Fakeha Rehman  ( Pathology Department, King Edward Medical University Lahore )
Muhammad Saqlain Haider  ( Department of Pathology, Tehsil Healthcare Unit, Nankana Sahib, Punjab, Pakistan )
Rakhshindah Bajwa  ( Department of Pathology, King Edward Medical University, Lahore, Pakistan )
Muhammad Raheel Anwar  ( Department of Pathology, King Edward Medical University, Lahore, Pakistan )
Muhammad Zeeshan Sarwar  ( East Surgical Ward, King Edward Medical University, Lahore, Pakistan )
Fatima Naumeri  ( Pediatric Surgery Department, King Edward Medical University, Lahore, Pakistan )
Zayed Rashid  ( Student, Final Year MBBS, King Edward Medical University, Lahore, Pakistan )

Objective: To evaluate pre-microscopic errors in anatomical pathology.

Methods: The cross-sectional descriptive study was conducted at the Department of Pathology of a tertiary care hospital in Lahore, Pakistan, from September, 2016, to January, 2017, and comprised surgical pathology specimens. Errors were noted across the pre-microscopic process. Defects per million opportunities were calculated to determine sigma metric value in every step, from requisition to slide preparation. Root cause analysis was applied to the process of histology preparation to identify the root cause of each previously identified problem using Eindhoven classification. All errors were recorded on a pre-designed proforma.

Results: There were 2420 specimens. While errors were encountered in all phases of the pre-microscopic process, but the (G6: n=1085, 44.83%), followed by requisition (R3: n=893, 36.9%) and cover slipping (C1: n=776, 32.06%).

Conclusion: Development of standard procedures and protocols with staff training is likely to help in controlling the errors.

Keywords: Anatomical pathology, Eindhoven, Errors, Root cause analysis, six sigma metrics. (JPMA 70: 0000; 2020)

https://doi.org/10.5455/JPMA.5565

 

Introduction

 

Errors are an integral part of human actions and healthcare systems. Surgical pathology errors are inevitable during any phase of laboratory testing, including pre-analytical, analytical and post-analytical phases. However, the main challenge is timely identification and rectification of these errors to ensure effective patient safety.¹ Surgical specimen errors can lead to delays in diagnosis and treatment, misdiagnosis, inappropriate treatment, repeat procedures or re-operations, and emotional distress or physical harm. Elimination of these errors is important for correct and valid diagnosis and for the provision of better treatment. Every area of laboratory should evaluate all possible errors and seek measures to avoid such errors.²

Many studies have been published^3-5 analysing errors in all phases of routine processing in anatomical pathology with a reported error rate of 35% in specimen labelling.¹ Local data on identification and evaluation of errors in anatomical pathology is scarce, but a study evaluated errors in a high volume clinical chemistry laboratory with an error rate of 0.45% and sigma level of 5.2.⁶

There are no existent well-defined structured tools to measure pre-microscopic errors in anatomical pathology. In addition, Eindhoven classification has not been previously used in our part of the world to identify potential sources in system that lead to these errors.⁴

The current study was planned to evaluate pre-microscopic errors in anatomical pathology using Sigma metric analysis and Eindhoven's classification

 

Material and Methods

 

The cross-sectional descriptive study was conducted at the Department of Pathology of a tertiary care hospital in Lahore, Pakistan, from September, 2016, to January, 2017, and comprised surgical biopsy specimens.

After obtaining approval from the institutional review board (IRB), the sample size was calculated with 95% confidence level, 5% margin of error and expected error percentage 7.6%.¹ Data was collected from all the surgical biopsy specimens submitted to the department using non-probability convenience sampling. Specimens submitted for frozen section and cytological analysis were excluded.

The study used pre-existing tissue obtained for clinical purposes from human subjects, and, thus, it was deemed to carry "minimal risk," and the requirement for informed consent was waived by the IRB. The questionnaire exploring the errors was prepared after extensive literature search.^1-3,5,7-11 It included the type of error observed in each phase, date on which the error was observed, and the person who observed the error. The questionnaire was later distributed among faculty members and subject specialists for content validity. Technical staff was distributed at each station accordingly. Error rate was analysed in all the pre-microscopic processes, including requisition, grossing, fixation, processing, embedding, microtomy, staining and cover slipping. The types of errors were noted and coded in the first step (Table-1).

Six Sigma is a metric that quantifies the performance of processes as a rate of Defects per Million Opportunities (DPMO).^3,6-8 Six Sigma programmes also encompass robust techniques such as Define-Measure-Analyse-Improve-Control (DMAIC) and Root Cause Analysis (RCA) to find and eliminate defects and variation within a process (Figure-1).

DPMO is defined as the average number of defects per unit divided by the number of opportunities to make a defect on the product during that run normalised to one million. Opportunity is the lowest defect noticeable by the customer.

