Male circumcision is performed for cultural, religious and medical reasons with a prevalence of about one third of the world’s male population . The focus on non-medical male circumcision has been gaining momentum in public debate in both Europe and the United States over the past few years. The Danish College of General Practitioners has defined non-medical circumcisions as mutilation . Some Danish medical professionals [3-6], Danish activists , and parliament members  have promoted the narrative that male circumcision results in decreased penile sensitivity or other types of male sexual dysfunction.
Circumcision carries a risk of complications like any other surgical intervention. Studies from Europe and the United States report overall complication rates of 0.19-3.8% . Complication rates are lower if circumcision is performed during infancy, by experienced providers and under sterile conditions . A Danish study from Rigshospitalet  reported an overall complication rate of 5.1% following circumcision in children 0-16 years of age.
Short-term complications comprised superficial skin infections (0.6%), bleeding (1.6%) and anaesthesiology complications (0.6%). Long-term complications included re-operations due to meatal stenosis (0.6%). No major complications such as amputation or death were seen . An age stratification of the data from the Danish study showed lower complication rates in younger boys.
These rates were comparable to the relatively low complication rates previously reported in US studies . The Danish Health Authorities do not recommend a lawenforced ban of non-medical circumcisions in Denmark based on these low rates of short-term complications; however, they do stress the lack of evidence with respect to long-term complications and male sexual function .
Inferior sexual function following circumcision is suggested to be caused by loss of sensory tissue followed by keratinisation and desensitisation of the glans penis [14-16]. This hypothesis is generated by two histopathological findings; the description of Meissner’s corpuscles in human prepuce and longer epithelial extensions into underlying connective tissue (rete ridges) in the dorsal glans of the circumcised penis [14, 17].
The purpose of the present study was to test the hypothesis of increased sexual dysfunction in circumcised men through a systematic review of the literature and to perform a detailed synthesis of the available evidence in order to guide patients, parents and decisionmakers on male circumcision.
The objective was to determine if circumcision had an impact on sexual function in males defined as perceived and self-reported erectile dysfunction, pain during intercourse, premature ejaculation, problems in obtaining orgasm, sexual drive, penile sensitivity or sexual satisfaction. A second objective was to determine whether medical circumcision or age at circumcision influenced perceived male sexual function.
A protocol including outcomes and overall design was written before searches were performed. Systematic searches were performed in the MEDLINE and EMBASE databases. Exploded index terms (MeSH) were “Circumcision, male” or “Circumcision” in combination with “Sexual dysfunction, physiological”, “Sexual dysfunction, psychological”, “Sexual dysfunction”, “Sexual arousal disorder”, “Premature ejaculation”, “Ejaculation disorder”, “Ejaculation”, “Erectile dysfunction”, “Penile erection”, “Orgasm”, “Orgasm disorder”, “Libido”, “Libido disorder”, “Sensibility” or “Sexual satisfaction”. Keywords were circumcision in combination with sensitivity, sensibility, sensory, neuro*, erectile, ejaculation, orgasm, libido, lust, desire, satisfaction, or sex*. Final searches were performed on 29 February 2016. Additional hand-searches were performed through screening reviews, original studies and their reference lists.
Endnote X7 was used for management of references.
Study selection included a screening of titles and abstracts by the primary author (DMS). Full texts of eligible studies were obtained and screened for the inclusion criteria by two authors independently (SD and DMS). Discrepancies were resolved through discussion until consensus was reached between all three authors.
The following inclusion criteria were applied:
1. Circumcision was the exposure or intervention.
2. Non-exposed controls were either a) uncircumcised participants, b) same participants assessed before circumcision, or c) individuals circumcised at different ages.
3. Outcomes had to include perceived adult male sexual function as defined in the previously mentioned objective. A long-term follow-up period was required.
4. All study designs including a non-exposed control were included. Statistical testing had to be performed in order to compare outcomes of exposed and non-exposed groups. A significance level of p < 0.05 was used to reject the null hypothesis of no difference between exposed and non-exposed participants.
