Cardiotocograph

Listed below are five descriptions of a cardiotocograph trace. With regards to signs of foetal distress, which one of the following is the SECOND most concerning trace?

a) Heart rate 90 beats/min, late decelerations, variability 5 beats/min

b) Heart rate 145 beats/min, early decelerations, variability 25 beats/min

c) Heart rate 40 beats/min, no decelerations, variability 2 beats/min

d) Heart rate 160 beats/min, variable decelerations, variability 30 beats/min

e) Heart rate 100 beats/min, early decelerations, variability 20 beats/min

Answer: A

Explanation

A healthy cardiotocograph (CTG) has foetal heart rate in the range of 110 to 150 beats/

min; decelerations of the heart rate only occur early with respect to uterine contractions,

and variability is in the range of 5 to 25 beats/min.

Bradycardia between 100 and 110 is suspicious, and below 100 is almost always

pathological. If sustained, this is a sign of foetal distress and the foetus should be

delivered. Tachycardia in the range of 150 to 170 beats/min is suspicious. Over 170 is

likely to be pathological, usually indicating problems such as foetal infection or

distress. Early decelerations are worst at the peak of uterine contraction, are caused

by foetal head compression and are usually benign. Variable decelerations occur after

the peak of contraction, but their timing is erratic. They may be a sign of umbilical

artery obstruction. Late decelerations are worst after the peak of contraction and may

be a sign of foetal hypoxia. Sustained reduction of variability, especially in combination

with sinister decelerations, would be indicative of foetal distress. In the question, the

traces would rank (c), (a), (e), (d), (b) with (c) the most sinister. Option (c) describes an

arresting bradycardia; (a) is a pathological bradycardia; (e) is a suspicious bradycardia;

(d) is a borderline tachycardia and (b) is normal.