Pediatric female pelvis — Reference values: Neonate (<3 months) — estrogenized uterus, Uterus — length by age, Body/cervix ratio (fundus/cervix).
Normal female pelvic measurements change substantially with age, so reading is age-banded. In the neonate (<3 months), maternal estrogen makes the uterus prominent, with a cervix larger than the body (body/cervix ratio ~1:2) and a visible echogenic endometrium — this is NORMAL and involutes within weeks. In prepubertal childhood (≈4 months to 8 years) the uterus is tubular (≤4 cm, thickness <1 cm), the body/cervix ratio is ~1:1, the ovary is <1–2 cm³ and the endometrium is not visible. At puberty the fundus becomes dominant (body/cervix 2:1–3:1), the uterus reaches 5–8 cm in a pear shape, the ovary exceeds ~3.5–4 cm³ and the endometrium becomes visible/cyclic. Colors: green = within the range for age; yellow = borderline/overlap zone; red = a pubertal finding under age 8 (suspected early estrogenization) or a measurement clearly outside the band. No single measurement is diagnostic — combine uterus, ovaries, endometrium, Tanner stage and growth curve.
Measurements and reference values
Measurement
Usual value
Note
Neonate (<3 months) — estrogenized uterus
length ~2.5–3.5 cm; body/cervix ratio ~1:2; visible endometrium cm
maternal estrogen effect; involutes over the first weeks/months. A visible endometrium and small ovarian cysts are physiologic at this stage.neonatal pattern: cervix-dominant, visible endometrium, expected involutionpersistent: prominent uterus not involuting on follow-upmass/obstruction: hydrometrocolpos, complicated or large ovarian cystSource: Radiologia Brasileira 2009 / StatPearls 2025 / Pediatric Radiology 2019
Uterus — length by age
prepubertal ≤4 cm; pubertal 5–8 cm cm
grows slowly until ~7–8 years and accelerates at puberty (Dixit: ~2.6 cm at 5y → 4.0 cm at 10y → 6.9 cm at 15–16y). Length >4–4.5 cm or a pubertal shape under age 8 favors early estrogenization.prepubertal: ≤4 cm and thickness <1 cm (tubular)borderline: 4–4.5 cm or thickness 1–1.5 cmadolescent (pubertal): 5–8 cm with fundal dominancepubertal under 8 years: >4.5 cm or thickness >1.5 cm✓ applied automatically in the reportSource: Dixit 2021 / Gilligan (Pediatric Radiology 2019) / Herter (AJR 2002) / Kelsey 2016
Body/cervix ratio (fundus/cervix)
neonate ~1:2; childhood ~1:1; pubertal 2:1–3:1
estrogenization marker: the fundus becomes dominant over the cervix with puberty. The ratio alone overlaps — combine with length, ovary and endometrium.tubular prepubertal: ≤1.2 (~1:1)transition: 1,2–1,4adolescent (pubertal): >1.4 (2:1–3:1)fundal dominance under 8 years: >1.4 (2:1–3:1)Source: Dixit 2021 (FCR) / Radiologia Brasileira 2009 / StatPearls 2025
Ovary — volume by age
prepubertal <1–2 cm³; pubertal >3.5–4 cm³ cm³
volume = 0.523 × L × W × D. Kelsey model: ~0.7 cm³ at age 2 → ~2.5 cm³ at 10 → ~7.7 cm³ at 20. There is substantial overlap between prepubertal and early pubertal.prepubertal: <1–2 cm³divergent: >2–3,5 cm³adolescent (pubertal): >3.5–4 cm³ (up to ~20 cm³)pubertal under 8 years: >3,5–4 cm³investigate mass/cyst: >20 cm³✓ applied automatically in the reportSource: Kelsey (PLoS ONE 2013) / Dixit 2021 / Gilligan 2019 / Herter (AJR 2002)
Pediatric endometrium
prepubertal: not visible; pubertal: visible/cyclic
a visible endometrium is a specific estrogenization marker (~100% specificity, lower sensitivity). Visible in the neonate and at puberty is normal; under age 8 outside the neonatal period it is a warning sign.prepubertal: not visiblethin line: early transition — correlatepubertal/neonate: visible/cyclic expectedvisible under 8 years: cyclic/thickened outside the neonatal periodSource: Radiologia Brasileira 2009 / Gilligan 2019 / StatPearls 2025
Ovarian follicles and cysts
small follicles/microcysts are physiologic at any pediatric age mm
small follicles do not indicate puberty; a dominant unilateral cyst changes interpretation and may be functional.usual childhood: <9 mmcontextual macrocystic: 9–20 mmdominant/complex: >20 mm or complex content/torsionSource: Gilligan 2019 / StatPearls 2025
Classifications and calculators
Calculator — pediatric female pelvis by age
Structure
Green (normal for age)
Red (alert)
Uterine length
≤4 cm prepubertal; grows with age up to 5–8 cm in adolescence (see table)
>4.5 cm or pubertal shape under 8 years
Body/cervix ratio
~1:1 in childhood; 2:1–3:1 at puberty
>1.4 (fundal dominance) under 8 years
Ovarian volume
<1–2 cm³ prepubertal; rises with age to >3.5 cm³ in adolescence (see table)
>3.5–4 cm³ under 8 years; >20 cm³ investigate
Endometrium
not visible in childhood; visible at puberty/neonate
visible/cyclic under 8 years (outside neonate)
The calculator reads each structure by age and flags early estrogenization when a pubertal finding appears under age 8. No single criterion is diagnostic — correlate with Tanner stage, growth curve and bone age, coordinating with pediatric endocrinology.
Normal by age — uterus, ovary and body/cervix ratio
Age
Uterine length (cm)
Mean ovarian volume (cm³)
Body/cervix ratio
Neonate
2,5–3,5
~1,0
~1:2
1–4 years
<3,0
~0,7–1,0
~1:1
5–6
2,6
0,5
0,9
6–7
3,1
0,6
1,0
7–8
3,3
0,8
1,1
8–9
3,5
1,3
1,3
9–10
3,8
1,8
1,3
10–11
4,0
2,0
1,3
11–12
4,6
2,1
1,3
12–13
5,5
3,0
1,5
13–14
6,1
3,5
1,5
14–15
6,5
4,4
1,7
15–16
6,9
4,6
1,8
Mean values (backbone Dixit 2021, cohort 5–16 years; neonate and 1–4 years from Radiologia Brasileira/Kelsey). These are means — use the green/yellow/red bands above and the clinical context; there is substantial overlap at early puberty.
Source: Dixit (Pediatr Endocrinol Diabetes Metab 2021) / Kelsey (PLoS ONE 2013) / Radiologia Brasileira 2009