Obstetrics and Gynecology

Electronic Fetal Monitoring

Topics:

Short term variability

Long term variability

Baseline:

Normal baseline is 120-160 bpm.

Short term variability:

Absent	0-2
Minimal	3-5
Average	6-10
Moderate	11-25
Marked	25+

Long term variability:

An FHR acceleration of 15 bpm lasting 15 seconds

Decelerations:

	30 seconds	30-60 sec.	60 seconds
70 bpm	mild	mild	mild
60-70	mild	mod	mod
60 bpm	mild	mod	severe

Early:

Description: Early decels mirror tonometer readings.

Etiology: Early decels result primarily from head compression.

Variable:

Description: Variable decels are generally v-shaped with shoulders and return to baseline.

Etiology: Variable decels result from cord compression.

Late:

Description: Late decels begin after the apex of a contraction. They may be repetitive and subtle. They are associated with decreased variability.

Etiology: Late decels indicate uteroplacental insufficiency.

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Last Modified December, 1996