Heart Rate Monitoring of Fetus

External and Internal Heart Rate Monitoring of the Fetus

(Fetal Monitoring, External and Internal)

Procedure Overview

What is external and internal fetal heart rate monitoring?

Fetal heart rate monitoring is a procedure used to evaluate the well-being of the fetus by assessing the rate and rhythm of the fetal heartbeat.

During late pregnancy and labor, your physician/midwife may recommend monitoring the fetal heart rate and other functions. The average fetal heart rate is between 110 and 160 beats per minute, and can vary five to 25 beats per minute. The fetal heart rate may change as the fetus responds to conditions in the uterus. An abnormal fetal heart rate or pattern may indicate that the fetus is not getting enough oxygen or that there are other problems.

There are two methods for fetal heart rate monitoring, external and internal:

During labor, uterine contractions are usually monitored along with the fetal heart rate. A pressure-sensitive device called a tocodynamometer is placed on the mother’s abdomen over the area of strongest contractions to measure the length, frequency, and strength of uterine contractions. Because the fetal heart rate and uterine contractions are recorded at the same time, these results can be examined together and compared.

Internal uterine pressure monitoring is sometimes used along with internal fetal heart rate monitoring. A fluid-filled catheter is placed through the cervical opening into the uterus beside the fetus and transmits uterine pressure readings to the monitor.

Other procedures that may be used to monitor the well-being of the fetus include amniocentesis and chorionic villus sampling. Please see these procedures for additional information.

Anatomy of the fetus:

Illustration of fetus in utero
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Reasons for the Procedure

Fetal heart rate monitoring is used in nearly every pregnancy to assess fetal well-being and identify any changes that might be associated with problems during pregnancy or labor. Fetal heart rate monitoring is especially helpful for high-risk pregnancy conditions such as diabetes, high blood pressure, and problems with fetal growth.

Situations during pregnancy in which fetal heart rate monitoring may be used include, but are not limited to, assessment of fetal heart rate during prenatal physician visits and monitoring the effect of preterm labor medications on the fetus.

Fetal heart rate monitoring may be used as a component of other procedures, including, but not limited to, the following:

Situations during labor which may affect the fetal heart rate and for which fetal heart rate monitoring may be used include, but are not limited to, the following:

There may be other reasons for your physician to recommend fetal heart rate monitoring.

Risks of the Procedure

There is no radiation used and generally no discomfort from the application of the transducer to the abdominal skin.

The elastic belts that hold the ultrasound and pressure transducers in place around your abdomen may be slightly uncomfortable. These can be readjusted to help you feel more comfortable.

You must lie still during some types of fetal heart rate monitoring. You may be required to stay in bed during labor.

With internal monitoring, you may experience some slight discomfort during the insertion of the electrode.

Risks of internal monitoring include, but are not limited to, infection and bruising of the fetal scalp or other body part.

Internal fetal heart rate monitoring is contraindicated in women with active herpes lesions on the cervix or vagina because of the risk of transferring the infection to the fetus.

There may be other risks depending upon your specific medical condition. Be sure to discuss any concerns with your physician/midwife prior to the procedure.

Certain factors or conditions may interfere with the results of the procedure. These include, but are not limited to, the following:

Before the Procedure

During the Procedure

Fetal heart rate monitoring may be performed in your physician’s office, on an outpatient basis, or as part of your stay in a hospital. Procedures may vary depending on your condition and your hospital’s practices.

Generally, fetal heart rate monitoring follows this process:

For external fetal heart rate monitoring:

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  1. Depending on the type of procedure, you may be asked to expose your abdomen, undress from the waist down, or undress completely and put on a hospital gown.
  2. You will lie on your back on an examination table.
  3. A clear gel will be applied to your abdomen (the gel acts as a conductor).
  4. The transducer will be pressed against the skin and moved around until the fetal heartbeat is located. You will be able to hear the sound of the fetal heart rate with Doppler or an electronic monitor.
  5. During labor, the fetal heart rate may be monitored intermittently or continuously, depending on your condition and the condition of your fetus.
  6. For continuous electronic monitoring, the transducer will be connected to the monitor with a cable. A wide elastic belt will be placed around your back to secure the transducer in place.
  7. The fetal heart rate will be recorded in the medical record. With continuous electronic monitoring, the fetal heart pattern will be displayed on a computer screen and printed onto graph paper.
  8. You may or may not be allowed to get out of bed with continuous external fetal heart rate monitoring.
  9. Once the procedure has been completed, the transducer will be removed and the gel will be wiped off.

For internal fetal heart rate monitoring:

Illustration of internal fetal heart rate monitoring
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  1. You will be asked to undress completely and put on a hospital gown, and lie on a labor bed, with your feet and legs supported as for a pelvic exam.
  2. The physician/midwife or nurse will perform a vaginal examination with a gloved hand to check cervical dilation (the amount the cervix has opened). This may be slightly uncomfortable.
  3. If the amniotic sac is still intact, your physician/midwife may break open the membranes with an instrument. You will feel warm fluid coming out of your vagina.
  4. The physician/midwife will feel the part of the fetus at the cervical opening with gloved fingers - this is usually the head of the fetus.
  5. A long, plastic electrode guide will be inserted into your vagina. A small spiral wire at the end of the electrode will be placed against the fetal part and gently rotated into the fetal skin.
  6. The guide will be removed and the electrode will be left in place, attached to the fetal part.
  7. The electrode wires will be connected to the monitor cable and secured with a band around your thigh.
  8. You may or may not be allowed to get out of bed with continuous internal fetal heart rate monitoring.
  9. Once the baby is born, the electrode will be removed.

After the Procedure

There is no special type of care required after external fetal heart rate monitoring. You may resume your normal diet and activity unless your physician/midwife advises you differently.

After internal fetal heart rate monitoring, the electrode site on the newborn baby will be examined for infection, bruising, or a laceration. The site may be cleansed with an antiseptic.

Your physician/midwife may give you additional or alternate instructions after the procedure, depending on your particular situation.

Online Resources

The content provided here is for informational purposes only, and was not designed to diagnose or treat a health problem or disease, or replace the professional medical advice you receive from your physician/midwife. Please consult your physician/midwife with any questions or concerns you may have regarding your condition.

This page contains links to other Web sites with information about this procedure and related health conditions. We hope you find these sites helpful, but please remember we do not control or endorse the information presented on these Web sites, nor do these sites endorse the information contained here.

American College of Obstetricians and Gynecologists

American Institute of Ultrasound in Medicine

National Institutes of Health (NIH)

National Library of Medicine

National Women's Health Information Center

 

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