All publication types indexed in databases and all languages were accepted. Chinese studies were translated orally by a fellow PhD student.
Data extraction from studies was performed onto preformatted sheets including the first author’s name, year of publication, country, overall study design, number of participants circumcised and non-circumcised, indication for circumcision, rates for medical and nonmedical circumcisions, age at circumcision, follow-up length, lost to follow-up and age adjustment. Based on the results of statistical testing, outcomes in circumcised males were defined as ”increased”, ”decreased” or ”non-significant”. Erectile dysfunction, pain, premature ejaculation, difficult ejaculation and problems in obtaining orgasm were defined as negative outcomes; and increased levels of sexual drive, penile sensitivity and satisfaction were defined as positive outcomes. If available, estimates adjusted for age were reported. Data extraction was performed by the primary author and reviewed by the co-authors.
The questionnaires used in the identified studies varied with respect to their assessment of ejaculatory function. Some assumptions therefore had to be made for this systematic review. The Brief Male Sexual Functioning Inventory and Male Sexual Health Questionnaire described difficulties in ejaculation, which was included as a separate outcome [18, 19]. The International Index of Erectile Function assessed problems in obtaining an orgasm . The Premature Ejaculation Diagnostic Tool assessed premature ejaculation . Where possible, results from these questionnaires were extracted for each sub-domain of erectile function, ejaculation, drive and satisfaction.
The quality of each study was assessed through levels of evidence for therapy developed by The Oxford Centre for Evidence-based Medicine in 2009 and 2011 [22, 23]. In brief, assessments were performed at the outcome level with the possibility of downgrading if studies failed to measure exposures and outcomes in the same way in both exposed and non-exposed participants, failed to control known confounders, or failed to carry out sufficiently follow-up . A cohort study only assessing sexual function retrospectively was downgraded due to inconsistencies in measuring outcomes and exposure causing recall bias. Both randomized studies and cohort studies were downgraded if the share of patients lost to follow-up exceeded 20% or if loss to follow up was not reported. Age at assessment and medical indication for circumcision were chosen as possible confounders. Sexual difficulties have a rising prevalence with age in men  and the indications for circumcision differ with age as well. Studies were downgraded if age was not included in the design through randomisation, through prospective assessments in cohort studies at fixed or short periods of follow-up or through matching. Age could also be included in the analysis through adjustment or stratification. Indication for circumcision was considered mainly medical or nonmedical if reported as such in more than half of the circumcisions performed in the study.
Randomised controlled trials were assessed for random sequence generation, allocation concealment, attrition and blinding of outcome assessment as recommended by the Cochrane Handbook . Blinding of participants or personnel was unfeasible because of the nature of circumcision. If the statistical significance of the intervention and control group had a small absolute effect size, the study was downgraded .
Perceived sexual function outcomes in circumcised males was reported overall across studies. Subgroup analyses were performed for circumcised versus uncircumcised males, before versus after circumcision, and both were stratified by medical indication for circumcision.
Evidence for each outcome was summarised as Grade A-D with A indicating the highest level of evidence.
In studies that had the same level of evidence, statistically significant results were given higher priority than nonsignificant results, and inconsistencies between statistically significant results were graded D . Reporting was performed according to the PRISMA statement .
The database searches yielded 3,673 records and the hand searches identified four additional studies [27-30].
Of 171 eligible studies, 133 were excluded leaving 38 studies for inclusion in this systematic review (Figure 1).
The included studies comprised 36 observational studies and two randomised controlled trials. The studies were performed in Asia, The Middle East, North and South America, Europe, Africa and Australia.
Indications for circumcision were mainly non-medical in 11 studies, medical in ten studies and not reported in 17 studies. Age at circumcision was categorised as adulthood or non-infancy in 22 studies, infancy in one study and childhood in three studies (Table 1).
