Fetal monitoring Flashcards

1
Q

What are the definitions of the following
-Tachysystole
-Hypertonus
-Hyperstimulation

A
  1. Tachysystole
    -More than 5 contractions in 10 minutes during active labour with no fetal HR abnormalities
  2. Hypertonus
    -Contraction lasting >2 mins or within 60 seconds of each other without fetal HR abnormalities
  3. Hyperstimulation
    -Either tachysystole or hypertonus with FHR abnormalities
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2
Q

Discuss excessive uterine activity
-Causes (5)
-Risks to fetus (2)
-Risk to mother (3)

A
  1. Causes
    -Prostaglandins for cervical ripening
    -Oxytocin for labour
    -Placental abruption
    -Intrauterine infection
    -Rarely seen in spontaneous labour
  2. Risks to fetus
    -Fetal hypoxia
    -Fetal acidosis
  3. Maternal risks
    -AFE
    -Uterine rupture
    -Risks associated with an emergency caesarian section
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3
Q

Discuss management for excessive uterine activity
-Steps to take with hyperstimulation (5)
-Indications for tocolysis
-Contra-indications for tocolysis

A
  1. Steps to take with hyperstimulation
    -Continue fetal monitoring
    -Stop / decrease oxytocin infusion
    -Consider tocolytics
    -Assess requirement for urgent delivery
    -Provide 1:1 care until normalised
  2. Indications for tocolysis
    -Excessive uterine activity resulting in hyperstimulation
    -If no evidence of fetal compromise tocolysis is not indicated
  3. Contra-indications for tocolysis
    -Placental abruption
    -Maternal cardia disease
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4
Q

Discuss terbutaline as a tocolytic
-Class of drug
-Mode of action
-Dose
-Side effects (5)
-Contra-indications (3)
-Literature findings (2)

A
  1. Class of drug - selective B2 adrenergic receptor agonist
  2. MOA - relaxation of uterine smooth muscle
  3. Dose 250mcg S/C stat. IV 50mcg in bolus
  4. Side effects
    -Maternal tachycardia, palpitations, arrythmia
    -Headache, anxiety , tremor
    -Nausea and vomiting
  5. Contraindications
    -Sympathomimetic amine sensitivity
    -Placental abruption
    -Relative contra-indications - maternal cardiac disease, Hypotension, hyperthyroidism
  6. Literature findings
    -Doesn’t increase bleeding risk regarding atony
    -Moderate evidence to suggest best tocolytic in terms of fetal HR abnormalities
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5
Q

Discuss salbutamol as a tocolytic
-Class of drug
-Mechanism of action
-Dose
-Side effects (6)
-Contra-indication (3)

A
  1. Class of drug: Selective B2 adrenergic receptor agonist
  2. MOA: Smooth muscle relaxation
  3. Dose
    IV 25-50mcg boluses to max of 250mcg
  4. Side effects
    -Maternal tachycardia, palpitations, arrythmias
    -Nausea and vomiting
    -Tremor, anxiety, headache
  5. Contra-indications
    -Cardiac disease
    -Hypertension
    -Hyperthyroid
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6
Q

Discuss GTN as a tocolytic
-Mechanism of action
-Dose
-Side effects (3)
-Contra-indications (4)

A
  1. MOA: Relaxes vascular smooth muscle and also uterine smooth muscle
  2. Dose 400mcg per spray. Can give 2 5 mins apart
  3. Side effects
    -Headache
    -Hypotension
    -Reflex tachycardia or bradycardia
  4. Contra-indications
    -Acute circulatory failure
    -Cardiac disease
    -Hypotension
    -Severe anaemia
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7
Q

Discuss fetal bradycardia
-Definition (2)
-What is the mechanism by which fetal bradycardia occurs

A
  1. Definition
    -FHR ,110
    -FHR < 15 beats below baseline for >5mins
  2. Mechanism
    -Fetal chemoreceptors identify reduced oxygen levels and this results in reflex vagal stimulation to reduce heart rate and cardiac output to reduce myocardial oxygen requirement
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8
Q

Discuss causes of acute fetal bradycardia
-Hypoxic causes attributed to the mother (4)
-Hypoxic causes attributed to the utero-placental unit (3)
-Hypoxic causes attributed to the fetus (3)

