O&G SAQs · Antenatal care — fetal surveillance
Fetal Dopplers in early-onset FGR — structured SAQ (15 marks)
FRANZCOG-format structured SAQ on early-onset fetal growth restriction with severe umbilical artery Doppler abnormality: initial assessment, the four Doppler vessels and what each tells you, the TRUFFLE delivery logic, and prognostic counselling. Per-sub-part marking rubric included.
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Prompt
You are the obstetric registrar in the fetal medicine clinic. A 30-year-old G1P0 woman at 29 weeks gestation has an estimated fetal weight on the 3rd centile with an umbilical artery pulsatility index above the 95th centile and absent end-diastolic flow. Her blood pressure is 138/88 mmHg. (a) Outline your initial assessment and immediate management. (4 marks) (b) Describe the Doppler surveillance you will perform and explain what each vessel tells you. (4 marks) (c) Explain the TRUFFLE-informed logic for the timing of delivery, including the role of the ductus venosus and the computerised CTG. (4 marks) (d) Describe the counselling you would give about prognosis and recurrence. (3 marks)
How this SAQ is marked
Twelve SAQs, 180 marks, two 2-hour papers — roughly 15 marks and 20 minutes each. Marks come from specifics: named vessels, named thresholds, the TRUFFLE delivery triggers and the reasoning that distinguishes a delivery vessel from a surveillance vessel. Write in short labelled points. [1][5]
Reveal model answer and mark schemeShowHide
(a) Initial assessment and immediate management (4 marks)
- Confirm the diagnosis and severity: EFW on the 3rd centile, UA-PI above the 95th centile, absent end-diastolic flow (AEDF) — this is severe early-onset fetal growth restriction with critical placental disease.
- Admit for inpatient surveillance with daily to alternate-day umbilical artery, middle cerebral artery, ductus venosus Doppler and computerised CTG short-term variation; continuous CTG if any concern.
- Administer corticosteroids for fetal lung maturation (betamethasone or dexamethasone) and magnesium sulfate for neuroprotection if delivery before 32 weeks is being considered.
- Assess the mother for pre-eclampsia: blood pressure 138/88 with early-onset FGR is concerning; check urine protein, bloods, and arrange senior review — the TRUFFLE insights paper notes that most women with early-onset FGR develop hypertension.[2]
(b) Doppler surveillance and what each vessel tells you (4 marks)
One mark per vessel with what it tells you. [1][5]
| Vessel | What it tells you | Abnormal = |
|---|---|---|
| Umbilical artery | Placental impedance | AEDF (here), REDF — the placenta in a waveform |
| Middle cerebral artery | Cerebral redistribution (brain-sparing) | MCA-PI below the 5th centile — compensation, not endpoint |
| Ductus venosus | Cardiac compromise, central venous pressure | Absent or reversed a-wave — late-stage decompensation |
| Uterine artery | Trophoblastic invasion (already abnormal here) | High PI with bilateral notching — failed placentation |
The sequence of deterioration is predictable: umbilical artery first, MCA second, ductus venosus last. The cerebroplacental ratio (MCA-PI divided by UA-PI) is a derived index that captures brain-sparing. [5]
(c) TRUFFLE-informed delivery logic (4 marks)
One mark per element with reasoning. [1][2][3]
- The TRUFFLE trial (Lees, Lancet 2015) randomised early-onset FGR at 26 to 32 weeks to delivery based on reduced cCTG short-term variation, early DV change (DV-PI above the 95th centile), or late DV change (absent or reversed a-wave). Among survivors, the late-DV group had the best 2-year neurodevelopmental outcome (95% free of neuroimpairment versus 85% for cCTG alone, p=0.005).[1]
- Deliver on late DV change or abnormal cCTG short-term variation (below the gestation-specific TRUFFLE cutoff).[1]
- Do NOT deliver on cerebral Doppler changes alone — cerebral redistribution (low MCA-PI) is a compensation, not an endpoint (TRUFFLE insights, Frusca 2018).[2]
- The combined GRIT/TRUFFLE analysis (Ganzevoort 2020) showed that cCTG plus DV Doppler gave the best 2-year survival without impairment (84%, 95% CI 80 to 89%).[3]
(d) Counselling on prognosis and recurrence (3 marks)
- Prognosis: AEDF and especially REDF carry the highest risk of perinatal mortality and long-term neurodevelopmental impairment; counsel honestly about the risks of prematurity (delivery likely by 32 to 34 weeks) and the 1% cerebral palsy rate seen in TRUFFLE.[2]
- Recurrence: counsel on the increased risk of FGR, pre-eclampsia and stillbirth in future pregnancies and the role of first-trimester aspirin prophylaxis (150 mg nocte from 12 weeks for high-risk women).[6]
- Placental histology at delivery to confirm the aetiology (maternal vascular malperfusion) and inform counselling and the plan for next time.
References5ShowHide
- [1]Lees CC, Marlow N, van Wassenaer-Leemhuis A, et al. 2 year neurodevelopmental and intermediate perinatal outcomes in infants with very preterm fetal growth restriction (TRUFFLE): a randomised trial Lancet, 2015.PMID 25747582
- [2]Frusca T, Todros T, Lees C, Bilardo CM; TRUFFLE Investigators Outcome in early-onset fetal growth restriction is best combining computerized fetal heart rate analysis with ductus venosus Doppler: insights from the Trial of Umbilical and Fetal Flow in Europe Am J Obstet Gynecol, 2018.PMID 29422211
- [3]Ganzevoort W, Thornton JG, Marlow N, et al. Comparative analysis of 2-year outcomes in GRIT and TRUFFLE trials Ultrasound Obstet Gynecol, 2020.PMID 31125465
- [5]Lees CC, Stampalija T, Baschat AA, et al. ISUOG Practice Guidelines: diagnosis and management of small-for-gestational-age fetus and fetal growth restriction Ultrasound Obstet Gynecol, 2020.PMID 32738107
- [6]Martins JG, Biggio JR, Abuhamad A Society for Maternal-Fetal Medicine Consult Series #52: Diagnosis and management of fetal growth restriction Am J Obstet Gynecol, 2020.PMID 32407785