Assessment of fetal wellbeing Flashcards
What is the pathophysiology of placental insufficiency?
1- inadequate perfusion of the placenta -> ischemia
2- decreased O2 delivery to the fetus or neonate -> hypoxemia
3- impairment of gaseous exchange & accumulation of CO2 -> asphyxia -> loss of fetal movement
What are the types of placental insufficiency?
ACUTE
- placenta Previa
- vasa Previa
- abrupto placentae
CHRONIC
- HTN
- DM
What are the causes of placental insufficiency?
1- hemorrhage
2- placenta Previa
3- vasa Previa
4- HTN states
5- diabetes
6- immunity related placental thrombosis
7- post-dated pregnancy
8- idiopathic
How is placental insufficiency suspected clinically?
1- history of any previous cause
2- poor weight gain
3- undersized uterus
4- small abdominal girth
What are the fetal wellbeing assessment tests?
ANTEPARTUM
1- OB ultrasound -> BPD, FL, AC, fetal weight
2- Biophysical tests -> DFMC, NST, OCT, BPP, Doppler
3- Biochemical tests -> urinary estriol, Human placental lactogen, heat stable alkaline phosphatase
4- vaginal smears
5- amnioscopy
INTRAPARTUM
1- Clinical tests
2- Biophysical tests -> CTG
3- Biochemical tests -> pH (fetal scalp blood sampling)
POSTPARTUM
1- APGAR score
2- umbilical cord pH
3- clinical presentation
How should the biophysical tests be preformed?
NORMAL RESULTS
1- daily fetal movement count -> after 30 weeks twice a week
- more than 10-12 movements within 2 hours (good)
2- NST -> 2 or more accelerations of FHR by 15b/m lasting 15s occur within 20 mins
3- Oxytocin Challenge Test -> if no late deceleration
4- Biophysical profile
5- Doppler study for placental & fetal circulation
What are the causes of reduced fetal movements?
1- busy mother
2- BMI > 35
3- oligo/polyhydramnios
4- heavy smoking Or alcohol
5- corticosteroids
6- macrosomic baby
7- anterior placenta
8- post date fetus
9- IUGR/CFMF
How is the fetal non-stress test preformed & what are its interpretations?
- only preformed if fetal movements are reduced to detect fetal heart rate & its response to movements
1- 20 min observation
2- another 20 mins can be added if no movements were detected in the first 20 mins
3- external stimulation of the fetus could be done if no movements are detected in the past 40 mins
Results
Reactive NST -> normal -> repeat every week
Non reactive NST -> abnormal -> OCT, BPP, Doppler
How is the oxytocin challenge test preformed & what are its interpretations?
Done after 32 weeks only if NST is non-reactive
- give small dose of oxytocin to produce 3 contractions in 10 mins
RESULTS
- negative OCT -> no late deceleration -> normal
- positive OCT -> late deceleration -> distressed fetus
What are the contraindications for OCT?
1- PROM
2- placenta Previa
3- incompetent cervix
4- preterm labour
5- previous scar in uterus
6- multiple pregnancy
What is monitored in the biophysical profile for 30 mins?
1- fetal movements -> 3 body or limb movements
2- fetal tone -> one episode of extension & flexion OR opening & closing of the hand
3- fetal breathing -> 1 episode of 30 seconds or more (including hiccups)
4- amniotic fluid volume -> 2cm x 2cm
5- NST -> 2 accelerations > 15 b/m of at 15 seconds or more
How is the biophysical profile score interpreted?
Every positive parameter takes 2 points
- 8-10 -> reassuring
- 6 -> in term: deliver
-> preterm: steroids & MgSO4 then repeat test after 24hrs
-> 6 + oligohydramnios: deliver - 2-4 -> immediate delivery
What indicates fetal distress in the color doppler study?
Ominous Sign
- high resistance in umbilical artery & low resistance in fetal middle cerebral artery
Doppler ultrasound can predict fetal distress earlier than BPP because it detects fetal hypoxia & acidosis
What are the causes of intrauterine fetal asphyxia?
ACUTE
- cord prolapse
- cord compression
- accidental hemorrhage
- placental separation
CHRONIC
- hypertension
- maternal hypoxia
What are the causes of intrapartum fetal distress?
