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Penile Length Measurement: Methodological Challenges and Recommendations, a Systematic Review
Omer Onur Cakir1, Edoardo Pozzi2, Fabio Castiglione2
1Institute of Andrology, University College London Hospital, London, United Kingdom.
Background:
Penile length measurement techniques vary widely in published studies leading to inaccurate and nonstandardized measurements.
Aim:
To review the methodology used to report data in studies evaluating penile length and provide a detailed recommendation in conducting future high-quality research.
Methods:
The MEDLINE database was searched for randomized clinical trials and open-label prospective or retrospective studies.
Outcomes:
The panel reviewed the modality of data reporting on these specific areas: patients' age and assessment, patient position, type of measurement instrument used, penile length technique description, examination conditions, and actual examiner.
Results:
Overall, 70 studies investigating penile length were selected; among these, 72.85% included at least 50 patients: 16 prospective studies, 5 randomized clinical trials, and 49 retrospective cross-sectional studies. Amongst all studies, 90% reported to measure penile length by health care practitioners in clinical settings. Penile length was assessed in all 70 studies, whereas penile girth was measured in 57.14% of patients. A semi-rigid ruler was the most commonly used measurement aid to assess penile length/girth in 62.86% of studies. Penile measurements were reportedly obtained: (i) stretched state, 60%; (ii) flaccid state only, 52.68%; and (iii) during erection, 27.43%. All studies investigating the penile length in an erect state were simultaneously assessing penile length in the flaccid state. About 90% of studies investigated penile length in adults, whereas 10% were conducted in adolescents.
Clinical Implications:
The use of shared methodology to assess penile length in both adults and adolescents allows more accurate and standardized measurements.
Strength & Limitations:
A systematic review of the published literature allowed proper data interpretation in order to provide accurate recommendations. Main limitations of the study relied on a relatively limited number of databases for the identification of potentially eligible studies.
Conclusion:
The methodology used in studies measuring penile length should be precise and standardized in order to provide accurate data to both clinicians and researchers. Cakir OO, Pozzi E, Castiglione F, et al. Penile Length Measurement: Methodological Challenges and Recommendations, a Systematic Review. J Sex Med 2021;18:433-439.
