Do you know how to assess patients for DVT?
ED nurses should be aware of risk factors, symptoms, and modes of presentation for diagnosis and assessment of DVT, says Gideon Bosker, MD, assistant clinical professor of emergency services at Yale University School of Medicine.
Risk factors for DVT include trauma to the lower extremities, obesity, long periods of airplane travel, previous DVT, abdominal surgery, and/or lower-limb orthopedic surgery, adds Bosker. Here are some items to consider:
Symptomatic patients complain of lower extremity pain or swelling. They often have a sense of fullness, which increases with standing or walking. Some even complain of pain in the lower extremity with cough or sneeze.
Electric type pain with coughing or sneezing is also associated with sciatica. Involvement is usually unilateral unless the vena cava occludes — a very rare catastrophic event. In one study, DVT never occurred in the patients with bilateral symptoms. It is important to determine the time course of symptoms and elicit history of recent trauma.1
Assess patients’ medical history
Venous thrombosis occurs subacutely over several days; and sudden, severe pain is more compatible with muscle rupture or injury. Associated symptoms are also important, especially the presence of chest pain or shortness of breath, which may denote PE.
Determine the medical history and assess risk factors for thromboembolic disease. Elicit the history of prior DVT, as up to 26% of patients have had a previous episode.
While patients with DVT may have a low-grade fever due to a systemic inflammatory response, this fever rarely exceeds 102° F.
Completely undress the patient with leg symptoms and inspect for lymphangitis, erythema, and ulcerations. Remember to examine the entire limb for abnormalities, as lymphangitis may have large "skip" areas. Be alert for psychiatric patients or prisoners who may tie a tourniquet around their thigh to produce factious DVT.
Lack of calf discrepancy does not rule out DVT. Some researchers standardize calf measurements at 10 cm below the tibial tuberosity. While asymmetry of the calves of 1 cm or more is abnormal, such asymmetry does not distinguish between patients with thromboembolic disease and those without. Asymmetric calf swelling of greater than 3 cm is a significant finding.
Bony tenderness does not rule out DVT. Indeed, up to 65% of patients with DVT will have pain with percussion of the medial tibia.
Bancroft or Moses’ sign is pain with compression of the calf against the tibia. Some patients with DVT will have more pain with this maneuver than with transverse compression of the gastrocnemius.
Homans’ sign is pain in the posterior calf or knee with forced dorsiflexion of the foot. It is often present in patients with sciatica. Despite its continuous promotion in the medical literature, this sign is inaccurate and performs no better than a coin toss.
The examination of the patient with DVT does not end with evaluation of the extremity. Search for stigmata of pulmonary embolism such as tachycardia, tachypnea, or chest findings, and examine for signs suggestive of underlying malignancy.
Diffuse swelling marks the presence of an upper extremity DVT. Effort thrombosis occurs in young active males, while catheter-related thrombosis is limited to patients with prior instrumentation or intravenous drug abuse.
Dilated collateral veins are frequent, but more easily seen in Caucasians. Look for arm discoloration and palpable axillary veins.
Clinical examination is only 20% to 30% accurate for DVT. Because of this inaccuracy, pursue the diagnosis in any patient with unexplained extremity pain or swelling.
A patient who presents with symptoms in both arms or both legs is unlikely to be suffering from bilateral thrombosis. However, a patient with unilateral complaints and no clear explanation (such as a direct blow to the extremity, twisted ankle, etc.) requires further evaluation.
The presence of risk factors must decrease the threshold for imaging studies. Nearly all patients with complaints compatible with venous thrombosis and no likely alternative diagnosis require an imaging study.
Laboratory tests for suspected DVT
Patients with suspected DVT who complain of chest pain or shortness of breath should have a ventilation perfusion scan to expedite the most serious diagnosis.
Two blood tests are valuable in the management of thromboembolic disease, the D-dimer and the INR. Current D-dimer assays can predict the likelihood of DVT, and the INR is useful in the management of known DVT in patients on warfarin. While no blood test can conclusively rule in or rule out thrombosis, a normal D-dimer in a patient with no risk factors for thrombosis makes proximal DVT extremely unlikely.
Despite that it is frequently ordered, a CBC rarely provides useful information in patients with leg signs or symptoms. The leukocyte count cannot distinguish between DVT and cellulitis and is neither sensitive nor specific for either.
Coagulation studies should rarely be part of the initial evaluation of venous thrombosis. They are occasionally valuable after Doppler demonstrates an acute clot, and in the patient who develops a clot while on warfarin.
While nearly every physician orders a PTT before starting heparin for DVT, this practice is not justified by the literature. For patients not on warfarin, knowledge of the PTT will almost never affect management.
Reference
1. Sheiman RG, Weintraub JL, McArdle CR. Bilateral lower extremity US in the patient with bilateral symptoms of deep venous thrombosis: Assessment of need. Radiology 1995;196:379-811.
Sources
For more information on low weight molecular heparins used in the ED, contact:
• Gideon Bosker, MD, E-mail: [email protected].
• Susan Lynch, RN, BSN, Jefferson University Hospital, 125 S. 9th St., Suite 502, Philadelphia, PA 19107. Telephone: (215) 503-1020. Fax: (215) 923-9239. E-mail: [email protected].
• Sandra Sieck, RN, BBA, Education Dept., Providence Hospital, 6801 Airport Blvd., Mobile, AL 36608. Fax: (334) 633-1527. E-mail: [email protected].
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