Intrauterine Growth Restriction

Roya Sohaey, MD

DIFFERENTIAL DIAGNOSIS

Common

Placental Insufficiency

Less Common

Chromosome Abnormality
- Trisomy 18 (T18)
- Trisomy 13 (T13)
- Triploidy
Twin-Twin Transfusion Syndrome
Isolated Anomalies with IUGR
- Gastroschisis
- Single Umbilical Artery

Rare but Important

Infection

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Intrauterine growth restriction (IUGR) defined as estimated fetal weight (EFW) < 10th percentile for gestational age (GA)
- Accurate GA essential for diagnosis
IUGR vs. small for gestational age (SGA)
- IUGR: Fetus not reached growth potential
- SGA: Fetus is small but normally grown
- Difficult to differentiate prenatally
  - Look at parents and siblings
Symmetric vs. asymmetric IUGR
- Symmetric: All biometry equally affected
  - Often early and severe IUGR
  - Suggests fetal problem
  - Possible early placental dysfunction
- Asymmetric: “Head sparing” with abdomen, extremities more severely affected
  - Often presents later in pregnancy
  - Suggests placental cause
  - Better prognosis if not severe
Early IUGR vs. late IUGR
- Early IUGR more likely fetal cause
  - Look for anomalies
  - Consider amniocentesis
- Late IUGR more likely placental cause
IUGR differential diagnosis approach
- Rule out fetal anomaly as cause for IUGR
  - Amniocentesis if fetal anomaly suspected
- Consider maternal medical history
- Assess amniotic fluid
- Assess fetal/placental circulation
  - Doppler
  - Biophysical profile (BPP)

Helpful Clues for Common Diagnoses

Placental Insufficiency
- Maternal causes
  - Hypertension (acute or chronic)
  - Uncontrolled diabetes mellitus
  - Thrombophilia
  - Collagen vascular disease
  - Drugs/alcohol/smoking
  - Malnutrition
- Uterine-placental causes
  - Chronic abruption
  - Infarction
  - Confined placental mosaicism
  - Marginal or velamentous cord insertion
- Doppler findings
  - ↑ Uterine artery (UtA) resistance with post-systolic notch
  - ↑ Umbilical artery (UA) resistance
  - ↑ Ductus venosus (DV) resistance
  - ↓ Middle cerebral artery (MCA) resistance
- Findings in addition to IUGR
  - Oligohydramnios
  - Placental sonolucencies
  - Poor BPP score
- Management/treatment
  - Manage maternal condition
  - Increased surveillance
  - Abnormal Doppler, fluid, BPP in 3rd trimester consider delivery

Helpful Clues for Less Common Diagnoses

Trisomy 18 (T18)
- IUGR in 51% (rarely isolated)
  - Early onset, symmetric IUGR
- Anomalies associated with T18
  - Cardiac defects
  - Dandy-Walker continuum
  - Spina bifida
  - Omphalocele
  - Clenched hands + overlapping index finger, rockerbottom feet
- Markers associated with T18
  - Choroid plexus cyst
  - Single umbilical artery
  - Umbilical cord cyst
  - Nuchal thickening
Trisomy 13 (T13)
- IUGR in 50% (rarely isolated)
  - Early onset, with microcephaly
- Anomalies associated with T13
  - Holoprosencephaly, microcephaly
  - Hypotelorism, cyclopia, proboscis
  - Dandy-Walker continuum
  - Polydactyly
  - Cardiac defects
  - Gastrointestinal anomalies
- Markers associated with T13
  - Echogenic cardiac focus
  - Single umbilical artery
  - Nuchal thickening
Triploidy
- 69 chromosomes (extra haploid set)
  - Maternal or paternal extra set
- Early severe IUGR is hallmark finding
  - Asymmetric if maternal extra set
- Variable placenta findings according to source of extra set
  - Thick and cystic (paternal)
  - Small or normal (maternal)
- Ovarian theca lutein cysts
- Fetal anomalies often severe but difficult to completely characterize prenatally
  - Small fetus
  - Oligohydramnios
  - Thick cystic placenta displaces fetus
Twin-Twin Transfusion Syndrome
- Monochorionic twinning with artery-to-vein anastomoses in placenta
  - Donor twin partly perfuses recipient twin
- Donor twin with IUGR
  - Oligohydramnios
  - Abnormal Doppler
Gastroschisis
- Bowel herniation through right paramedial abdominal wall defect
- 50% develop IUGR
  - Often leads to early delivery
- Bowel complications may develop during pregnancy
  - Dilatation, ischemia, rupture
Single Umbilical Artery
- 15% of fetuses with an isolated single umbilical artery (SUA) have IUGR
  - Follow-up for growth into 3rd trimester
- Non-isolated SUA
  - 50% aneuploidy rate
  - T18 most common

Helpful Clues for Rare Diagnoses

Infection
- IUGR and hydrops are early findings
- Common infections: Parvovirus, cytomegalovirus, toxoplasmosis, varicella
- Other findings
  - Echogenic bowel
  - Brain, liver, spleen calcifications

Other Essential Information

Late presentation case: Is fetus small or are dates wrong?
- Look for lower extremity ossification centers to verify dating
  - Distal femoral epiphyseal ossification ≥ 32 weeks
  - Proximal tibial epiphyseal ossification ≥ 35 weeks
- Look at fluid and Doppler values
IUGR + polyhydramnios bad prognosis
- Associated with aneuploidy, syndromes
- Amniocentesis warranted

Image Gallery

Pulsed Doppler ultrasound of the umbilical artery shows elevated UA resistance in a fetus with third trimester IUGR and oligohydramnios. The systolic/diastolic ratio (S/D) is 5.6 and should be < 3.0.

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