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Keywords:

  • penis size;
  • nomogram;
  • micropenis;
  • small penis syndrome;
  • penile lengthening

Study Type – Diagnostic (validating cohort)

Level of Evidence 2a

What’s known on the subject? and What does the study add?

Reference ranges for normal penile length have been reported from several different countries and anthropometric differences have been noted between different nationalities and ethnic backgrounds.

This study describes one of the largest cohorts of men undergoing penile size measurements in Europe and the largest UK study. The range of measurements collected in this study will be of use to clinicians treating men with concerns over penile length, as well as helping to diagnose patients with true micropenis.

OBJECTIVES

• To establish a reference range for adult male genital size in the UK using penile length measurements.

• To compare the reference ranges for normal penile length reported from several different countries and the anthropometric differences noted between different nationalities and ethnic backgrounds.

METHODS AND MATERIALS

• Over 20 months, genital measurements were taken from all men undergoing routine examination in clinics (n= 499) and in operating theatres during examination under anaesthetic (n= 110).

• Using a rigid metric ruler three penile measurements were taken: flaccid pendulous penile length, flaccid penopubic penile length (to the pubic arch) and stretched flaccid penopubic length. In addition, testicular size was measured using an orchidometer.

• The patient’s age and the reason for referral were recorded.

• Statistical analysis was carried out using Pearson correlation analysis.

RESULTS

• Measurements from 610 patients aged 16–90 years were available for analysis.

• The mean penile lengths were: pendulous length 8.7 cm (sd 1.6 cm), penopubic length 10.2 cm (sd 1.4 cm) and stretched length 14.3 cm (sd 1.7 cm). The mean testicular volume was 19.8 mL (sd 5.4 mL) for both left and right testicles.

• Men with penile disease (including phimosis and Peyronie’s disease) had slightly reduced penile length (pendulous −3.3 mm, P= 0.014; penopubic −2.3 mm, P= 0.029; stretched −5.1 mm, P < 0.001) compared with other referral groups (erectile dysfunction, testicular disease, prostate and bladder disease).

• There was no significant correlation between penile length and age or testicular size

CONCLUSION

• These data establish a reference range for adult male genital size in the UK, which should be helpful for urologists when counselling patients.