Haematology II Flashcards Preview

Question Bank MRCS A. > Haematology II > Flashcards

Flashcards in Haematology II Deck (22):
1

Which of the following is true regarding the prothrombin time (PT)?
(Please select 1 option)
Assesses the intrinsic pathway of the blood coagulation cascade
Is increased with low molecular weight heparin
Is increased with warfarin
Is not prolonged in patients with fat malabsorption
May be restored to normal by the administration of protamine

Is increased with warfarin

It assesses the extrinsic pathway and therefore is prolonged with abnormalities of factors VII, X, V, or II.

The normal prothrombin time is 16-18s and is prolonged in patients with fat absorption.

The coumarin warfarin interferes with vitamin K metabolism, which inhibits the ã-carboxylation of factors II, VII, IX, and X and thus prolongs the prothrombin time.

Heparin has an immediate effect on coagulation by potentiation of the formation of irreversible complexes between antithrombin and activated serine protease coagulation factors and thus has minimal effects on the prothrombin time.

Low molecular weight heparin specifically acts on factor Xa and thus is not monitored either through activated partial thromboplastin time (APTT) or PT.

Vitamin K restores a normal prothrombin time and is used therapeutically if the PT is prolonged or the INR is very high.

2

Which one of the following is true of blood coagulation?
(Please select 1 option)
Addition of vitamin K to freshly drawn blood delays clotting
Heparin inhibits blood coagulation through its interference with vitamin K metabolism in the liver
Platelets are essential for blood clot
Thrombin converts fibrin to fibrinogen
Vitamin K is required for the production of factors III, VI, XI and XII

Platelets are essential for blood clot

Regarding blood coagulation:

Heparin increases the activity of anti-thrombin III which inhibits the clotting cascade
Vitamin K is used in liver to produce clotting factors and on its own has no anti-coagulation effect
Thrombin is important in the clotting cascade by releasing fibrin from fibrinogen
Platelets are essential for clotting factors II, VII, IX and X are produced in liver with vitamin K.

3

Which of the following is true of endotoxins?
(Please select 1 option)
Are involved in botulism
Can often survive autoclaving
Elicit an antibody response which may protect the host from future attack
Is found in the vesicle of bacterial cytoplasm
Is produced mainly by Gram positive bacteria

Can often survive autoclaving

Endotoxins:

Are lipopolysaccharides derived from the cell wall of Gram negative bacteria
Are heat stable (compare with exotoxin)
Are non-antigenic (compare with exotoxin)
Cause septicaemia and fever
Activate the alternative complement pathway.

4

Which of the following is correct regarding blood group antibodies?:
(Please select 1 option)
Anti-A and anti-B antibodies are usually IgM
Anti-A and anti-B are warm antibodies
Anti-D is a cold antibody
IgM antibodies are capable of transplacental passage
The rhesus antibody, anti-D is an IgM antibody

Anti-A and anti-B antibodies are usually IgM

Anti-A and anti-B are naturally occurring antibodies and are usually IgM. They react optimally at cold temperatures (4°C) and although reactive at body temperature they are called cold antibodies.

Immune antibodies like the rhesus antibody, anti-D, are commonly IgG. They react optimally at 37°C and are called warm antibodies.

Only IgG antibodies are capable of transplacental passage to the fetus.

5

A patient on the ward receiving a blood transfusion after hip replacement surgery is noted to have rigours.
On examination his temperature is 39°C ( baseline 36.5°C ). He also complains of abdominal pain and his blood pressure is 90 /55 mmHg (baseline 126/84 mmHg).
Which of the following is the next step in management of this patient?
(Please select 1 option)
Continue 10 min observations till completion of transfusion
Give the patient 1 g of paracetamol and continue transfusion
Give the patient chlorpheniramine 10 mg and paracetamol 1 g while slowing the rate of transfusion
Notify blood bank to recheck cross match
Stop the transfusion immediately and commence IV fluids

Stop the transfusion immediately and commence IV fluids This is the correct answerThis is the correct answer
This patient should be suspected to have an acute haemolytic transfusion reaction given the more than 2°C rise in temperature, abdominal pain and hypotension.

The transfusion should be stopped immediately, the set taken down and saline infusion commenced.

The blood bank needs to be notified and a sample may need to be collected but this is not the first priority.

If a severe haemolytic transfusion reaction is suspected the transfusion should not be continued (hence the remaining answer options are incorrect).

6

Which of the following statements is true about the storage conditions and shelf life of blood products?
(Please select 1 option)
Fresh frozen plasma is stored at −30°C for 12 months IncorrectIncorrect answer selected
Fresh frozen plasma is stored at −30°C for up to 24 months This is the correct answerThis is the correct answer
Packed red cells are stored at 4°C for up to 25 days
Platelets are stored at 4°C for up to 5 days
Platelets stored for 5 days at 22°C in a temperature controlled fridge

Fresh frozen plasma can be stored up to 24 months at −30°C.

