Basic Fetal Monitoring



Introduction to Fetal Monitoring

During labor, standard of care requires nurses to monitor the labor process and fetal oxygenation using fetal monitors:

• Can monitor without machines by using your hands, a doppler and a watch.

• Most commonly performed obstetric procedure in the United States

• No reduction in the overall risk of perinatal death or cerebral palsy

• Associated with increases in C/S rates and assisted vaginal delivery (vacuum/ forcep)

• Helps reduce miscommunication among providers

Pathophysiology

Oxygen Pathway:

• Primary purpose for the use of electronic FHR monitoring is to determine if the fetus is well oxygenated

• Maternal lungs – Heart – Vasculature – Uterus – Placenta – Umbilical Vein - Fetus

• Deoxygenated blood leaves the fetus through two umbilical arteries

• UC compress vessels and decrease O2 to fetus

• Head pressure, occlusion of vessels and hypoxia cause fetal hypertension that stimulates baroreceptors and chemoreceptors. These receptors stimulate the vagal nerve causing a decrease in FHR

Through fetal monitoring, we are able to observe whether this is negatively affecting the fetus as we evaluate fetal well-being and tolerance to labor

If oxygenation is severely disrupted, damage can occur to the vital organs (brain, heart, adrenals) due to metabolic acidosis (build up of lactic acid). This may result in permanent brain damage/cerebral palsy and fetal death.

Obstetrical Liability

Fetal Monitoring (improper monitoring and/or delay of care in response to changes) is the #1 legal case issue, followed by VBAC (Vaginal Birth After Cesarean), Shoulder Dystocia, and Maternal Injury.

A 2008 review in Obstetrics & Gynecology concluded, “Most money paid in conjunction with malpractice cases is a result of actual substandard care resulting in preventable injury.”

Healthtrek newsletter (2008) reported the top 6 largest obstetrical verdicts/settlements cost $103.8 million dollars. 98% settled prior to or during trial; only 2% went to verdict.

Charting Criteria

Fetal Heart Rate (FHR), Uterine Contractions (UC) & BP Charting

Frequency of monitoring

Low risk

Every 30 minutes in first stage of labor (0-10 cm)

Every 15 minutes in second stage of labor (10 cm to birth)

High risk

Every ___________________ in first stage of labor

Every _____________________ in second stage of labor

External Monitoring Equipment

Ultrasound: FHR

Location - fetal back or shoulder

Tocotransducer: UC

Location - Uterine fundus

Advantages

Non-invasive

Easy to apply

No complications

Disadvantages

Poor with obese/activity

Artifacts

Inaccurate with uterine tone and intensity

Internal Monitoring Equipment

Fetal Scalp Electrode: Fetal ECG

Location - fetal scalp

Intrauterine Pressure Catheter: IUPC

Location - intrauterine after ROM

Advantages

Freedom to move

Accuracy in monitoring

Disadvantages

Requires ROM & dilatation

Risk fetal infection

Risk insertion error

Fetal Heart Rate Tracing: Baseline

• Patterns are gestational age-dependent

• Can differ based on fetal gestational age and maternal status

• Can be effected by maternal medical status, use of medications, and prior fetal assessments

• Components of FHR tracing do not occur in isolation and generally evolve over time

• Important to look at the “big picture”

Baseline normal is ____________________ BPM

• Round to increments of 5 beats/minute during a 10 minute segment

• Minimum duration in this segment must be at least ______________ long

• Exclude ________________________________ and periods of marked variability (_________________________)

Tachycardia - > 160 BPM

Causes include:

Early hypoxia

__________________________________

Beta-sympathomimetic drugs (epinephrine, terbutaline)

__________________________________

Maternal hyperthyroidism

Fetal anemia

Bradycardia - < 110 BPM

Causes include:

____________________________________

7. ___________________________________

Prolonged umbilical cord compression

Fetal arrhythmia

Baseline FHR Variability

Defined: fluctuations in the fetal heart rate baseline that are irregular in amplitude; peak to trough in beats per minute.

Fluctuations in FHR that cause the printed line to have a rough appearance

- variations around the baseline

Presence is reassuring - means regulation of HR by CNS is intact and able to respond to stressors

Rhythmic waves of the entire printed line

Difference b/t lowest and highest rates

Classified as:

Absent – _____________________________

Minimal – ____________________________

Moderate – ___________________________

Marked – ______________________________

Causes of decreased variability include:

hypoxia and acidosis

drugs that depress fetal CNS

fetal sleep cycle

Causes of increased variability include:

early mild hypoxia

fetal stimulation

Accelerations

Apparent abrupt increase in FHR above the baseline with a peak of at least 15 bpm lasting 15 seconds but less than 2 minutes with return to baseline

< 30 seconds from the onset to the acme

Reassuring sign, reflecting a responsive, non-acidotic fetus – no treatment

- Prolonged if > 2 minutes duration

- Baseline change if > 10 minutes

- Before 32 weeks, peak of 10 beats/minute lasting 10 seconds, but < 2 minutes

- Causes: scalp stimulation, fetal movement with uterine contractions, and pelvic examination

Decelerations

Early Decelerations:

A non-concerning sign of fetal head compression

10. __________________________________

11. Associated with a contraction

12. Uniform in shape “cup-like”/ mirrors the contraction

13. Onset, nadir, and recovery occurs with the beginning, peak and ending of the contractions; onset to nadir is > 30 seconds

