baseline and reduced variability indicating hypoxia.
• Clinically, cord prolapse is an obstetric emergency characterized by the cord descending through the cervix or vagina, which can be confirmed by vaginal examination.
• Variable decelerations caused by cord compression (including prolapse) are usually intermittent and vary in timing relative to contractions, but in prolapse, they tend to be more severe and persistent.
• Other causes of FHR deceleration, such as head compression, cause early decelerations which are usually benign, with decelerations starting early in the contraction and returning to baseline by the end of the contraction without other CTG abnormalities.
• Late decelerations, starting after the peak of contractions and associated with uteroplacental insufficiency, differ in timing and pattern from variable decelerations seen in cord prolapse.
• In the presence of suspicious or pathological CTG changes, including decelerations, a full clinical assessment including maternal position, contraction frequency, and fetal wellbeing should be performed.
• Immediate obstetric review is essential if cord prolapse is suspected, and conservative measures such as maternal repositioning may be attempted while preparing for expedited delivery.

Thus, the key to differentiation lies in the sudden onset of severe variable decelerations with clinical evidence of cord prolapse on examination, contrasted with the timing and pattern of decelerations from other causes on CTG and clinical context ¹.