Using Clinical Reasoning in Exams (SBAs and OSCEs)

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Medical school assessments are designed to ensure you are prepared to work as a doctor. As discussed in our introduction to clinical reasoning page, a robust approach to collecting, filtering and evaluating clinical information is a key aptitude that all doctors must possess.

For this reason, clinical reasoning is one of the skills often tested in assessments – it’s why exam questions often start with a clinical case and why some exams allow you to discuss your thoughts with the examiner.

Single best answer questions (SBAs)

The need for clinical reasoning is one of the major differences between multiple choice questions (MCQs) and single best answer (SBA) questions.

In MCQs, there is typically only one correct answer, usually based on factual recall. SBAs, however, may come with multiple β€˜feasible’ options, but it is up to the student to determine which one represents the most appropriate or β€˜best’ option.

This is where clinical reasoning comes into play. The ability to identify, prioritise and evaluate clinical information allows you to identify the β€˜most likely’ diagnosis or the β€˜most appropriate’ investigation etc.

How does clinical reasoning help us answer SBAs?

To illustrate how clinical reasoning helps you answer SBA questions, try answering the question below.

Example question

Ali is seen by his GP due to regular episodes of shortness of breath.

Which is the most appropriate management for this patient’s likely diagnosis?

  • Co-amoxiclav
  • Furosemide
  • IM adrenaline
  • Low-dose morphine
  • Salbutamol

This is quite a difficult question to answer. You are probably thinking:

  • β€œHow old is the patient?”
  • β€œWere there any signs on examination?”
  • β€œWhat past medical history does the patient have?”

The questions you are considering reflect the initial steps of clinical reasoning. Adding further informationβ€”and knowing what information to seekβ€”helps you determine how best to treat the patient.

Try answering the question again with additional information.

Revised question with additional detail

Ali is a 13-year-old patient who is seen by his GP due to regular episodes of shortness of breath. The episodes predominantly occur when he plays hockey outside in the cold weather. He has not had a fever or a productive cough. When he feels short of breath, Ali’s dad reports that he can hear wheezing from his chest.

Ali was born prematurely at 32 weeks gestation but has had all of his immunisations and progressed as expected through his developmental milestones. Ali’s mother has a history of eczema and hay fever.

Which is the most appropriate management for this patient’s likely diagnosis?

  • Co-amoxiclav
  • Furosemide
  • IM Adrenaline
  • Low-dose morphine
  • Salbutamol


Question walkthrough

As we progress through the summary, there are many β€˜clues’ that increase the likelihood of an asthma diagnosis but also rule out other relevant diagnoses.

  • Ali’s age makes it more likely for us to consider a diagnosis that might present in early life (e.g. asthma, allergy, chest infections) rather than a diagnosis that may present in later life (e.g. heart failure, lung cancer).
  • The trigger history (i.e. cold weather and exercise), which exacerbates the shortness of breath, makes an asthma diagnosis more likely.
  • The absence of fever or cough means it is less likely that Ali has a chest infection (an important negative); therefore, treating with antibiotics is unlikely to be the most appropriate option.
  • His birth history gives a risk factor for developing asthma, and his immunisation history makes certain respiratory diseases less likely as he is vaccinated against them.
  • Finally, the family history of atopy, in combination with the finding of wheeze on examination, gives a strong likelihood that the diagnosis is asthma.
  • Therefore, the most appropriate management option is salbutamol.

In this stem, the components of β€˜clinical reasoning concepts’, β€˜history and physical examination’ and β€˜problem identification and management’ were particularly important to reach the correct answer.

Let’s now consider a question with different clinical details.

Revised question with different details

Ali is a 78-year-old patient who is seen by his GP due to regular episodes of shortness of breath. He was initially seen by his GP 2 months ago with haemoptysis, weight loss and breathlessness. A chest x-ray at the time revealed multiple large opacities throughout the lung fields, however he elected not to proceed with any further investigations or treatments. He does not want to be admitted to hospital.

Ali has been nursed in bed by the district nurses for the past 2 weeks and has eaten very little in the last 48 hours. His breathlessness is now causing him extreme distress.

Which is the most appropriate management for this patient’s likely diagnosis?

  • Co-amoxiclav
  • Furosemide
  • IM Adrenaline
  • Low-dose morphine
  • Salbutamol

Low-dose morphine

Question walkthrough

In this case, the different β€˜clues’ give us a completely different clinical impression about the best approach to caring for this patient.

  • The age of the patient makes diagnoses in younger patients (e.g. new onset asthma) less likely, but increases the likelihood of age-related conditions (e.g. heart failure, malignancy).
  • The 2-month history of haemoptysis, weight loss and breathlessness provides important positive red flag features for malignancy.
  • The interpretation of clinical imaging gives us another strong indicator that malignancy is likely in this patient.
  • Shared-decision making is an important step in clinical reasoning, as it highlights the options we may need to consider in forming a management plan. Evaluating the clinical situation and maintaining situational awareness will help in this scenario. Consider how the management may differ if the patient wanted active treatment, including hospital admission.

All of these factors combined make it most likely, out of the available SBA options, that treating Ali with low-dose morphine is most appropriate as he is likely in the final stages of palliative treatment for metastatic lung malignancy.

