for p16, a marker for high-risk HPV, is referred to as LSIL. Those that are p16-positive are referred to as HSIL. CIN 3 is referred to as HSIL. Screening The two screening methods available are the Pap smear and testing for HPV.CIN is usually discovered by a screening test, the Pap smear. The purpose of this test is to detect potentially precancerous changes through random sampling of the transformation zone. Pap smear results may be reported using the Bethesda system (see above). The sensitivity and specificity of this test were variable in a systematic review looking at accuracy of the test. An abnormal Pap smear result may lead to a recommendation for colposcopy of the cervix, an in office procedure during which the cervix is examined under magnification. A biopsy is taken of any abnormal appearing areas. Colposcopy can be painful and so researchers have tried to find which pain relief is best for women with CIN to use. Research suggests that compared to a placebo, the injection of a local anaesthetic and vasoconstrictor (medicine that causes blood vessels to narrow) into the cervix may lower blood loss and pain during colposcopy. HPV testing can identify most of the high-risk HPV types responsible for CIN. HPV screening happens either as a co-test with the Pap smear or can be done after a Pap smear showing abnormal cells, called reflex testing. Frequency of screening changes based on guidelines from the Society of Lower Genital Tract Disorders (ASCCP). The World Health Organization also has screening and treatment guidelines for precancerous cervical lesions and prevention of cervical cancer. Primary prevention HPV vaccination is the approach to primary prevention of both CIN and cervical cancer. It is important to note that these vaccines do not protect against 100% of types of HPV known to cause cancer. Therefore, screening is still recommended in vaccinated individuals. Secondary prevention Appropriate management with monitoring and treatment is the approach to secondary prevention of cervical cancer in cases of persons with CIN. Treatment Treatment for CIN 1, mild dysplasia, is not recommended if it lasts fewer than two years. Usually, when a biopsy detects CIN 1, the woman has an HPV infection, which may clear on its own within 12 months. Therefore, it is instead followed for later testing rather than treated. In young women closely monitoring CIN 2 lesions also appears reasonable. Treatment for higher-grade CIN involves removal