Post-mortem toxicology screening has many phases

Why do toxicology results take so long?

Prince's autopsy was conducted by A. Quinn Strobl, MD, FCAP, a member of the College of American Pathologists. The results are expected to take at least two weeks, perhaps as many as six full weeks. This tragedy has people asking again "Why do toxicology results take so long?"

Several autopsies include post-mortem toxicology screenings to determine which, if any, drugs were in a person's system. The results of these tests are necessary to determine - or rule out -- a cause of death.

During an autopsy, blood, tissue and, when possible, urine samples are taken from the body in preparation for the toxicology tests. Because the concentration of drugs can vary throughout the body, the pathologist collects blood from multiple areas, including the heart and the femoral vein in the leg.

Among the tissue sample tested in a forensic toxicology test are those from the liver, brain, kidney and the eyes. Samples of the contents of a person's stomach and bile secreted by the liver are also usually collected.

Medical examiner personnel often then conduct toxicology drug testing for the autopsy. Toxicology drug testing laboratories where such analyses are conducted are accredited by the College of American Pathologists or other organizations to ensure quality standards are met. Often, specimens are turned over to a toxicology expert for testing.

Pathologists, toxicologists and chemists collaborate in the process to ensure correct results.

The first tests are basic screens for drugs in the blood and urine. This type of test uses specific antibodies that detect various classes of drugs; the search would be for drugs such as opiates, amphetamines, marijuana, alcohol, and barbiturates.

If any drug type is flagged by the first test, pathologists and other scientists run several tests to confirm that result. These tests can take several days and sometimes have to be repeated.

If the presence of a drug is confirmed, a second, more sophisticated test is done. This test may try to identify chemicals in substances by measuring their mass and other characteristics. Depending on the test and type of drug, this step can take several more days to complete. Often, these samples are sent to a lab that specializes in testing for certain drugs.

The presence of multiple drugs, or the emergence of a second drug in a deceased person's system can require additional tests and calculations, which can add time to the process. Determining the specific levels of individual or multiple drugs in a deceased person's body - as well as the possibly fatal combinations of these combinations - can add additional time to the testing process.

Guidelines from the National Association of Medical Examiners (NAME) state that 90 percent of autopsies should be finalized within 90 days.

As with any laboratory test, in an autopsy pathologists are doing their work as disease detectives to determine not only a specific cause of death, but to better understand disease to assist the living. It is estimated that only 20 percent of deaths are followed by an autopsy, representing hundreds of thousands of lost opportunities to learn about disease - and improve public health - every year.