Maternal
- severe anemia or excessive hemorrhage
- congestive heart failure
- pulmonary disease
- eclamptic fit
- anesthesia
Placental
- compression
- separation
- insufficiency
- uterine hypertonicity
Cord
- true knots
- coils around neck
- vasa Previa rupture
- hematoma
- compression
- prolapse
Fetal
- prolonged head compression -> severe oligohydramnios
- congenital or chromosomal abnormality
How is fetal distress intrapartum suspected clinically?
1- weak pulsation in prolapsed cord
2- passage of meconium in amniotic fluid in cephalic presentation -> due to asphyxia
- thick fresh green meconium -> acute
- yellowish green lightly stained -> chronic
What is the normal CTG interpretation?
1- FHR -> 110 - 160 b/m
2- pattern -> beat to beat variability (5-10 b/m)
3- normal periodic patterns -> acceleration & early deceleration
What are the abnormal findings that may be found on a CTG?
1- baseline bradycardia -> FHR <100 bpm
2- baseline tachycardia -> FHR >160 bpm
3- absence of beat to beat variability -> < 5 bpm
4- late deceleration -> persists after end of contraction
5- variable deceleration -> not related to contractions
6- prolonged deceleration -> drop in FHR of 30 bpm or more lasting at least 2 mins
What are the causes a of baseline bradycardia?
1- post date
2- drugs
3- idiopathic
4- hypothermia (increased vagal tone due to long standing hypoxia)
5- cord compression
What are the causes of baseline tachycardia?
1- long standing asphyxia -> stimulation of sympathetic
2- drugs
3- prematurity
4- maternal fever
5- maternal thyrotoxicosis
6- maternal anxiety
What are the causes for absence of beat to beat variability?
- LACK of variability -> feto-maternal hemorrhage
- SINUSOIDAL pattern -> acute fetal-maternal hemorrhage or twin to twin transfusion syndrome
- Long term variability
What are the causes of early deceleration?
Due to head compression during contractions & stimulation of the vagus nerve
It’s normal
What are the causes of late deceleration?
Uteroplacenal insufficiency -> metabolic acidosis (asphyxia)
- deliver baby immediately
What are the causes of variable deceleration?
Cord compression -> respiratory acidosis (hypoxia)
- change position of patient to improve CTG
What are the the causes of prolonged deceleration?
1- cord prolapse
2- maternal hypertension -> abruptio placentae
3- uterine hypertonia
4- ruptured uterus
How many Montevideo units are adequate for labour to progress?
MVUs > 200 in a 10 minute period
What is the classification of fetal heart rate features?
REASSURING
- baseline FHR = 110 - 160
- variability = 5 - 25
- deceleration = none or early
- acceleration = present
NON REASSURING (if 1 is present)
- baseline FHR = 100 - 109 OR 161 - 180
- variability = < 5 in 30 - 50 mins OR > 25 in 15 - 25 mins
- deceleration = typical or atypical variable decelerations
- acceleration = absent
ABNORMAL
- baseline FHR = < 100 OR > 180
- variability = < 5 for > 50mins OR > 25 for > 25mins OR sinusoidal for 10mins or more
- deceleration = later deceleration OR single prolonged deceleration
- acceleration = absent
How is a final diagnosis made based on CTG reading?
- Normal -> all 4 features are reassuring
- Suspicious -> 1 of non-reassuring
- pathological -> 2 or more non reassuring OR 1 or more abnormal
What is the normal fetal pH?
7.25 - 7.35
Mild acidosis = < 7.25
Severe acidosis = < 7.2
Based on the CTG features, what would be the proper management for every category?
NORMAL
- reassurance + usual care + auscultation
- continuous CTG tracing in high risk women
SUSPICIOUS conservative measures
1- stop oxytocin infusion
2- 02 mask + proper hydration & IV fluids
3- place mother in left lateral position
4- tocolysis (maybe)
5- reevaluate findings
PATHOLOGICAL
1- exclude acute events
2- start conservative measures
3- if CTG still pathological -> digital fetal scalp stimulation
4- if no fetal response -> fetal scalp blood sample -> if pH < 7.2 immediate delivery
