Specialist Haematology —
Training activity: 8

Details

Analyse and interpret an inhibitor screen and calculate the level in Bethesda units

Type

Developmental training activity (DTA)

Evidence requirements

Evidence the activity has been undertaken by the trainee​.

Reflection on the activity at one or more time points after the event including learning from the activity and/or areas of the trainees practice for development.

An action plan to implement learning and/or to address skills or knowledge gaps identified.

Reflective practice guidance

The guidance below is provided to support reflection at different time points, providing you with questions to aid you to reflect for this training activity. They are provided for guidance and should not be considered as a mandatory checklist. Trainees should not be expected to provide answers to each of the guidance questions listed.

Before action

What are the intended outcomes of the training activity?

• How will you focus your attention on identifying appropriate investigations, interpreting results in a clinical context, and performing quality assurance for haemostasis?
• What foundational knowledge do you need to possess regarding coagulation factors, the nature of circulating inhibitors, and the principles of the Bethesda assay before you begin?
• Is your objective to demonstrate a high-level understanding of the mathematical calculation of Bethesda units and how this informs the clinical management of patients with inhibitors?

What do you anticipate you will learn from the experience?

• What specific insights do you hope to gain regarding the practical aspects of interpreting an inhibitor screen, such as distinguishing between a factor deficiency and a time-dependent inhibitor?
• Based on what you already know about prolonged APTT investigations, what do you expect to learn about the pitfalls of the Bethesda assay, such as the impact of sample dilution or incubation times?
• How will this experience improve your ability to draw conclusions about assay performance by applying internal quality control (IQC) principles to a complex, multi-step calculation?
• In what ways will this activity prepare you for the interpretive responsibilities of a post-programme Clinical Scientist, particularly in reporting results that dictate treatment strategies for bleeding disorders?

What actions will you take in preparation for the experience?

• How will you discuss the specific analytical protocols and calculation steps with your Training Officer to ensure you understand the laboratory’s Standard Operating Procedures (SOPs) for Bethesda units?
• What possible challenges have you identified—such as the risk of technical errors during calculation or the interference of a Lupus Anticoagulant—and how do you plan to handle them?
• Which national or international guidelines (e.g., BSH or WHO) will you review beforehand to ensure your interpretations are aligned with current best practices for the diagnosis of haematological disorders?
• How do you feel about embarking on this task? Recognising whether you feel confident or perhaps anxious about the mathematical complexity can help you focus your preparation on the areas where you need the most support.

In action

What are you doing?

• As you perform the inhibitor screen assay, are you meticulously following the established laboratory protocol for incubation and mixing?
• What decisions are you making regarding the selection of investigations—for example, which dilutions are you choosing to ensure you capture the inhibitor strength accurately within the measurable range of the Bethesda assay?
• How are you approaching the mathematical calculation of Bethesda units? Which parts of the process feel intuitive due to your knowledge of the coagulation cascade, and which require more conscious effort, such as the logarithmic conversion of residual factor activity?
• Why are you performing the steps in this specific order, and how does this ensure the stability of the coagulation factors involved?

How are you progressing with the activity?

• How effective are your actions in interpreting the initial screen—are you able to distinguish between a simple factor deficiency and a true circulating inhibitor in real-time?
• What challenges are you facing during the calculation, such as managing potential sources of error in the dilution series or identifying unusual patterns in the assay results?
• How are you applying the principles of internal quality control (IQC) in the moment to ensure the performance of the assay is reliable before you proceed to the final calculation?
• How does this activity connect to your existing knowledge of bleeding disorders and the scientific basis of Bethesda unit quantification?

How are you adapting to the situation?

• If the results are unexpected or the residual activity is outside the linear range of the assay, what alternative approaches or additional dilutions are you considering in the moment?
• What support or guidance might you need if you encounter technical difficulties with the analyser or discrepancies in the results that impact the clinical context of the report?
• Are you working within your defined scope of practice, particularly when reporting results that may significantly alter a patient’s treatment strategy?
• How are you adapting your reporting style to ensure the final Bethesda level is presented clearly and accurately to healthcare professional colleagues?

On action

What did you notice?

