Fetal Coarctation Risk Tool v2.0

Left-heart obstruction spectrum · evidence-anchored risk stratification · fetal-echo.org

fetal-echo.org

Risk-stratification aid — not a diagnostic test. This tool aggregates published fetal predictors of coarctation (CoA) into a transparent risk index. It does not output a validated, calibrated probability and does not replace expert fetal-cardiology assessment. Every clinical decision needs independent review.

Step 1 · Core measurements

Start with the views you can obtain on most scans. The risk estimate updates live. All Z-scores use gestational age only — no femur length needed.

Gestational age decimal weeks · e.g. 26.5

18–35 wks optimal

Mitral valve annulus mm · 4CV end-diastole

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Tricuspid valve annulus mm · 4CV end-diastole

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Aortic valve annulus mm · LVOT end-systole

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Pulmonary valve annulus mm · end-systole

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Ascending aorta mm · above sinotubular jn

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Aortic isthmus — 3VT view mm · widest systolic

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LCA–LSA distance mm · L-carotid to L-subclavian · for CSAI

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▸ Add advanced parameters (arch detail, Doppler, strain, structural) — refines the estimate

Step 2 · Advanced parameters

Optional. These add high-specificity confirmatory signs and help separate CoA from HLHS and interrupted arch (IAA). Leave blank what you don't have.

Arch detail & ratios

Aortic isthmus — sagittal mm

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Ductus arteriosus mm · 3VT, aortic end

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Descending aorta mm · below ductal insertion

For DA index

Arch at L-subclavian (LSA) mm · for CSAI

CSAI uses this ÷ LCA–LSA dist

AOI/DA ratio — enter isthmus and ductus above (threshold < 0.74 · Pasquini 2007)

Ventricular dimensions · mm · García-Otero 2020 · individual Z-scores + LV/RV ratio for HLHS grading

LV mid-transverse width mm · 4CV

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RV mid-transverse width mm · 4CV

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LV longitudinal length mm · apex to mitral plane

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RV longitudinal length mm · apex to tricuspid plane

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LV/RV width ratio — enter both LV and RV width above

Doppler & flow

Aortic isthmus flow

PW proximal to ductal insertion

Foramen ovale flow

Key HLHS differentiator

Transverse arch flow

Retrograde/absent → severe obstruction or HLHS/IAA

LV global longitudinal strain % · negative, e.g. −15

Speckle tracking. Less negative = worse

Structural / binary

Ventricular septal defect

Arch continuity

Persistent left SVC

Thymus

Bicuspid aortic valve

Redundant / aneurysmal FO flap

Result · Coarctation risk

Enter gestational age and at least one measurement to begin.

Awaiting input

What's driving this estimate

No positive predictors yet

Differentiation flags

HLHS features

Interrupted arch (IAA) features

Recommendation will appear here.

← All Calculators

Evidence base

Every predictor below was checked against its source. Performance figures are the authors' own; several derive from small single-centre cohorts (note the n) and should be read as indicative, not definitive.

Gómez-Montes E, et al. Prediction of coarctation of the aorta in the second half of pregnancy. Ultrasound Obstet Gynecol 2013;41(3):298–305. Multiparametric score (GA ≤28wk, Z-AscAo ≤−1.5, PV/AV ≥1.6, Z-AOI[3VT] ≤−2); n=85. DOI
Gómez-Montes E, et al. Gestational age-specific scoring systems for the prediction of coarctation. Prenat Diagn 2014;34(12):1198–206. Early ≤28wk AUC 0.98; late >28wk AUC 0.84; n=115. DOI
Liu J, et al. Incremental value of myocardial deformation in predicting postnatal CoA. J Am Soc Echocardiogr 2022;35(12):1298–1310. Model GA + AOI-Z + LV strain; C-stat 0.945; n=122+48. DOI
Fujisaki T, et al. Novel echocardiographic measurements to improve prenatal CoA diagnosis. Sci Rep 2023;13:4912. Their "DA index" (arch-at-subclavian ÷ carotid–subclavian distance) ≥1.28 → AUC 0.94, 85%/94%, n=30. Not implemented here — it needs specific neck-vessel geometry; the related carotid–subclavian signal is captured by Fricke's CSAI. DOI
Fricke K, et al. Fetal echocardiographic dimension indices: predictors of postnatal coarctation. Pediatr Cardiol 2020;42(3):517–525. CSAI <0.78 → 92%/97%; I/D×MV/TV <0.37 → 100%/95%; n=65. DOI
Pasquini L, et al. Z-scores of the fetal aortic isthmus and duct. Ultrasound Obstet Gynecol 2007 (PMID 17476706). Isthmus & duct nomograms used here. PubMed
van Oostrum NHM, et al. Fetal myocardial deformation (2D-STE): reference values, 124 fetuses. Ultrasound Obstet Gynecol 2022;59(5):651–659. LV-GLS nomogram. DOI
Vigneswaran TV, et al. Reference ranges for fetal cardiac outflow tract dimensions (13–36 wks). Circ Cardiovasc Imaging 2018. AoV / PV / transverse-arch nomograms. (widely cited; confirm DOI at source)
Krishnan A, et al. Fetal cardiac Z-score nomograms, 2016. Mitral, tricuspid, ventricular-length nomograms. (confirm DOI at source)
García-Otero L, et al. Nomograms of Fetal Cardiac Dimensions at 18–41 Weeks of Gestation. Fetal Diagn Ther 2020;47(5):387–398. Ventricular width (mid-transverse) and length (longitudinal) Z-scores used in HLHS grading panel. DOI

Ascending-aorta and main-pulmonary-artery Z-scores use a linear approximation derived from published normal curves, not a single primary nomogram — interpret those two with extra caution. The earlier "Villalain 2024" citation has been removed: it could not be verified.