When a child is thought to have been sexually abused, a second medical exam may be key to picking up injuries and sexually transmitted infections, a study found.
The American Academy of Pediatrics already recommends that kids being examined for sexual assault have a follow-up exam in the weeks afterward.
But until now, no studies had looked at the benefits of doing that.
For the new report, researchers reviewed the records of 727 children and teenagers who were evaluated for sexual abuse or assault over a five-year period.
They found that almost one-quarter of the time, the patients' second exam changed the findings of the first.
In 18 percent of cases, there was a shift in the diagnosis of traumatic injuries.
Most often, the original examiner had said it was unclear whether the child had an injury suggestive of sexual assault (like tears or bruising), but the second examiner concluded that the findings were "normal."
However, that "does not in any way" mean the child wasn't sexually abused, said Dr. Nancy D. Kellogg, one of the researchers on the study and a child abuse expert at the University of Texas Health Science Center in San Antonio.
It's well known that sex-abuse victims often do not have telltale traumatic injuries, Kellogg told Reuters Health.
So it's what the child says that's most important.
Kellogg's team also found that the second medical exam helped pick up sexually transmitted diseases that weren't caught initially. That was true in nearly seven percent of cases.
Most often, Kellogg said, the follow-up exam caught genital warts -- which would not yet have been apparent during the first exam.
The findings, reported in the journal Pediatrics, are based on 727 children and teens who were first examined at one San Antonio ER or the regional child advocacy center. A doctor or nurse trained in child abuse cases performed the exams.
The second exam was done about a month later at the child advocacy center, by an experienced child-abuse doctor or nurse.
During the initial exam, Kellogg explained, kids are "anxious or in pain -- they're traumatized. And that can affect the examiner's ability to detect things."
But the researchers also found that the first examiner's experience mattered. If he or she had done fewer than 100 such exams, the second examiner was more likely to reach different conclusions on whether the child had a traumatic injury.
That, Kellogg said, points to the importance of having an experienced doctor or nurse do the second exam.
Some hospitals, she noted, have special "child abuse teams" who can evaluate kids for sexual assault. There may also be a nearby child advocacy center with doctors or nurses who can do the exam.
As for areas where those services aren't available, Kellogg said she hopes the current findings give less-experienced pediatricians some guidance in evaluating kids for sexual abuse.
"We were a bit surprised by the findings," she noted. "We didn't expect the follow-up exam to make such a big difference in so many kids."