Fetal Surveillance: Antepartum Surveillance

Surveillance is the best way to take care of pregnant women. There are two main tools of surveillance.

• Antepartum Surveillance is done before delivery 
• Intrapartum Surveillance is During delivery

Antepartum Surveillance

There are 4 Antenatal care visits scheduled to OPD throughout the pregnancy. Antepartum surveillance is done in high-risk pregnancies. The high-risk pregnancies are:

• IUGR- Intrauterine growth reduction 
• PIH- Pregnancy-induced hypertension 
• APLA- Antiphospholipid antibody syndrome 
• GDM- Gestational diabetes mellitus 
• Decreased fetal movement 
• Post-term pregnancy 
• Multiple pregnancies
• Oligohydramnios
• Heart disease
• Previous anomalous babies
• Previous abortions, preterm labor

Tools of Antepartum Surveillance

Tools such as a stethoscope and a Pinard fetoscope are used to measure the fetus's heart rate. 

The daily fetal movement count is closely monitored after the patient is admitted to the hospital. The “Cardiff count of 10” says the time needed to feel 10 movements each day. A Healthy baby has at least 10 movements per day.

Monitoring the heart rate 

Basic patterns of fetal heart rate

The Normal heart rate of the fetus is between 120 to 160 or 110 to 160

If the heart rate is <110, then it is known as Bradycardia. Bradycardia is seen in 

• Heart block
• Prolonged cord compression
• Cord prolapse
• Tetanic uterine contractions
• Paracervical block
• Serious fetal compromise

If the heart rate is >160, then it is known as Tachycardia, and it is seen in

• Maternal fever
• Fetal hypoxia 
• Fetal anemia 
• Amnionitis 
• Drugs like Beta-mimetics and Phenothiazines

Beat-to-beat Variability

In a fetus, it is normal to have beat-to-beat variation in heart rate. The Baseline fetal heart rate is taken over 10 mins of time. Variation is seen between the beats. The increase in heart rate is known as Acceleration. Whereas, when the Baseline is decreased and then increased, then it is known as Deceleration

• Minimal beat to beat Variability is <5 BPM
• Moderate beat to beat Variability is  6-25 BPM
• Marked beat to beat Variability is >25 BPM

Non-Stress Test (NST)

A Doppler probe is placed on the abdomen. 

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Press the button attached to the hand to feel the heart of the fetus.

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Fetal heart rate is heard through the instrument.

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Variation in heart rate is observed.

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Determine the functioning of the sympathetic and parasympathetic nervous system.

In a non-stress test, the Sympathetic and parasympathetic nervous systems are assessed. This is done by 28 weeks. This reading disappears first with progressive fetal compromise. It is an OPD procedure that is done when the patient is Seated or lying down, toward the right or left. It is usually done after breakfast or lunch.

Having 2 or more accelerations of more than 15 beats, which last for more than 15 seconds in a 20-minute observation time, is known as a reactive non-stress test.

Frequency of NST

NST is started at 32 weeks and is done Once a week for all pregnancies. In high-risk pregnancies, it is done Twice a week and Daily for uncontrolled DM and HTN.

Non reactive Non Stress Test

In a noon reactive no stress test a 40-minute or longer tracing should be performed. It accounts Account for the fetus sleep cycle

• VAST could be used to stimulate the fetus
  • Stimulus of 1-2 seconds 
  • It is ominous for >90 mins
  • VAST- Vibroacoustic stimulation test
• Continuous nonreactive NST- Suggests central nervous system depression
• Can do for Biophysical profile, contraction stress test 

False reactive non stress test 

• Asymmetric IUGR
• Oligohydramnios

To learn about the Biophysical Profile (BPP) and Amniotic fluid index topic log on to the prepladder app and watch the related video under thee same topic of Obstetrics and Gynaecology.

Doppler

Dopplers assess blood flow patterns. Let's read about the most common types of dopplers used in the Obstetrics and Gynaecology Department.

Doppler Umbilical Artery

Doppler of the umbilical artery is most commonly done for the assessment of fetal well being. It is a Reliable method to know about fetal growth restrictions. In the Doppler of the umbilical artery, the Systolic and diastolic ratios more than 95 percentile for gestational age are considered abnormal. In Fetal compromise, Diastolic notching can be seen. It is the first sign of fetal compromise. There is Absent diastolic flow and Flow is only present in systole in the cases of Severe compromise. Severe compromise Requires immediate delivery or termination of the pregnancy.

If a Reverse diastolic flow is seen during the Doppler of the umbilical artery, it signifies Imminent death. If the fetus is more than 28 weeks, then a C-section is done to remove the dead fetus.

Middle cerebral artery Doppler

Doppler of the middle cerebral artery is a Reliable method to test for fetal anemia. It is also known as the primary method to assess fetal anemia; however, it is not recommended as a primary method for fetal compromise.

Intrapartum fetal surveillance 

The Fetal heart rates are checked with the help of a Stethoscope And Pinards fetoscope. Pinnard’s fetoscope is Conical in shape and is Made up of aluminum. It includes tests such as:

1. Fetal scalp blood Ph

2. Internal Electronic Monitoring

It is also known as Indirect electronic monitoring. In this method, a Bipolar electrode is placed on the fetal head. It Detects fetal P, QRS, and T complex. Peak R wave is most reliable in internal electronic monitoring.

3. External (Indirect) Electronic Monitoring

It is the most important method for fetal monitoring. It includes cardiotocography. In this method two probes are placed on the abdomen of mother and the Fetal heart rate and uterine contractions are assessed

Summary of Definitions

Frequently asked questions

Question: What could cause a Type 1 deceleration in fetal monitoring?

Answer: Head compression

Question: What could cause a sinusoidal pattern in fetal monitoring?

Answer: Acidosis

Question: What does a fetal scalp blood pH below 7.2 indicate? 

Answer: Acidosis

Question: What fetal condition might be suggested by asymmetric intrauterine growth restriction (IUGR)?

Answer: Oligohydramnios

Question: DOC for hypertension with pregnancy?

Answer: Labetalol

Question: DOC for diabetes in pregnancy?

Answer: Insulin

Related: Parturition, Stages of Labour and Partogram

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