Nine cohort studies had a risk of attrition bias due to insufficient completion of follow-up [28, 31-38], and ten observational studies did not adjust for age [28, 29, 37-44]. A risk of recall bias was present in four retrospective cohort studies [28, 36-38] (Table 1).
The two randomised controlled trials had adequate random sequence generation, allocation concealment [45, 46], and follow-up at one year. No blinding of outcome assessment was performed [47, 48]. One trial was graded down due to a very small absolute effect size, where 98.0-99.4% had a positive sexual function at baseline and an almost equally high sexual function (98.7-99.9%) at follow-up in both arms .
A qualitative synthesis without meta-analysis was chosen due to considerable clinical heterogeneity in circumcision indications and procedures, study designs, quality and reporting of results in the identified studies.
Overall sexual function and circumcision status
When all studies were assessed without stratification, non-significant differences were found for erectile dysfunction, pain, problems in obtaining an orgasm, satisfaction (Grade A) and difficult ejaculation (Grade B) (Table 2) in circumcised compared with uncircumcised males. Premature ejaculation was decreased (Grade A) (Table 2), drive and penile sensitivity were increased (Grade B) in the circumcised participants (Table 3).
Circumcised versus uncircumcised
Sexual function outcomes in circumcised versus uncircumcised participants were reported in 19 studies (Table 2). In non-medically circumcised participants, nonsignificant differences were found for erectile dysfunction, pain, problems in obtaining an orgasm, satisfaction (Grade A), difficult ejaculation and drive (Grade B). Premature ejaculation was significantly decreased (Grade A).
No assessment for penile sensitivity was identified. In medically circumcised participants, a non-significant difference was found for erectile dysfunction (Grade B).
Premature ejaculation was found to be decreased and satisfaction increased (Grade B). No assessments for pain, difficult ejaculation, problems in obtaining an orgasm,
drive or sensitivity were identified (Table 2).
Before versus after circumcision
Sexual function in participants undergoing circumcision was reported in 21 studies (Table 3). Following nonmedical circumcision, difficult ejaculation was non-significantly changed (Grade B). Erectile dysfunction, pain, premature ejaculation and problems in obtaining an orgasm were decreased (Grade B). Drive, penile sensitivity and satisfaction were increased (Grade B). Following medical circumcisions, pain, difficult ejaculation, drive and sensitivity were non-significantly changed (Grade B).
Premature ejaculation was decreased and satisfaction increased (Grade B). Problems in obtaining an orgasm were increased (Grade C) and results for erectile dysfunction were reported with inconsistency (Grade D) (Table 3).
Age at circumcision
Five studies reported adult sexual function outcomes for participants who were circumcised as children or infants compared with participants who were circumcised later in life [29, 40-42, 49]. Four of these did not report indication or adjust for age at assessment [29, 40-42] (Table 1). Circumcision after infancy was associated with nonsignificant differences in satisfaction, increased erection difficulties and decreased premature ejaculation (Grade B). Indication for circumcision after infancy was reported in 49% and the most frequent indication was phimosis . Adult circumcision caused increased pain at intercourse and decreased satisfaction (Grade C) . Circumcision above the age of seven caused increased premature ejaculation (Grade C) . When comparing age groups of 0-12 years or the specific period of 3-6 years at circumcision, non-significant differences were found for erectile dysfunction, premature ejaculation, problems in obtaining orgasm, desire and satisfaction (Grade C) [41, 42].
The results of the present systematic review indicate that non-medical circumcision does not generally seem to cause an inferior male sexual function at a statistically significant level (Grade A-B). Following medical circumcisions, erectile dysfunction, pain, difficult ejaculation, drive and sensitivity were all found to be non-significantly changed, whereas premature ejaculation decreased and satisfaction improved (Grade B). However, inconsistencies in reporting of erectile dysfunction (Grade D) were identified in studies with the same level of evidence, and problems in obtaining an orgasm were increased (Grade C). A higher age at circumcision was associated with negative sexual function (Grades B-C).
