Fetal growth restriction

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Fetal growth restriction

• Joseph Breuner, MD
• 8-08-05

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Objectives

• Define risk factors
• Define screening
• Define diagnosis
• Define management

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Take-home points

• Risk factors if positive, obtain ultrasound for
  growth 16-24 wks
• if negative, use fundal height to screen

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Take-home points

• Screening use fundal height gt 2cm discordant
  from GA after 20 wks or 2cm discordant from GA
  on serial visits
• Either risk factor or fundal height discrepancy
  ultrasound
• both fh and us most accurate 18-34 wks

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Take-home points

• Define fetal growth restriction as lt3rdile
• follow 3-6thile carefully

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Take-home points

• Red flags
• oligo AFI lt 5 deliver
• systolic/diast ratio gt95th ile deliver
• asymmetry--HC/AC gt95. Lower threshold for
  delivery, track other parameters closely

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Risk Factors

• Fetal
• birth defect history (genetic syndromes,
  anomalies, karyotype abnormalities)
• multiple gestation
• uteroplacental insufficiency

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Risk factors

• Maternal disease
• starvation
• hypoxemia due to heart/lung disease
• antiphospholipid Ab syndrome
• renal disease, chronic htn
• pre-eclampsia

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Risk factors

• Maternal exposure
• infections prior to 20 wks rubella,
  toxoplasmosis, cmv, vzv, malaria
• substance abuse smoking, alcohol, drug use
• meds coumadin, anticonvulsants, antineoplastic
  agents, folic acid antagonists

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Risk Factors

• Maternal demographics
• high altitude
• race
• extremes reproductive age
• nullip or grand multip
• prior FGR neonate (29 vs 9)
• prepreg wt lt10ile or no wt gain

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Risk Factors

• Conspicuous by their absence
• maternal wt gain 10-24 lbs

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Screening

• Order
• basic ultrasound from hospital or swedish nuc
  med/ultrasound, because umbilical artery
  measurements are useful by themselves
• anatomic survey comes with this scan, is useful
  to dx birth defects group

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Diagnosis

• Ultrasound EFW based on AC, BPD and FL is best
  single measure to dx FGR and has
• sensitivity 90
• specificity 85
• PPV 80
• NPV 90

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Diagnosis

• Understand three different entities present as
  small baby
• constitutionally small fetus
• fetus with structural/chromosomal abn, fetal
  infection
• uteroplacental insuffiency

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diagnosis

• 3 phases of growth
• cellular hyperplasia up to 16 wks
• cellular hyperplasia and hypertrophy 16 to 32 wks
• cellular hypertrophy 32 wks to term

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diagnosis

• Use 3 features to dx among 3 different entities
• symmetric vs. asymmetric
• AFI
• umbilical artery velocimetry (S/D ratio)

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diagnosis

• Symmetric vs. asymmetric
• symmetric growth restricted babies are small from
  the beginning, all measurements are equally small
  and grow on their own curve, hence title
• includes constitutional and birth-defect
• 20-30 of growth restricted fetuses

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diagnosis

• Asymmetric relatively greater decrease in
  abdominal size than head circumference
• results from redistribution of blood flow to
  vital organs in UPI
• 70-80 of growth-restricted fetuses

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Diagnosis

• Ultrasound use AC, along with HC/AC and FL/AC
  ratios to dx asymmetric FGR
• HC/AC ratio decreases linearly so is expressed in
  terms of SD above the mean. 2 SD gtmean for GA is
  abnormal
• FL/AC ratio is independent of GA after 20wks. gt
  23.5 is abnormal

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Diagnosis

• Systolic/diastolic ratio of umbilical artery flow
  is abnormal if gt 95ile for GA or absent/reversed
  in gt 18-20 wk fetus
• for diagnosing FGR, in comparison to US,
• less sensitive (55 vs. 76)
• more specific (92 vs 80)
• higher PPV (73 vs 58)

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Management

• Mortality rises quickly with SGA

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management

• Severe FGRdelivery gt 32-34 weeks,
• weigh fetal mortality vs neonatal morbidity at
  earlier GA

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Management

• FGR lt6 but gt3rd ile
• if constitutional, follow to term
• if birth defect manage per the dx
• if asymmetric, weigh fetal well-being vs neonatal
  morbidity

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Management

• FGR lt6 but gt3rd ile
• Growth scans every 2-4 weeks
• Be aggressive re UAV
• BPP/AFI q wk in some birth defects group and
  all uteroplacental insufficiency
• increase BPP/AFI to daily if abnl but delivery
  risk gt in utero risk

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Take-home points

• Risk factors if positive, obtain ultrasound for
  growth 16-24 wks
• if negative, use fundal height to screen

32
Take-home points

• Screening use fundal height gt 2cm discordant
  from GA after 20 wks or 2cm discordant from GA
  on serial visits
• Either risk factor or fundal height discrepancy
  ultrasound
• both fh and us most accurate 18-34 wks

33
Take-home points

• Define fetal growth restriction as lt3rdile
• follow 3-6thile carefully

34
Take-home points

• Red flags
• oligo AFI lt 5 deliver
• systolic/diast ratio gt95th ile deliver
• asymmetry--HC/AC gt95. Lower threshold for
  delivery, track other parameters closely

35
references

• Williams chapter 29 2002 (pocket pc memo avail)
• Up to date march 2005

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Case 1

• 26 yo G3P1SAB1 has normal prenatal course. No FH
  birth defects. You obtain clinic US for gender at
  22 wks and they measure size 20 wks /- 2 wks.
  FH are normal.
• What do you do?

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Case 1

• You decide to obtain a hospital ultrasound 4 wks
  later, now 26 wks by LMP
• shows EFW 15 ile for LMP
• GA is 24 wks /-2 wks by biometry
• umbilical artery S/D ratio is 1.4
• whats your dx?
• What do you do?

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Case 1

• More results from same US
• no anatomic defects
• HC ile close to AC ile, HC/AC and FL/AC
  ratios are normal
• NOW what do you do?

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Case 1

• 2nd scan 4wks later at 30 wks LMP
• EFW 7ile for LMP
• symmetric
• normal UAV
• what do you do?

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Case 2

• 22 yo G1P1 smoker has hx IVDU and remote hx
  hypertension
• 2nd prenatal visit is 28 wks
• insists she knows when she got pregnant
• what do you do?

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Case 2

• Maternal tox screen negative
• Basic US shows EFW 6ile for LMP GA
• what else do you want to know about US?

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Case 2

• Anatomic survey intact
• AC 4 ile
• HC/AC ratio 1.6 standard deviations above mean
• UAV S/D ratio 1.8, normal for this GA
• Dx ?

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Case 2

• Management?

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Case 2

• Follow up scan at 31 wks
• EFW 4ile
• AC2ile
• HC/AC gt2 SD
• FL/AC 28
• S/D ratio 2.8, abnl is 3 for this GA
• management?