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🤰 Gestational Age from CRL (Ultrasound)

UseEstimate gestational age when CRL dating is most accurate.

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SourceRobinson HP, Fleming JE. A critical evaluation of sonar crown-rump length measurements. BJOG 1975

Runs locally in your browser (no PHI uploaded). For licensed clinicians — not a substitute for clinical judgement.
Stored on this device for revisit reminders

This-shift next steps

After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.

Scene next step
📋obgynOpen scene pack →
Related scores
Matching pathway
🧭eclampsiaOpen pathway →
Score + version; reference only — not a substitute for care · no HIS write

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Methodology · worked example, guidelines & full notes
Clinical takeaway

First-trimester CRL is the most accurate dating method.

When to use

Estimate gestational age when CRL dating is most accurate.

How it works

GA (days) = 8.052 × √(CRL·1.037) + 23.73, with CRL in mm. Best at ~ CRL 15–95 mm (7–14 weeks).

Key points

  • First-trimester CRL is the most accurate dating method.
  • Does not apply at very small or large CRL.
  • Use BPD/HC/AC/FL for later pregnancy.

References

Worked calculation

The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.

Crown-rump length (CRL)45 mm

→Estimated gestational age11w 2d

  • Equivalent：79 days
  • Formula：Robinson: GA (days) = 8.052·√(CRL·1.037) + 23.73
Verification & sources · governance
FAQ

Frequently asked questions

What are the limits and cautions when using Gestational Age from CRL (Ultrasound)?
For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
Does Gestational Age from CRL (Ultrasound) upload patient data? Where is it calculated?
Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
How is Gestational Age from CRL (Ultrasound) calculated in practice? Can you show a worked example?
Inputs: Crown-rump length (CRL) 45 mm → Result: Estimated gestational age 11w 2d（Equivalent: 79 days, Formula: Robinson: GA (days) = 8.052·√(CRL·1.037) + 23.73）
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