A
  1. Hypoxic causes - maternal
    -Maternal hypoxemia - seizure, hypoventilation, resp disease
    -Maternal hypotension - positioning, epidural, sepsis
    -Reduced oxygen carrying capacity - anaemia, smoking
    -Chronic medical conditions - diabetes, HTN
  2. Utero-placental unit causes
    -Excessive uterine activity
    -Reduced surface area of placenta for gas exchange - abruption, IUGR
    -Uterine rupture
  3. Fetal causes
    -Cord compression - Cord prolapse, true knot in cord, oligohydramnios.
    -Decreased oxygen carrying capacity- fetal anaemia
    -Rapid decent of fetal head through pelvis
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9
Q

What are the causes of a fetal baseline bradycardia
-Maternal (4)
-Fetal (2)

A
  1. Maternal
    -Recording maternal HR
    -Opiates
    -Beta blockers
    -MgSO4
  2. Fetal
    -Post dates with increased PNS drive
    -Fetal heart conduction defect - Fetal heart block
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10
Q

Discuss fetal blood sampling
-Normal lactate and pH
-Pre-acidotic lactate range and pH
-Acidotic range and pH

A
  1. Normal range
    -Lactate <4.0
    -pH >7.25
  2. Pre-acidotic
    -Lactate 4.1 - 4.7
    -pH 7.21- 7.24
  3. Acidotic range
    -Lactate >4.7
    -pH <7.21
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11
Q

What are the contra-indications to FBS (5)

A
  1. < 34 weeks
  2. Non-vertex presentation
  3. Possible fetal bleeding disorder
  4. Maternal infection - HIV/ Hep B, HSV (GBS doesn’t preclude FBS)
  5. Evidence of serious sustained fetal compromise
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12
Q

Discuss action for the following FBS findings
-Lactate <4.0 (pH > = 7.25)
-Lactate 4.1 - 4.7 (pH 7.21 - 7.24)
-Lactate >4.7 (pH <7.20)

A
  1. Lactate <4.0 - Normal range
    -If CTG returns to normal no need to repeat lactate
    -If CTG abnormalities persist repeat in an hr
    -If CTG abnormalities worsen repeat in less than an hour
  2. Lactate 4.1-4.7 - Pre-acidotic
    -Recheck in 30 mins to see trend
    -Deliver earlier if significant deterioration
  3. Lactate >4.7 - Acidotic
    -Stop oxytocin if in process
    -Expedite delivery - CS or Instrumental
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13
Q

What are the advantages and disadvantages to FBS
-Advantages (2)
-Disadvantages (1)

A
  1. Advantages
    Can assist in the interpretation of equivocal CTG
    Can reduce CS rates
    -CS risk if CTG and no FBS - OR - 2
    -CS risk if CTG and FBS OR 1.55
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14
Q

Discuss cord blood sampling
-When should it be taken (4)

A

-Apgar <4 and 1 min
-Apgar <7 at 5 mins
-Fetal scalp sampling during labour
-Operative delivery undertaken for fetal compromise

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15
Q

What do the cord bloods represent
-Venous gas
-Arterial gas
-Abnormal results (6)
-How are they used (2)

A
  1. Venous gas
    - maternal acid-base status and placental function
    -Expect to be less acidotic - normal >7.32
  2. Arterial gas
    -fetal status
    -Expect to be more acidotic as more CO2 from fetal metabolism - normal >7.24
  3. Abnormal results
    -Lactate >7.5
    -Base excess <-12
    -pH <7.0
    -Big difference between arterial (acidotic) and venous (less acidotic) - suggests cord compression of umbi vein
    -Both bad - likely placental
    -Both the same then probably both venous
  4. How are cord gases used
    -Can predict poor neurological outcomes if baby also unwell
    -Can guide when to cool babies - pH <7 and Base excess <-12
    -Base excess from -12 -> -16 is a significant predictor of neonatal neurological morbidity. 10% chance of severe neurological impairment
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16
Q

What is the evidence behind fetal monitoring (2)

A
  1. Use of continuous CTG statistically significantly reduces long term neonatal outcomes - e.g. CP
  2. Statistically significantly increases the risk of unnecessary operative delivery
17
Q

In what conditions is CTG not indicated
-RANZCOG overall recommendation
-Antenatal risk factors (6)
-Intrapartum risk factors (1)

A
  1. RANZCOG supports intermittent ascultation for low risk women
  2. Antenatal risk factors where intrapartum CTG is not required if in isolation (CTG if multiple conditions)
    -Pregnancy <42 weeks gestation
    -GHTN
    -GDM without complication
    -BMI <40
    -Maternal age <42
    -AFI 5-8cm / DVP 2-3cm
  3. Intrapartum risk factors
    -Maternal pyrexia <38 degrees
18
Q