Studies not reporting indication for circumcision did not reach a high enough level of evidence for assessment of overall sexual function, and some reported inconsistent results when compared with studies of a higher level of evidence. Best level of evidence including randomised controlled trials was identified only for non-medical circumcisions.
Although many of the outcomes of non-medical circumcisions were from one well-designed randomized study, outcomes from lower-quality studies were also consistent with a conclusion of no negative impact on sexual function in circumcised males . Satisfaction was decreased in one randomised study; however, absolute effects were negligible and probably a chance finding due to a type 1 error . Among studies not reporting the indication for circumcision, four were performed in countries where non-medical circumcisions are uncommon and indications were therefore most likely medical [40, 50-52]. Sexual function following medical circumcisions was explored in non-randomised studies only and reported with some inconsistencies. Age at circumcision was only explored in studies including circumcised participants. Optimally, such studies should compare different ages of circumcision to age-matched non-circumcised controls at outcome assessment.
Therefore, studies on medical circumcision and on age at circumcision were more biased than studies about nonmedical circumcisions; and conclusions should accordingly be interpreted with caution. The discrepancy between sexual outcomes following medical and non-medical circumcisions identified in this systematic review has been reported before and it has been suggested that it is confounded by penile pathology causing sexual dysfunction prior to circumcision . Adult medical circumcision is most often performed due to pathological conditions in prepuce, which presumably causes inferior sexual function and mental health disturbances [53-55]. Hence, precircumcision penile pathology may explain the identified discrepancies in obtaining an orgasm when comparing medical and non-medical circumcisions (Table 3) as well as the discrepancies in the results of the many studies not reporting indication when compared with results from studies reporting indication (Table 2 and Table 3).
Therefore, circumcision serves as a proxy for underlying penile pathology, and studies including participants with mainly medical circumcision therefore measure the impact of pathology on sexual function rather than the impact of circumcision. Such selection bias and confounding are best avoided through a randomised design, and future observational studies should at least perform stratification or adjustment for penile pathology. Risks of observer and selective reporting bias were present in the included studies since none had blinded outcome assessment, only half of the studies included validated questionnaires and some studies reported only parts of questionnaires. Health-promoting beliefs related to non-medical circumcisions are present in some cultures  and may have caused overestimation of perceived sexual function towards the positive. Other limitations included short follow-up periods of 1-2 years in the prospective studies. Many results were non-significant, possibly due to small sample sizes causing a risk of type II error. Most studies focused on the heterosexual practice of intravaginal intercourse and did not take into account other important heterosexual or homosexual practices that comprise male sexual function.
The strength of this systematic review was the broad search strategy and the inclusion of non-English literature, thereby including participants from all populated continents. The qualitative assessment of the existing literature focused on minimising bias. The stratification by medical indication was performed in order to explore confounding. Other possible confounding factors such as cardiovascular, neurological, and psychiatric co-morbidities, illegal substances, complications to surgery, lifestyle and drugs such as use of psychopharmaceuticals may contribute to an inferior sexual function.
Some of the studies adjusted for these factors; however, many of the factors are age-dependent why adjustment for age at assessment was most important.
The limitation was the inability to perform a meta-analysis.
A pooled analysis could, possibly, have identified more significant associations.
This systematic review focused on the participantcentred sexual function. A number of experimental tudies have investigated male sexual function through objective measures. In circumcised compared with uncircumcised males, differences in sensory tactile thresholds have been found to be non-significant [57-59] and increased [60, 61], and differences in ejaculatory latency period have been found to be non-significant [37, 62,
63] as well as increased [31, 32, 34, 64, 65]. Differences in penile temperature, penilo-cavernous reflexes and penile pudendal-evoked potentials [32, 58, 66] have also been reported. The interpretation of such measures is beyond what is known about male sexual function and these measures were therefore not included in the present systematic review. A recent review with focus on gaps in male circumcision research has specified the needs for consistent objective measures and for correlation of objective to subjective male sexual function outcomes . Other systematic reviews from paediatric societies in the USA and Canada also conclude that circumcision is unlikely to change male sexual function [9, 68].
