If It's Not Abuse…

When pathologist and blood-clotting expert Dr. Michael Laposata was first asked to testify in a child abuse case, the prosecutor asked him how many cases were in the medical literature about children with diseases that were mistaken for child abuse.

"As it turns out, there were really none," he recalls.

Over the next 20 years, Laposata researched and collected interesting cases he saw, and in 2005, he published an article in the American Journal of Clinical Pathology reviewing some of the diseases that had led to child abuse misdiagnoses.

In particular, Laposata's article focuses on blood disorders that can lead to bleeding and/or bruising, including:

• Von Willebrand disease -- a hereditary disorder that prevents blood from clotting properly
• Vitamin K deficiency -- a rare condition where the body can't absorb the vitamin, which is necessary for blood to properly clot
• Leukemia -- cancer of the blood cells
• Ideopathic thrombocytopenic purpura (ITP) -- a condition where a low platelet count prevents blood from clotting properly
• Henoch-Schonlein purpura -- an abnormal immune system response that manifests as purple spots on the skin. The cause of this condition is unknown, and it's more common in children than adults.

Laposata created a PowerPoint presentation that highlights the difficulty in diagnosing abuse cases. He shows a photo of a child with bruises from a bleeding disorder next to a photo of a child who was abused and asks which of the cases is abuse. "I've been looking at patients with bleeding problems for years, more than two decades," he says. "And if you show me the two children with the bruises on their legs, I couldn't tell you that that one is the bleeding disorder. I'd have to do the blood test to find out."

"What's very clear is that the major misdiagnosis out there with child abuse is missing it," Laposata tells FRONTLINE. But, he says, "overdiagnosis may be even worse than underdiagnosis, because not only are we affecting the child, we are now affecting another person, a parent who is being accused of abusing the child."