A discreet and in-depth look at sexual abuse of children.

Is widespread sexual abuse of children a new phenomenon or merely a creation of today's sensation-hungry news media? The Silent Shame (NBC, Saturday, Aug. 25, 10-11 p.m.) is an NBC News investigative documentary - produced by Chuck Collins and reported by correspondent Mark Nykanen - which dares to to speak out with its own version of the facts as articulated by Dr. Roland Summit, a UCLA psychiatrist and leading expert on sexual abuse of children: ''Children have been molested throughout history, adults have been blameless and immune from discovery throughout history.''

According to this shocking NBC Report, a federally funded study found that about 1 out of every 3 girls has been sexually molested, and many experts believe the figure for boys may be just as high. Since Mr. Nykanen goes on to try to prove that there is a firm connection between sexual abuse of children and child pornography, most of the program is taken up with pornography, its production, and its effect upon abusers. Too much so, perhaps.

''The Silent Shame'' is disturbing television, and many viewers may prefer not to hear some of the matters discussed. But it is important television, done with discretion and decency. One would hope that more thorough, in-depth investigative work in the field will soon be done - certainly the topic requires further TV investigation.

At least NBC News has resisted TV's often hypocritical habit of presenting this type of delicate subject matter as a titillating, problem-of-the-week, made-for-TV drama. Instead it is presented in the straightforward, responsible documentary form which can bring the matter to the attention of those who may realize they need help in solving such problems in their own communities. And one thing the documentary makes clear: The problem does exist in just about every community.