Red cells are stored at 4°C for up to 35 days and platelets at 22°C for 5 days on a platelet shaker/agitator.

7

Which of the following is true about manufacture of pooled plasma derivatives?
(Please select 1 option)
Pooled plasma is often sourced from within the UK
The end product is a freeze dried product
The process does not involve any viral inactivation steps
These are usually manufactured from 10 donors at a time
These products have a short half life typically days

The end product is a freeze dried product

The plasma derivatives (such as Factor VIII) are prepared from several thousand plasma donations, typically 20,000 or 5000kg of plasma at a time. Pooled plasma has been sourced from outside UK since 1999 to avoid vCJD risks. The process involves several chemical steps including ethanol extraction, chromatography and viral inactivation steps, which results in a freeze dried product. These products have a long shelf life of several months to years.

8

Which of the following infusion times would be appropriate during the transfusion of a blood product in a stable patient?
(Please select 1 option)
A packed cell transfusion should be given over 20 minutes
A packed cell transfusion should be given over 90 minutes
A platelet transfusion should be given over 60 minutes
A platelet transfusion should be given over 90 minutes
A platelet transfusion should be given over 120 minutes

A packed cell transfusion should be given over 90 minutes

In a stable patient red cell packs may be transfused over 90-120 minutes while a platelet transfusion should not take more than 20-30 minutes.

Rapid infusion of red cells or fresh frozen plasma may be required in acutely bleeding patient but not in this patient who is stable.

9

What is the minimum dataset required for identifying a patient and a sample for purpose of a blood transfusion request?
(Please select 1 option)
Full name and gender
Full name, gender and patient identity number
Full name, gender, address and patient identity number
Full name, gender, date of birth, address and patient identity number
Full name, gender, previous blood grouping details, address and patient identity number

Full name, gender, date of birth, address and patient identity number

Given that maximum errors and near misses occur because of mislabelling or mistaken identity of patient or the sample a minimum data set is prescribed for transfusion requests.

This involves recording the full name, gender, date of birth, address (in some areas) and patient identity number. Previous blood grouping details are not required and missing elements of this minimum dataset are not acceptable in the transfusion service.

10

For which of the following patients would a gamma irradiated blood product be recommended?
(Please select 1 option)
16-year-old thalassaemic receiving regular transfusions
19-year-old nulliparous female after a road traffic accident
37-year-old patient with Hodgkin's lymphoma receiving chemotherapy
42-year-old lady receiving adjuvant hormonal therapy for breast cancer post radical mastectomy
Post operatively for carcinoma of the colon in a 50-year-old male

37-year-old patient with Hodgkin's lymphoma receiving chemotherapy

The most common indications for irradiated blood products include those at risk of transfusion associated graft versus host disease such as:

Neonates
Those receiving purine analogue based chemotherapy
Hodgkin's lymphoma
Immunodeficiency states
Post bone marrow transplants
The other scenarious described here do not necessarily represent an immunosupressed state in the list of conditions eligible for an irradiated blood product.

11

A pre-transfusion sample shows that a patient has blood group O.
This means that which of the following is true?
(Please select 1 option)
The red cells have A/B antigen but no antibodies in the plasma
The red cells have absent A/B antigen and plasma has anti A and anti B antibodies
The red cells have antigen A and plasma has anti B antibodies
The red cells have antigen B and plasma has A antibodies
The red cells may have any antigen but plasma has anti A and anti B antibodies

The red cells have absent A/B antigen and plasma has anti A and anti B antibodies

The answer options represent the following blood groups:

Blood Group O: The red cells have absent A/B antigen and plasma has anti A and anti B antibodies
Blood Group AB: The red cells have A /B antigen but no antibodies in the plasma
Blood Group A: The red cells have antigen A and plasma has anti B antibodies
Blood Group B: The red cells have antigen B and plasma has A antibodies
The remaining incorrect answer option does not represent any blood group

12

The risk of a viral infection transmitted via a transfusion is widely variable.
In the UK, the risk of transmission of hepatitis B would be best described as which of the following?
(Please select 1 option)
Slightly less than 0.01 per million donations
0.05 per million donations
0.2 per million donations
1 per million donations
Slightly more than 2 per million donations

Slightly more than 2 per million donations This is the correct answerThis is the correct answer
The common viral infections considered in the infective risks of a blood transfusion are hepatitis B, hepatitis C and HIV.

