A diagnostic tool that works better is the Wells’ Criteria, which operates on a points system (with 3-8 points indicating high probability of DVT, 1-2 points indicating moderate probability, and less than 1 point indicating low probability).1 Patients are assessed according to the following criteria:
- Paralysis, paresis, or recent orthopedic casting of lower extremity (1 pt)
- Recently bedridden (> 3 d) or major surgery within past 4 weeks (1 pt)
- Localized tenderness in deep vein system (1 pt)
- Swelling of entire leg (1 pt)
- Calf swelling 3 cm greater than other leg (measured 10 cm below the tibial tuberosity) (1 pt)
- Pitting edema greater in the symptomatic leg (1 pt)
- Collateral nonvaricose superficial veins (1 pt)
- Active cancer or cancer treated within 6 months (1 pt)
- Alternative diagnosis more likely than DVT (Baker cyst, cellulitis, muscle damage, superficial venous thrombosis, postphlebitic syndrome, inguinal lymphadenopathy, external venous compression) (–2 pts).1
Moving through the Wells’ score system, we don’t have enough clinical data input for this patient. We do know he had leg pain and possibly swelling (1 pt). His knee was immobilized (albeit without plaster) (1 pt). We don’t know how “bedridden” he was. I’ll argue we should not deduct for “an alternative diagnosis more likely” because the decedent injured his knee and we can expect knee pain and knee swelling, not symptoms and findings involving the entire leg. So this patient would score at least 1 point, possibly 2, and thus be stratified as “moderate probability.”
There was an initial suspicion of DVT in this patient, and a Doppler was ordered on August 10. The patient’s symptoms persisted. However, in light of the negative Doppler results, the continued symptoms were attributed to the knee derangement and not a DVT.
Which brings us to the first malpractice trap: reliance on a prior negative study to rule out a dynamic condition. For any condition that can evolve, do not hesitate to order a repeat test when needed. DVT is a dynamic process; given the right clinical setup (in this case, immobility and ongoing/increasing symptoms), a clinician should not be bashful about ordering a follow-up study. As providers, we recognize the static nature of certain studies and have no reservations about ordering serial complete blood counts or a repeat chest film. Yet we are more reluctant to order repeat studies for equally dynamic disease processes—even when they are required by the standard of care. Here, reliance on a 3-day-old Doppler was problematic. Don’t rely on an old study if the disease under suspicion evolves rapidly.
The second trap: Do not allow yourself to be scolded (or engage in self-scolding) if a correctly ordered test is negative. A clinical decision is correct if it is based on science and in the interest of safeguarding the patient. Don’t buy into the trap that your decision needs to be validated by a positive result. Here, the persisting or worsening leg pain with entire leg swelling warranted a new study—even if the result was expected to be negative.
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