What is the likelihood of deep‑vein thrombosis (DVT) or pulmonary embolism (PE) with a D‑dimer level of 1.32 µg/mL fibrinogen‑equivalent units (FEU)?

Likelihood of DVT or PE with D-Dimer 1.32 µg/mL FEU

A D-dimer of 1.32 µg/mL FEU (1320 ng/mL) is moderately elevated and cannot diagnose or exclude DVT or PE on its own—you must immediately assess clinical probability using a validated score (Wells or Geneva), then proceed to imaging if probability is moderate-to-high, or use the D-dimer to rule out disease only if probability is low. 1

Critical First Step: Clinical Probability Assessment

• Never interpret D-dimer without first calculating a validated clinical probability score—this is the most common and dangerous pitfall in VTE diagnosis. 1
• Use the Wells score for DVT (assigns points for localized tenderness, leg swelling, pitting edema, collateral veins, previous DVT, active cancer, paralysis/immobilization, and alternative diagnosis) or the revised Geneva score for PE (assigns points for previous VTE, heart rate >75 bpm, surgery/fracture within 1 month, hemoptysis, active cancer, unilateral leg pain, and pain on palpation). 1

Risk-Stratified Management Algorithm

Low Clinical Probability (≤10% pretest probability)

• Your D-dimer of 1320 ng/mL is positive (above the standard 500 ng/mL cutoff), so you cannot rule out VTE. 1
• Proceed immediately to imaging: proximal compression ultrasound or whole-leg ultrasound for suspected DVT; CT pulmonary angiography for suspected PE. 1
• A negative highly sensitive D-dimer in this group would have safely excluded VTE with 99–100% negative predictive value and <1% 3-month thromboembolic risk, but your elevated result mandates imaging. 1, 2

Moderate Clinical Probability (~25% pretest probability)

• Skip D-dimer interpretation entirely and proceed directly to imaging—whole-leg ultrasound for DVT or CT pulmonary angiography for PE. 1
• D-dimer adds minimal diagnostic value in this risk stratum. 1

High Clinical Probability (≥40–50% pretest probability)

• Proceed immediately to definitive imaging without considering the D-dimer result—proximal compression ultrasound or whole-leg ultrasound for DVT; CT pulmonary angiography for PE. 1
• A normal D-dimer does not safely exclude VTE in high-probability patients. 1

Age-Adjusted Interpretation (If Patient >50 Years)

• For patients older than 50 years, use the age-adjusted cutoff: age × 10 ng/mL (e.g., 700 ng/mL for a 70-year-old). 1
• This adjustment maintains >97% sensitivity while improving specificity from ~35% to ~46%, increasing the proportion of elderly patients in whom VTE can be safely excluded from 6% to 30%. 1
• Your D-dimer of 1320 ng/mL would exceed the age-adjusted threshold for anyone under 132 years old, so it remains positive regardless of age. 1

Quantitative Risk Stratification Based on D-Dimer Magnitude

• D-dimer levels between 500–1000 ng/mL carry baseline PE prevalence; levels 1000–2000 ng/mL double the risk; levels 2000–4000 ng/mL increase risk fourfold; and levels >4000 ng/mL carry very high PE prevalence independent of clinical score. 3
• Your level of 1320 ng/mL falls in the intermediate elevation range, where PE prevalence is approximately double that of minimally elevated D-dimer. 3
• Patients with D-dimer >2000 ng/mL and an "unlikely" clinical probability score had a 36% PE prevalence—comparable to the "likely" clinical probability group—demonstrating that markedly elevated D-dimer can override low clinical probability. 3

Populations Where D-Dimer Has Severely Limited Utility

• Do not rely on D-dimer in hospitalized patients, post-surgical patients, cancer patients, pregnant women, patients with active infection/sepsis, or trauma patients—specificity drops to ~10% in these groups, and the number needed to test to exclude one PE rises from 3 to >10. 1, 4, 5, 6
• In trauma patients within the first 4 days post-injury, tissue injury elevates D-dimer independently of thrombosis, yielding a 24% false-negative rate and 76% sensitivity for DVT—proceed directly to imaging regardless of D-dimer. 5, 6
• In cancer patients, active malignancy is worth 2 points on the Wells score, automatically placing most into at least moderate clinical probability; proceed directly to imaging rather than interpreting D-dimer. 4

Critical Pitfalls to Avoid

• Never diagnose VTE based solely on a positive D-dimer—imaging confirmation is mandatory before initiating anticoagulation. 1
• Never order D-dimer in high clinical probability patients—it wastes time and resources while delaying definitive imaging. 1
• Never use D-dimer as a screening test in hospitalized patients—the false-positive rate is unacceptably high (specificity ~10%). 1
• Never perform additional testing after a negative proximal or whole-leg ultrasound in low-risk populations—this leads to unnecessary procedures. 1

Prognostic Significance

• D-dimer levels 3–4 times above normal (>1500–2000 ng/mL) warrant hospital admission consideration even without severe symptoms, as this signifies substantial thrombin generation and increased mortality risk. 1
• Your level of 1320 ng/mL approaches but does not exceed this threshold, so admission decisions should be based primarily on clinical presentation and imaging findings rather than D-dimer alone. 1