Regional Laboratory
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Cervical screening and the conventional Pap smear have resulted in a significant decrease in mortality due to cervical cancer over the past 40 years. However, using the conventional Pap smear, the false negative rate for the detection of SIL/carcinoma averages 5-20% with rates of 10% or less difficult to achieve with current methods.
In order to reduce the false negative rate, alternative methods of collection and screening have been devised. In the past few years, automated rescreening devices, primary screening instruments and collection systems utilizing fluid-based collection and monolayer preparation have been developed and FDA approved.
ThinPrep (CYTYC Corporation) received FDA approval in 1996 for fluid-based collection and preparation of Pap smears. When using the ThinPrep method, the gynecologic specimen is obtained by the clinician in the usual manner. The clinician then rinses the collection device in a vial containing PreservCyt solution. The specimen is forwarded to the laboratory where the vial is placed in the ThinPrep processor along with a disposable filter cylinder. The slide is prepared in three steps: dispersion, filtration and transfer of cells to the slide. Once transfer is complete, the slide is ready for routine staining and coverslipping.
The advantage of this method is two-fold. First, at the point of collection, the transfer of cells from the collection device to the solution is complete; whereas utilizing the conventional method, it has been estimated that up to 60% of the sample is not transferred to the slide but remains on the collection device. Second, the monolayer technique evenly distributes the material to a 20 mm circular area on the slide. Common findings on conventional slides such as thick areas and air-drying artifact which can compromise interpretation are eliminated. In addition, while blood and inflammation which can obscure areas on the conventional smear are not eliminated, on the ThinPrep smear they aggregate between cells without obscuring cellular detail.
In two recently conducted clinical trials, the ThinPrep Pap Test reduced false negative diagnoses by 61% (5.6% false negative incidence for conventional Pap smears vs. 2.2% for ThinPrep specimens). At MAWD Pathology Group, our experience with 2000 ThinPrep smears has shown: 1) a reduction in the number of less-than-optimal and unsatisfactory smears; 2) reduction in equivocal diagnoses (ASCUS and AGUS); and 3) an increase in the number of significant lesions (LGSIL and higher) detected.
Payment for the ThinPrep Pap Test by managed care payers is variable.
The April 1998 issue of the “RLA Physician Letter” discussed enteroviral meningitis. Testing for the Enterovirus is now available at The Children’s Mercy Hospital June through October. Testing is performed 7 days/week. Specimens received by 0600 will have results available in the early afternoon. The specimen requirement is 0.5cc of CSF. Specimens should be refrigerated and transported to The Children’s Mercy Hospital as soon as possible on ice. A specimen from a traumatic tap is acceptable. Concomitant culture will not be performed unless so ordered.