In order to calculate DPMO, three distinct pieces of information are required: the number of units (tests) produced; the number of defect opportunities per unit (test); and the number of defects.^8,12

DPMO = (Number of Defects X 1,000,000)

(Number of Defect Opportunities/Unit) x Number of Units)

Using the Six Sigma metrics reference table (Table-2),

DPMOs and Sigma metrics for errors every step of the specimen processing were calculated.^6-8

RCA was applied to the process of histology preparation in order to identify the root cause of each previously identified problem using Eindhoven classification.⁴

 

Results

 

There were 2420 samples. Errors were reported in all stages of the surgical specimen handling process, with the highest frequency in grossing (G6: n=1085, 44.83%) (Figure-3),

followed by requisition (R3: n=893, 36.9%) and cover slipping (C1: n=776, 32.06%) (Table-3).

RCA done using Eindhoven classification revealed contributing factors, like lack of organisation, inappropriate process flow, poor knowledge and unawareness of facts regarding patient safety (Table-4, 5).

 

Discussion

 

Histopathological diagnosis of tissue sections is wholly dependent upon microscopic examination and interpretation. Basic requirements for arriving at a conclusive diagnosis include correct biopsy procedure, proper fixation and processing techniques, adequate sectioning and staining. RCA is an effective way to highlight errors in routine histopathology and their attributes. Six Sigma is a technique that allows objective assessment of process performance. Several studies have examined the importance of Sigma metrics in quantifying the performance of an analytical testing process.^7-11 In our study, Six Sigma metrics value for all the steps involved in the production of slides specimen receiving and processing was less than 3 which is far less than previously reported;^1,4-6 indicating lack of quality management and standard protocols.

Majority of requisition errors (36%, Sigma metrics 1.9) were due to insufficient clinical information needed for specimen processing and histological diagnosis which was in contrast to 3.6% and 6% reported earlier.^1,13 A study revealed that additional clinical information resulted in amended reports in 10% cases.^14,15 Second major requisition and accessioning error was mainly due to the use of inappropriate container and inadequate fixative volume ratio. There was no technical staff assigned for the accessioning bench. Maximum errors were noted in grossing, floatation of tissue sections and routine H&E staining. In one study, errors detected in each phase were: accessioning (6.5%), gross dissecting (28%), processing (1.5%), embedding (4.5%), tissue cutting and slide mounting (23%), staining, (1.5%), labelling and releasing (35%)¹ (Figure-3).

Grossing errors were attributed to lack of knowledge, training and expertise in resident pathologists. Study carried out in Brazil revealed that inappropriate macroscopic description of the specimen and inadequate representative sections may result in a very serious damage to the patient.¹⁵ A study proposed a patient safety curriculum for anatomical pathology residents to improve their skills and, in turn, provision of improved patient care.¹⁶ A study at a Nigerian laboratory observed that majority of errors were due to missing demographic information on request forms (22.8%), poor technical quality of slide sections (18.4%) and typographical errors by the typists (12.3%).¹⁷

Processing errors were mainly due to running wrong processing schedules (24%, Sigma metrics 2.3) occurring as a result of inconsistency in the level of knowledge and training of different technicians handling the equipment. Improper tissue orientation (6%, Sigma metrics 3.1) during embedding may result in missing the relevant diagnostic material. Inappropriate ribbon thickness (15%, Sigma metrics 2.6), tissue folds, mislabelled slides were the major causative factors, resulting in microtomy errors (Figures-2, 3).

Floaters and carry-overs may result in near-missed events, thus affecting final histological diagnosis as demonstrated in a study.^18,19 Most of the artefacts during staining are due to altered staining intensity as a result of low-quality stains, impurities attributed to insufficient filtration of staining solutions, and lack of potential of hydrogen (pH) and temperature monitoring^17,19 (Figure-3). Majority of technicians never consulted equipment manual for handling operating errors; whereas the technical persons of the relevant companies supplying the equipment lacked the sufficient knowledge and competency to handle trouble-shootings. Standard operating procedures (SOPs) were either lacking or were not being followed (Table-5).

According to a study, the higher the number of methods with a Sigma metric of 5 or better, the lower are the costs for reagents, supplies and control material required to monitor the performance of the methods.8 RCA in the current study revealed that most of the pre-microscopic errors were due to failure in workflow process, inappropriate knowledge and malpractice of laboratory workers, provision of low-quality reagents, lack of organisational standards and responsibilities (Table-5).

The unwillingness of laboratory workers to report errors, lack of laboratory information system for data retrieval, improper record maintenance and data entry on registers and charts, and lack of organisational support were limitations of the current study.

Findings of the current study indicate that by highlighting the most relevant points of interest, it is possible to improve both the methodology and the procedural safety. A follow-up study is recommended after the adoption of lean methodology to re-evaluate the impact of new quality measures on Six Sigma metrics. Furthermore, errors in the post-analytical phase and other tests, including fine needle aspiration cytology (FNAC) and frozen sections, should also be subjected to Six Sigma metrics and RCA using Eindhoven classification.

 

Conclusion

 

Errors were found at almost every step of the process. A step-wise implementation of quality control and strict internal audit are needed to avoid these errors which significantly affect test results and customer satisfaction, thus sabotaging the laboratory image.

 

Disclaimer: None.

Conflict of Interest: The person who signed the ethical review statement was also a co-author.

Source of Funding: None.

 

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