Fetal Growth Restriction (FGR)
FGR refers to a fetus that fails to reach its genetically determined growth potential. It is most commonly defined as an Estimated Fetal Weight (EFW) < 10th percentile.
Classification
- Symmetric (Early onset): Usually due to chromosomal abnormalities, genetic syndromes, or congenital infections (TORCH). The entire fetus is small.
- Asymmetric (Late onset): Usually due to uteroplacental insufficiency (e.g., pre-eclampsia). The head is spared (“head-sparing effect”), while the abdomen is small.
Key Diagnostic Indicators
| Assessment | Significance |
|---|---|
| Umbilical Artery Doppler | Assesses placental resistance. Absent or reversed end-diastolic flow (AEDF/REDF) is a critical indicator of severe hypoxia. |
| Serial Ultrasound | The gold standard for tracking growth velocity (typically every 2–4 weeks). |
High-Yield Exam Pearl:
- SGA vs. FGR: “Small for Gestational Age” (SGA) is a descriptive term for weight < 10th percentile, while “FGR” implies a pathological process.
- Management: Delivery is the only definitive treatment for severe FGR. Timing is a balance between fetal distress (hypoxia) and prematurity risks, guided by Doppler studies and biophysical profiles (BPP).