Helping patients choose the proper contraceptive requires familiarity with the specific advantages and disadvantages, as well as failure rates, of available methods. Spermicides, condoms and contraceptive sponges are inexpensive and do not require physician prescription. Diaphragms and cervical caps help protect against sexually transmitted diseases but are more difficult to use effectively. Oral contraceptives are highly effective but have estrogen- and progesterone-related side effects. Norplant is ideally suited for less motivated users but requires an office surgical procedure. Depo-Provera provides another long-term option but may result in amenorrhea. Intrauterine devices provide long-term contraception without hormonal side effects but increase the risk of pelvic infection and may cause heavy menstrual bleeding. Tubal ligation and vasectomy are options for permanent contraception when childbearing is no longer desired.