Module 6

Question 1

What is the STRONGEST patient-based predictor of VTE risk and why? What are some other risk factors?

Answer 1

AGE: chronic inflammation, increased vWF, VIII, endothelial dysfunction, thickened valves

hospitalisation (100x community risk)
previous VTE
obesity
trauma/surgery
immobilisation
hormonal therapy
acute infection/inflammation
cancer
APL
CVC insertion
ICU or CCU admission
Inherited thrombophilias (rare)

Question 2

What is the caprini model used for?

What are the cut off scores that determine risk?

Answer 2

Estimates the perioperative risk of VTE based on patient factors and operative factors

0 : very low risk <0.5%
1-2: low risk 1.5%
3-4: moderate risk 3.0%
≥5: high risk 6%

moderate and above get chemical prophylaxis unless high risk bleeding

Question 3

Which of the following is most likely to present with a recurrent VTE?

• PE
• proximal DVT
• distal DVT

Answer 3

proximal DVT: recurrence 26% (85% as DVT)
PE: recurrence 22% (50% as PE)
distal DVT: 7.% (85% as DVT)

Question 4

How does a prior history of superficial thrombophlebitis affect future DVT risk?

Answer 4

Increases with odds ratio 4-6

modulators that further increase risk (in order of highest risk to lowest)

• major surgery
• hormone therapy
• hospitalisation
• smoking/obesity

Question 5

How do hormonal therapies affect VTE risk?

Answer 5

Combined hormonal contraceptives increases risk by 2-4 fold (oral, transdermal patches and vaginal rings)
○ Baseline risk 2/10,000 woman years
○ COC: 5-12/10,000 woman years
Lowest risk with levonorgestrel

Question 6

What are the 3 key mechanisms that drive COVID-related coagulopathy?

Answer 6

ENDOTHELIAL DYSFUNCTION

• virus enters EC via ACE2
• complement mediated injury
• NETS
• antiphospholipid antibodies
• CVCs

STASIS

• prolonged immobility
• ACE2 mediated stasis
• myocarditis
• sepsis related flow and vasodilatation

HYPERCOAGULABILITY

• EC injury, plt activation
• vWF, PAI-1 and TF release
• increase in globulins, cytokines and chemokines

Question 7

What are the laboratory characteristics of COVID-coagulopathy?

Answer 7

FBC: lymphopenia, neutrophilia, thrombocytopenia or thrombocytosis

Mild prolonged APTT/PT or isolated APTT (transient LAC)

D-dimer markedly raised

Raised fibrinogen

Question 8

How do we adjust d-dimers for age?

Answer 8

Age adjusted d dimer score for patients >50 : Age x 10ug/L (conventional cut off is 500ug/L)

Question 9

What are the PERC criteria? (8)

Answer 9

Age <50
Pulse <100
O2> 94%
No haemoptysis
No prior history of VTE
No surgery or trauma in 4 weeks
No oestrogen use
No unilateral leg swelling

Question 10

What are the cut-off scores for risk tiers using the wells score for DVT and PE?

Answer 10

DVT
0 low
1-2 intermediate
3-8 high

PE
0-1-low
2-6 intermediate
7 and above high

Question 11

What are some signs on XR of PE?

Answer 11

Fleischner sign: enlarged PA
Westermark sign: regional oligaemia
Hapton’s hump: wedge shaped infarc
Pleural effusion/diaphragmatic elevation

Question 12

What are some signs of right heart strain on CTPA?

Answer 12

RV size : LV Size ratio >1
Flattened IV septum
Reflux of contrast into IVF or hepatic veins

Question 13

What are some mimics of an un-matched V/Q defect?

Answer 13

vasculitis
congenital vascular anomaly
malignancy
mediastinal adenopathy

Question 14

What are the VTE prophylaxis recommendations for TKA/hip fractures/THA?

Answer 14

○ LMWH, UFH, VKA, fondaparinux, DOACs (apix, rivaroxaban), aspirin or IPC
○ At least 10-14 days, up to 28-35 days
○ Combined pharmacological + IPC for at least 18 hours daily

Question 15

What are the VTE prophylaxis recommendations for knee arthroscopy?

Answer 15

if no prior VTE, no prophylaxis
if prior VTE, malignancy or >1 RF, consider prophylaxis
if total anaesthesia >90mins or VTE risk greater than bleeding, LMWH for 14 days