Fetal ________________________ alters cerebral blood flow causing vagal nerve to slow HR

• Not associated with fetal compromise

• No treatment

Variable Decelerations:

Defined

5 Apparent abrupt decrease in FHR below baseline

6 May or may not be associated with contractions

7 Onset to nadir is < 30 seconds

8 Decelerations is > 15 BPM, lasting > 15 seconds but less than 2 minutes

9 No uniform appearance (usually “U” or “V”)

Cause: Compression reducing blood flow between placenta and fetus

Things that can increase risk of compression

Oligohydramnios: see at the onset of active labor or ROM

Descent: see at 8-10 cms with a nuchal cord and pushing

Prolapse: see with ROM in an unengaged fetus or abnormal presentation

Non Reassuring

Late Decelerations:

Defined

20 Apparent gradual decrease in FHR and return to baseline associated with uterine contraction

21 Onset to nadir is 30 seconds or longer

22 Nadir of the deceleration occurs after the peak of the contraction

23 Onset, nadir, and recovery of the deceleration occur after the beginning, peak and end of the contraction

Caused by ______________________________ insufficiency resulting from decreased blood flow and oxygen transfer to the fetus through the placenta during contractions

Non-reassuring sign if recurrent

Associated with decreased variability

Related to:

o Maternal blood problems (anemia)

o ________________________________

o Hypertension

o Mother supine

o ________________________________

o Placental decay (post dates)

4. Prolonged Decelerations:

A sign of interruption of oxygen transfer

• Apparent decrease in fetal heart rate below baseline

• Decrease lasts > 2 minutes but less than 10 minutes

• Considered change in baseline if > 10 minutes

• Non-reassuring

• Gradual or abrupt decrease in fetal heart rate below baseline

Recurrent

o Occur with 50% or more of contractions in any 20-minute segment

Intermittent

o Occur with less than 50% of uterine contractions in any 20-minute segment

Periodic/Episodic

o Associated with/independent of contractions

Fetal Heart Rate Patterns

– Provide information on the ____________________ acid-base balance of the fetus.

– Two findings predict the absence of academia

o _______________________________

o _______________________________

o Absence of these findings doesn’t predict fetal hypoxemia or metabolic academia

Sinusoidal - Apparent, smooth, sine-wave-like undulating pattern

o Cycle frequency of 3 to 5 per minute

o Persists for _______________________________

FHR Interpretation System

Category I – normal tracing

o Strongly predicts normal fetal acid-base status

o Routine management

o Includes ALL of the following:

▪ Baseline rate _________________________________

▪ Variability ___________________________________

▪ Absence of late or variable decelerations

▪ Early decelerations may or may not be present

▪ Accelerations may or may not be present

Category II – indeterminate tracing

o Not predictive of abnormal fetal acid-base status

o Requires evaluation and continued surveillance

o May need further testing (fetal scalp stimulation, vibroacoustic stimulation) or “intrauterine resuscitative measures” including

▪ Change position

▪ Stop labor stimulating agent

o Cervical exam, fetal scalp stimulation

o Monitor maternal blood pressure, give O2/fluids

o Assess for uterine tachysystole, give tocolytics

Includes ANY of the following:

▪ Baseline: ________________________ or ____________________ without absent baseline variability

▪ Minimal/marked variability

• Absent variability with no decelerations

▪ Accelerations: absent after fetal stimulation

▪ Periodic or episodic decelerations

• Recurrent variables with minimal/moderate variability

• Prolonged deceleration

• Recurrent late decelerations with moderate variability

Category III – _____________________________________

o Predictive of abnormal fetal acid-base status

o Requires prompt evaluation and treatment if intrauterine resuscitation doesn’t work

o Includes EITHER:

▪ Absent baseline variability with any of the following

• Recurrent late decelerations

• Recurrent variable decelerations

• ______________________________________________

Or a Sinusoidal pattern

Uterine Activity

Four components of assessment

Duration: How long the contractions last. Measured in seconds, count from the beginning of the contraction to the end.

Frequency: How often the contractions occur. Measured in minute increments, count from beginning of one contraction to the beginning of the next

Intensity: mild, moderate, or strong with external monitors or numerical values

in mmHg by IUPC

Uterine resting tone: soft or rigid by palpation or mmHg by IUPC

Labor progression is defined as contractions that are getting longer, stronger, and closer together. Ideally, contractions occur q 2-3 min, lasting 60-90 seconds, are moderate to strong in intensity, and resting tone is soft.

• Normal 5 contractions or less in 10 minutes

Abnormal Contractions

Duration is > 1 ½ to 2 minutes

Intensity is > 90 mmHg

Tachysystole - > 5 contractions in 10 minutes

Presence or absence of decelerations

Can occur with spontaneous or stimulated labor

Responses may be different

Resting tone is > 20 mmHg

Implications of abnormal patterns:

fetal hypoxia

rise in resting tone due to uterine abruption, Pitocin hyperstimulation, paracervical block, hypertension

• Treatment

• O2, Pitocin off, turn to left side, terbutaline, bolus of IV fluids, call MD

Remember

• Must look at all of the components of the fetal heart rate pattern

• Take into account the clinical circumstances

• Mother’s well-being effects fetus’ well-being

• Using the correct terminology reduces miscommunication between providers

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