Table of contents
Overview
- Symphysis Fundal Height (SFH)
- 20-31 weeks = gestational age (GA), 32-40weeks +2 = GA
- Wt Gain
- Maternal Serum Screen (MSS) (16 weeks for spina bifida)
- Ultrasound (see below)
- Non-Stress Test (NST) (20 min HR monitor)
- Contraction Stress Test (give oxytosin)
- Chorionic Villus Sampling
- Amniocentesis
Fetal Monitoring
Ultrasound Anatomy
-
- Early: r/o ectopic
- 12 weeks: Nuchal fold
- 18-20 weeks: fetal anatomy + dates
- Later: Growth, placenta location, fetal wellbeing (BPP)
- IUGR Screen:
- 10-25% mid IUGR
- <10% moderate IURG
- <3% severe IUGR
- Head Circumference / Abdominal Circumference
- Until 34wks --> HC > AC
- After 34wks --> AC > HC
- First Trimester Scan - r/o viability, r/o ectopic, # of fetuses+chorionicity, nuchal translucency (NT)
- Complete Obstetrical Scan (18-20 week scan - anatomy)
- Third Trimester Scan - Some order, no proven benefit, identifies position, placenta etc..
Doppler Flow Studies
-
- UA - Umbilical Artery
- Growth-resticted fetuses
- End-diastolic flow most important (if absent need admission +/- delivery)
- MCA - Middle Cerebral Artery- If fetus in trouble, will decrease resistance in brain, causing incr diastolic flow (identifies fetal anemia)
- UTA - Maternal Uterine Artery - if increased resistance, RF for uteroplacental vascular insufficiency (IUGR) and preeclampsia
- UA - Umbilical Artery
Biophysical Profile
-
- Fetal Movement (2) - 3 discreet body or limb movements
- Fetal Tone (2) - One limb extension and back to flexion
- Fetal Breathing (2) Least important - 30s of breathing (diaphragm movement, kidneys, or abdo wall)
- Amnionic Fluid Volume (2) Most important, if low, do NST - Single pocket 2x2
- Largest pocket <2cm OR
- Amniotic fluid index <5cm (add two largest pockets) (also measure fluid in each quadrant - variant?)
- Total: /8
- Total (with NST) /10
- Fetal Movement (2) - 3 discreet body or limb movements
Non-Stress Test (NST)
Must be >28 weeks, measures whether the fetus is getting adequate oxygenation.
-
- 20 min monitor of fetal heart rate (FHR)
- 2 accelerations of 15bpm, lasting 15 sec = normal (supposedly represents fetal movement)
- Reactive (normal)-
- 1. presence of ≥2 fetal heart rate accelerations lasting 15sec within a 20-minute period (with or w/o fetal movement)
- 2. beat-to-beat variability +/-5bpm is normal (symp vs. parasymp well developed). (if not, abnormal)
- 3. Absent decelerations
- Nonreactive-
- 1. presence of <2 fetal heart rate accelerations within a 20-minute period over a 40-minute testing period.
- 2. No beat-to-beat variability
- 3. Spontaneous decelerations.
- Reactive (normal)-
Oxytocin Contraction Stress Test (OCT)
-
- Stimulate 3 contractions in 10min --> observe decelerations (late decels are bad)
- Now replaced by BPP
- Stimulate 3 contractions in 10min --> observe decelerations (late decels are bad)
Scalp pH
-
- Take via vagina small amount of blood from fetal scalp
- Meaning
- <7.20 = fetal acidosis (deliver!)
- 7.2-7.25 = repeat 20-30min
- 7.25-7.35 = normal
- Poor accuracy, lots of false positives
Fetal Heart Tracing
- Baseline (must have minimum 2min, otherwise indeterminate)
- Good baseline: 110-160bpm
- Tachycardia: In presence of good variabiliy, not a sign of distress. May be increase in fetal activity. Causes:
- Maternal Fever, fetal hypoxia, fetal anemia, amnionitis, tachyarrhythmia.
