Haematology Flashcards
Disseminated Intravascular Coagulation (DIC)
Pathophysiology
Clinical Features
Diagnosis/Investigations
1.) Pathophysiology - procoagulant state due to dysregulation of coagulation and fibrinolysis causing widespread clotting and bleeding
- causes: an acutely unwell patient, sepsis, trauma, malignancy, obstetric (pre-eclampsia, amniotic fluid embolism, AFLP)
- release of tissue factor (TF) which binds to coagulation factors that then trigger the extrinsic pathway (via Factor VII) which subsequently triggers the intrinsic pathway (12, 11, 10, 9, 2, 1) of coagulation
2.) Clinical Features
- bleeding: e.g. epistaxis, easy bruising, petechiae/purpura, gums,
GI bleeding, blood in stools, haematuria, menorrhagia
- clotting: can cause strokes, MI and PEs
- anaemia: fatigue, pallor, SOB etc
- shock: reduced blood flow can lead to organ damage
3.) Diagnosis/Investigations
- clotting: low platelets and low fibrinogen with increased fibrinogen degradation products, prolonged PT and APTT
- blood film: schistocytes (due to MAHA)
4.) Management
Haemolytic Uraemic Syndrome
Pathophysiology
Clinical Features
Investigations
Management
1.) Pathophysiology - occurs when there is thrombosis within small blood vessels throughout the body which produces a classical triad of:
- MAHA (↓Hb) + thrombocytopenia + AKI
- usually triggered by Shiga toxin (E.coli 0157) (90% in kids), increased risk when using Abx and anti-motility medication to treat E.coli gastroenteritis
- mainly seen in young children
- other causes: pneumococcal infection, HIV, SLE, drugs, cancer
2.) Clinical Features
- brief gastroenteritis, often with bloody diarrhoea
- HUS sx often starts 5 days after onset of diarrhoea:
- reduced urine output, haematuria, bruising
- abdominal pain, oedema, hypertension
- lethargy and irritability, confusion
3.) Investigations
- bloods: FBC (↓Hb), clotting (↓plts), U+Es (AKI)
- blood film: schistocytes
- MAHA: confirmed if Hb <80 w/ a negative Coombs test
- stool culture: looking for STEC infection (PCR for Shiga toxins)
4.) Management - medical emergency (10% mortality)
- urgent referral to the paediatric renal unit
- self-limiting but supportive management is vital
- careful maintenance of fluid balance
- if required: dialysis, antihypertensive, transfusions
- 70 to 80% of patients make a full recovery
