a technical means of recording (-graphy) the fetalheartbeat (cardio-) and the uterine contractions (-toco-) during pregnancy or labour . The term usedto describe the monitoring is called acardiotocograph, commonly known as an electronicfetal monitor (EFM).

1 - Uterine Activity ( contractions ) :

Several factors assessing uterine contractions :

• Frequency : the amount of time between the start of contraction to the start of next contraction

• Duration : the amount of time from the start of the contraction to the end of the same contraction

• Intensity : measures the strength of contractions in mm/Hg

2 - Baseline Fetal Heart Rate :

between 120 – 160 bpm

Abnormalities :

Fetal bradycardia (FHR ˂ 110 bpm ) indicates :

1. Fetal Hypoxia. Bradycardia is a late sign of fetal hypoxia (a continual lack of oxygen)

2. Medications. Medications such as narcotics cause bradycardia by preventing receptor sites in the fetal heart muscle from accepting epinephrine, which works to increase heart rate

3. Maternal Hypothyroidism

Fetal bradycardia (FHR ˂ 110 bpm ) indicates :

4. Observed in epidural anesthesia ; Epidurals cause vasodilation, which leads to an increase in the incidence of maternal hypotension during labor cause bradycardia indirectly due to a reflex mechanism or as a result of hypotension

5. Synthetic Oxytocin may produce bradycardia by causing a hyperstimulation of the uterine muscle (myometrium), resulting in hypoxia

• Fetal tachycardia (FHR ˃ 160 bpm ) indicates :

1. Fetal Hypoxia. early sign of hypoxia

2. Maternal pyrexia

3. Fetal Infection. early sign of an intrauterine infection (a stress reaction to sepsis).

4. Medications. ; Sympathomimetic ( ritodrine )

5. Prematurity. Due to immature CNS

6. Maternal Anxiety. During periods of maternal stress and anxiety, epinephrine is released into the mother’s blood stream that crosses the placenta, resulting in an increase in fetal heart rate.

3 - Variability :

the normal irregular changes and fluctuations in thefetal heart rate.

Types :

Short term variability :

normally FHR changes by 5-10 bpm ( beat to beat Variability )

Long term variability :

Long-term variability is fluctuations around the fetal heart rate baseline

3 - Variability :

Long-term variability can be divided into the following categories:

Decreased variability: minimal variability (0-5 bpm).

Moderate variability: normal variability (6-25 bpm).

Marked variability: saltatory variability (<25bpm)

3 - Variability :

Decreased variability may occur in the following situations:

1. Hypoxia and acidosis

2. Prematurity

3. Fetal sleep

Loss of variability associated with :

1. Any fetal tachycardia

2. Intra amniotic infections

3. Fetal congenital anomalies

3 - Variability :

Diminished or lost variability indicates depression of brain stem centers controlling the interaction between sympathetic and parasympathetic tones

Persistent minimal or absent variability is requiring immediate inervention

4- Accelerations :

transient increase in FHR of 15 bpm lasting for 15seconds

5- Decelerations :

decrease in FHR > 15 beats per minute for < 30 second

Types :

1. Early

2. Variable

3. Late.

4. Prolonged

5- Decelerations :

• Early deceleration:

begins at or after the onset of a contraction andreturns to the baseline rate by the time thecontraction has finished and produces a mirrorimage of the contraction.