The highest level of evidence shows no perceived inferior male sexual function following non-medical circumcision.
Medical circumcisions have negative outcomes for obtaining orgasm and discrepancies for erectile dysfunction.
Younger age at circumcision seemed to cause less sexual dysfunction than circumcision later in life. The two latter findings are most likely not causal and more likely biased by observational designs. Future randomized controlled trials of medical circumcisions should be performed. Such studies should include noncircumcised controls and sexual function assessment at entry and at longer-term follow-up beyond two years.
Age at circumcision should be explored in prospective studies including non-circumcised age-matched controls.
The hypothesis of inferior male sexual function following circumcision is not supported by the findings of this systematic review. The popular narrative that male circumcision results in sexual dysfunction does not seem to be supported by evidence.
CORRESPONDENCE: Daniel Mønsted Shabanzadeh. E-mail:daniel.moensted.
ACC EPTED: 5 April 2016
CONFLICTS OF INTEREST: Disclosure forms provided by the authors are available with the full text of this article at www.danmedj.dk
AC KNOWLEDGEMENTS: We would like to thank PhD student Lin Chia-Hsien from Department of Public Health at the University of Copenhagen for her assistance with the Chinese articles, and Birthe Frimodt-Møller for linguistic assessment.
- WHO, UNAIDS. Male circumcision: global trends and determinants of prevalence, safety and acceptability. www.who.int/reproductivehealth/publications/rtis/9789241596169/en/: WHO Press, 2015 (11 Nov 2015).
- Kommentar til vejledning om omskæring af drenge. www.dsam.dk/flx/forsiden/nyheder/kommentar-til-vejledning-om-omskaering-af-drenge/: The Danish College of General Practitioners 2013 (9 Nov 2015).
- Søe K. Rituel omskæring af drengebørn. Ugeskr Læger 2001;163:1049.
- Graugaard C. Skal vi lade vores drengebørn omskære? Netdoktor A/S. 15-04-2011 ed. www.netdoktor.dk/brevkasser/arkiv/200958.htm (4 Jan 2016).
- Frisch M. Forhudsamputation har altid konsekvenser. Information. 06-03-2013 ed. www.information.dk/453437, 2013 (9 Nov 2015).
- Frisch M. Time for U.S. Parents to Reconsider the Acceptability of Infant Male Circumcision. 04-09-2015 ed. www.huffingtonpost.com/mortenfrisch/time-for-us-parents-to-reconsider-the-acceptability-of-infant-malecircumcision_b_7031972.html: Huffington Post, 2015 (11 Nov 2015).
- Nyhus L. MYTE vs FAKTA: Omskæring fjerner halvdelen af følsomheden i penis – måske mere. 14-10-2013 ed. www.intactdenmark.wordpress. com/2013/10/14/myte-vs-fakta-omskaering-fjerner-halvdelen-affolsomheden-i-penis-maske-mere/#comments: Intact Denmark, 2013 (9 Nov 2015).
- Pedersen D. Det undrer mig, at en biskop opfordrer til religiøs omskæring. Jyllands-Posten 30-10-2015 ed. www.jyllands-posten.dk/protected/premium/indland/ECE8169519/%C2%BBDet-undrer-mig-at-en-biskopopfordrer-til-religi%C3%B8s-omsk%C3%A6ring%C2%AB/ (18 Nov 2015).
- American Academy of Pediatrics Task Force on C. Male circumcision. Pediatrics 2012;130:e756-85.
- Weiss HA, Larke N, Halperin D, Schenker I. Complications of circumcision in male neonates, infants and children: a systematic review. BMC Urol 2010;10:2.
- Thorup J, Thorup SC, Ifaoui IB. Complication rate after circumcision in a paediatric surgical setting should not be neglected. Dan Med J 2013;60(8): A4681.
