Objective criteria (Geneva, Wells, etc.) is equal to gestalt in assessing pre-test probability (ACEP Level B)
Initial Wells study and prospective validation  used a three tier system (low 0-1, intermediate 2-6, high >6) to establish pretest probability with a small sample size
The larger Christopher Study group used a larger sample size to derive the simplified dichotomized/two tier model below
Score 0-4 =<unk>  Unlikely (12.1% incidence of<unk> 
Check D-dimer
If D-dimer positive then obtain CTPA or V/Q scan
If D-dimer negative, no further workup needed (0.5% incidence of<unk>  at 3 month follow up)
Score >4 =<unk>  Likely (37.1% incidence of<unk> 
Obtain CT<unk>  Angiography or V/Q Scan
New evidence suggests lower Wells Score with D-dimer <1000 ng/mL is effective at ruling out<unk>  without imaging
Check D-dimer
If D-dimer positive then obtain CTPA or V/Q scan
If D-dimer negative, no further workup needed (0.5% incidence of<unk>  at 3 month follow up)
If D-dimer positive then obtain CTPA or V/Q scan
If D-dimer negative, no further workup needed (0.5% incidence of<unk>  at 3 month follow up)
Obtain CT<unk>  Angiography or V/Q Scan<unk> RC Rule negative, then no further workup (ACEP Level B)
Avoid CT<unk>  angiography in low pretest probability patients that are either<unk> RC rule negative or have a negative d-dimer (ACEP choosing wisely)
D-dimer NPV is 99.5%<unk> RC Rule positive, then D-dimer (see Moderate-Probability Testing below)  (ACEP Level B)
Can also consider using Wells score as above to determine further testing
Avoid CT<unk>  angiography in low pretest probability patients that are either<unk> RC rule negative or have a negative d-dimer (ACEP choosing wisely)
D-dimer NPV is 99.5%
Can also consider using Wells score as above to determine further testing
For certain patients a higher d-dimer can be used
Age Adjusted D-Dimer
YEARS Algorithm<unk> GeD
HIV (protein wasting nephropathy)
Nephrotic Syndrome
SLE with anti-cardiolipin Ab
Exogenous hormones (specifically estrogen)
homozygous Factor V Leiden
Antithrombin III deficiency
Protein C deficiency
Protein S deficiency
Hyperhomocysteinemia
HAS-BLED score (developed to evaluate bleeding risk for anticoagulation in Afib) can also identify patients with acute VTE at high risk for bleeding complications within 6 months
When applied to VTE patients on vitamin K-antagonists, NOT DOACs (in first 6 months of treatment):
Score 0-2 = 1.3% incidence of major bleeds
Score 3+ = 9.6% incidence of major bleeds
Other bleeding risk models include the RIETE score (validated in patients taking VKA or rivaroxaban) and VTE-BLEED score (validated in patients taking warfarin and edoxaban).
Score 0-2 = 1.3% incidence of major bleeds
Score 3+ = 9.6% incidence of major bleeds
based on ACCP 2016 Guidelines
Pulmonary embolism
Acute coronary syndromes 
Pleural effusion
STEMI
Arterial gas embolism
Non-STEMI
Pleuritis
Unstable angina