Discuss fetal monitoring in low risk women
-Grounds for admission CTG (3)
-Grounds for ongoing fetal monitoring (3)

A
  1. Admission CTG
    -Inconsistent evidence
    -Overall likely to increase number of women on CTG and therefore operative delivery
    -May identify at risk babies
  2. Ongoing fetal monitoring
    -Systematic review showed significant reduction in neonatal seizures
    -Systematic review found significantly significant increase in CS rates
    -Not recommended by RANZCOG
19
Q

What is the definition of
-Normal fetal BL heart rate
-Baseline bradycardia
-Baseline tachycardia

A
  1. Normal BL
    110-160
  2. Baseline bradycardia
    <110
  3. Baseline tachycardia
    >160
20
Q

What are the definitions of variability
-Normal baseline variability
-Reduced baseline variability
-Absent baseline variability
-Increased baseline variability
-Sinusoidal pattern

A
  1. Normal baseline variability
    6-25 bpm
  2. Reduced baseline variability
    3-5bpm
  3. Absent variability
    <3 bpm
  4. Increase baseline variability
    6-25 bpm
  5. Sinusoidal pattern
    -regular oscillation of baseline with a smooth pattern replicated in 2-5 cycles per minute with an amplitude of 5-15bpm
21
Q

What are the definitions for decelerations
-Decelerations
-Early decelerations
-Variable decelerations
-Complicated variable decelerations
-Prolonged decelerations
-Late deceleration

A
  1. Decelerations
    -A drop from BL of >15 bpm for >15 seconds
  2. Early decelerations
    -Uniform repetitive decelerations with slow onset early in the contraction and slow return to baseline by the end of the contraction
  3. Variable deceleration
    -Repetitive or intermittent rapid decrease in the FHR with rapid return to BL with or without a contraction
  4. Complicated variable deceleration
    Variable decelerations with the following
    -Rising BL or fetal tachycardia
    -Reduced BL variability
    -Slow return to BL
    -Large amplitude by 60bpm or to 60bpm
    -Long duration >60seconds
    -Smooth post deceleration overshoot
  5. prolonged deceleration
    -Fall in FHR for >90 seconds
  6. Late deceleration
    -Uniform repetitive decreasing FRH usually slow onset from middle to late start of contraction with recovery after the contraction. Where there is reduced variability the depth of deceleration may be <15bpm
22
Q

What abnormal CTG features when seen in isolation are unlikely to be associated with fetal compromise (5)

A

-Baseline of 100-109
-Reduced variability 3-5bpm
-Absence of accelerations
-Early decelerations
-Variable decelerations without complicating features

23
Q

What abnormal CTG features may be associated with significant fetal compromise and require further action (5)

A
  1. BL tachycardia
  2. Rising BL even if within normal range
  3. Complicated variable decelerations
  4. Late decelerations
  5. Prolonged decelerations
24
Q

What abnormal CTG features are associated with significant fetal compromise and require immediate action (5)

A
  1. Bradycardia
  2. Absent BL variability
  3. Sinusoidal pattern
  4. Complicated variable decelerations with reduced or absent variability
  5. Late decelerations with absent variability
25
Q

What are the differential Dx for the following CTG patterns
-BL Bradycardia (2)
-Prolonged deceleration (2)
-Tachycardia (5)
-Reduced variability (4)
-Sinusoidal pattern (2)

A
  1. BL bradycardia
    -Post dates
    -Fetal Heart block / cardiac malformation
  2. Prolonged deceleration
    -Head compression
    -Maternal hypotension
  3. Tachycardia
    -Increased fetal activity
    -Prematurity
    -Fetal anaemia
    -Fetal cardiac disease or Heart block
    -Maternal tachycardia (Fever, dehydration)
    -Hyperthermia
  4. Reduced variability
    -Fetal sleep
    -Prematurity <32/40
    -Drugs (Opiates, beta blockers, MgSO4)
  5. Sinusoidal pattern
    -Fetal anaemia
    -Pseudosinusoidal from rhythmic fetal movement
26
Q

What are the recommendations regarding home fetal monitoring (3 points)

A
  1. Strongly recommended against women using hand held dopplers to monitor their baby.
  2. May lead to false reassurance
  3. Women with concern for their babies should seek medical evaluation