Beware of the downsides to molecular testing. (Communication with the Lab is Key).

BANFF, ALTA. -- Don't get too comfortable with the latest molecular test methods for determining the presence of ob.gyn. infections, Peter H. Gilligan, Ph.D., warned at the annual meeting of the Infectious Diseases Society for Obstetrics and Gynecology.

Molecular testing methods "sound great. And they are great, but there are problems with these tests that you need to be aware of and talk to your lab about," he said. Even if a test is conducted by molecular amplification, "if it doesn't match up with your clinical impression, it's incumbent upon the physician to understand this issue and to be aggressive in saying to the laboratory: 'You need to repeat this test. I don't think it's accurate.'

"Lab technicians aren't going to know the very subtle things that are important in the care of your patients," continued Dr. Gilligan, director of the clinical microbiology lab at the University of North Carolina at Chapel Hill. Yet in his 18 years at the university's lab, he says that he's rarely seen anyone from the ob.gyn. department come into his lab.

Perseverance and communication between the ob.gyn. and lab departments paid off in one particular case: A 36-year-old woman presented for an evaluation at the hospital's infertility clinic. Her physical and cervical examinations were unremarkable. However, a polymerase chain reaction test for Chlamydia trachomatis was positive, and her husband's tests were all negative. The patient, who claimed to have been in a monogamous relationship with her husband for more than 10 years, said that it was impossible for her to have C. trachomatis.

Molecular amplification techniques are the most accurate and sensitive way of diagnosing C. trachomatis. However, "there is no perfect laboratory test," he pointed out, so physicians should know the rate of false positives and false negatives ...