Haematology Flashcards
(178 cards)
Disseminated intravascular coagulation
Pathophysiology
- Hemostasis goes out of control
- Various blood clots form –> organ ischaemia (kidneys, liver, lungs, brain)
- These clots consume platelets and clotting factors
- Therefore the rest of the blood is low on these factors
- Fibrin degradation products in the circulation (from breakdown of the clots) also interferes with new clot formation
- Therefore resulting in bleeding with even the slightest damage to vessel walls
= Bleeding and clotting
Disseminated intravascular coagulation
Investigations
- Decreased platelets
- Decreased fibrinogen
- Prolonged prothrombin time (PT)
- Prolonged activated partial thromboplastin time (APTT)
PT and PTT reflect low circulating coagulation factors - Elevated D-Dimer (fibrin degradation product)
- Schistocytes due to microangiopathic haemolytic anaemia
Disseminated intravascular coagulation
When might you see chronic DIC
- Solid tumours
- Large aortic aneurysms
Disseminated intravascular coagulation
What would you see on investigations
- Relatively normall findings due to compensation
Disseminated intravascular coagulation
Management
Focus on underlying cause
- Support underlying organs (ventilator, haemodynamic support, tranfusions if needed)
Disseminated intravascular coagulation
Causes
- Sepsis
- Trauma
- Obstetric complications, e.g. HELLP syndrome, amniotic fluid embolism
- Malignancy
Can all initially tip the balance in favour of clotting –> starting the process of DIC
Haemophilia
Pathophysiology
- Deficiency of clotting factors
- Leading to bleeding
Haemophilia
Inheritance
X-linked recessive
- All of the X chromosomes need to have the abnormal gene
- Men only require one abnormal copy as they only have one X chromosome
- Women require two abnormal copies
- If they only have one copy –> carrier
- Almost exclusively affects males as for a female to be affected it would require an affected father and an affected/carrier mother
Haemophilia
Features
- Excessive bleeding in response to minor trauma
- Risk of spontaneous hemorrhage
- Haemoarthroses (bleeding into joints)
- Haematomas
- Prolonged bleeding after trauma/surgery
- Cord bleeding in neonates
- Bleeding of gums, GI tract, UT (haematuria), retroperitoneal space, intracranial
KEY presentation of severe disease = spontaneous bleeding into joints and muscles
Haemophilia
Investigations
- Prolonged APTT
- Bleeding time, thrombin time and prothrombin time all normal
- Genetic testing
Haemophilia
Management
Prophylactically:
- Replace clotting factors via IV
- Complication = formation of antibodies against the clotting factor, making it ineffective Tx
Acutely:
- Infusions of affected factor (VIII or IX)
- Desmopressin to stimulate release of von Willebrand factor
- Antifibrinolytics, e.g. tranexamic acid
Haemophilia
Types
- Type A = deficiency in factor VIII
- Type B = deficiency in factor IX (Christmas disease)
Hyposplenism
Causes
- Splenectomy
- Sickle-cell
- Coeliac disease, dermatitis herpetiformis
- Graves’ disease
- Systemic lupus erythematosus
- Amyloid
Hyposplenism
Features on blood film
- Howell-Jolly bodies
- Siderocytes
Splenectomy
Post-splenectomy risks
- Pneumococcus
- Haemophilus
- Meningococcus
- Capnocytophaga canimorsus (dog bites)
Splenectomy
Vaccination
If elective, should be done 2 weeks prior to operation:
- Haemophilus influenza Type B (HiB)
- Meningitis A&C
Also:
- Annual influenza
- Pneumococcal every 5 years
Splenectomy
Antibiotic prophylaxis
- Penicillin V for at least 2 years or until 16 yrs old
- Can sometimes be for life
Splenectomy
Indications
- Trauma (1/4 = iatrogenic)
- Spontanous rupture (EBV)
- Hypersplenism (hereditaory sphero/elliptocytosis)
- Malignancy (lymphoma, leukaemia)
- Splenic cysts, hydatid cysts, splenic abscesses
Splenectomy
Complications
- Haemorrhage - from SHORT GASTRIC or SPLENIC HILAR vessels
- Pancreatic fistula (from iatrogenic damage to tail)
- Thrombocytosis - prophylactic aspirin
- Encapsulated bacteria infection (strep pneumo, haem influenza, Neisseria meningitidis)
Splenectomy
Post-splenectomy changes
- Platelets will rise first
- Blood film will change after following weeks
- Howell-Jolly bodies will appear on the film
- May also see target cells, pappenheimer bodies
- Increased risk of post-splenectomy sepsis -> prophylactic Abx and pneumococcal vaccine
Splenectomy
Post-splenectomy sepsis
- Typically occur with encapsulated organisms
- Risk is greatest in < 16 yrs and > 50 yrs
- Tx = Penicillin V 500 mg BD and Amoxicillin 250 mg BD
Splenectomy
Travel
- Asplenic individuals travelling to malaria endemic areas are at high risk and should have both pharmacological and mechanical protection
Myeloproliferative disorders
Umbrella term for what?
- Primary myelofibrosis
- Polycythaemia vera
- Essential thrombocythaemia
Myeloproliferative disorders
Pathophysiology
- Uncontrolled proliferation of a single type of stem cell
- Considered a type of bone marrow cancer