- Bretthauer M, Hem E. Omskjæring av gutter. Tidsskr Nor Laegeforen 2015;135:1926-7.
- Sundhedsstyrelsen. Omskæring af drenge – Notat. www.sundhedsstyrelsen.dk/da/nyheder/2013/omskaering-afdrengeboern: The Danish Health Authorities, 2013 (11 Nov 2015).
- Taylor JR, Lockwood AP, Taylor AJ. The prepuce: specialized mucosa of the penis and its loss to circumcision. Br J Urol 1996;77:291-5.
- Immerman RS, Mackey WC. A biocultural analysis of circumcision. Soc Biol 1997;44:265-75.
- Cold CJ, Taylor JR. The prepuce. BJU Int 1999;83(suppl1):34-44.
- Halata Z, Munger BL. The neuroanatomical basis for the protopathic sensibility of the human glans penis. Brain Res 1986;371:205-30.
- O’Leary MP, Fowler FJ, Lenderking WR et al. A brief male sexual function inventory for urology. Urology 1995;46:697-706.
- Rosen RC, Catania J, Pollack L et al. Male Sexual Health Questionnaire (MSHQ): scale development and psychometric validation. Urology 2004;64:777-82.
- Rosen RC, Riley A, Wagner G et al. The international index of erectile function (IIEF): a multidimensional scale for assessment of erectile dysfunction. Urology 1997;49:822-30.
- Symonds T, Perelman MA, Althof S et al. Development and validation of a premature ejaculation diagnostic tool. Eur Urol 2007;52:565-73.
- Levels of Evidence (March 2009). www.cebm.net/oxford-centre-evidencebased-medicine-levels-evidence-march-2009/: Oxford Centre for Evidence-based Medicine, 2009 (11 Oct 2015).
- The Oxford 2011 Levels of Evidence. www.cebm.net/ocebm-levels-ofevidence/: Oxford Centre for Evidence-Based Medicine, 2011 (11 Oct 2015).
- Laumann EO, Nicolosi A, Glasser DB et al. Sexual problems among women and men aged 40-80 y: prevalence and correlates identified in the Global Study of Sexual Attitudes and Behaviors. Int J Impot Res 2005;17:39-57.
- Cochrane Handbook for Systematic Reviews of Interventions. In: Higgins J, Green S, eds. 5.1.0 ed. www.handbook.cochrane.org/: The Cochrane Collaboration, 2011 (5 Nov 2015)
- Moher D, Liberati A, Tetzlaff J et al. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med 2009;6:e1000097.
- Laumann EO, Paik A, Rosen RC. Sexual dysfunction in the United States: prevalence and predictors. JAMA 1999;281:537-44.
- Feldblum PJ, Okech J, Ochieng R et al. Longer-term follow-up of Kenyan men circumcised using the ShangRing device. PLoS One 2015;10: e0137510.
- Cuceloglu EA, Hosrik ME, Ak M et al. The effects of age at circumcision on premature ejaculation. Turk Psikiyatri Derg 2012;23:99-107.
- Zulu R, Jones D, Chitalu N et al. Sexual satisfaction, performance, and partner response following voluntary medical male circumcision in Zambia: The Spear and Shield Project. Glob Health Sci Pract 2015;3:606-18.
- Senkul T, Işerl C, şen B et al. Circumcision in adults: effect on sexual function. Urology 2004;63:155-8.
- Senol MG, Sen B, Karademir K, Sen H, Saracoglu M. The effect of male circumcision on pudendal evoked potentials and sexual satisfaction. Acta Neurol Belg 2008;108:90-3.
- Senel FM, Demirelli M, Misirlioglu F et al. Adult male circumcision performed with plastic clamp technique in Turkey: results and long-term effects on sexual function. Urol J 2012;9:700-5.
