Influence of the history on physicians' interpretations of girls' genital findings

Because physicians customarily obtain histories before examining children in cases of possible sexual abuse, and because the resulting diagnostic opinions can influence important social and legal decisions, we investigated whether clinical histories influence physicians' interpretations of girls' genital findings. In mailed questionnaires, 1387 randomly selected Fellows of the American Academy of Pediatrics and all 802 members of four professional groups concerned with child abuse or pediatric gynecology were asked to interpret seven simulated cases. Respondents were asked to interpret seven additional cases in separate questionnaires mailed 4 months later. Both sets of cases involved the same seven photographs of girls' external genitalia. However, in six of the seven case pairs, the histories in the two questionnaires differed in the extent to which they suggested sexual abuse. In the remaining (control) pair, the same history was presented in both questionnaires. Of 2189 physicians, 1114 (50.9%) responded. Responses from 604 physicians (54.2%) were eligible for analysis. Overall, the genital findings were interpreted most consistently by the most experienced physicians and least consistently by the least experienced physicians. The proportion of physicians whose interpretations of a photograph reversed in the direction suggested by the change in the associated history from "no indication of abuse" to "probable abuse," or vice versa, ranged for experienced physicians from none to 5.6%; for moderately experienced physicians from 1.6% to 19.8%; and for inexperienced physicians from 3.6% to 27.2%. This difference between the experience groups was statistically significant in four case pairs. Mean interpretation scores for genital findings changed significantly when the histories changed in two case pairs for the experienced physicians, in five pairs for the moderately experienced physicians, and in all six pairs for the inexperienced physicians. In some cases and especially for less experienced physicians, diagnostic expectation appears likely to influence physicians' interpretations of girls' genital findings. Physicians should be alert to the possibility of diagnostic expectation bias and its potentially serious social and legal consequences.