In this instance, the components of β€˜history and physical examination’, β€˜choosing and interpreting diagnostic tests’ and β€˜shared decision-making’ are particularly important in determining the most appropriate course of action.

Pattern recognition vs analytical reasoning

Because asthma and lung cancer are fairly common diagnoses, you are likely to have encountered them in several textbooks/lectures/case discussions and met patients on clinical placement who have these diagnoses.

You may have been able to employ an intuitive approach (pattern recognition) to these questions because you are highly familiar with the illness scripts for asthma and lung cancer.

However, if you encountered the following question:

Example question

Daria is a 62-year-old Caucasian cleaner who has recently been diagnosed with type 2 diabetes. She presents to the GP with lethargy, generalised arthralgia (particularly affecting the hands) and 1kg of weight loss in the last 3 months.


Investigation Result Reference Range
Hb 160 115 – 165 g/L
White cell count 4.2 3.6 – 11.0 x10^9/L
Platelets 234 140 – 400 x10^9/L
CRP 7 <5 mg/L
eGFR 86 >90 ml/min/1.73m2
Ferritin 1569 10 – 300 ug/L
ALT 32 <33 U/L
ALP 128 30–130 U/L
Adjusted Calcium 2.34 2.2-2.6 mmol/L
HbA1C 52 < 42 mmol/mol
Glucose (fasting) 7.5 4-6 mmol/L

Which is the most likely diagnosis?

  • Diabetic ketoacidosis
  • Haemochromatosis
  • Myeloma
  • Rheumatoid arthritis
  • Systemic lupus erythematosus


Question walkthrough

Relying on pattern recognition from the stem is much more difficult in this situation. We must employ analytical reasoning to review the investigation results and rule in/out potential differential diagnoses.

  • Diabetic ketoacidosis (DKA) is unlikely in this case due to the prolonged symptom history (3 months). Furthermore, it is less likely (although not impossible) in type 2 diabetes. The fasting glucose level of 7.5 mmol/L also makes DKA less likely (although euglycaemic DKA is possible).
  • Haemochromatosis is a disorder which causes a build-up of excess iron in the body. It is a genetic condition that can display variable penetrance. In female patients with milder forms of haemochromatosis, it may not become symptomatic until after menstruation stops (which may be the case in this patient). The raised ferritin fits with this diagnosis. It may also explain the small joint arthralgia and the recent diagnosis of diabetes.
  • Myeloma may account for the bone pain (although pain in the hands is atypical), weight loss and lethargy. However, the lack of anaemia (normal Hb), normal adjusted Ca, and appropriate eGFR would make this less likely.
  • Rheumatoid arthritis (RA) might explain the hand pain, and it can also cause systemic symptoms like weight loss and lethargy. Whilst it is more common in women, it typically presents aged 25-50 (although not impossible in later life). The CRP in this patient is very slightly elevated (7), but the CRP is more likely to be >10 in patients with untreated RA.
  • Systemic lupus erythematosus (SLE) may also explain the joint pain and systemic symptoms. CRP is also likely to be more raised in SLE than is seen in this patient. From an epidemiological perspective, haemochromatosis is more common in a Caucasian population than SLE which makes SLE less likely than other answers in this case.

This question requires us to work through potential differentials, and investigation results logically and systematically to identify the most likely diagnosis. Several factors must be considered to reach the correct answer, and reasoning must be applied across multiple levels (e.g., epidemiology, history, investigation findings).

Practical assessments and OSCEs

Clinical reasoning is also very important in your practical assessments. In objective structured clinical examinations (OSCEs), your clinical reasoning will be tested when translating your case vignette into a focused and precise clinical assessment.

Some medical schools have specific components of their practical examinations which purposefully assess clinical reasoning (such as questions at the end of OSCE stations).

Example case vignette

Mela is a 69-year-old woman who presents to the GP with a 3-month history of slowed movement, reduced facial expressions, a resting tremor and an increasingly β€˜shuffling’ gait. Please conduct a neurological examination of this patient and present your findings and differential diagnoses.

Your clinical reasoning skills may allow you to deduce that it is highly likely that Mela has a new diagnosis of Parkinson’s disease (PD).

In this situation, 3 core components of the clinical examination make PD highly likely: bradykinesia, resting tremor, and rigidity.

You should, therefore, actively look for these signs on examination to help confirm your diagnosis. You may choose to perform additional special tests which further increase the likelihood of Parkinson’s disease (e.g. assessing for distractable cogwheel rigidity, assessing writing size, assessing for slow speed of movement such as the toe-tap test).

You may also wish to include additional examination components that help you distinguish Parkinson’s disease from other differentials (e.g. looking for evidence of vertical gaze issues which may increase the likelihood of progressive supra-nuclear palsy). By engaging in clinical reasoning, you can ensure that your examination is comprehensive enough to rule in/rule out any suspected diagnoses where possible.

Note: You should always refer to the guidance from your medical school when preparing for examinations. Some institutions may require you to perform a β€˜standardised’ examination or history in an exam setting.

Clinical reasoning resources

For more information on clinical reasoning, check out our range of free clinical reasoning resources:


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