Fetal heart monitoring

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Fetal heart and uterine contraction monitor

Internal fetal monitoring

Overview

Risks

Results

Fetal heart monitoring

Alternative Names:

Non-stress test; NST; CST; Contraction; Scalp monitoring
How the test is performed:

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EXTERNAL FETAL MONITORING

By definition, external fetal monitoring is done through the skin (transdermally) and is not meant to be invasive. You will sit with knees and back partially elevated with a cushion under the right hip, which moves your uterus to the left, or however you are comfortable, as long as your uterus is displaced to the left or for brief periods on the right.

Sensitive electrodes (monitors) are placed on your abdomen over conducting jelly that can sense both fetal heart rate (FHR) and the strength and duration of uterine contractions. Usually, the output or results of this test are continuous and are printed out, or appear on a computer screen.

This allows your health care provider to monitor if your baby is experiencing fetal distress, and how well the fetus is tolerating the contractions. The decision to move to internal fetal monitoring is based on the information first obtained by external fetal monitoring.

NON-STRESS TEST (NST)

The NST is another way of externally monitoring your baby. The NST can be done as early as the 27th week of pregnancy, and it measures the FHR accelerations with normal movement. For this test, you will sit with knees and back partially elevated with a cushion under the right hip, which moves your uterus to the left.

The same monitors described above are placed on your abdomen to measure the ability of the uterus to contract and the FHR. If there is no activity after 30-40 minutes, you will be given something to drink or a small meal which may stimulate fetal activity. Other interventions that might encourage fetal movement include the use of fetal acoustic stimulation (sending sounds to the fetus) and gently placing your hands on your abdomen and moving the fetus.

CONTRACTION STRESS TEST (CST)

The CST is a final method of externally monitoring your baby. This test measures the ability of the placenta to adequately oxygenate the fetus under pressure (contractions).

For this test, you will sit with knees and back partially elevated with a cushion under the right hip, which moves your uterus to the left. The same monitors described above are placed on your abdomen to measure uterine contractility and FHR. If contractions are not occurring spontaneously, either a medication (called oxytocin) will be given intravenously, or nipple stimulation will be used to induce contractions.