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Cervical Length / Umbilical & Cerebroplacental Doppler

1.0.0

Transvaginal cervical length screening for short cervix, plus umbilical and middle cerebral artery pulsatility indices to compute the cerebroplacental ratio (CPR) and flag brain-sparing physiology and raised placental resistance in context of gestational age.

Also searched as: short cervix · preterm birth · umbilical artery · MCA · CPR · cerebroplacental ratio · FGR · obstetric · women · cervix · pregnancy

Transvaginal cervical length

Closed TV CL from internal to external os, standardized technique (empty bladder, no fundal pressure). Midtrimester short cervix: ≤25 mm.

mm
Gestational age

Completed weeks + fraction (e.g. 32.4 ≈ 32+3). Used for short-cervix timing context and approximate UA-PI reference.

weeks
Umbilical artery PI (UA-PI)

Free-loop umbilical artery pulsatility index. Document AEDF/REDF separately if present (ratio interpretation limited).

Middle cerebral artery PI (MCA-PI)

MCA PI sampled in the proximal MCA near the circle of Willis, angle of insonation near 0°, without fetal breathing/movement.

Information
Incomplete input
  • Please provide: cervical length and/or UA-PI and/or MCA-PI.

How this tool works

Midtrimester transvaginal cervical length (TV CL) ≤25 mm defines a short cervix in singleton pregnancy without prior spontaneous preterm birth (SMFM Consult Series #70); treatment thresholds (e.g., vaginal progesterone at ≤20 mm before 24 weeks) are clinical decisions. Fetal Doppler: umbilical artery PI (UA-PI) rises with placental resistance; middle cerebral artery PI (MCA-PI) falls with cerebral redistribution. Cerebroplacental ratio CPR = MCA-PI / UA-PI integrates both. A commonly cited fixed abnormal cutoff is CPR <1.08 (Gramellini et al.); many protocols and ISUOG late-onset FGR criteria prefer gestational-age–specific centiles (e.g., CPR <5th). UA-PI should be interpreted against a validated reference chart (>95th or AEDF/REDF). Approximate UA-PI 95th values are shown for context only—use a locally validated nomogram for formal reporting.

References

Implemented from the cited published sources. Educational use only; confirm against current guidelines before clinical use.

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