8. Fetal Surveillance During Labor Flashcards
Drawbacks of Fetal Heart Rate Monitoring
- Incidence of neurologic damage and perinatal death is NOT significantly lower than older methods
- No decrease in cerebral palsy
- Increases # of c-sections and operative vaginal deliveries
Benefits of Fetal Heart Monitoring (& why we dont go back to old methods)
- Nomal continous FHR data = 98% chance that there will be a good fetal/neonatal outcome.
- 1:1 patient to nurse interaction needed with intermittent ausculatation is a HUGE expense
- Even though a non-reassuring continous FHR monitoring is not associated with poor perinatal outcome, it does give a warning of potential problems and fetuses responses to actions taken to help fetus
What are the 2 types of Fetal Heart Rate Monitoring?
- External monitoring
- Internal monitoring
Describe how a External Electronic Fetal Monitoring is done
- Dopple US transducer is placed on moms abdomen, overlying BB heart and detects fetal HR
- Pressure-sensitive toco transducer monitors frequency of contraction, but not strength

Pros and Cons of External Electronic Fetal HR Monitoring
- Pro: Simple, safe and gives us good info on timing of contractions and fetal response
- Con: Not acurate if mom is obsese
Internal Electronic Fetal Heart Monitoring is the most accurate.
How is it performed?
- Membranes have to be ruptured
- FSE (fetal scalp electrode), an internal fetal heart monitor is places on the scalp
- IUPC (intrauterine pressure catheter), is an internal contraction monitor that tells us the INTENSITY of the contractions

Using a fetal scalp electrode for internal monitoring should be avoided in which patients?
HIV patients
What is the pH of fetal scalp blood that is considered abnormal (fetal acidosis)?
pH <7.20
On the Fetal Monitoring Strip
- Upper tracing monitors _____.
- Lower tracing monitors _____.

- Upper tracing monitors FHR.
- Lower tracing monitors uterine contractions.

What is considered normal vs. tachysystole for uterine contractions when monitoring?
- Normal = 5 contractions or less in 10 minutes, averaged over 30 mins
- Tachysystole = >5 contractions in 10 minutes, averaged over 30 mins
- May or may not be associated with FHR decelerations
How do we measure contractions on the FHR monitor?
Peak => peak.

What is a NL amount of contractions?
3 contractions in 8 minutes; should occur on average every 2-3 minutes.

What is a Montevideo unit (MVU)?
How is it measured?
What is NL?
-
Montevideo unit (MVU) = done via IUPC to detect the strength of contractions in a 10 minute period (summed together)
- (Pressure - baseline pressure) + all for 10 minutes
- >200 MVU’s for at least 2 hours

What is your evaluation of the uterus based on this strip?

Tachysystole ( >5 contractions in 10 minutes)
What is the baseline FHR?
-
Baseline FHR is the mean HR, rounded to the nearest 5 bpm in a 10 minute period that we take BETWEEN contractions
- => NL, tachycardia or bradycardia
When detecting baselineFHR (NL, bradycardia, tachy), at what point on the strip do you assess?
Between contractions
What is a normal FHR, tachycardia, and bradycardia?
- Normal = 110-160 bpm
- Tachy = >160 bpm
- Brady = <110 bpm
Baseline HR?

NL; make sure to check between contractions
What is the most common cause of fetal tachycardia?
Fetal infections –> Chorioamnionitis
What are fetal bradycardia?
- Fetal hypoxia (late sign)
- Obstetric anesthesia
- Pitocin
- Maternal hypotension
- Prolapsed or prolonged compression of umbillical cord
- Heart block
What are fetal tachycardia?
- Fetal hypoxia (early sign)
- Meds (too much oxytocin augmentation)
- Arrhythmias
- Prematurity
- Maternal fever
- Fetal infections (chorioamniotitis)
What is baseline FHR variablity?
Fluctuations in the baseline HR that are irregular in amplitude and frequency.

How can we label baseline variability?
- Absent: amplitude range is undetected
- Minimal: amplitude range detectable less than or equal 5 bpm
- Moderate (NL): amplitude range 6-25 bpm
- Marked: amplitude range > 25 bpm










Decreased variability
- Indicator of __________
- Omnious if associated with ___________
- Is associated with: _____ and ______
- Possible fetal stress
- Persistant late decelerations
- Hypoxia and acidemia
What are causes of decreased baseline variability?
- Prematurity
- Sleep cycle
- Fetal tachycardia (chorioamnionitis)
- Fetal congenital anomalies (CNS and cardiac)
- Maternal fever
- Maternal hyperthyroidism
- Maternal drugs or substances (caffeine, nicotine, cocaine & meth and narcotics)
What are periodic FHR changes?
- FHR that changes with uterine contractions by slowing/accelerating.
- 1. No change
- 2. Acceleration (prolonged acceleration)
- 3. Deceleration (early, variable, late & prolonged deceleration)
Describe the periodic FHR changes.

