August 2012
Cytopathology and More

Ann T. Moriarty, MD

The Laboratory Accreditation Program Complaints Committee investigates complaints against CAP-accredited laboratories and requires laboratories to take corrective action when the lab does not meet CAP requirements. During an investigation of a cytology laboratory, it may identify previously undiscovered issues, most often screening individuals who may have exceeded workload limits. Additionally, the Complaints Committee may discover diagnostic error—for instance, a Pap test originally reported as negative but found to contain abnormal cells upon subsequent re-review (triggered either by an abnormal biopsy or during a five-year retrospective review in the presence of a current high-grade squamous intraepithelial lesion, or HSIL). How extensive should the investigations of the laboratories be, and what corrective actions should be required?

The workload violation is usually a violation of the 12.5 slides per hour limit and not a violation of a daily total. Often, it is identified because the cytotechnologist or laboratory manager does not understand the correct way to calculate the workload. This is especially problematic when image-assisted screening instruments are used. Requiring the lab to rescreen the daily workload of the individual in violation is a reasonable response, but it is unlikely to yield clinically useful findings. Any retrospective review of daily workload will probably yield a few cases of Pap tests demonstrating atypical squamous cells of undetermined significance (ASC-US) based upon the biased nature of the retrospective review. Additionally, when an hourly workload limit is exceeded, there is not usually an issue of patient safety. The arbitrary nature of the screening limits means that a cytotechnologist does not become less vigilant after the magic 12.5 slides per hour. Labs need not issue an amended report for anything other than an intraepithelial lesion (and if the patient has had an HPV-negative co-test, those slides may not need to be rescreened). More importantly, the laboratory should be able to satisfy the CAP that it: 1) understands how to calculate workload, 2) has an internal corrective plan if it discovers a CT who has exceeded workload, and 3) documents completion of the plan if it discovers further violations.

What happens when retrospective reviews of Pap tests uncover a significant intraepithelial lesion? Is it a symptom of poor performance or simply a random error due to human nature? Abnormalities detected upon retrospective review are always a conundrum. Too many random errors are detected by this quality assurance exercise. The five-year retrospective review is used for quality assurance purposes to identify false-negative cases in a patient who has proved to be “high risk” by currently having a high-grade squamous intraepithelial lesion. These reviews should be used to educate or identify systematic error in screening. There is little problem with individual patient safety because the HSIL/CIN3 lesion has been detected already and the patient is being treated. In fact, we are required to amend a report only if it affects current patient care. So in retrospective reviews of current HSIL, an amended report is issued only for the discovery of squamous carcinoma on a previous Pap test. Again, the retrospective review is biased and often a few “abnormal” cells will be detected, but not HSIL. If a significant abnormality had been missed in the past, retrospective review of that cytotechnologist’s daily work is a nightmare and not likely to yield anything. (Statistically there will be very few opportunities to miss a significant lesion since the prevalence of HSIL is so low in the population; more likely it will turn up cases with minimal abnormalities.)

If approached correctly, retrospective review can be very helpful to laboratories in identifying CTs who may be having problems or to pinpoint subjects for whom additional education is needed. Philosophically, we do not want to penalize the cytotechnologist who “missed” something; instead we want to make sure the laboratory has an active program to identify those situations and offers educational opportunities to the cytotechnologist. If a cytotechnologist seems to have a pattern of “missing” significant lesions, it is a warning sign that he or she may be having difficulties.

We have to use a standard to define “significant miss.” Not all errors in detection are due to poor performance. Every cytotechnologist will “miss” something significant because we are human. We can predict those cases that will be problematic: few cells, hyperchromatic crowded groups, or trigger cells that are outside the field of view (for image-assisted cases). Blinded reviews can be used to identify a significant miss only if the panel of cytotechnologists is blinded to the slide in question and to the situation of its review. Blinded review is optimal but difficult to implement in a routine laboratory setting. Another method is to use a pre-defined “sentinel miss” definition. In this method, the supervisor and medical director could define a sentinel miss as one that most cytotechnologists would be able to avoid—that is, the cytotechnologists would be able to find the abnormal cells without difficulty. That miss, then, would be a sentinel event and launch a cascade of events.

For example, if a sentinel miss or a significant error is discovered during blinded rescreening, an initial step could be to increase the second review rate of the individual. This measure could be used instead of rescreening slides from the remote past. The daily QC rate of the technologist could be increased (for example, from 10 percent to 25 percent) and monitored closely for agreement, as compared with the QC agreement rate of the laboratory as a whole. If further issues are noted with the increased QC rate or another sentinel event is discovered, the cytotechnologist could be removed from primary screening duties while completing an educational module. When the CT returns to screening, he or she could have 100 percent rescreen for at least one month. If significant findings are missed, then the termination process could begin. (It is important to compare the cytotechnologist in question with the laboratory as a whole, so as not to set an arbitrary level that may not be statistically valid. ASC-US “misses” should not be included, nor should “downgrades.” We are investigating locator errors, not interpretive errors.)

To summarize:

• Workload limit violations are usually due to a misunderstanding in how to calculate workload. Laboratories should be required to demonstrate that they can calculate the workload and that when a violation occurs they have a plan in place to address it (which could include review of the cases from that day, or a portion of that day, or review of the abnormal rate for the technologist and assuring that it is not below that of the lab as a whole).



• Discovery of a significant lesion upon retrospective reviews is problematic because it is difficult to determine if the error in screening is random or systematic error and because a second review process is biased. The laboratory should have a plan for when a significant or sentinel miss is identified upon retrospective review. The laboratory could choose to increase the QC for that technologist to a higher rate (for example, 25 percent) and compare his or her abnormal rate during that time with that of the lab as a whole (excluding ASC-US and downgrades). The laboratory should have a plan for educational programs, with subsequent escalating restrictions if significant abnormalities or low abnormal rates are found compared with those of the lab as a whole. Of course, the laboratory must always be able to demonstrate its procedures for retrospective review and document compliance with those procedures.