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Fetal Doppler PI/RI Calculator v1.0

Umbilical & middle cerebral artery, cerebroplacental ratio, uterine artery, ductus venosus, MCA-PSV anemia surveillance · fetal-echo.org

fetal-echo.org

Clinical decision-support aid — not a diagnostic test. Percentiles/Z-scores are computed from the published reference populations listed at the bottom of each module and are valid only within each source's gestational-age range. Published Doppler reference charts differ from one another by a clinically meaningful margin (Oros et al., Ultrasound Obstet Gynecol 2019;53:454-464; Ruiz-Martinez et al., Ultrasound Obstet Gynecol 2020;56:166-172) — always correlate with growth biometry, serial trends and the wider clinical picture. Assumes a singleton pregnancy with an accurately dated gestational age.

Patient & gestational age

Enter once — every module below uses it. Name and ID are optional and only used to label a printout.

For clinician use. This screen shows full percentiles, normal ranges and interpretive flags. The only patient-facing output is the separate numbers-only printout below — nothing interpretive is ever printed for the patient.
Fetal growth restriction — arterial & venous Doppler UA · MCA · CPR · UtA · DV

Enter umbilical artery and middle cerebral artery PI to get cerebroplacental ratio (CPR) automatically. Uterine artery and ductus venosus are optional add-ons for staged/advanced assessment — add them if resistance is already abnormal or on your unit's protocol.

Core — umbilical & middle cerebral artery
Umbilical artery PI
Ciobanu et al. 2019
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Middle cerebral artery PI
Ciobanu et al. 2019
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Cerebroplacental ratio (CPR)
= MCA-PI ÷ UA-PI · auto-calculated
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+ Add uteroplacental & venous Doppler (uterine artery, ductus venosus)
Uteroplacental — uterine artery
Mean uterine artery PI
Gómez et al. 2008 · average of both sides
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Venous — ductus venosus
Ductus venosus PIV
Kessler et al. 2006
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References (verified against full text):

  • Ciobanu A, Wright A, Syngelaki A, Wright D, Akolekar R, Nicolaides KH. Fetal Medicine Foundation reference ranges for umbilical artery and middle cerebral artery pulsatility index and cerebroplacental ratio. Ultrasound Obstet Gynecol 2019;53(4):465–472. doi:10.1002/uog.20157
  • Gómez O, Figueras F, Fernández S, et al. Reference ranges for uterine artery mean pulsatility index at 11–41 weeks of gestation. Ultrasound Obstet Gynecol 2008;32(2):128–132. doi:10.1002/uog.5315
  • Kessler J, Rasmussen S, Hanson M, Kiserud T. Longitudinal reference ranges for ductus venosus flow velocities and waveform indices. Ultrasound Obstet Gynecol 2006;28(7):890–898. doi:10.1002/uog.3857

Fetal anemia surveillance — MCA-PSV alloimmunization · parvovirus risk

Separate clinical question from growth restriction — used to time invasive testing (cordocentesis) in pregnancies at risk of fetal anemia (red-cell alloimmunization, parvovirus B19). Not a growth/placental-function test.

MCA peak systolic velocity
cm/sec · Mari et al. 2000 (NEJM)
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Reference (verified against full text):

  • Mari G, for the Collaborative Group for Doppler Assessment of the Blood Velocity in Anemic Fetuses. Noninvasive diagnosis by Doppler ultrasonography of fetal anemia due to maternal red-cell alloimmunization. N Engl J Med 2000;342(1):9–14. doi:10.1056/NEJM200001063420102

Privacy: this calculator runs entirely in your browser. No measurements, names or IDs are transmitted or stored anywhere — closing this page clears everything.

Fetal Doppler Report

fetal-echo.org
Generated
Umbilical & cerebral Doppler

This report lists measured values and their percentile position for gestational age only. It is not a diagnosis. Please discuss these results with your treating obstetrician / fetal medicine specialist.