Tuesday, November 6, 2007

Week 19 - Quality Assurance & Quality Control

hey people,im really sorry for the super late posting..for this posting i will share with u guys the quality assurance and quality control in the histopathological laboratory where im attached to.

Quality Assurance(QA) and Quality Control(QC)

QA is a program in which overall activities conducted by the institution are directed towards assuring the quality of the products and services provided. QC is under QA in which products and services provided are evaluated in hopes of achieving high accuracy and reliability of test results and also aids troubleshooting. This involves continuous monitoring of operations and systemic day-today checking of the produced data to decide whether these are reliable enough to be released.

Application of QC protocol to:

Tissue processing
The ATPs are checked against maintenance checklist to ensure that all reagents are properly loaded and in sufficient amounts prior to start of processing. Reagents are maintained (after 20 cycles) to ensure a certain standard of quality of processing in subsequent cases.

Paraffin dispensers are emptied monthly to clear debris collected at the bottom of the container.

The temperature of floatation baths are checked and recorded daily on the temperature log as part of equipment maintenance to ensure that it is in top condition during production of results. If out of range (less than 44oC or more than 50oC), corrective actions are taken by adjusting control knob. The microtomes and floatation baths are cleaned daily to remove debris after all sectioning done.

Working thermometer and equipment temperature display are calibrated monthly to make sure that readings displayed on ovens and refrigerators are within control range. The coldroom used to store special staining kits is inspected daily to ensure that it can function properly. The accuracy of its temperature is checked daily as the activity of special stains will be very much affected by temperature. When preparing staining reagents, the electronic balance may be used to measure out certain ingredients. Therefore, it is calibrated yearly to make sure the reading is accurate and within 1% of the reference mass as certain special stains are sensitive to quantity. Control samples are stained simultaneously with patients’ samples and observed for its quality. This is to ensure that any poor staining caused by defective reagents detected by control samples can be corrected at first hand before the sections are stained. H&E and special stains controls are evaluated and graded according to their quality from 5 (excellent) to 2 and below (inadequate in which remedial actions are to be taken). For H&E control, the nuclear and cytoplasmic control must be well defined and contrasted. As for special stains controls, there must be relatively good demonstration of 75% or more of the cells without background staining. During staining of patients’ samples, 10% of the slides contained in a rack are sent for microscopic examination for grading as part of QA. The slides are evaluated to detect any faults in staining, sectioning and mounting. Percentage of unsatisfactory slides caused by errors in staining, sectioning or mounting are counted monthly as well. Weekly, at the end of every Tuesday and Friday, reagents used for routine H&E are changed as part of QC so that the quality of staining can be consistent throughout. Records are maintained which indicate the type of reagent that is changed, filtered or replaced. Since Haematoxylin and eosin are prepared once a week, they are filtered daily to remove debris left by the previous slides. Before sending the slides for mounting, the machine is primed to remove any air bubbles present as it can affect the microscopic examination and thus, the quality of staining.

Dispatch slides
All slides are checked against tissue blocks prior to their dispatching. If unsatisfactory, they are
sent for recuts. Also, the number of slides indicated on request forms must tally against the amount being stained.

Lastly, pathologists evaluate the results in areas of sectioning, staining and mounting as these are the criteria that will affect the quality of section and thus, hinder diagnosis. The total number of errors that are being raised in all stages of workflow (from processing to labeling) are counted monthly and systematically documented in an ‘EVENTS’ file. In addition, a maintenance program for all equipment and instruments, listing the model and serial number, dates of services performed, parts installed, and the interval and date of the next service are kept and recorded. There is also a complete equipment inventory, listing the name and manufacturer of the instrument, model and serial number, purchased from, personnel who installed the instrument, the date, length of warranty, purchase price , and location of the manual of instructions covering the equipment.

This shall be the end of my posting. thanks for reading. :)

Sharon Ang