The new health-care law encourages people to get the preventive services they need by requiring that most health plans cover cancer screenings, contraceptives and vaccines, among other things, without charging patients anything out of pocket. Some patients, however, are running up against coverage exceptions and extra costs when they try to get those services. Advocates and policy experts agree that more federal guidance is needed to clarify the rules. Rebecca Hyde of Woodstock, Conn., was angry when, after getting a colonoscopy to screen for cancer in December, she got a notice that her insurer was charging a hospital "facility fee" of $1,935 against her $6,000 deductible. Such fees are not uncommon for hospital-based care.