No change: FHR maintains the same characteristics as in the preceding baseline FHR.
Describe the periodic FHR changes.

Acceleration: abrupt increase in FHR that is NORMAL
What is considered an acceleration of FHR at ≥ 32 weeks and at <32 weeks gestation?
- ≥ 32 weeks: HR ≥ 15 bpm above baseline for 15 sec or more (but <2 mins)
- <32 weeks: HR ≥ 10 bpm above baselines for 10 sec or more (but <2 mins)

Describe the periodic FHR changes.

Prolonged acceleration: lasts 2 or more minutes

What is considered a prolonged acceleration of FHR and how long is considered a change in baseline?
- Prolonged acceleration = ≥ 2 mins
- Change in baseline = ≥ 10 mins

When do you see a change in baseline?
If acceleration lasts 10 or more minutes.
What can cause acceleration in the FHR?
- Spontaneous fetal mvoements
- Stimulation of the scalp/ Vibroacoustic stimulation
- Vaginal exam
What are decelerations?
Types of deceleration?
Decrease in FHR due to uterine contractions that can be classified as early, variable or late
EARLY deceleration
- Caused by:
- How is it detected?
- Head compression (no fetal distress)
- Occurs when the nadir of the deceleration (where it goes down) occurs at the same time as the peak of the contraction (mirror images).

Variable deceleration
Caused by:
How is it detected?
- Compression of the umbilical cord
- Abrupt ↓ in FHR ≥ 15 bpm lasting ≥ 15 sec => 2 min (looks like big ‘V’) that occurs before, during or after contractions start
Late decelerations
- Cause and why are they a bad sign?
- How is it detected?
- Uterine placental insufficiency (UPI)
- Most ominous type => repetitive decelerations usually indicate fetal metabolic acidosis and low arterial pH
- Lowest point of deceleration occurs after peak of the contraction

2 other potential causes of late decelerations.
- Excessive uterine acticity
- Maternal supine hypotension
Prolonged deceleration
- Cause
- How can we detect?
- Maternal pushing
- Decrease in FHR from the basline that is > 15 bpm lasting in between 2-10 minutes.
What is this?

Prolonged deceleration
What is this?

Sinusoidal pattern= often seen with fetal anemia and a smooth wave like pattern with a 3-5 bpm frequency
what is this

early deceleration
what is this

late deceleration
what is this

variable deceleration
What kind of variability, accelerations, and decelerations may be seen in category I interpretation of FHR pattern?
- Moderate variability
- NO late or variable decelerations
- Accelerations and early decelerations may or may not be present
Category II
- 1. Intermittant variable decelerations = NL outcomes
- 2. Recurrent variable decelerations = d/t compression of umbilical cord
Goals and Management for Category II, recurrent variable decelerations (>50% of contractions)?
GOAL: alleviate cord compression by 2 ways:
- Repositioning amnioinfusion (1st stage of labor) = instillation of NL saline though a transcervical IUPC
- Have mom push w/ every other contraction

Goals and management of category II, tachysystole, if seen on fetal heart monitoring?
- GOAL: to reduce activity of uterus
- Lateral positioning + IV bolus + ↓ oxytocin rate or discontinue
- If no response, give uterine tocolytic (Terbutaline SQ or IV)
What seen on fetal heart rate tracing would be considered category III?
-
No baseline variability
- Recurrent late decelerations
- Variable decels
- Bradycardia
- Sinusoidal pattern
Goals and management for Category 3
Goal: prepare mom to deliver
Management:
- Reposition mom
- IV bolus
- O2 supp
- Scalp stimulation
- If no improvement and scalp stimulation test does not cause acceleration => deliver
When would you do fetal scalp stimulation and what is a normal response?
- Differentiate fetal sleep from acidosis, when the fetal tracing shows ↓ variability but no decelerations
- NL: Stimulate scalp => acceleration of 15 bpm for 15 sec occurs then the fetal pH = 7.2 or greater
how many minutes do you have to deliver an emergent c-section
30 minutes
What is the condition of babies delivered if there is a non-reassuring FHR?
most are healthy
What are 2 potential causes of late decelerations?
- Excessive uterine activity
- Maternal supine HYPOtension
What tracings would we see with cord compression?
- Variable decelerations
- Prolonged deceleration
- Fetal bradycardia