From the Guidelines
For swelling and pain in one arm, I recommend a comprehensive blood panel including complete blood count (CBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and D-dimer test, as suggested by the most recent guidelines 1. These tests can help identify potential causes such as infection, inflammation, or blood clots. The CBC will assess for elevated white blood cells suggesting infection, while CRP and ESR measure inflammation levels in the body. A D-dimer test is important to rule out deep vein thrombosis, which can cause arm swelling and pain. Some key points to consider when evaluating a patient with swelling and pain in one arm include:
- Clinical symptoms such as swelling of the unilateral extremity, heaviness in the extremity distal to the site of the venous thrombosis, pain in the extremity, unexplained persistent calf cramping, swelling in the face, neck, or supraclavicular space, and catheter dysfunction (if a catheter is present) 1
- The importance of a comprehensive medical history and physical examination, as well as laboratory tests such as CBC with platelet count, PT, aPTT, fibrinogen, and liver and kidney function tests 1
- The use of venous ultrasound as the preferred imaging method for the initial diagnosis of DVT, and the potential use of other imaging modalities such as contrast-enhanced CT venography (CTV) and magnetic resonance venogram (MRV) with contrast in cases of negative or indeterminate ultrasound results 1 Depending on clinical suspicion, additional tests might include uric acid levels (for gout), rheumatoid factor and anti-CCP antibodies (for autoimmune conditions), or electrolytes and kidney function tests. These blood tests should be ordered promptly, especially if the swelling is sudden, severe, or accompanied by redness, warmth, or fever. The results will guide appropriate treatment, which might include antibiotics for infection, anti-inflammatory medications for inflammatory conditions, or anticoagulants for blood clots. While waiting for bloodwork results, elevating the affected arm, applying cold compresses, and taking over-the-counter pain relievers like acetaminophen may provide temporary relief. It's also important to note that the diagnosis of DVT should be tempered by an increased level of clinical suspicion on presentation of any clinically overt signs/symptoms that could represent an acute DVT, and early initiation of anticoagulation should be considered while awaiting results from imaging studies 1.
From the Research
Bloodwork Recommendation for Swelling and Pain of One Arm
- The patient's symptoms of swelling and pain in one arm may be indicative of deep vein thrombosis (DVT) 2.
- A D-dimer test can be used to rule out DVT, with a negative predictive value of 98% for excluding DVT in symptomatic outpatients 3.
- The D-dimer test can be used as a stand-alone test to rule out DVT, with a failure rate of 1.8% (95% CI 0.8%-3.5%) 4.
- The whole blood agglutination D-dimer test has a sensitivity of 88.4% and a specificity of 53% for DVT diagnosis, with a positive predictive value of 82.6% and a negative predictive value of 64.3% 5.
- If DVT is suspected, a clinical decision rule can be used to assess the pre-test probability, and if the probability is "unlikely", a D-dimer test can be performed to rule out DVT 2.
- If the D-dimer level is normal, DVT can be excluded, but if the level is increased, compression ultrasound should be performed to confirm the diagnosis 2.
Diagnostic Approach
- Initial blood work may include a D-dimer test to rule out DVT 3, 4.
- If the D-dimer test is positive, compression ultrasound should be performed to confirm the diagnosis of DVT 2.
- If the D-dimer test is negative, DVT can be excluded, but other causes of swelling and pain in the arm should be investigated 3, 4.