To the Editor: The Times reports that St. Vincent's and other Catholic hospitals plan to merge so that they can compete with the "prestigious academic medical centers" while protecting their "values, especially regarding opposition to abortion." The problem is that these two positions are diametrically opposed. It is impossible for a Catholic hospital to meet professional standards and to offer adequate health care services to women when it must adhere to the Church's "Ethical and Religious Directives for Catholic Health Care Services." The Directives prohibit Catholic hospitals and providers from providing or even directly referring patients to the most basic services and information that are essential to women's health care -- even for women who do not share their religious beliefs or understand how the lack of these services affects their health. The Directives prohibit doctors and nurses from doing their jobs according to professional standards: birth control pills, condoms, abortion and sterilization cannot even be considered. A hospital that fails to provide essential reproductive health services cannot hope to be considered a top-flight health care provider. An institution that fails to disclose to its patients the nature of the religious limitations on the services and information it offers to patients of all faiths violates a cardinal principle of all health care: informed consent. Sincerely, Donna Lieberman