Management of Patient with Low D-dimer Level in Suspected DVT/PE
A negative D-dimer test with a value of 1 reliably excludes deep vein thrombosis (DVT) or pulmonary embolism (PE) in patients with low clinical probability, and no further imaging is required for these patients. 1
Clinical Probability Assessment
- Always begin by assessing clinical probability using validated clinical prediction rules before interpreting D-dimer results 1
- Common validated tools include Wells score, Geneva score, or YEARS criteria to stratify patients into low, intermediate, or high probability categories 1, 2
- Document the clinical probability assessment in the medical record 1
Interpretation of D-dimer Result of 1
- A D-dimer level of 1 (assuming units are below the laboratory's cutoff value) is considered negative 1, 2
- A negative D-dimer test reliably excludes PE in patients with low clinical probability with a negative predictive value of approximately 99% 1, 3
- For patients with low clinical probability and negative D-dimer, no further testing is required 1, 2
Management Algorithm Based on Clinical Probability
Low Clinical Probability:
- With negative D-dimer (value of 1): No further testing needed, PE/DVT is excluded 1
- Consider alternative diagnoses for the patient's symptoms 1
Intermediate Clinical Probability:
- With negative D-dimer (value of 1): PE/DVT can be safely excluded if using a high-sensitivity D-dimer assay (Vidas, MDA) 1
- If using a less sensitive D-dimer assay (SimpliRED), consider additional imaging 1
High Clinical Probability:
- D-dimer testing should not be performed in patients with high clinical probability 1
- Proceed directly to imaging studies (CTPA for PE, compression ultrasound for DVT) 1
Special Considerations
- Age-adjusted D-dimer thresholds (age × 10 ng/mL rather than a generic 500 ng/mL) should be used in patients older than 50 years 1, 2
- D-dimer has limited utility in hospitalized patients, post-surgical patients, pregnant women, and cancer patients due to frequently elevated levels regardless of VTE status 1, 2
- For trauma patients, be cautious with negative D-dimer results within the first 4 days after injury, as false negatives can occur 4
Pitfalls to Avoid
- Never use D-dimer testing as the sole diagnostic criterion without assessing clinical probability first 1, 2
- Do not perform D-dimer testing in patients with high clinical probability of PE/DVT 1
- A single normal leg ultrasound should not be relied upon for exclusion of subclinical DVT 1
- Be aware that different D-dimer assays have varying sensitivities and specificities; know which assay your institution uses 2