DVT complete diagnostic approach resident survival guide

Complete Diagnostic Approach

A complete diagnostic approach should be carried out after a focused initial rapid evaluation is conducted and following initiation of any urgent intervention.

Characterize the symptoms in the involved extremity: ❑ Swelling ❑ Pain ❑ Erythema ❑ Warmth

Identify possible precipitating factors: ❑ Recent surgery ❑ Hospitalization ❑ Trauma ❑ Pregnancy ❑ Postpartum ❑ Heart failure ❑ Immobility ❑ Obesity ❑ Malignancy ❑ Stroke ❑ Oral contraceptive or hormone replacement therapy Obtain a detailed history: ❑ Previous episode of VTE ❑ Age ❑ Location ❑ Past medical history: ❑ Atherosclerosis ❑ Collagen vascular disease ❑ Heart failure ❑ Myeloproliferative disease ❑ Nephrotic syndrome ❑ Abortion at second or third trimester of pregnancy (suggestive of an inherited thrombophilia or APS) ❑ Drugs that may induce APS ❑ Hydralazine ❑ Phenothiazine ❑ Procainamide

❑ Examine the patient: Extremities ❑ Unilateral calf or thigh tenderness ❑ Unilateral calf or thigh edema ❑ Unilateral calf or thigh warmth ❑ Unilateral calf or thigh erythema ❑ Palpable cord (suggestive of thrombosed vein) ❑ Difference in calf diameters ❑ Dilatation of a superficial vein ❑ Homan's sign (not reliable) ❑ Generalized edema (suggestive of nephrotic syndrome) Abdominal exam ❑ Ascites (suggestive of Budd Chiari syndrome, that is hepatic vein thrombosis) ❑ Hepatomegaly (suggestive of Budd Chiari syndrome, that is hepatic vein thrombosis)

Assess the pretest probability of DVT (Wells score shown below)

Consider alternative diagnoses: ❑ Muscle strain or muscle tear ❑ Immobilization that led to leg swelling ❑ Lymphedema ❑ Lymphangitis ❑ Chronic venous insufficiency ❑ Venous obstruction ❑ Baker's cyst ❑ Cellulitis ❑ Superficial thrombophlebitis ❑ Hypoproteinemia ❑ Nephrotic syndrome ❑ Cirrhosis

Order tests: ❑ CBC-D ❑ PT and aPTT ❑ Creatinine ❑ Liver function test

Is the suspected DVT a first or a recurrent episode?

First suspected episode

Suspected recurrent episode

Assess the pretest probability of DVT (Wells score shown below)

(Click here for the diagnostic approach)

Low pretest probability (Click here for the diagnostic approach)

Moderate pretest probability (Click here for the diagnostic approach)

High pretest probability (Click here for the diagnostic approach)

Assessment of the Pre-Test Probability of DVT

Calculation of Wells Score for DVT

Variables	Score
Active cancer with either palliative therapy or treatment that is either ongoing or within the prior 6 months	1
Patient was recently bedridden for at least 3 days OR Major surgery in the prior 12 weeks necessitating general or regional anesthesia	1
Recent plaster immobilization, paresis or paralysis of the lower extremities	1
Tenderness that is localized is the distribution of the deep veins	1
Leg is entirely swollen	1
Calf is swollen for 3 cm or move compared to the other calf	1
Pitting edema in the symptomatic leg	1
Presence of collateral superficial veins	1
Previous DVT	1
There is an alternative diagnosis as likely as DVT	-2

Interpretation of Wells Score for DVT

Score	Pretest probability
≥3	High
1 or 2	Moderate
0 or less	Low

Anticoagulation for VTE

Warfarin

• Begin with 10 mg warfarin for 2 days followed by dosing based on the INR
• Start at the 1st or 2nd day of the initial parenteral therapy
• Target INR is 2-3
• Monitor INR:
  • If stable, repeat INR every 12 weeks
  • If stable but one value 0.5 below or above the target range, continue the same dose and repeat INR within 1-2 weeks
• Avoid NSAIDs, COX2 selective NSAIDs and some antibiotics

Heparin

IV-UFH

• 80 U/kg as bolus, followed by 18 U/kg/h
• 70 U/kg as bolus, followed by 15 U/kg/h for stroke or cardiac patients

SC-UFH

• 333 U/kg as bolus, followed by 250 U/kg

LMWH: decrease dose in renal insufficiency (Creatinine clearance < 30 mL/min)

Fondaparinux

• 7.5 mg daily
• 10 mg daily if weight>100 Kg

Long Term Treatment

Shown below is the long term treatment for DVT. Note that not all patients with isolated distal DVT are started on anticoagulation, only those who are started require long term therapy with anticoagulation. Patients who are planned to receive long term therapy with anticoagulation should be assessed regularly for the risks vs benefits of anticoagulation therapy.

Is the DVT provoked or unprovoked?

Provoked

Unprovoked

What is the predisposing factor?

Is this the first or second episode?

Surgical OR Transient non surgical predisposing factor

Cancer

First episode

Second episode

Therapy for 3 months ❑ VKA (first line) OR ❑ LMWH (2nd line) OR ❑ Dabigatran OR ❑ Rivaroxaban

Extended therapy or until cancer is cured ❑ LMWH (first line) OR ❑ VKA (2nd line) OR ❑ Dabigatran OR ❑ Rivaroxaban

Is the DVT proximal or distal?

What is the risk of bleeding?

Proximal DVT

Isolated distal DVT

Low or moderate risk of bleeding

High risk of bleeding

What is the risk of bleeding?

Therapy for 3 months (irrespective of the risk of bleeding) ❑ VKA (first line) OR ❑ LMWH (2nd line) OR ❑ Dabigatran OR ❑ Rivaroxaban

Extended therapy ❑ VKA (first line) OR ❑ LMWH (2nd line) OR ❑ Dabigatran OR ❑ Rivaroxaban

Therapy for 3 months ❑ VKA (first line) OR ❑ LMWH (2nd line) OR ❑ Dabigatran OR ❑ Rivaroxaban

Low or moderate

High

Extended therapy ❑ VKA (first line) OR ❑ LMWH (2nd line) OR ❑ Dabigatran OR ❑ Rivaroxaban

Therapy for 3 months ❑ VKA (first line) OR ❑ LMWH (2nd line) OR ❑ Dabigatran OR ❑ Rivaroxaban

Do's

• If long term anticoagulation is extended for a longer period beyond 3 months, the same drug initially started should be continued.