Medical Evidence

Assertions identified as medical evidence are given considerable credence in sexual abuse allegations. Often what is represented as medical evidence or opinion is given unwarranted weight. Although mental health professionals do not perform physical examinations of children, nor ordinarily give testimony concerning them, the results of such examinations may convince a professional involved in investigation or therapy that the child has, in fact, been abused. Such a mind set is likely to bias the interview or evaluation.

Much medical "evidence" is actually inconclusive and nonspecific. Abuse allegations may involve exhibitionism, fondling, and masturbation so one would not expect physical evidence. But when there are allegations of anal or vaginal penetration, the medical report will often state the findings are "consistent with abuse" or "typical of abuse." If a physician makes such a claim, it may exceed the competence of physicians. Many physicians are not trained in causality, statistical inference, nor the laws of probability. If a medical opinion includes such opinions that is in the area of competence of a trained scientist, not the physician.

Unfortunately, many observations commonly seen in medical reports are not supported by scientific, empirical data. A 1983 paper by Cantwell is still sometimes cited to support the claim that a vaginal opening size above 4 millimeters indicates abuse, although there has been little empirical support for this assertion. Vague and ambiguous findings, such as genital redness, are deemed to be "consistent with" sexual abuse. The physician generally obtains a history from the person who brings the child in for the examination and then concludes, "sexual abuse based on history." Such statements are taken seriously by police, social workers, prosecutors, defense attorneys, and therapists and used as evidence that the physical examination has substantiated the allegation.

Such medical findings are apt to be in error (Coleman, 1989). Paradise (1989) estimates that 65% false positives occur when assessing penetration and 73% false positives with assessment of digital penetration. This raises serious questions about the validity and reliability of medical examinations.

Until recently, the greatest difficulty in evaluating physical findings was the absence of baseline data-that is, information about the appearance of the genitals in normal, nonabused children. But McCann and his colleagues have now conducted research on 267 prepubertal nonabused children (McCann et al., 1989, 1990a, 1990b). They report a high incidence of nonspecific findings such as erythema, tags, fissures, scars, adhesions, notches, thickening, and anal relaxation in their sample of nonabused children. They also report a large range of vertical and horizontal hymenal orifice diameters that varied, not only by age group, but according to the technique and position used to measure them. Emans et al. (1987) also report a large range of hymenal openings in their subjects and note that the genital findings of sexually abused girls were similar to nonabused girls who had other genital complaints, such as vaginitis, vulvitis, bleeding, or dysuria.

Even sexually transmitted diseases do not unequivocally establish sexual abuse. Although sexual contact is the most common means of transmission, there are alternative explanations for contracting the disease (Wakefield and Underwager, 1988a). In addition, the test used may be inaccurate or inappropriate. For example, a chlamydia screening test meant for an adult may be highly inaccurate with a child, and produce false positives because the test reacts positively to certain bacteria which are normally found in the intestinal tract of children (Fay, 1991).

he only specific and unambiguous physical findings demonstrating sexual contact are pregnancy or sperm in the vagina or anus. As Krugman (1989) observes:

The medical diagnosis of sexual abuse usually cannot be made on the basis of physical findings alone. With the exception of acquired gonorrhea or syphilis, or the presence of forensic evidence of sperm or semen, there are no pathognomic signs for sexual abuse. (pp. 165-166)

There is no diagnosis of sexual abuse. No nosology or disease nomenclature includes such a diagnostic category. Sexual abuse is an event, not an illness. Just as it would be foolish to diagnose an emergency room patient as "auto accident" instead of a fractured tibia or concussion, so it is foolish to speak of diagnosing sexual abuse. Any medical professional using the term diagnosis to refer to sexual abuse is confusing the medical procedure of ruling out all but one possibility with the investigative process of gathering all relevant information.