A difficult diagnosis

Spotting SIDS would seem fairly straightforward, but the truth is quite the opposite. And that makes it very hard to know exactly how and why babies succumb, or why the highest rates occur in infants between 2 and 4 months old. The condition can be diagnosed only when a death has been carefully investigated -- including an autopsy, a study of the scene and circumstances of death, and an examination of the baby's medical history -- so that all other possibilities can be ruled out. The process is expensive, and many counties don't have the resources to conduct such thorough investigations, says Amy Martin, M.D., Denver's chief medical examiner. The result? Some cases may be missed.

Government bureaucracy only compounds the problem. In 2006 the CDC acknowledged that its SIDS reporting form, which each medical examiner's office is charged with completing, was unnecessarily confusing; the revised form can be completed almost entirely by checking boxes. But for on-the-ground forensic pathologists, says Dr. Martin, the new version is still problematic. "If you don't have enough trained investigators who can go out to the death scene, you're going to have a difficult time filling out a form like that -- not to mention getting to the bottom of what really happened," she says.

And yet even when resources are available, identifying a true case of SIDS can be challenging. When a baby is found lying on her tummy -- or in a bed with adults, or a crib full of soft toys -- the coroner can't rule out the possibility that the baby was accidentally smothered and may call it "possible accidental asphyxia" or "threats to breathing" rather than SIDS. That's why some states today report no SIDS deaths at all, despite the fact that babies still die there every year, says Fern R. Hauck, M.D., associate professor of family medicine and public health sciences at the University of Virginia.

As Melissa Haberzettl found out, this variation in labeling -- a phenomenon called code-shifting -- can happen if the examiner discovers a possibly unrelated underlying condition as well. Five weeks after offering a preliminary assessment that Jake had died of SIDS, the Colorado Springs coroner changed his diagnosis. Even though the baby showed no signs of illness, the medical examiner concluded that Jake had died of viral pneumonia. "I kept asking, 'How can a healthy baby die of pneumonia?' but I never got a straight answer," says Melissa.

She sought out a second opinion from Henry Krous, M.D., a SIDS researcher at Rady Children's Hospital in San Diego. In his view, the local examiner had missed a perfectly obvious case of SIDS: "With viral pneumonia, infants don't die suddenly without getting sick first," says Dr. Krous. "If one has a degree of pneumonia that can be seen only with a microscope, and then the infant dies, he dies with it, not of it."

Regardless of how or why it happens, code-shifting helps to explain why SIDS deaths have dropped in the past 14 years while other sudden infant deaths, like those attributed to accidental suffocation or even, simply, undefined causes, have increased significantly. If true SIDS cases are being assigned a wide variety of other diagnoses, it makes it nearly impossible for researchers to get a good handle on what's happening with the rates and risk factors right now, says Dr. Hauck. That's why for parents, it's more important than ever to follow the safe-sleep recommendations, including putting babies down on their backs, says Dr. Krous. "Nothing we know at the present time will absolutely prevent SIDS, but the risk can be substantially reduced."

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