Repetitive with uniform shape

Onset-with Onset Of Contraction

Duration-length Of Contraction

Proposed Mechanism-head Compression

5- Decelerations :

• Early deceleration:

Early decelerations occur most frequently in the following clinical situations:

During sterile vaginal examinations

In second stage of labor during pushing

After amniotic sac has ruptured

Common In Primigravidas

5- Decelerations :

• Early deceleration:

5- Decelerations :

Late Decelerations:

Late decelerations are transitory decreases in heart rate due to uteroplacental insufficiency

The late deceleration begins after the onset of the peak or middle of the contraction and ends after the contraction

5- Decelerations :

Late Decelerations: Causes of Late Decelerations :

1. Excessive uterine contractions, maternal hypotension, or maternal hypoxemia.

2. Reduced placental exchange as in hypertensive disorders, diabetes, IUGR, abruption

5- Decelerations :

Late Decelerations: Management of Late Decelerations

1. Place patient on side

2. Discontinue oxytocin

3. Correct any hypotension

4. IV hydration.

5. Tocolysis

6. Administer O2 by tight face mask [25, 40]

7. If late decelerations persist for more than 30 minutes fetal scalp pH is indicated.

5- Decelerations :

Variable decelerations :

• They may appear V-shaped or U-shaped not related to contractions

• They mean umbilical cord compression

• They indicate possible compromise if they become prolonged or are persistent

• May suggest oligohydraminos ( dangerous with IUGR and postdate )

5- Decelerations :

Variable decelerations :

Definition :

1ry screening test for fetal surveillance bycontinuous electronic monitoring of the fetal heartrate and observing its significant accelerations inassociation with fetal movement perceived by themother

Principal : normally the fetal heart rate acceleratesin response to fetal movement

Performing NST :

1. Positioning the patient on semisetting on her back to release the weight of the uterus from inferior vena cava

2. External monitor applied to the mothers abdomen for 20 minutes

3. Instruct the mother to press a button when she feels the fetal movement

4. If no fetal movement recorded for 20 minutes : ( correction of hypoglyvemia if present - acoustic stimulation to stimulate the fetal movement - external manipulations of the fetus )

Results :

1. Reactive ( -ve test ) : when at least two or moremovement accompanied by accelerations of FHR of 15bpm lasting for 15 seconds .Reactive NST means that thefetus will survive safely for one week ( recently 3 days )

2. Non-Reactive NST ( +ve test ) : means absence of fetal accelerations in response to fetal movement . ( should be repeated next day after breakfast ) .normally non-reactive before 30 weeks due to CNS immaturity .The test must be repeated every 3 days in cases of : ( Unstable DM , SPET , Oligohydraminos ) The test must be repeated daily in cases of PROM

Other Variations :

1. Uterine contractions recorded : evaluated as CST

2. Spontaneous decelaeration ( bad sign ) associated with 50 % fetal Distress

• Advantages :

• Has no contraindications ( can be done for any patient )

• Low false negative rate

• Disadvantages :

• Subjective test ( depend on maternal perception of fetal movement )

• High false positive due to

1. maternal hypoglycemia

2. testing during the baby is sleep

3. maternal administration of alcohols or drugs

4. preterm baby

“ oxytocin challenge test “• Indications : when NST is abnormal

• Performing CST :

• The same protocol as NST but physiological uterine contraction is stimulated by :

1. Nipple stimulation for 10 min till contractions occur

2. Diluted oxytocin start by 0.5 mu/min then ↑ every 15-20 min

3. Contractions are satisfactory when reached 3-5 / 10 min lasting for 45 sec

“ oxytocin challenge test “

• Principal :

Uterine contraction compresses spiral arterioles

oxygen to the fetus

If :

Good metabolic reserve no hypoxia , no late decelerations

Low metabolic reserve hypoxia and late decelerations

• Results :

1. Negative result ( Reassuring ) : repeat weekly or whenindicated

2. Positive result

If mature termination of pregnancy

If ˂ 32 weeks biophysical profile

3. Equivocal : When stimulation associated withdecelerations cannot be interpreted repeat next day ordo biophysical profile

• Advantages

Early warning test for fetal hypoxia with low false negative value 1/1000

• Disadvantages :

1. High false positive value 25-75 % (although less than NST )

2. Has many contraindications

I. Patients with potential weak scar

II. Predispose to preterm labour

III. History of antepartum haemorrhage

IV. Placenta previa

V. Incompetent cervix

VI. Multiple gestation