••• Chapter 4^ Antepartum Management and Fetal Surveillance^43
❍ What types of anomalies are associated with decreased activity?
CNS anomalies and neuromuscular disorders.
❍ What maternal factors influence the evaluation of fetal movement?
Maternal activity, obesity, and medications.
❍ Which position do mothers appear to appreciate fetal movements best?
Left lateral recumbent position.
❍ Which maternal medications depress fetal movement?
Narcotics and barbiturates.
❍ What is a CST?
Response of fetal heart rate (FHR) to uterine contractions. Relies on the premise that fetal oxygenation will be
compromised or worsened by uterine contractions.
❍ How should the CST be performed?
The patient is placed in the semi-Fowler’s position at a 30- to 45-degree angle with a slight left tilt to avoid the
supine hypotensive syndrome. FHR is recorded and uterine contractions are monitored. Maternal blood pressure
is determined every 5 to 10 minutes to detect maternal hypotension. Baseline FHR and uterine tone are recorded
for 10 to 20 minutes. A CST then requires uterine contractions of moderate intensity, either spontaneous or
stimulated, lasting approximately 40 to 60 seconds with a frequency of three in 10 minutes.
❍ How can uterine activity be stimulated?
Nipple stimulation or intravenous oxytocin.
❍ How is oxytocin administered for the CST?
By an infusion pump at 0.5 mU/min. The infusion rate is doubled every 20 minutes until adequate uterine
contractions are produced.
❍ What is the advantage of generating uterine contractions with nipple stimulation versus intravenous
oxytocin administration?
The CST can be completed in less time (on average, 30 minutes as opposed to 90 minutes). Also, an intravenous
infusion is not required.
❍ How is nipple stimulation achieved for the CST?
One of two methods may be utilized. The patient may apply a warm moist towel to each breast for 5 minutes.
If uterine activity is not adequate, the patient is asked to massage one nipple for 10 minutes. A second method
involves using intermittent nipple stimulation. The patient gently strokes the nipple of one breast with the palmer
surface of her fingers through her clothes for 2 minutes and then stops for 5 minutes. The cycle is repeated only
as needed to achieve adequate uterine activity.
❍ How long should a patient be monitored after the CST has been completed?
The patient should be observed until uterine activity has returned to baseline.