- Alp BF, Uguz S, Malkoc E et al. Does circumcision have a relationship with ejaculation time? Premature ejaculation evaluated using new diagnostic tools. Int J Impot Res 2014;26:121-3.
- Masood S, Patel HR, Himpson RC et al. Penile sensitivity and sexual satisfaction after circumcision: are we informing men correctly? Urol Int 2005;75:62-6.
- Fink KS, Carson CC, DeVellis RF. Adult circumcision outcomes study: effect on erectile function, penile sensitivity, sexual activity and satisfaction. J Urol 2002;167:2113-6.
- Kim D, Pang MG. The effect of male circumcision on sexuality. BJU Int 2007;99:619-22.
- Dias J, Freitas R, Amorim R et al. Adult circumcision and male sexual health: a retrospective analysis. Andrologia 2014;46:459-64.
- Tang WS, Khoo EM. Prevalence and correlates of premature ejaculation in a primary care setting: a preliminary cross-sectional study. J Sex Med 2011;8:2071-8.
- Bronselaer GA, Schober JM, Meyer-Bahlburg HF et al. Male circumcision decreases penile sensitivity as measured in a large cohort. BJU Int 2013;111:820-7.
- Aydur E, Gungor S, Ceyhan ST et al. Effects of childhood circumcision age on adult male sexual functions. Int J Impot Res 2007;19:424-31.
- Armagan A, Silay MS, Karatag T et al. Circumcision during the phallic period: does it affect the psychosexual functions in adulthood? Andrologia 2014;46:254-7.
- Shaeer O, Shaeer K. The Global Online Sexuality Survey (GOSS): ejaculatory function, penile anatomy, and contraceptive usage among Arabic-speaking Internet users in the Middle East. J Sex Med 2012;9:425-33.
- Shaeer O. The global online sexuality survey (GOSS): The United States of America in 2011 Chapter III – Premature ejaculation among Englishspeaking male Internet users. J Sex Med 2013;10:1882-8.
- Gray RH, Kigozi G, Serwadda D et al. Male circumcision for HIV prevention in men in Rakai, Uganda: a randomised trial. Lancet 2007;369:657-66.
- Bailey RC, Moses S, Parker CB et al. Male circumcision for HIV prevention in young men in Kisumu, Kenya: a randomised controlled trial. Lancet 2007;369:643-56.
- Kigozi G, Watya S, Polis CB et al. The effect of male circumcision on sexual satisfaction and function, results from a randomized trial of male circumcision for human immunodeficiency virus prevention, Rakai, Uganda. BJU Int 2008;101:65-70.
- Krieger JN, Mehta SD, Bailey RC et al. Adult male circumcision: effects on sexual function and sexual satisfaction in Kisumu, Kenya. J Sex Med 2008;5:2610-22.
- Mao L, Templeton DJ, Crawford J et al. Does circumcision make a difference to the sexual experience of gay men? Findings from the Health in Men (HIM) cohort. J Sex Med 2008;5:2557-61.
- Frisch M, Lindholm M, Gronbaek M. Male circumcision and sexual function in men and women: a survey-based, cross-sectional study in Denmark. Int J Epidemiol 2011;40:1367-81.
- Hoschke B, Fenske S, Brookman-May S et al. [Male circumcision is not associated with an increased prevalence of erectile dysfunction: results of the Cottbus 10,000-men survey]. Urologe A 2013;52:562-9.
- Homfray V, Tanton C, Mitchell KR et al. Examining the association between male circumcision and sexual function: evidence from a British probability survey. AIDS 2015;29:1411-6.
- Thorvaldsen MA, Meyhoff HH. Pathological or physiological phimosis? Ugeskr Læger 2005;167:1858-62.
- Kantere D, Lowhagen GB, Alvengren G et al. The clinical spectrum of lichen sclerosus in male patients – a retrospective study. Acta Derm Venereol 2014;94:542-6.
