of pain; use of the Mogen clamp was found to result in a shorter procedure time and less pain-induced stress than the use of the Gomco clamp or the Plastibell. The available evidence does not indicate that post-procedure pain management is needed. For adults, topical anesthesia, ring block, dorsal penile nerve block (DPNB) and general anesthesia are all options, and the procedure requires four to six weeks of abstinence from masturbation or intercourse to allow the wound to heal. Effects Sexually transmitted diseases Human immunodeficiency virus There is strong evidence that circumcision reduces the risk of men acquiring HIV infection in areas of the world with high rates of HIV. This evidence is principally derived from three randomized controlled studies conducted in Africa in 2002. Evidence among heterosexual men in sub-Saharan Africa shows an absolute decrease in risk of 1.8% which is a relative decrease of between 38% and 66% over two years, and in this population studies rate it cost-effective. Whether it is of benefit in developed countries is undetermined. There are plausible explanations based on human biology for how circumcision can decrease the likelihood of female-to-male HIV transmission. The superficial skin layers of the penis contain Langerhans cells, which are targeted by HIV; removing the foreskin reduces the number of these cells. When an uncircumcised penis is erect during intercourse, any small tears on the inner surface of the foreskin come into direct contact with the vaginal walls, providing a pathway for transmission. When an uncircumcised penis is flaccid, the pocket between the inside of the foreskin and the head of the penis provides an environment conducive to pathogen survival; circumcision eliminates this pocket. Some experimental evidence has been provided to support these theories. The WHO and the UNAIDS state that male circumcision is an efficacious intervention for HIV prevention, but should be carried out by well-trained medical professionals and under conditions of informed consent (parents' consent for their infant boys). The WHO has judged circumcision to be a cost-effective public health intervention against the spread of HIV in Africa, although not necessarily more cost-effective than condoms. The joint WHO/UNAIDS recommendation also notes that circumcision only provides partial protection from HIV and should not replace known methods of HIV prevention. Male circumcision provides only indirect HIV protection for heterosexual women. The WHO does not recommend circumcision as a protection for male-to-male HIV transmission. Evidence is lacking with regards