The risks are variable depending on the source of donation and the type of testing employed but generally in the United Kingdom the risks for hepatitis B are in the order of 2.2/ million donations while those for HIV and hepatitis C are 0.2 and 0.05/ million donations.

A broad knowledge of the risks may be required while consenting a patient for blood transfusion.

13

Which of the following is the blood product with the highest risk of transmission of a bacterial infection related to transfusion?
(Please select 1 option)
Cryoprecipitate
Fresh frozen plasma
Factor VIII concentrates
Packed red cells
Platelets

Platelets This is the correct answerThis is the correct answer
Since platelets are stored at room temperature (22°C), the risk of bacterial contamination is highest in this blood product.

In contrast, packed red cells are stored at an average of 4°C, while fresh frozen plasma as well as cryoprecipitate are stored at -20°C.

Factor VIII concentrates are heat inactivated freeze dried products with a minimal risk of bacterial contamination.

14

Which of the following potential blood donors would be excluded from donating whole blood or plasma?
(Please select 1 option)
A 27-year-old man who has had a tattoo on his arm for the last ten years
A 32-year-old lady whose sister was diagnosed with Creutzfeld-Jakob disease 3 years ago
A 38-year-old lady who underwent acupuncture for leg pain 5 months ago with a registered health professional
A 42-year-old man with a history of hepatitis when he was aged 18 years
A 56-year-old man who had a course of antibiotics for an upper respiratory tract infection which was completed 4 weeks ago

A 32-year-old lady whose sister was diagnosed with Creutzfeld-Jakob disease 3 years ago

Any potential donor whose immediate family member (parent or sibling) has had Creutzfeld-Jakob disease needs to be excluded from blood donation.

All other options cannot be excluded on the basis of the current blood donation guidelines (National blood service UK).

Hepatitis or jaundice would be an exclusion only if it occurred in the last 12 months.

Acupuncture in the last four months (unless performed by a registered professional) or body piercing /tattoos in the last six months would also be an exclusion.

Any infection in the preceding two weeks or a course of antibiotics within the last seven days would be considered an exclusion.

15

A 56-year-old man is being reviewed for an elective cholecystectomy in the pre-op clinic.
He has no co-morbidities apart from 2 attacks of cholecytitis in the last 12 months. He has never received a blood transfusion in the past.
What should the request for the blood bank include?
(Please select 1 option)
Cross match for 3 units only
Group and Save as well as cross match
Group and Save, direct Coombs' Test and a cross match for 2 units
Group and Save, direct Coombs' Test and a cross match for 3 units
Group and Save only

Group and Save only This is the correct answerThis is the correct answer
A 'group and save' is adequate for elective surgeries and is standard practise in most modern blood banks. This will involve blood grouping and its confirmation as well as an antibody screen.

Other options include crossmatch and a direct Coombs' Test (DAT) which are often done only if the antibody screen test is positive. These are not routinely done for elective surgery unless the patient has had a recent blood transfusion or a history of previous known red cell antibodies.

16

The most common error in transfusion according to the SHOT (serious hazards of transfusion) analysis is which of the following?
(Please select 1 option)
Cross match error in the blood bank laboratory
Incorrect indication for transfusion
Inability to detect antibodies in the blood bank laboratory
Incorrect storage temperature for blood products
Wrong identification or mislabelling of patient or sample

Wrong identification or mislabelling of patient or sample This is the correct answerThis is the correct answer
Mislabelling of samples, requests or wrongly identifying recipients are the most common of transfusion errors.

This was borne out in the SHOT study which analysed transfusion errors and 'near misses' in a UK wide audit. Other errors such as cross match error, incorrect storage and transfusion reaction due to an antibody not detected do occur but are rare.

17

A diabetic patient with idiopathic thrombocytopenic purpura presents with a leg ulcer which needs debridement.
His platelet counts are 15 ×109/L (NR 150-400). His blood sugars are poorly controlled and he has been started on a sliding scale insulin. He has previously responded to steroids and immunoglobulin infusions.
The product of choice to raise his platelets to a safe level for the debridement surgery is which of the following?
(Please select 1 option)
Intravenous immunoglobulin
Pooled platelets
Prothrombin concentrates
Single donor platelets
Trial of high dose steroids

Intravenous immunoglobulin

Intravenous immunoglobulin would be the product of choice in this patient given his diabetic status.

A trial of steroids is generally used if the patients have no contraindications for steroid related complications.

Platelets do not usually raise platelet counts in ITP as they are destroyed by the antibodies but could be used to treat a major bleeding emergency.

