TIFFA scan with small baby

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The textbooks don't have a dedicated TIFFA section, but I have sufficient knowledge to provide a comprehensive answer. Let me compile this now.

TIFFA Scan with a Small Baby (Fetal Growth Restriction / SGA)

TIFFA = Targeted Imaging for Fetal Anomalies — a detailed morphological ultrasound scan typically performed at 18–20 weeks of gestation. It is the standard "level 2" or "anomaly scan" used to systematically evaluate fetal anatomy.

What TIFFA Assesses

System	Structures Evaluated
CNS	Head shape, BPD, cerebellum, cavum septum pellucidum, choroid plexus, ventricles
Face	Orbits, nose, lips (cleft lip detection)
Neck	Nuchal fold thickness
Thorax	Lung echogenicity, heart (4-chamber view, LVOT, RVOT, 3-vessel view)
Abdomen	Stomach bubble, abdominal wall, liver, kidneys, bladder
Spine	Longitudinal + transverse views (neural tube defects)
Limbs	Long bones, hands, feet
Placenta & Liquor	Position, morphology, AFI/deepest vertical pool
Biometry	BPD, HC, AC, FL → estimated fetal weight (EFW)

When TIFFA Shows a Small Baby

"Small baby" on TIFFA typically means one or more of the following biometric parameters are below the expected range for gestational age:

Measurement	Concern when...
EFW / AC	< 10th centile → suspect SGA / FGR
FL/AC ratio	Elevated → asymmetric growth restriction
HC/AC ratio	Elevated → brain-sparing pattern

Key Distinction: SGA vs. FGR

	SGA (Small for Gestational Age)	FGR (Fetal Growth Restriction)
Definition	EFW < 10th centile	EFW < 3rd centile or < 10th centile + abnormal Doppler/liquor
Etiology	Often constitutional (small but healthy)	Placental insufficiency, chromosomal, infection, structural
Doppler	Normal	Abnormal UA PI, MCA PI, CPR, ductus venosus

Causes to Consider on TIFFA

Placental causes (most common)

Placental insufficiency
Abnormal cord insertion (velamentous, marginal)

Fetal causes

Chromosomal anomalies (trisomy 13, 18, 21, Turner syndrome) — look for associated structural defects
TORCH infections (cytomegalovirus, toxoplasmosis, rubella) — periventricular calcifications, hepatosplenomegaly
Skeletal dysplasias — short long bones, abnormal bone echogenicity
Structural anomalies (cardiac, renal, GI)

Maternal causes

Hypertension / pre-eclampsia
Diabetes, renal disease, thrombophilia

Additional Assessments at TIFFA When Baby is Small

Amniotic fluid index (AFI) — oligohydramnios supports placental insufficiency
Doppler studies (if EFW < 10th centile):
- Umbilical artery (UA) PI — elevated → placental resistance ↑
- Middle cerebral artery (MCA) PI — decreased → brain-sparing
- Cerebroplacental ratio (CPR) = MCA PI / UA PI — < 1.0 is concerning
- Uterine artery PI — notching suggests uteroplacental insufficiency
Detailed fetal anatomy — to exclude structural/chromosomal cause
Placental morphology — abnormal texture, circumvallate insertion

Management Algorithm After TIFFA Small Baby

EFW < 10th centile on TIFFA
        |
        ├── Normal anatomy + normal Doppler + normal liquor
        │       → Serial growth scans every 2–4 weeks
        │         Likely constitutional SGA
        │
        ├── Abnormal Doppler (UA PI ↑) or oligohydramnios
        │       → FGR likely; intensify surveillance
        │         Refer MFM (Maternal-Fetal Medicine)
        │         Consider steroids if preterm delivery anticipated
        │
        └── Structural anomalies detected
                → Genetic counseling, karyotyping / chromosomal microarray
                  TORCH serology
                  Fetal echocardiography

Surveillance in FGR (After Diagnosis at TIFFA)

Doppler Finding	Action
Elevated UA PI, normal diastolic flow	Growth scan + Doppler every 2 weeks
Absent end-diastolic flow (AEDF)	Admit; daily/alternate-day Doppler; deliver at 34 weeks
Reversed end-diastolic flow (REDF)	Urgent delivery (after steroids if < 34 weeks)
Abnormal ductus venosus (absent/reversed a-wave)	Immediate delivery consideration

Key Points Summary

A small baby on TIFFA must be characterized as SGA vs. FGR using Doppler and liquor assessment
Always perform a detailed anatomy survey to exclude structural/chromosomal causes
Umbilical artery Doppler is the primary surveillance tool in suspected placental FGR
MCA PI and CPR add value in near-term fetuses with late-onset FGR
Timing of delivery depends on gestational age + severity of Doppler changes
Constitutional SGA (normal Doppler, normal anatomy, appropriate parental size) has a good prognosis with serial monitoring

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