• How would you summarise the key procedural steps involved in performing the inhibitor screen and the Bethesda assay?
• What reagents and controls were selected for the assay, and did they perform within expected parameters?
• What were the results of the initial screening test, and what specific evidence (such as a failure to correct a prolonged APTT upon mixing) indicated the presence of an inhibitor?
• If an inhibitor was detected, what range of dilutions did you perform for the Bethesda assay to ensure the residual factor activity fell within the accurate range for calculation?
• What was the final calculated inhibitor level in Bethesda units, and were there any specific patterns in the data you noticed during the analysis?

What did you learn from the activity?

• What did you learn about the clinical significance of factor inhibitors in haemostasis and how their presence complicates the management of bleeding disorders?
• How has this activity improved your understanding of the scientific principles of the Bethesda assay, particularly how the incubation of patient plasma with normal plasma allows for the quantification of inhibitor potency?
• What technical challenges did you encounter during the assay or the mathematical calculation, and what did they teach you about the limitations of the technique?
• In what ways did your reflection-in-action (decisions made during the multi-step process) influence the accuracy of the final interpretation?
• How does the ability to accurately interpret and report these results relate to the high-level interpretive requirements for post-programme practice as a Clinical Scientist?

What will you take from the experience moving forward?

• What specific areas for continued development have you identified, such as improving your proficiency in logarithmic calculations or managing complex, time-dependent inhibitors?
• How will you apply the learning from this activity to your routine practice when identifying appropriate investigations for patients with unexplained bleeding?
• What factors that can affect the accuracy of inhibitor assays (e.g., sample handling, incubation temperature, or presence of Lupus Anticoagulant) will you be more vigilant about in the future?
• What ‘next steps’ will you take—such as reviewing BSH guidelines or local Standard Operating Procedures (SOPs)—to ensure your future reports are reported accurately and in a clinically meaningful way?
• What resources or specialist mentoring would be beneficial to further develop your expertise in the investigation of acquired and hereditary bleeding disorders?

Beyond action

Have you revisited the experiences?

• Since completing this training activity, have you had further opportunities to perform inhibitor screens or calculate Bethesda units, and did you encounter different types of inhibitors (e.g., acquired vs. congenital)?
• How has your understanding of the quantification of inhibitors deepened since you first reviewed your “reflect-on-action” notes for this activity?
• When reviewing the Specialist Haematology (S-HT-S2) module as a whole, how does this activity connect to your broader understanding of the clinical and laboratory investigation of bleeding disorders?
• Have you engaged in professional storytelling with senior staff or peers regarding the clinical significance of these results? How did their perspectives on patient management or treatment failure change your view of the laboratory’s role?

How have these experiences impacted upon your current practice?

• How has this training activity improved your technical proficiency in the multi-step Bethesda assay, particularly regarding precise pipetting and complex data analysis?
• In what ways has this experience influenced your routine interpretation of coagulation results, especially when faced with cases of unexpected bleeding?
• How has the knowledge gained from this task helped you in performing quality assurance tasks for other complex haemostasis investigations to ensure assay performance is reliable?
• How has this activity supported your preparation for observed ‘in-person’ assessments, such as the DOPS for investigating a patient with unexplained bleeding or determining the cause of a prolonged APTT?

How might these experiences contribute towards your future practice?

• What transferable skills have you developed, such as the ability to integrate clinical history with mathematical laboratory models, that will be essential in your future career?
• How will your ability to accurately interpret and report these assays contribute to effective patient diagnosis and the management of high-risk bleeding disorders?
• Based on these reflections, what clear actions for continued development have you identified, such as pursuing involvement in specialised coagulation research or the implementation of new testing methodologies?
• How does the mastery of this activity provide the foundation for the high-level analytical and interpretive responsibilities you will hold as a post-programme Clinical Scientist?

Relevant learning outcomes

#	Outcome
# 1	Outcome Identify appropriate clinical and laboratory investigations for the investigation of haemostasis.
# 2	Outcome Interpret and report results of investigations of haemostasis in the correct clinical context.
# 7	Outcome Perform quality assurance and control tasks across the range of investigations.