Pediatric Radiology

, Volume 48, Issue 12, pp 1771–1778 | Cite as

Ultrasound-based measurements of testicular volume in 6- to 16-year-old boys — intra- and interobserver agreement and comparison with Prader orchidometry

  • Ninnie Helén Bakken OehmeEmail author
  • Mathieu Roelants
  • Ingvild Særvold Bruserud
  • Geir Egil Eide
  • Robert Bjerknes
  • Karen Rosendahl
  • Pétur B. Júlíusson
Original Article



Prader orchidometry has been the standard method for evaluating testicular size. As this technique is subjective and tends to overestimate the testicular volume, ultrasound (US) has been proposed as more reliable.


To evaluate the intra- and interobserver agreement of US measurements of testicular volume and to compare US with the Prader orchidometer.

Materials and methods

Dimensions of the right testicle were measured using US in 57 boys ages 6.5 to 16.4 years (mean: 12.0 years). The measurements were performed twice by one main observer and once by a second observer. A third observer estimated testicular volume using a Prader orchidometer. Agreement was investigated with Bland-Altman plots, summarized as the mean and standard deviation (SD) of differences, 95% limits of agreement and technical error of measurement.


Mean intra-observer difference of testicular volume was 2.2%, SD=9.2% (limits of agreement: -20.3 to 15.9%) and technical error of measurement 6.5%. The mean interobserver difference was 4.8%, SD=20.7% (limits of agreement: -35.7 to 45.3%) and technical error of measurement 14.6%. Comparing US and orchidometer volumes required conversion that was nonlinear and volume dependent, estimated as VolOM = 1.96×VolUS0.71. The mean difference after transformation was 0.7% with an SD of 18.0% (limits of agreement: -34.5 to 35.9%).


Our results showed a small mean intra- and interobserver difference that indicates the potential of US for measurement of testicular volume at group level. The intra-observer error was limited, which justifies its use in longitudinal follow-up of testicular development in an individual child, but the larger interobserver variability indicates the need for good standardization of methods. Agreement between the two methods requires a power transformation.


Children Interobserver Observer variability Orchidometer Precision Testicular volume Ultrasound 



We thank Magnus R. Sveen for his substantial help during data collection and all the participants.

Compliance with ethical standards

Conflicts of interest


Supplementary material

247_2018_4195_MOESM1_ESM.pdf (302 kb)
ESM 1 (PDF 301 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Ninnie Helén Bakken Oehme
    • 1
    • 2
    Email author
  • Mathieu Roelants
    • 3
  • Ingvild Særvold Bruserud
    • 1
    • 2
  • Geir Egil Eide
    • 4
    • 5
  • Robert Bjerknes
    • 1
    • 2
  • Karen Rosendahl
    • 6
    • 7
  • Pétur B. Júlíusson
    • 1
    • 2
  1. 1.Department of Clinical ScienceUniversity of BergenBergenNorway
  2. 2.Department of PediatricsHaukeland University HospitalBergenNorway
  3. 3.Environment and Health, Department of Public Health and Primary CareKU Leuven – University of LeuvenLeuvenBelgium
  4. 4.Centre for Clinical ResearchHaukeland University HospitalBergenNorway
  5. 5.Department of Global Public Health and Primary CareUniversity of BergenBergenNorway
  6. 6.Department of RadiologyHaukeland University HospitalBergenNorway
  7. 7.Department of Clinical MedicineUniversity of BergenBergenNorway

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