FINE-TOUCH PRESSURE THRESHOLDS IN THE ADULT PENIS

Sir,

Now that the medical benefits of circumcision have been convincingly shown (http://www.circinfo.net), campaigning by anti-circumcision groups has retreated to claims that circumcision is sexually damaging. The largest, the National Organization of Circumcision Information and Resource Centers (NOCIRC), insists that ‘without this protection [of the prepuce] the glans becomes . . . desensitized from exposure and chafing’[despite available evidence to the contrary] and that ‘specialized nerve endings in the foreskin enhance sexual pleasure’[1]. To support their claim of decreased sensitivity, they now report in BJU Int fine-touch pressure sensitivity thresholds on 19 areas of the uncircumcised penis, nine also being on the circumcised penis [2].

Poor methods and erroneous statistical analysis mar this paper; e.g. in their Table 2 they fail to compare the same points on the circumcised and uncircumcised penis. Using their data we find no significant differences (Table 1), consistent with previous findings [2,3]. Only in their multivariate analysis were P values of apparent significance. They claim that several locations on the uncircumcised penis are significantly more sensitive than the most sensitive location on the circumcised penis (the ventral scar), yet their Table 2 shows this applies only to their position 3, the orifice rim of the prepuce. However, after we used the Bonferroni method to correct for multiple comparisons, this significance disappeared. Statistical naiveté is also apparent in their expression of values to up to four significant figures!

Table 1.  Comparison between points on the circumcised and uncircumcised penis*

Position	Uncircumcised	Circumcised	P (t-test)
* Mean (sem), exactly as presented in Table 2 of Sorrells et al.[2]. Positions 2–5 and 13–16 are not shown, as these are for the prepuce and thus not present on a circumcised penis.
N	68	91
1	0.681 (0.135)	0.716 (0.081)	0.82
6	0.371 (0.069)	0.445 (0.063)	0.43
7	0.519 (0.085)	0.7099 (0.105)	0.18
8	0.778 (0.112)	0.941 (0.097)	0.27
9	1.141 (0.163)	1.180 (0.117)	0.84
10	0.979 (0.158)	0.911 (0.1406)	0.75
11	0.952 (0.155)	1.1273 (0.151)	0.43
12	0.407 (0.063)	0.433 (0.081)	0.81
17	0.759 (0.188)	0.562 (0.095)	0.32

Although their Methods section states that they recruited participants through ‘fliers’ at a medical school, announcements on a radio programme, and newspaper advertisements, their Table 1 shows only 13 (19%) uncircumcised and 35 (38%) of circumcised participants were recruited in this way. This table reveals that more, 33 (49%) of the uncircumcised and 32 (35%) of the circumcised participants, were recruited via a ‘friend’, the ‘Internet’ and even the ‘study leader’! Even then, their Table 1 is incomplete, as the referral sources of 30 (44%) uncircumcised and 24 (26%) circumcised participants are unaccounted for.

In an attempt to support their wish that uncircumcised men are better lovers they refer to a ‘preliminary survey’ of women recruited in part through an anti-circumcision newsletter. Yet this states ‘this study has some obvious methodological flaws’ and that ‘it is important that these findings be confirmed by a prospective study of a randomly selected population of women’[4]. A more credible study, not cited, found that most women prefer the circumcised penis for appearance, hygiene and sex [5].

By contrast to the authors’ distorted discussion of the literature, most studies reported improved satisfaction after circumcision. Particularly notable are two large clinical trials involving circumcision of healthy volunteers, where 98.5% and 99.5% were ‘very satisfied’[6,7].

The authors conclude that ‘circumcision ablates the most sensitive parts of the penis’, although they only tested the ability of subjects to detect the lightest touch. Meissner’s corpuscles, being light-touch receptors, would be expected to cause such a measurement to exaggerate the sensitivity of the prepuce. However, sensitivity, particularly when discussing erogenous sensation, depends on several different modes of stimulation and their interaction. In addition, sexual sensation depends upon the types of mechanical stimulation generated during intercourse, which might in turn be influenced by circumcision status. Thus circumcision has the potential to either increase or decrease sexual sensation.

Surprisingly, the study omitted to address sexual pleasure. The existence of a market for lidocaine-based products to reduce penile sensitivity attests to the desire by some men for a penis with reduced, not heightened, sensitivity. Moreover, undesirable preputial sensations such as pain, discomfort and irritation must be considered. While results are somewhat mixed, one study found reduced pain in 69% of men after circumcision [8]. Thus it would seem that a more important question is whether sexual pleasure is affected. In two very much larger surveys, no association was found between circumcision status and failure to enjoy sex [9,10].

In conclusion, despite a poorly representative sample and methods prone to exaggerating the sensitivity of the prepuce, NOCIRC’s claims remain unconfirmed. When the authors’ data are analysed properly, no significant differences exist. Thus the claim that circumcision adversely affects penile sensitivity is poorly supported, and this study provides no evidence for the belief that circumcision adversely affects sexual pleasure.