Checking cervical cells with the Papanicolaou test (Pap test) for cervical pre-cancer has dramatically reduced the number of cases of, and mortality from, cervical cancer. Liquid-based cytology may reduced the number of inadequate samples. Pap test screening every three to five years with appropriate follow-up can reduce cervical cancer incidence up to 80%. Abnormal results may suggest the presence of precancerous changes, allowing examination and possible preventive treatment, known as colposcopy. The treatment of low-grade lesions may adversely affect subsequent fertility and pregnancy. Personal invitations encouraging women to get screened are effective at increasing the likelihood they will do so. Educational materials also help increase the likelihood women will go for screening, but they are not as effective as invitations.