What is the normal size and volume of the uterus?

Normal Uterine Size and Volume

The normal uterus in reproductive-age nulliparous women measures approximately 7.0-8.0 cm in length, with a volume typically ranging from 50-90 cm³, though these measurements vary significantly with age, parity, and hormonal status. 1, 2, 3

Standard Measurement Technique

• Ultrasound examination should be performed systematically in at least two orthogonal planes (sagittal and transverse), tracing completely from fundus to cervix to ensure accurate assessment. 1

• The transvaginal approach is preferred when acceptable to the patient for optimal visualization. 1

• For transabdominal scanning, the bladder should be adequately distended to serve as an acoustic window, with the bladder dome positioned just above the uterine fundus. 1

• Uterine volume is calculated using the prolate ellipsoid formula (length × width × anteroposterior diameter × 0.523), which shows high correlation with actual measured volumes. 2

Normal Measurements by Age and Parity Status

Nulliparous Women (Reproductive Age)

• Median uterine length: 7.0 cm (interquartile range 7.0-7.8 cm) in the IVF population. 4

• Fundal thickness progressively increases with age:

  • Ages 15-24 years: mean 10.8 mm (range 5.6-15.8 mm)
  • Ages 25-34 years: mean 12.3 mm (range 7.0-18.7 mm)
  • Ages 35-45 years: mean 13.6 mm (range 7.3-19.8 mm) 5

• Intercornual distance also increases with age:

  • Ages 15-24 years: mean 41.4 mm (range 30.6-50.7 mm)
  • Ages 25-34 years: mean 44.5 mm (range 31.5-57.3 mm)
  • Ages 35-45 years: mean 47.2 mm (range 35.2-61.0 mm) 5

• Median fundal indentation: 1.7 mm (90th percentile: 4.8 mm). 3

• Median indentation angle: 161.8°. 3

General Adult Women

• Mean uterine volume in normal-sized uteri ranges from approximately 50-90 cm³, with significant individual variation. 2

• Uterine length is positively associated with BMI and presence of fibroids. 4

Clinical Significance of Abnormal Measurements

• Women with uterine lengths <7.0 cm or >9.0 cm demonstrate reduced live birth rates in IVF populations, following an inverse U-shaped relationship. 4

• Very short uteri (<6.0 cm) are associated with:

  • 47% reduction in live birth rates (RR: 0.53,95% CI: 0.35-0.81)
  • More than doubled spontaneous abortion risk (RR: 2.16,95% CI: 1.23-3.78) 4

• Ovarian enlargement is defined as maximal dimension >4 cm or volume >20 cm³ in premenopausal patients. 6

• A volume ≥10 ml in any ovary is considered increased when using endovaginal transducers with frequency including 8 MHz. 1

Special Populations

Postmenopausal Women

• Subjective evaluation of uterine enlargement is particularly difficult in postmenopausal patients, making objective sonographic measurements especially valuable. 2

• Normal postmenopausal uteri are significantly smaller than reproductive-age uteri due to hormonal changes.

Women with Hormonal Deficiencies

• Women with isolated growth hormone deficiency show median uterine cross-sectional area of 18.0 cm² (range 9.9-28.6 cm²) compared to 23.0 cm² (range 16.1-31.7 cm²) in healthy controls. 7

• Women with hypogonadotropic hypogonadism demonstrate markedly reduced measurements with median cross-sectional area of 7.0 cm² (range 1.3-18.5 cm²). 7

• Standard estrogen replacement therapy often does not result in achievement of normal uterine dimensions in women with prepubertal-onset hormonal deficiencies. 7

Critical Documentation Requirements

• The date of last menstruation must be documented, as measurements vary throughout the menstrual cycle. 1

• Document the transducer frequency used and approach (transabdominal vs transvaginal). 1

• Record all three dimensions (length, width, anteroposterior diameter) and calculated volume. 1

• Document endometrial thickness and appearance, noting the three-layer pattern when present for screening of endometrial pathology. 1

Common Pitfalls to Avoid

• Failure to examine in two complete orthogonal planes can miss important findings such as interstitial pregnancy or fibroids located outside the central endometrial canal. 1

• Incomplete tracing from fundus to cervix may result in mistaking a large ectopic pregnancy for the uterus itself. 1

• Inadequate bladder distension significantly limits visualization quality in the transabdominal approach. 1

• When a sonographically enlarged but otherwise morphologically normal uterus is discovered, it may contain leiomyomas or other pathology not detectable by ultrasound appearance alone. 2