NUMBERS & MEASUREMENTS

Quick reference for diagnostic thresholds, normal values, and measurement criteria

MSK (Musculoskeletal)

Femoroacetabular Impingement (FAI)

Center Edge Angle:

<20°: Acetabular dysplasia

20-25°: Borderline acetabular dysplasia

25-40°: Normal

>40°: Pincer type morphology

Vascular

Aorta

Ascending Aorta:

4.0-4.4 cm: Ectasia

>4.5 cm: Aneurysm

Infrarenal Aorta:

>3 cm (outer wall to outer wall): Aneurysm

Main Pulmonary Artery

<2.9 cm: Normal

Gastrointestinal

Organ Size Thresholds

Hepatomegaly: >18 cm craniocaudal

Splenomegaly: >13 cm craniocaudal

Genitourinary

Uterine Measurements

Thickened junctional zone: >12 mm

Head

Vestibular Aqueduct

Large vestibular aqueduct: ≥1 mm at midpoint

OR ≥2 mm at distal opening

Cardiac

Aortic Stenosis Severity

Mild: <2 cm²

Severe: <1 cm²

Critical: <0.8 cm²

Ultrasound

Doppler & Flow

Portal Vein Flow: <15 cm/s

Endometrium

<5 mm: Likely atrophy

4-5 mm: Requires biopsy

Bladder

Postvoid Volume: <100 mL

Amniotic Fluid

Amniotic Fluid Index (AFI):

<5 cm: Oligohydramnios

>25 cm: Polyhydramnios

Deepest Vertical Pocket:

<2 cm: Oligohydramnios

>8 cm: Polyhydramnios

Pediatrics

Catheter Positioning

Umbilical Artery Catheter: T5-T9

Pyloric Stenosis

Pyloric wall thickness: >3 mm

Pyloric channel length: >15 mm

Other Pediatric Measurements

Intussusception diameter: >2.5 cm

ECMO catheter tip: Right atrium