20: Fetal Heart Monitoring Flashcards
How often should you be intermittently monitoring a patient if pregnancy if uncomplicated?
q30 min in active phase of 1st stage of labor
q15 min in 2nd stage of labor
How often should you be intermittently monitoring a patient if pregnancy is complicated?
q15 min in active phase of 1st stage of labor
q5 min during 2nd stage
Which type of monitoring will provide more accurate tracings?
Internal monitoring
What is the normal pH of fetal scalp blood?
7.25-7.30
When is the pH of fetal scalp blood considered abnormal (fetal acidosis)?
pH < 7.20
What does the upper tracing in a fetal monitoring strip show?
FHR
What does the lower tracing in a fetal monitoring strip show?
Uterine contraction
Normal uterine activity
5 contractions in 10 minutes, averaged over a 30 minute window
Tachysystole
More than 5 contractions in 10 minutes averaged over a 30 minute window
Normal contractions
3 contractions in 8 minutes; contractions occurring every 2-3 minutes
MVUs
Montevideo units (measured by IUPC); the sum of contractions in a 10 minute period; need greater than 200 for at least 2 hours
Baseline FHR
Mean FHR rounded to increments of 5 bpm during a 10 minute segment. Assessed between contractions
Normal FHR baseline
110-160 bpm
Tachycardia FHR baseline
Greater than 160 bpm
Bradycardia FHR baseline
Less than 110 bpm
Most common cause of fetal tachycardhia
CHORIOAMNIONITIS/fetal infection
Baseline Variability
Amplitude of the peak-to-trough in bpm of change in baseline rate
Absent variability
Amplitude range undetected
Minimal variability
Amplitude range detectable but less than or equal to 5 bpm
Moderate (normal) variability
Amplitude range 6-25 bpm
Marked variability
Amplitude range greater than 25 bpm
Decreased variability
Can indicate possible fetal stress, especially ominous with late persistent decelerations; associated with hypoxia and acidemia
Accelerations
Abrupt increase in FHR and NORMAL
Non-reactive Stress Test
Heart rate of 15 or more bpm above baseline for 15 sec or more (but less than 2 minutes)
Prolonged accelerations
Last 2 minutes or longer
Deceleration
FHR decreases in response to uterine contractions
Early decelerations
GOOD - secondary to head compression; nadir of deceleration occurs at same time as peak of contraction causing a “mirror” image on monitoring strip
Variable decelerations
Secondary to umbilical cord compression; abrupt decrease in FHR that can occur at anytime on monitoring strip
Decrease more than 15 bpm lasting 15 sec-2 minutes
“Shoulder” phenomenon
When slight increase in FHR is followed by major drop in FHR
Late decelerations
BAD - Caused by uterine placental insufficiency. Most ominous deceleration - indicates fetal metabolic acidosis and low arterial pH; Nadir of deceleration occurs after the peak of the contraction
Prolonged decelerations
Decrease in FHR from baseline that is more than 15 bpm lasting over 2 minutes but less than 10 minutes; commonly seen during maternal pushing
Sinusoidal pattern
Smooth sine wave like pattern in FHR with 3-5 cycles per minute; NOT good - associated with fetal anemia
Baseline 110-160 bpm, moderate variablity, no late/variable decelerations
Category I
Intermittent variable decelerations or recurrent decelerations; tachysystole
Category II
Absent baseline variability, recurrent late decels, recurrent variable decels, bradycardia, sinusoidal pattern
Category III
