Keeping you up to date on recent headlines in diagnostics.

TER discovers more polyps than standard colonscopy tech ... Recent advances in colonoscopic technology are featured in a number of studies presented at the Annual Scientific Meeting of the American College of Gastroenterology. In this research some technologies fare better than others at improving detection of potentially pre-cancerous growths in the colon known as adenomas. Interim results of a multi-center study of detection rates for polyps and adenomas using a retrograde-viewing device for the colonoscope, known as the Third Eye Retroscope (TER), found that endoscopists missed more polyps with the colonoscope alone than when using the TER with the colonoscope. In a separate study, investigators found that the overall detection of both polyps and adenomas was improved with use of TER, especially after the endoscopist had completed 15 procedures, suggesting a "learning curve." The TER is a disposable device that is passed through the instrument channel of a standard colonoscope to provide a retrograde view that complements the forward view of the colonoscopy during withdrawal of the scope from the colon, allowing a rearview or backwards look at the far side of the numerous anatomical folds and bends in the colon. Peter Siersema MD reports interim findings from a randomized, controlled, prospective study of the effectiveness of the TER for increasing the diagnostic yield of colonoscopy. This preliminary analysis of 126 patients who underwent same-day back-to-back colonoscopy and colonoscopy with TER found that the relative risk of missing a lesion with colonoscopy versus TER was 2.57 for all polyps. "When endoscopists used the colonoscope alone, they missed 2.57 times more polyps then when the used the retrograde viewing device along with the colonoscope," explains Siersema. Daniel DeMarco, MD, Medical Director of Endoscopy at Baylor University Medical Center (Dallas) presented interim data from a multi-center study involving 17 investigators at nine medical institutions in the U.S. looking at detection rates and withdrawal of the scope. The prospective study suggests that TER can lead to an enhancement of the detection rate of polyps and adenomas compared to standard colonoscopy.

Survey shows docs lack sufficient syphilis tests ... Although syphilis is one of the oldest known diseases, most health professionals do not have access to the tests necessary to reliably diagnose it in its earliest and most infectious stage. A recent survey of infectious diseases specialists regarding the diagnosis and treatment of syphilis appears in the Nov. 15, 2009 issue of Clinical Infectious Diseases, now available online. Definitive diagnosis of primary syphilis (the earliest stage of syphilis infection) relies on direct fluorescent antibody testing or darkfield microscopy, both of which are often unavailable in a clinical setting. Blood tests are commonly used to diagnose syphilis; however those tests produce false negatives in 20%-30% of primary syphilis cases, allowing for the possibility of ongoing transmission. According to study author Deborah Dowell, MD, of the Centers for Disease Control and Prevention (Atlanta), "Eighty-one percent of our survey respondents did not have access to darkfield microscopy. These clinicians should treat presumptively if they suspect early syphilis in their patients." Dowell also notes that there is a clinical and public health need for a rapid point of care test to reliably diagnose primary syphilis. The survey also shows that most respondents treat HIV-positive patients who have secondary syphilis with three weekly penicillin injections although there is no evidence of improved outcomes for treating with more than one injection. Physicians with more syphilis management experience were more likely to treat with the recommended one injection, which suggests that physicians with less experience managing syphilis may lack confidence that management according to established guidelines is sufficient to prevent adverse outcomes.

Research details ways to test for early identification of mitochondrial disorders ... . Research published in BioMed Central's open access journal, Genome Medicine, outlines an innovative clinical diagnostic test for the early identification of a wide range of mitochondrial disorders. Mutations to one of the mitochondrial genes, or to a number of nuclear genes with roles in mitochondrial function, can cause diseases which have very similar symptoms, making them difficult to diagnose and treat. Researchers from the Seattle Children's Research Institute teamed up with researchers from the Genome Sciences and Pediatrics Departments of the University of Washington (Seattle) to create a molecular diagnostic tool that uses targeted genetic sequencing to screen patient's DNA for variations in 362 genes which have been associated with mitochondrial disease or mitochondrial function. They tested this tool by using it to screen three DNA samples. Two of these samples were taken from patients with mitochondrial disorders, who had been previously diagnosed by traditional sequencing methods, while the third came from a healthy individual selected from the Coriell Repositories HapMap catalogue of human DNA samples. The researchers then assessed the potential impact of all the novel mutations they detected. They found that the new method was able to accurately identify the mutation underlying each patient's condition. The large number of candidate genes examined is likely to increase sensitivity for identifying previously unknown genes responsible for mitochondrial disorders. "Early and effective diagnosis [of mitochondrial disorders] is crucial for permitting appropriate management and accurate counseling," say lead authors, Jay Shendure and Sihoun Hahn. "Mitochondrial diseases affect as many as 1 in 5000 children; however diagnosis is notoriously difficult due to the huge number of genes potentially responsible for these disorders. For these reasons, some patients may remain undiagnosed and even die of untreated disease," Hahn said. In addition to providing accurate diagnosis, the large number of genes used in this method allows a large number of potentially harmful mutations to be detected which might otherwise be missed. He adds, "Our study indicates that the use of next generation sequencing technology holds great promise as a tool for screening mitochondrial disorders."

– Compiled by Omar Ford, MDD