18

Which of the following is true regarding anaemia after partial gastrectomy?
(Please select 1 option)
Is usually due to iron deficiency
Is more common after Billroth I than Polya operations
May be due to folate deficiency
May result from malabsorption
Occurs in approximately 10% of untreated patients after three years

May result from malabsorption

Partial gastrectomies were traditionally performed for recurrent peptic ulceration. With the advent of H. pylori eradication therapy partial gastrectomies are now rarely performed. However, partial gastrectomies are still performed for peptic ulceration refractory to medical therapy.

Typically B12 deficiency is due to the impaired production of intrinsic factor, but it may be associated with iron and folate deficiency.

Billroth II more commonly than I.

Anaemia after partial gastrectomy occurs in over 70% of untreated patients after three years.

19

Which of the following is correct concerning platelet activation?
(Please select 1 option)
Is caused by von Willebrand factor
Is increased by prostacyclin (PGI2)
Is increased by endothelium derived nitric oxide
Is inhibited by thromboxane A2
Leads to the inhibition of glycoprotein IIb/IIIa complexes

Is caused by von Willebrand factor

von Willebrand factor causes platelet activation by binding to glycoprotein Ib receptors and exposed sub-endothelial components. Platelet activation (especially in areas of high shear) via vWf leads to aggregation.

Adenosine diphosphate (ADP) and thromboxane A2 are released by platelet degranulation and lead to further platelet activation.

Platelet surface glycoprotein complexes which are involved in platelet aggregation with fibrin and von Willebrand factor acting as ligands.

20

In red blood cells, which of the following is correct?
(Please select 1 option)
Carbon dioxide binds with reduced haemoglobin
Carbonic anhydrase is absent
Most carbon dioxide in venous blood is transported bound to albumin
Oxygen affinity of fetal haemoglobin is less than adult haemoglobin
Oxygen affinity of haemoglobin is increased in the presence of acidosis

Carbon dioxide binds with reduced haemoglobin

Carbon dioxide is carried in the blood in three forms:

Dissolved (10%)
Bicarbonate, the formation of which is encouraged by carbonic anhydrase present in the red cell
As carbamino compounds: hydrogen ions liberated from the bicarbonate reaction are bound to haemoglobin which encourages the release of oxygen, since reduced haemoglobin is less acid than the oxygenated forms.
Thus the presence of reduced haemoglobin in the peripheral blood helps with the loading of carbon dioxide, while the oxygenation which occurs in the pulmonary capillary assists in its unloading. The fact that the deoxygenation of the blood increases its ability to carry carbon dioxide is often known as the Haldane effect.

Fetal haemoglobin contains g-polypeptide chains in place of the b-chains of Hb A. Its resistance to denaturation by strong alkali is used in its quantitations.

Hb F is the predominant haemoglobin from eight weeks gestation, and constitutes 90% of the total haemoglobin of the 6 month fetus. At birth 70% of the total is Hb F, and synthesis decreases rapidly postnatally, such that by a year only 2% is present.

Hb F has a greater oxygen affinity than Hb A, so the growing fetus is preferentially nourished by oxygen in utero.

21

Which one of the following is an oncogene?
(Please select 1 option)
The BCR-abl translocation (Philadelphia chromosome)
The N-myc gene
The retinoblastoma gene
The WT1 (first Wilm's tumour) gene
The WT2 (second Wilm's tumour) gene

The N-myc gene

Oncogenes are endogenous human DNA sequences that arise from normal genes called proto-oncogenes.

Proto-oncogenes are normally expressed in many cells, particularly during fetal development, and are thought to play an important regulatory role in cell growth and development. Alterations in the proto-oncogene can activate an oncogene which produces unregulated gene activity, contributing directly to tumourigenesis.

Oncogene alterations are important causes of:

Rhabdomyosarcomas (ras oncogene)
Burkitt's lymphoma (C-myc is translocated intact from its normal position on chromosome 8 to chromosome 14)
Neuroblastoma (N-myc proto-oncogene is seen in a proportion of patients with poor prognosis).
They should be contrasted with tumour suppressor genes. In this situation the genes normally down regulate cell growth and require inactivation to allow malignant growth. Examples include retinoblastoma.

22

Post splenectomy, which of the following is correct?
(Please select 1 option)
Causes hypergammaglobulinaemia
Heinz bodies are seen in the peripheral film
Is less likely to result in morbidity if performed in childhood
Patients rarely require penicillin prophylaxis
Thrombocytopenia is a feature

Heinz bodies are seen in the peripheral film

Post-splenectomy patients are susceptible to encapsulated bacteria, thus immunisation and prophylactic antibiotics are required. If performed in childhood there is a greater chance of disease.

Features include:

Howell-Jolly bodies
Hypogammaglobulinaemia
Heinz bodies
Lymphocytosis and thrombocytosis are also seen.