Measuring the penis in an erect state, rather than a flaccid one, is a more accurate way to determine length and girth, according to a recent Journal of Sexual Medicine study.
Researchers from Egypt, the Kingdom of Saudi Arabia, the United Kingdom, and the United States found that flaccid measurements could be underestimated. There is also “significant” interobserver variability, they reported.
Many men feel insecure about the length of their penis. Those with small penis anxiety or body dysmorphic disorder may consider having penile augmentation surgery, even if their penis is in the normal size range.
Such surgery comes with risks, however. Past studies have reported complications like penile deformity, scarring, shortening of the penis, and sexual dysfunction. On the other hand, counseling can help patients understand that their penis is “normal” and that surgery is not necessary.
How can clinicians reassure such patients? Measuring the penis is one way, but currently there are no standardized methods for doing so.
The research team recruited 201 men with a mean age of 50 years to take part in the study.
Penises were measured in both flaccid and erect states. (Intracavernosal injections were used to induce erections.) Using a plastic ruler, a researcher measured length from the pubic bone to the tip of the glans. Girth was measured with a disposable paper tape placed at the base of the penis.
The erect measurements were considered the “true” values, with flaccid measurements used for comparison.
Mean length was 14.3 cm when erect and 11.7 cm when flaccid. For circumference, these values were 11.6 cm when erect and 9.4 when flaccid.
The researchers concluded that the flaccid measurements were “both unreliable and observer dependent.”
Flaccid measurements were taken at a 90-degree angle from the body, they explained. However, different practitioners may apply different degrees of axial traction when measuring, depending on the patient’s comfort level.
In addition, practitioners may interpret “skin-to-tip” length in variable ways, choosing different end points in the pubic area.
“We have demonstrated the potential for misdiagnosis and misinformation of patients introduced by observer error,” the authors wrote.
“It does however seem logical to assume that a fully erect penis, not requiring stretching or support, should be the easiest to measure,” they added.
The differences in girth measurements may be explained by “morphological changes that occur with engorgement” and were likely not due to human error.
“Our data in this respect confirm that men can be reassured that flaccid girth does not correlate with erect girth,” they noted.
Resources
The Journal of Sexual Medicine
Habous. Mohamad, FEBU, MD, et al.
“Analysis of the Interobserver Variability in Penile Length Assessment”
(Full-text. First published online: October 6, 2015)
http://onlinelibrary.wiley.com/doi/10.1111/jsm.13005/full