New York, NY, April 14, 2016 - Few data are available concerning the consequences of neonatal circumcision on penile sensitivity in adults. New research reported in The Journal of Urology® indicates that there are no differences in penile sensitivity for a variety of stimulus types and penile sites between circumcised and intact men. Additionally, this study challenges past research suggesting that the foreskin is the most sensitive and, in turn, most sexually relevant, part of the adult penis.
When the American Academy of Pediatrics and Canadian Pediatric Society recently revised their policies concerning routine neonatal circumcision, public interest was reignited in this long-running debate. Focusing on health outcomes, particularly protection against sexually transmitted infections, rather than penile sensitivity, the American policy statement supports routine circumcision of newborn males, while the Canadian policy does not.
Investigators examined two hypotheses that might support decreased penile sensitivity: whether the exposed glans penis of circumcised men is less sensitive than that of intact men (where keratinization is hypothesized to take place), and if the highly innervated foreskin is more sensitive than other sites of the penis.
"We directly tested whether circumcision is associated with a reduction in penile sensitivity by testing tactile detection, pain, warmth detection, and heat pain thresholds at multiple sites on the penis between groups of healthy (neonatally) circumcised and intact men," explained lead author Jennifer Bossio, PhD candidate in Clinical Psychology of the Department of Psychology, Queen's University, Ontario, Canada (working with Dr. Caroline Pukall, PhD, and Dr. Stephen Steele, MD). "This study indicates that neonatal circumcision is not associated with changes in penile sensitivity and provides preliminary evidence to suggest that the foreskin is not the most sensitive part of the penis."
Sixty-two men between the ages of 18 and 37 (30 circumcised, 32 intact) participated in the study. Quantitative sensory testing (QST) protocols assessed touch and pain thresholds and warmth detection and heat pain thresholds at a control site (forearm) and three to four penile sites (glans penis, midline shaft, proximal to midline shaft, and foreskin, if present). The authors reported that the pain, warmth detection, and heat pain stimuli likely activate nerve fibers more relevant to sexual pleasure than touch thresholds, which has been the focus of previous research.
Although in a previous study lower tactile thresholds were noted at the glans penis in circumcised men, the current investigation found no between-group differences in sensitivity across four stimulation types, lending no support to the widely accepted, but largely untested, keratinization hypothesis.
The investigators also found that the foreskin had similar sensitivity as the control site on the forearm for any stimulus type tested. Given that other genital sites (e.g., glans penis, midline shaft) were more sensitive to pain stimuli than the forearm, removing the highly innervated foreskin does not appear to remove the most sensitive part of the penis.
Sexual function was assessed via the International Index of Erectile Functioning (IIEF), a 15-item measure of men's sexual functioning over the past four weeks across the five domains of erectile function: intercourse satisfaction, orgasmic function, sexual desire, and overall satisfaction. No differences between the groups were observed on any of these measures, suggesting that sexual functioning may not differ across circumcision status.
"Methodology and results from this study build on previous research and imply that if sexual functioning is related to circumcision status, this relationship is not likely the result of decreased penile sensitivity stemming from neonatal circumcision," observed Ms. Bossio.