haematology - venous thrombosis

Question 1

risk factors for venous thrombosis

Answer 1

Virchows triad

1. vessel wall
2. blood
3. flow

Question 2

Wells scores for DVT

Answer 2

0 = low risk
1-2 = moderate risk
3-7 = high risk

Question 3

Wells scores for PE

Answer 3

0-1.5 = low risk
2-6 = moderate risk
6.5-12.5 = high risk

Question 4

high Wells score

Answer 4

US of affected limb

CTPA

Question 5

intermediate Wells score

Answer 5

D dimer
if D dimer high -> US/CTPA
if D dimer low -> rule out

Question 6

low Wells score

Answer 6

consider other

Question 7

risk factors for venous thrombosis

Answer 7

age
obesity
previous DVT/PE
immobilisation
major surgery
long distance travel
malignancy
pregnancy
COCP
HRT

Question 8

inherited causes of venous thrombosis

Answer 8

antithrombin deficiency
protein C deficiency
protein S deficiency
factor V leiden
lupus anticoagulant

Question 9

DVT prophylaxis

Answer 9

daily subcut LMWH
TED stockings

some DOACs licensed in post-op ortho patients

Question 10

DVT/PE treatment

Answer 10

LMWH
warfarin or DOAC

stop LMWH once INR is 2-3

Question 11

why is LMWH continued while warfarin is started

Answer 11

warfarin also affects protein C/S and can lead to procoagulant state before anticoagulant effect

Question 12

recurrent VTE

Answer 12

lifelong treatment

Question 13

duration of treatment for VTE

Answer 13

3 months minimum

provoked VTE: stop after 3 months

otherwise: risk stratification

Question 14

action of heparin

Answer 14

potentiates antithrombin III which inactivates thrombin and factor IX, X, XI

Question 15

LMWH delivery

Answer 15

subcut once daily

does not require monitoring unless late pregnancy, renal failure (monitor anti-Xa levels)

Question 16

heparin infusion cautions

Answer 16

monitor APTT

Question 17

antidote for heparin infusion

Answer 17

protamine sulphate

Question 18

side effects of heparin

Answer 18

bleeding
heparin induced thrombocytopenia
HIT
osteoporosis with long term use

Question 19

action of warfarin

Answer 19

inhibits reductase enzyme
no regeneration of active vit K
inhibits synthesis of factors II, VII, IX, X, and proteins C, S, and Z

adjust dose to maintain INR

Question 20

caution with warfarin in

Answer 20

pregnancy

risk of teratogenicity

Question 21

warfarin reversal

Answer 21

IV vit K (6 hours)

prothrombin complex concentrate - octaplex/beriplex (30 mins)

Question 22

target INR for 1st episode of DVT/PE

Answer 22

2-3

Question 23

target INR for recurrent DVT/PE

Answer 23

2.5-3.5

Question 24

protocol if INR 5-8 with no bleeding

Answer 24

withhold some doses
reduce maintenance
restart when <5

Question 25

protocol if INR 5-8 with minor bleeding

Answer 25

stop warfarin
slow IV vit K
restart when <5

Question 26

protocol if INR >8

Answer 26

stop warfarin
oral/IV vit K
check INR daily

Question 27

protocol if major bleeding

Answer 27

stop warfarin
prothrombin complex concentrate/FFP
IV vit K