- Variability
- Variation in cycles more than 2 cycles/min... indication of sympathetic/parasympathetic responses working well
- Measure variability peak-to-trough:
- Minimal <5bpm
- Moderate 5-25bpm
- Marked >25bpm
- Poor variability is a bad sign...fetal distress
- Accelerations:
- <32 weeks defined as 10x10 (10bpm over 10s)
- >32 weeks defined as 15x15
- 2 accelerations of 15x15 over 20 minute period = reactive NST (good sign) 98% of fetuses have it by 34 weeks.
- If no reactivity/accelerations, can try scalp stimulation
- EARLY: Head Compression
- Come with contractions
- Mirror contractions
- VARIABLE: Cord Compression
- Grabs the cord or shoulder compresses it against something
- 15bpm x 15sec
- LATE Deceleration (Serious)
- Starts with contraction + prolonged after contraction
- SUSTAINED Decelerations (Most Serious)
- Treatment
- Call for help
- Stop oxytosin
- I.V. Fluid Bolus (Improves blood volume, flow, oxygenation)
- Oxygen - face mask, prongs
- Maternal left side (relieves vena cava, increases return to heart)
- Pelvic exam (Check for cord prolapse, determine stage)
- Delivery? mode
Chronic Fetal Distress
- Long-term
- Symphysis fundal height (SFH) / Weight
- Ultrasound (best measure of wellbeing)
- Causes:
- HTN
- Smoking
- Poor nutrition
- chromosomal
- etc.
Acute Fetal Distress
- Sudden-onset
- Fetal heart rate patterns
- Meconium (green-colored stool)
- Scalp pH (oxygenation of blood)
- Causes:
- Abruption
- Infection
- Cord Accident
- Preeclampsia
Intrauterine Growth Restriction (IUGR)
Definition
- Infant weight <10%ile
- Suboptimal intrauterine growth
- Oligohydraminos
- Abnormal umbilical doppler flow
- Increase HC/AC (head circ/ abdo circ)
- Severe IUGR: <3%ile
Etiology
- Weights <1500-2500g have 5-30x higher mortality
- Infants <1500g at term have 70-100x mortality
- Female infants do better than male
- Risk Factors
- Maternal
- Prev low birth weight
- Race (black)
- Substance use, chronic HTN, cyanotic heart/lung disease, hyperthyroidism
- Placental
- Placental insufficiency
- Hypertension/PIH
- Poor placentation (abruption)
- Vascular Disease (diabetes)
- Fetal
- Congenital abnormalities
- Fetal Infections (TORCH)
- Toxoplasmosis
- Rubella
- CMV
- HIV
- Syphilis
- Unexplained (50% of IUGR)
- Maternal
Stage Causes Growth Result EARLY Infection,drugs, congenital Symmetric MSK and organ size affected LATE Poor nutrition, utero-placental Asymmetric MSK ok, organ & fat affected
- If happens EARLY in pregnancy: Symmetric IUGR (MSK and organ size affected)
- No head sparing
- HC/AC ratio may be normal
- If happens LATE in pregnancy: Asymmetric IUGR (MSK ok, but organ size & fat are affected)
- Head Sparing (Biparietal Diameter - transverse head diameter is normal)
- HC/AC abnormal (i.e. HC > AC) [see below]
- Fetal Growth Priority (if hypoxemia/nutrients/renal function or other insult)
1. Brain/Head
2. Organs
3. Skeletal Tissue
4. Subcutaneous Fat - Dx
- Ultrasound
- 10-25% mid IUGR
- <10% moderate IURG
- <3% severe IUGR
- Head Circumference / Abdominal Circumference
- Until 34wks --> HC > AC
- After 34wks --> AC > HC
- Progression of fetal insult:
1. Umbilical systolic/diastolic ratio rises (vascular resistance)
2. Fetal growth on U/S slows/stops
3. Oligohydraminos develops (Largest pocket <2cm OR Amniotic fluid index <5cm [two pockets of fluid add up to max])
4. Fetal heart rate loses reactivity
5. Fetal heart rate decelerations
6. Fetal movement diminishes/stops
7. Fetus dies
- Ultrasound
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