CTG intepretation & Biophysical Profile

Normal antepartum fetal CTG :

Baseline rate : 110-150 bpm
Baseline variability : 10-25 bpm
2 accelerations in 20 min
Absence of deccelerations


Suspicious fetal CTG :

Absence of accelerations
Variable deccelerations
Abnormal baseline rate (<110 or >150 bpm)
Abnormal baseline variability (<10 bpm)

Abnormal CTG :

Absence of accelerations, accompanied by 2 or more factors as stated below :

a) Abnormal baseline rate
b) Abnormal baseline variability
c) Presence of late deccelerations
d) Variable baseline variability with omnious features :

Duration >60 sec
Late recovery from baseline
Late decceleration components
Poor variability in between/during decceleration

What to do?

For a suspicious CTG -> in the presence of maternal risk factors -> might be an indication for delivery

In the absence of risk factors -> repeat it later in the same day

Biophysical profile (30 min score)


In order to refine the accuracy in assessing the fetal well-being by CTG, 5 different variables (or parameters) have been put forward, where a normal parameter scores 2, wheareas an abnormal parameter scores 0.

1) Fetal breathing movements

Normal (score = 2) if > 1 episode for 30 sec
Abnormal (score = 0) if absent or <30 sec

2) Gross fetal movements

Normal (score = 2) if 3 or more bodily/limb movements
Abnormal (score = 0) if < 3 bodily/limb movements

3) Fetal tone

Normal (score = 2) in presence of full extension (body/limb), followed by flexion and an open/close hand cycle

Abnormal (score = 0) = slow or absence of such movements

4) Non-stress CTG

Normal (score = 2) if presence of 2 accelerations
Abnormal (score = 0) if <2 accelerations + 1 decceleration

5) Amniotic fluid volume

Normal (score = 2) if there's at least 1 measurable pool of fluid, and at least 1 cm x 1cm in size

Abnormal (score = 0) if there's no measurable pool of fluid, or < 1cm x 1cm in size 

What's non-stress CTG and stress CTG?

The usual CTG done is the non-stress type.
Usually a stress CTG is unpopular in the UK, but is used to predict the fetal outcome in USA. It's done in the same manner as a non-stress CTG, with the exception of the administration of IV oxytocin for uterine stimulation in case of a stress-CTG.
A positive result = as a response towards IV oxytocin, there's evidence of fetal cardiac decceleration

However, it's unpopular in UK, mainly because of it's false-positivity, causing uterine hyperstimulation time consuming, invasive

Other methods of stimulation : acoustic, light, exercise, nipple stimulation

Category: Obstetrics Notes