The evaluation of
Fetal heart Rate patterns (without the added stress
of induced contractions) has been widely incorporated
into antenatal care for both screening and diagnosis.
It is an assessment of immediate fetal condition.
The rationale underlying
this is that the presence of spontaneous fetal
heart rate accelerations associated with fetal
movements (FETAL REACTIVITY) is an indicator of
fetal well being and vice versa. A REACTIVE TEST
is present when two or more fetal heart rate accelerations
are clearly recorded during a 20 minute period,
each acceleration of 15 or more beats per minute
and lasting 15 or more seconds, usually occurring
simultaneously with episodes of fetal activity. NST has high frequency
of false positive results (n50-80%). False negative
rate is only 3.2 per 1000, so the likelihood of
fetal death or serious fetal morbidity following
a negative (reactive test is extremely low. |
