Pathology of Haemostasis

Question 1

Define menorrhagia

Answer 1

Abnormally heavy bleeding on menstruation

Question 2

Define epistaxis

Answer 2

Acute haemorrhage from the nostril

Question 3

Define haemarthroses

Answer 3

Bleeding into the joints (often as a result of haemophilia)

Question 4

How would haemophilia appear in a blood test?

Answer 4

There would be elevated APTT due to issues is the formation of the intrinsic ten-ase complex. However, the rest of the test would be normal i.e. normal PT, TT, FBC and vWF.

Question 5

What causes haemophilia A?

Answer 5

Factor VIII deficiency

Question 6

What causes haemophilia B?

Answer 6

Factor IX deficiency

Question 7

What is von Willebrand disease?

Answer 7

An autosomal dominant disease where vWF levels are below the normal reference range

Question 8

What are the symptoms of von Willebrand disease?

Answer 8

There is a mild to moderate tendency to bleed, giving rise to bruising, nose bleeds, gingival haemorrhage, post-surgical bleeding and menorrhagia (excess loss of blood during menstruation)

Question 9

How would von Willebrand disease appear in a blood test?

Answer 9

There is prolongation of APTT (intrinsic pathway mainly affected)

PT, TT and platelet count remain unchanged.

Question 10

How may vitamin-K deficiency affect the coagulation cascade?

Answer 10

Vitamin K is required in order for the use of factor II (prothrombin), VII, IX and X, and therefore a lack of vitamin K can lead to the deficiency of the factors that it activates

Question 11

What may cause vitamin-K deficiency?

Answer 11

Haemorrhagic diseases of the newborn, biliary obstruction or malabsorption of vitamin-K or vitamin-K antagonist use

Question 12

Describe haemorrhagic disease of the newborn

Answer 12

Vitamin K may be low at birth due to no bacterial gut synthesis of vitamin K, liver immaturity or low vitamin K levels in breast milk. This vitamin-K deficiency leads to the inability to activate factor II, VII, IX and X

Question 13

How may haemorrhagic disease of the newborn be diagnosed from blood tests?

Answer 13

This is diagnosed by a prolonged PT and APTT (both intrinsic and extrinsic pathways are affected) but TT is normal (common pathway is normal)

Question 14

How is haemorrhagic disease of the newborn treated?

Answer 14

Prevention involves the prophylactic administration of vitamin K at birth, or treatment with IV vitamin K

Question 15

Where are coagulation factors produced?

Answer 15

The liver

Question 16

Describe how liver disease affects coagulation

Answer 16

Failure to produce coagulation factors, failure to absorb or use vitamin K, abnormal fibrinogen production (leading to an excess of sialic acid), hypersplenism and portal hypertension also lead to the increased destruction of platelets (thrombocytopenia).

Question 17

How may liver disease be diagnosed from blood tests?

Answer 17

This can be diagnosed due to a prolonged PT, APTT (which reflect the severity of liver cell failure) and TT (due to dysfibrinogenaemia) and increased FDPs (fibrin degradation products due to increased fibrinolysis) and thrombocytopenia

Question 18

How may kidney disease lead to impaired haemostasis?

Answer 18

Ineffective renal clearance leads to increased levels of plasma urea which leads to impaired platelet function

Question 19

How may kidney disease be diagnosed from blood tests?

Answer 19

This condition will present with a normal PT, APTT and TT as it exerts no direct effects on the coagulation cascade, but there will be a normal-low platelet count and therefore there will be a prolonged bleeding time due to the increased time taken for the platelets to aggregate (primary haemostasis)

Question 20

What is disseminated intravascular coagulation (DIC)?

Answer 20

This condition occurs when there is a widespread intravascular deposition of fibrin with the use of factors and platelets leading to an inappropriate and excessive activation of the haemostatic system. This condition can be compensated where the symptoms are sub-clinical, or can be decompensated where the individual presents with florid bleeding

Question 21

What may cause disseminated intravascular coagulation (DIC)?

Answer 21

Infection, malignancy, obstetric disorders, shock, liver disease, acute transplantation rejection, snake bites and intravascular haemolysis due to ABO incompatibility

Question 22

How may disseminated intravascular coagulation (DIC) be diagnosed from blood tests?

Answer 22

Lab tests will indicate a reduced platelet count due to their excess usage, prolonged PT, APTT and TT (due to the depletion of all coagulation factors), low fibrinogen and raised fibrin degradation products

Question 23

What is massive transfusion syndrome?

Answer 23

When blood is stored after donation, red blood cells lose the store of coagulation factors and platelets, and therefore if a large proportion of blood has to be transfused into a patient as a result of acute blood loss or trauma, then it is highly likely that they will develop a coagulation defect as a result.

Question 24

How may massive transfusion syndrome be diagnosed from blood tests?

Answer 24

The main diagnostic factor is whether there is knowledge of mass transfusion having taken place. Aside from this, there will be a prolonged PT, APTT and a normal or prolonged TT. There will be low platelet levels and low fibrinogen due to lack of stores.

Question 25

What is the treatment for massive transfusion syndrome?

Answer 25

In order to compensate, they should be given platelets, cryoprecipitate or free frozen plasma