[Histonet] IHC repeat rates

Tony Henwood (SCHN) tony.henwood at health.nsw.gov.au
Thu Jun 25 19:15:40 CDT 2015

The RCPA (in Australia) recently requested that laboratories perform Technical Failure Repeat Audits that might be of use.
Subsequently I produced a brief report for our Society's journal:

Audit of Technical Failures
Tony Henwood
The Children's Hospital at Westmead, Sydney
The RCPA has requested that laboratories implement the Internal Quality Assurance Framework-Pilot Program for the interpretative and morphological disciplines. There is also a requirement for 2.5 hours of 'other', internal quality activities relating to the technical and service measures section of the framework (over a 3 month timeframe). One of these is the re-staining required due to technical failure (H&E, special stain, Immunoperoxidase, etc.). This Technical Failures Audit records the number of stains of a certain type requiring repeat over total number stained during a 3 month audit period. One would also include those instances where recuts or deeper sections are requested due to sectioning artefacts or incomplete full face.  The necessity for repeat staining reflects the quality of technical work and has impact on overall laboratory efficiency.
This audit is one of the measures recommended to monitor the analytic phase of the test cycle. The analytic phase of the test cycle represents all of the steps in processing and evaluating the specimen in the laboratory until a diagnosis is rendered (3). Other audits include (6):
*	Quality of histologic sections
*	Specimens lost in processing
*	Turnaround time (TAT)
*	Block labelling
*	Slide labelling
*	Extraneous tissue
*	TAT for immunohistochemical analysis
*	Report audit for integration of stains with morphologic diagnosis
*	Annual review of antibody inventory and frequency of use
The Association of Directors of Anatomic and Surgical Pathology have included "Frequency and causes of repeated stains" under Immunohistochemical analysis (6). But one would think that this could, and probably should, be applied across all the technical aspects of the analytical phase of histopathology.
An effective audit needs to be relevant, objective, quantified and repeatable with formal identification of areas requiring improvement (1, 2). It also provides a method for reassessment of performance once appropriate changes have been implemented (1).
Although errors causing patient harm are unfortunate, it must be acknowledged that a certain error rate is prevalent. Error levels that may be deemed within an acceptable range should be determined based on the literature for that measure, with the goal of modification by continuous improvement (6)
It has been recommended that a Quality Assurance Monitor should include a targeted acceptable range and reference benchmark data (3). It is appropriate to complete this audit, but it can be of limited use unless we have appropriate benchmarks to compare our laboratories data to. 
>From the literature:
*	Zuk et al (1) found 19% of cases were technical unsatisfactory ("holes", folds, debris, "chatters", "scores" or absence of full transverse section). They also found that H&E staining was poor in a 2% of cases. This study recorded all cases of technical failure, not just those requiring a repeat in order to facilitate a diagnosis.
*	In the manufacturing industry, six sigma has emerged as a generic quality standard. This standard aims to have the total number of failures in quality, or customer satisfaction at 3.4 defects or fewer than 4 defects per million products (4).
*	Morelli et al (5) found in their study of errors in histology preparation that 0.03% of cases required the repeat of one or more processes;
To implement this audit we also need to determine the "Rules of Engagement"- what parameters need to be observed in order to render the results meaningful?
*	Should a repeat caused by microscopic incomplete full face (not obvious from scrutinising the paraffin block) be counted?
*	Should further sections and in particular serials to improve the detection of a small focus of disease be counted as a technical failure?
So, what do you think?
Please send your thoughts to the editor
1.	Zuk, J. A., Kenyon, W. E., & Myskow, M. W. (1991). Audit in histopathology: description of an internal quality assessment scheme with analysis of preliminary results. Journal of clinical pathology, 44(1), 10-16.
2.	Shaw CD, Costain DW. "1989" Guidelines for medical audit: seven principles. Br Med J 299:498-9.
3.	Nakhleh, R. E. (2009). Core components of a comprehensive quality assurance program in anatomic pathology. Advances in anatomic pathology, 16(6), 418-423.
4.	Nakhleh, R. E. (2006). What is quality in surgical pathology?. Journal of clinical pathology, 59(7), 669-672.
5.	Morelli, P., Porazzi, E., Ruspini, M., Restelli, U., & Banfi, G. (2013). Analysis of errors in histology by root cause analysis: a pilot study. J Prev Med Hyg, 54, 90-6.
6.	Association of Directors of Anatomic and Surgical Pathology. (2006). Recommendations for quality assurance and improvement in surgical and autopsy pathology. Am J Clin Pathol 126:337-340

Tony Henwood JP, MSc, BAppSc, GradDipSysAnalys, CT(ASC), FFSc(RCPA) 
Laboratory Manager & Senior Scientist, the Children's Hospital at Westmead
Adjunct Fellow, School of Medicine, University of Western Sydney 
Tel: 612 9845 3306 
Fax: 612 9845 3318 
Pathology Department
the children's hospital at westmead
Cnr Hawkesbury Road and Hainsworth Street, Westmead
Locked Bag 4001, Westmead NSW 2145, AUSTRALIA 

-----Original Message-----
From: Bitting, Angela K. [mailto:akbitting at geisinger.edu] 
Sent: Friday, 26 June 2015 1:09 AM
To: 'histonet at lists.utsouthwestern.edu'
Subject: [Histonet] IHC repeat rates

What does this group feel is an acceptable repeat rate for automated IHC staining??

Thanks for your responses in advance.


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