Discussion - Part 2 (Testing Errors)

Testing errors within a transfusion service laboratory encompass a broad range of error types and can be defined in many ways. How such errors are defined influences their relative frequency as causes of serous adverse events.

• Categorizing testing errors
• Testing errors as root causes
• Types of conduct
• This case
• Further reading

CATEGORIZING TESTING ERRORS 

Before discussing "testing errors," error needs to be defined and understood. Hofer et al. believe that medical errors should be defined in terms of failed processes that are clearly linked to adverse outcomes:

• Hofer TP, Kerr EA, Hayward RA. What is an error? (Effective Clinical Practice,  Nov/Dec 2000; American College of Physicians website)

Besides understanding what errors are, it is important to remember that healthcare workers are reluctant to report errors unless the organization has a blame-free culture of error management.

• Lawton R, D Parker D. Barriers to incident reporting in a healthcare system. Qual Saf Health Care 2002;11:15-8.

As discussed earlier, RCA requires standardized terminology, including the need to have a common understanding of what constitutes "testing error" as a root cause. In the blood bank we are accustomed to referring to errors made by technologists when performing laboratory tests by the catchall phrase "technical errors" or "human technical errors", including errors of interpretation.

In contrast, MERS-TM limits technical error to "physical items such as equipment, physical installations, software, materials, labels and forms". 

In MERS-TM, based on the Eindhoven classification, human testing errors would fall into one of the following categories (Table 1):

Table 1. Partial MERS-TM classification of root causes Full codes:  MERS-TM codes
Category			Description	Code
ACTIVE ERRORS (HUMAN)			Errors or failures resulting from human behavior
		External	Human failures originating beyond the control and responsibility of the investigating organization	HEX
	Knowledge-based behaviors
		Knowledge-based errors	The inability of an individual to apply existing knowledge to a novel situation	HKK
	Rule-based behaviors
		Qualification	Incorrect fit between an individual's qualifications, training, or education and a particular task	HRQ
		Coordination	Lack of task coordination within a health care team in an organization	HRC
		Verification	Failures in the correct and complete assessment of a situation, including relevant conditions of the patient and materials to be used, before starting the intervention	HRV
		Intervention	Failures that result from faulty task planning (selecting the wrong protocol) and/or execution (selecting the right protocol but carrying it out incorrectly)	HRI
		Monitoring	Failures during monitoring of the process or patient status during or after the intervention	HRM
	Skill-based behaviors
		Slips	Failures in performance of fine motor skills	HSS
		Tripping	Failures in whole-body movements	HST

TESTING ERROR AS A ROOT CAUSE 

Regardless of how testing errors are categorized, adverse events caused  by technologists making mistakes when performing laboratory tests remain a significant source of serious adverse events. For example, the SHOT Annual Report 2003 includes183 errors made in transfusion service laboratories involving errors in ABO and Rh typing,  antibody identification, as well as errors unrelated to laboratory testing. Example:

• Case 18. A BMS (lab technologist) not normally working in transfusion misread manual ABO group. 2 units ABO incompatible blood given before error realised. Patient died from injuries.

• Case 19.  Uncrossmatched group specific blood requested. An inexperienced BMS misread manual group, checked by senior BMS but error not recognised. ABO incompatible blood given. Patient survived.

• Case 27. A 42 year old female patient underwent reconstructive surgery following mastectomy, following which she required urgent transfusion. Pretransfusion testing was carried out urgently by a BMS not normally working in transfusion. The patient’s Rh group was incorrectly determined as positive and Group O Rh positive blood was crossmatched and issued. The patient was aware that she was Rh negative and queried the group of the transfused blood, but was reassured by a nurse.

• Case 30. Blood was requested out of hours for a routine transfusion. The on-call BMS did not normally work in the transfusion laboratory. The antibody screen was positive, however the BMS wrongly interpreted it as due to ‘non-specific IAT antibodies’ despite a negative IAT control. He crossmatched and issued apparently compatible blood. The following day further investigations showed an anti-S and anti-Kp^a. Two of the transfused units were S positive. The patient had a poor haemoglobin increment. The BMS was suspended from on-call duties.

TYPES OF CONDUCT 

Marx has outlined 4 types of overlapping conduct related to error: human error, negligence, reckless conduct, and intentional rule violations (examples shown are added by TraQ): 

Marx D. Patient safety and the “just culture”: A primer for health care executives

Human error. Mistakes and lapses that have an inadvertent outcome, e.g., 

• Technologist is distracted and inadvertently adds the incorrect reagent to a test, resulting in wrong results. 

Negligence. Failure to exercise the skill, care, and learning expected of a reasonably prudent healthcare practitioner. Negligent actions are different from "honest mistakes". Negligence involves preventable, harmful errors that fall below the standard expected of a reasonably careful and knowledgeable practitioner acting in a similar situation.

Legally, negligence can be proved only if certain conditions are met: (i) a duty of care was owed; (ii) the duty was breached; (iii) injury or loss occurred; and (iv) the breach caused the damage, e.g., 

• Physician fails to order prenatal testing on pregnant woman throughout her pregnancy  and maternal antibody causes severe hemolytic disease in fetus

Reckless conduct (gross negligence). Involves conscious disregard of a visible, significant risk, e.g.,

• Nurse fails to check patient identity before hanging a unit of blood

Intentional rule violations. Intention to violate a known rule, procedure, or duty in the course of performing a task, e.g.,

• Blood collector knows that samples must be labelled at the bedside but prelabels them in order to complete afternoon collections and leave work early.

As shown, these types of conduct overlap as the examples can fall into more than one category.

THIS CASE 

In Case A8, an informal but expanded investigation was performed (not a formal RCA). The cause of the transfusion reaction was identified as "human error" on the part of the student and supervising technologist, with the recognition that the process for training students and new staff to perform batch testing needed to be reviewed to identify how it could be improved.

Using MERS-TM codes the root causes perhaps would have been identified as 

1. Active Errors (Human)--> Skill Based Behavior -->Slip -->code HSS
   • HSS definition: Failures in the performance of highly developed skills. An
     example could be a technologist adding drops of reagent to a row
     of test tubes and then missing a tube or computer entry error.
2. Latent Errors --> Organizational -->Transfer of Knowledge -->code OK
   • OK definition: Failures resulting from inadequate measures taken to ensure that situational or site-specific knowledge or information is transferred to all new or inexperienced staff.

   To suggest other MERS-TMcodes, please e-mail Pat

In terms of the types of conduct outlined by Marx, human error would seem to apply to both the student and supervising technologist. There was no reckless conduct or intentional rule violation. Was there negligence? What do you think?

TraQ self study question  

1. In Case 30 (SHOT 2003) it appears that a general duty technologist who did not normally work in the transfusion service incorrectly interpreted a positive antibody screen and wrongly issued crossmatch-compatible blood instead of identifying the antibody and crossmatching antigen-negative units.  

What are possible ways that the root cause(s) of this event could be coded using MERS-TM codes? (refer to MERS-TM codes)

MORE DISCUSSION...

• Part 1: Root cause analysis
• Part 2: Testing errors <--You are here
• Part 3: Risk management
• Part 4: Supervision of students
• Part 5: Regulations and standards

FURTHER READING

• Hofer TP, Kerr EA, Hayward RA. What is an error? (Effective Clinical Practice,  Nov/Dec 2000; American College of Physicians website)

• Lawton R, D Parker D. Barriers to incident reporting in a healthcare system. Qual Saf Health Care 2002;11:15-8.

• Marx D. Patient safety and the “just culture”: A primer for health care executives

• SHOT Annual report 2003

• MERS-TM
  • MERS-TM codes

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