A biophysical profile (BPP), also known as a fetal BPP, is performed in the later stages of pregnancy to assess fetal well-being. The BPP is more accurate and provides more information than does the NST alone. It can identify the fetus affected by hypoxia that is at risk for intrauterine distress or death. In high-risk pregnancies, testing usually begins by 32–34 weeks of gestation; those with severe complications may require earlier testing at 26–28 weeks.

The BPP uses ultrasound imaging to evaluate five distinct parameters: (1) evidence of FHR (cardiac rate) accelerations (NST), (2) muscle tone, (3) fetal movement, (4) fetal breathing, and (5) volume of amniotic fluid. Based on sonographic evidence during a typical 20- to 30-minute survey, each parameter is assigned a value of 0–2 points (2 is optimal). The maximum number of points obtainable is 10; a score of 10 indicates a normal test without evidence of fetal distress. Generally, a score >8 indicates fetal well-being. The BPP also provides the healthcare provider with valuable information regarding fetal size and position, number of fetuses, placental location and grade, and evidence of specific fetal activities such as micturition and eye movements.

Another version of the BPP, termed the modified biophysical profile, has become a primary mode of antepartum fetal testing. The modified version includes the NST as a measure of fetal acid–base status and the amniotic fluid index (AFI) as a long-term placental function assessment. The modified BPP is normal if the NST is reactive and if the AFI is >5. Abnormal results include nonreactive NST and AFI ≥5.

In some laboratories, Doppler examinations of the umbilical vessels assess uterofetal blood flow. Abnormal Doppler blood flow studies (umbilical artery velocimetry) may be detected before changes in NST, CST, or BPP are detectable. Abnormal Doppler umbilical artery waveforms become indicative of acidosis, hypoxia, and fetal growth restriction, which result in a poor outcome. Doppler velocimetry has demonstrated benefits for fetuses with suspected fetal growth restriction.

1. Explain test purpose and procedure.

2. Position the patient on her back and apply a gel (coupling agent) to the skin of the lower abdomen. Then, move the ultrasound transducer across the lower abdominal area to visualize the fetus and surrounding structures.

3. Examining time is usually 30 minutes but may vary because of fetal age or fetal state.

4. A CST or NST is also done at this time.

1. Variables that influence BPP include fetal age, fetal behavioral states, maternal or fetal infection, hypoglycemia, hyperglycemia, and postmaturity.

2. If a fetus <36 weeks of gestation does not have stable behaviors, a longer test may be needed. Infection may cause absence of FHR reactivity and fetal breathing movements. Frequency of fetal breathing increases during maternal hyperglycemia and decreases with maternal hypoglycemia. Other variables that influence BPP include use of therapeutic or nontherapeutic chemicals. Magnesium sulfate may decrease or eliminate fetal breathing movements and decrease FHR variability. Nicotine can decrease the profile parameters, and cocaine may also decrease the FBP score.

3. When the five major BPP parameters can be observed, the fetus is considered to be free of distress. Generally, a score of 8 points indicates fetal well-being.

4. A score of 6 points is equivocal, and retesting should be done in 12–24 hours.

5. A score of less than 4 indicates the potential for or the existence of fetal distress. This warrants further testing or the consideration of delivery.

Pretest Patient Care

1. Explain the test purpose and procedure and include information regarding each part of the test and how it relates to fetal well-being.

2. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Normal

• BPP score: >8 points, based on normal NST; normal fetal muscle tone, movement, and breathing; and normal volume of amniotic fluid