Haematology OSCE Stations

Haematology

Haematology OSCE stations are an important part of medical education and assessment, providing medical students with the opportunity to demonstrate their knowledge and skills in the diagnosis and management of haematological disorders. During a haematology OSCE station, students will typically be presented with a simulated patient scenario and will be asked to perform a range of tasks, such as taking a patient history, examining the patient, interpreting blood test results, and making recommendations for treatment.

Haematology OSCE stations are designed to mimic real-world clinical situations and to assess students’ ability to apply their knowledge and skills in a practical, hands-on setting. They are an essential part of the medical student curriculum and are used to evaluate students’ competence and preparedness for clinical practice. Try these two patient scenarios below.

Patient 1

A 63 year old male who was previously fit and well presents with easy bruising and profusely bleeding gums when he cleans his teeth. He has had the symptoms for 5 weeks.

Examination

On examination he has numerous echymoses and purpura. You can feel no lymph nodes.

What is the most important following test?

  • Group and save
  • Renal function
  • Liver function
  • Full blood count
  • Bone marrow biopsy

Full blood count

As his INR is “normal for him” and the symptoms have been present for 6 weeksd then next most important test is a full blood count. This will tell you his:

HB

White Blood Cell Count

Platelets

MCV

And a number of other things if a haematologist looks at the blood film (can be done straight from the full blood count sample by putting some blood on a slide).

Test results

His FBC shows the Following:

Hb 8.8 (13.5-15g/dl)
Platelets63 (150400 x 109)
WCC0.9 (4-11 x 109)
MCV83 (78-98fL)

What does this show? Please select ONE answer only.

  • Pancytopaenia
  • Thrombocytopaenia
  • Neutropaenia
  • Disseminated Intravascular coagulation
  • Haemeolysis

Pancytopaenia

A reduction in all major blood components (platelets, WCC and Hb) for exam purposes = pancytopaenia.

It’s a marker of marrow failure i.e. the bone marrow is not making “anything” effectively.

It most commonly occurs following Bone Marrow failure of any cause (e.g. cytotoxic drugs (chemotherapy), infiltration (cancer, tuberculosis), and infective causes.

Although there “is” neutopaenia and thrombocytopaenia, because of the findings together both those answers are “less right” and therefore no marks!

Diagnosis

His wife arrives in the clinic late. She explains that he’s a forgetful chap and forgot to tell you he’s taking warfarin for atrial fibrillation. She tells you he also had some antibiotics for a sore throat.

She shows you his INR book with the readings from the previous 6 weeks

DateINR
3 days ago2.0
3 weeks ago2.1
5 weeks ago2.3
7 weeks ago1.8
13 weeks ago2.6

What is the most likely explanation for his symptoms?

  • Cranberry juice ingestion
  • Antibiotics affecting warfarin
  • Accidental overdosing of warfarin
  • Other concomitant medication
  • None of the above

None of the above

The key question is : “what is the explanation for his symptoms”, not “what is the effect of antibiotics on warfarin”.

His INR is stable. This does therefore NOT explain his symptoms over the the past 5 weeks and an alternative cause should be sought.

His INR level does not explain his bruiding, therefore there must be another explanation.

Things like…

Cranberry juice
Omeprazole
Disulfiram
Sodium Valproate

…are all enzyme inhibitors which can reduce the metabolism of warfarin BUT there is no evidence that this is happening here.

Patient 2

A 62 year old man presents with a swollen right calf 3 weeks following a left hip replacement.

He is otherwise fit and well.

He is known to have rheumatoid arthritis.

He was concerned about a deep vein thrombosis.

Examination

On examination his left leg is 4cm more swollen than his right leg. His calf is tender along the venous system

What would be the investigation of choice to confirm this?

  • D-Dimer Test
  • MRI lower limb
  • Ultrasound Doppler right calf
  • Venography
  • None of the answers listed here

Ultrasound Doppler right calf

An ultrasound scan will confirm clot in the venous system. It is the simplest and least invasive of the tests available.

Always be wary when offered unusual sounding investigations like MRI calf. Although it may well show up the DVT, it wouldn’t be the investigation of choice in a routine patient.

Test results

An Emergency Department doctor tells you that he feels the patient can be discharged. He tells you this because he shows you the D-Dimer result, which is “negative”. The result is shown below.

 D-Dimer 0.08 (Normal range 0-0.18)

Which of the following statements is true about D-Dimer testing in general patients with a suspected DVT?

  • It can be used to discharge patients based on their underlying clinical risk
  • It can never be used alone as a basis to discharge patients
  • It can never be used to discharge patients even combined with a clinical risk score
  • It can be used to discharge patients suspected of having a DVT in combination with duplex ultrasound
  • None of the listed answers are correct.

It can be used to discharge patients based on their underliying clinical risk

D-dimer test can be used to exclude DVT in patients who are assessed to be “low clinical risk” of DVT.

An individuals pre test risk can be checked using a “Wells score”.

A patient who is clinically “low risk” with a negative D dimmer can be reassured.

The WELLS score is shown below:

The WELLS Score

Active Cancer+1
Paralysis Paresis or plaster to extremity+1
Bedridden for 3 days/ surgery within last 12 weeks+1
Localised tenderness alone distribution of deep venous system+1
Entire leg swollen+1
Calf swelling >3cm compared to the other leg+1
Pitting oedema confined to the symptomatic leg+1
Previous DVT+1
Alternative diagnosis less likely than DVT-2

<0 = Low Pre-test Probability – Check D dimer
1-2 = Moderate Pre-test Probability – Check D dimer
>3 = high pre-test probability – DO ULTRASOUND

Next steps

What is the most appropriate action?

  • Assuming no contraindications: give low molecular weight heparin injection and arrange Doppler ultrasound
  • Assuming no contraindications: give aspirin 300mg and arrange Doppler ultrasound
  • Discharge with follow up review at GP
  • Assuming no contraindications: give warfarin 10mg and arrange Doppler ultrasound
  • Assuming no contraindications: give Clopidrogel 300mg and arrange Doppler ultrasound

Assuming no contraindications: give low molecular weight heparin injection and arrange Doppler ultrasound

Using the wells score he is “high risk”.

I.e. >3cm swelling

Post op <12 weeks post surgery

Tenderness over deep venous system.

I.e. 3 = high risk. A D dimer in a high risk patient CANNOT be used to “rule out” a DVT. An ultrasound should be arranged.