- Yang L, Ruan LM, Yan ZJ et al. [Sexual function and mental state in patients with redundant prepuce or phimosis]. Zhonghua Nan Ke Xue 2010;16: 1095-7.
- Ngalande RC, Levy J, Kapondo CP et al. Acceptability of male circumcision for prevention of HIV infection in Malawi. AIDS & Behavior 2006;10:377-85.
- Bleustein CB, Fogarty JD, Eckholdt H et al. Effect of neonatal circumcision on penile neurologic sensation. Urology 2005;65:773-7.
- Payne K, Thaler L, Kukkonen T et al. Sensation and sexual arousal in circumcised and uncircumcised men. J Sex Med 2007;4:667-74.
- Kim JY. Does circumcision decrease penis sensitivity? Journal of Sexual Medicine 2012;9:61-62.
- Sorrells ML, Snyder JL, Reiss MD et al. Fine-touch pressure thresholds in the adult penis. BJU Int 2007;99:864-9.
- Yang DM, Lin H, Zhang B et al. [Circumcision affects glans penis vibration perception threshold]. Zhonghua Nan Ke Xue 2008;14:328-30.
- Waldinger MD, McIntosh J, Schweitzer DH. A five-nation survey to assess the distribution of the intravaginal ejaculatory latency time among the general male population. J Sex Med 2009;6:2888-95.
- Yang MH, Tsao CW, Wu ST et al. The effect of circumcision on young adult sexual function. Kaohsiung J Med Sci 2014;30:305-9.
- Zhang S, Zhao Y, Zheng S et al. [Corelation between premature ejaculation and redundant prepuce]. Zhonghua Nan Ke Xue 2006;12:225-7.
- Gao J, Xu C, Zhang J et al. Effects of adult male circumcision on premature ejaculation: results from a prospective study in China. Biomed Res Int 2015;2015:417846.
- Podnar S. Clinical elicitation of the penilo-cavernosus reflex in circumcised men. BJU Int 2012;109:582-5.
- Bossio JA, Pukall CF, Steele S. A review of the current state of the male circumcision literature. J Sex Med 2014;11:2847-64.
- Sorokan ST, Finlay JC, Jefferies AL. Newborn male circumcision. Paediatrics and Child Health (Canada) 2015;20:311-315.
- Decastro B, Gurski J, Peterson A. Adult template circumcision: a prospective, randomized, patient-blinded, comparative study evaluating the safety and efficacy of a novel circumcision device. Urology 2010;76:810-4.
- Collins S, Upshaw J, Rutchik S et al. Effects of circumcision on male sexual function: debunking a myth? J Urol 2002;167:2111-2.
- Shen Z, Chen S, Zhu C et al. [Erectile function evaluation after adult circumcision]. Zhonghua Nan Ke Xue 2004;10:18-9.
- Cortes-Gonzalez JR, Arratia-Maqueo JA, Martinez-Montelongo R et al. [Does circumcision affect male’s perception of sexual satisfaction?]. Arch Esp Urol 2009;62:733-6.
- Yu S, Zhang W. [Effects of circumcision on male and female sexual function]. Chinese Journal of Andrology 2009;23:44-46,50.
- Yue C, Kerong W, Jun YZ et al. Long-term follow-up for Shang ring male circumcision. Chin Med J 2014;127:1879-83.
- Laumann EO, Masi CM, Zuckerman EW. Circumcision in the United States. Prevalence, prophylactic effects, and sexual practice. JAMA 1997;277:1052-7.
- Richters J, Smith AM, de Visser RO et al. Circumcision in Australia: prevalence and effects on sexual health. Int J STD AIDS 2006;17:547-54.
- Son H, Song SH, Kim SW et al. Self-reported premature ejaculation prevalence and characteristics in Korean young males: community-based data from an internet survey. J Androl 2010;31:540-6.
- Ferris JA, Richters J, Pitts MK et al. Circumcision in Australia: further evidence on its effects on sexual health and wellbeing. Aust N Z J Public Health 2010;34:160-4.