The role of venous ultrasonography in the diagnosis of suspected deep venous thrombosis and pulmonary embolism

This paper describes the role of venous ultrasonography in the diagnosis of suspected deep venous thrombosis and pulmonary embolism. Inability to compress the common femoral or popliteal vein is usually diagnostic of a first episode of deep venous thrombosis in symptomatic patients (positive predictive value of about 97%). Full compressibility of both of these sites excludes proximal deep venous thrombosis in symptomatic patients (negative predictive value of about 98%). In patients with suspected deep venous thrombosis or in those who present with suspected pulmonary embolism but have a nondiagnostic lung scan, the subsequent risk for symptomatic venous thromboembolism is very low (<2% during 6 months of follow-up) provided that ultrasonography of the proximal veins remains normal in the course of 1 week (suspected deep venous thrombosis) or 2 weeks (suspected pulmonary embolism). Anticoagulation and further diagnostic testing can usually be safely withheld in these situations. Venous ultrasonography is much less reliable for the diagnosis of asymptomatic, isolated distal, and recurrent deep venous thrombosis than for the diagnosis of a first episode of proximal deep venous thrombosis in symptomatic patients. Clinical evaluation of the probability of deep venous thrombosis or pulmonary embolism, preferably by using a validated clinical model, complements venous ultrasonographic findings and helps to identify patients who would benefit from additional (often invasive) diagnostic testing. Thus, venous ultrasonography is thought to be a very valuable test for the diagnosis and management of patients with suspected deep venous thrombosis or pulmonary embolism.     

Deep venous thrombosis and neoplastic pathology: our experience in emergencies

Deep vein thrombosis incidence is 1/1000 per year; it is associated with many risk factors which is considered as "thrombophilic states". Its pathogenesis is complex, caused by alterations of hemostasis system. Many studies have established the relation between cancer and subsequent venous thromboembolism, confirming the relationship of neoplastic cell interaction with coagulation system. Forty-seven patients admitted to the hospital from 1987 to 1996 with symptomatic clinically proved deep vein thrombosis were included in a retrospective study. Routine examination at the time of diagnosis of deep vein thrombosis revealed an occult cancer in 8 out of 47 patients; 9 out of 47 patients were admitted in hospital with vein thrombosis and known cancer. The aim of this study is to suggest the best, first treatment of vein thromboembolism in emergency to avoid the dangerous pulmonary embolism complication. The patients affected with deep vein thrombosis and cancer were elderly (over 70 years old, in mean); the neoplasia was of digestive system (8/17) in advanced metastatic stage there was cancer familiarity in 7 out of 47 patients. The high risk of pulmonary embolism associated to deep vein thrombosis suggests the importance of early starting the anticoagulant therapy and placing caval filter.     

Distribution of thrombosis in patients with symptomatic deep vein thrombosis. Implications for simplifying the diagnostic process with compression ultrasound

BACKGROUND: Two different diagnostic strategies are used to perform compression (real-time) ultrasound for the diagnosis of clinically suspected deep-vein thrombosis. One is to examine the entire proximal venous system from common femoral to distal popliteal vein; the other is a limited examination of only the common femoral and the entire popliteal vein. The latter strategy, which is less time-consuming and requires less expensive equipment, is based on a strong impression from prospective studies using limited compression ultrasound that proximal vein thrombi always involve the common femoral or popliteal vein. This impression, which is supported by the demonstrated safety at long-term follow-up of not treating patients whose limited compression ultrasound is normal at presentation and then repeated within the next week, has not been tested in a formal study. Therefore, we reviewed a large series of venograms performed in consecutive patients with clinically suspected venous thrombosis to determine the distribution of venous thrombosis in symptomatic patients. METHODS: Venograms were performed using 150 mL of radiographic contrast material. Before the study, a panel of experts agreed on the standardized criteria for the assessment of venograms. Venograms were adjudicated blindly for the presence of deep vein thrombosis and to determine the distribution of proximal vein thrombosis and isolated calf-vein thrombosis, the size of proximal thrombi, and whether they were occlusive or nonocclusive. Subsequently, the duration of symptoms was related to the venographic findings. RESULTS: Five hundred sixty-two venograms from consecutive patients with a first episode of clinically suspected deep vein thrombosis were adjudicated. Of these, 20 (3.6%) were inadequate for interpretation. In the remaining 542, venous thrombosis was demonstrated in 189 instances (prevalence, 35%; 95% confidence interval, 31% to 39%) and were located in the proximal veins in 166 (88%; 95% confidence interval, 82% to 92%) venograms. Isolated calf-vein thrombosis was present in the remaining 23 (12%; 95% confidence interval, 8% to 18%) venograms. Proximal with concurrent calf thrombosis was detected in 164 (99%) of the 166 patients. Proximal thrombi involved only the popliteal vein in 16 (10%); the popliteal and superficial femoral veins in 70 (42%); and the popliteal, superficial, and common femoral vein in eight (5%); whereas thrombi involving the entire proximal deep venous system were detected in 58 (35%) venograms. Isolated thrombosis of the superficial femoral, common femoral, and iliac vein was not observed. Proximal venous thrombi were occlusive in 146 (88%) patients. No relation between the duration of symptoms and the extent or the occlusiveness of venous thrombi could be demonstrated. CONCLUSIONS: Most symptomatic patients have extensive occlusive proximal vein thrombosis at the time of presentation. Thrombi isolated to the superficial femoral or iliac vein were not observed in this large sample of consecutive patients. Our data support the use of the relatively simple, inexpensive, and rapid compression ultrasound method that limits the examination of the proximal veins to the common femoral and popliteal veins.     

Epidemiological study of angioedema and ACE inhibitors

A total 30,040 pregnancies were reviewed at one institution over 5 years to determine the incidence of venous thrombotic complications. Thirty-one patients experienced such complications related to pregnancy (incidence 0.1%); 13 had deep venous thrombosis and 14 had superficial venous thrombophlebitis diagnosed by duplex ultrasound. Four had pelvic vein thrombophlebitis diagnosed by computed tomography scan; three patients (one from each group) sustained a non-fatal pulmonary embolus. Of those with deep venous thrombosis, 10 (77%) were left-sided, and three (23%) were right-sided. Three had a prior history of deep venous thrombosis and one of pulmonary embolism. Of those with superficial venous thrombophlebitis, seven (50%) were left-sided, six (43%) were right-sided, and one (7%) was bilateral. Most with deep venous thrombosis presented later in pregnancy; three in the first trimester, two in the second, three in the third, and five early postpartum. Most (10/14) with superficial venous thrombophlebitis presented within 48 hours of delivery. Distribution of thrombi in those with deep venous thrombosis was compared with 643 non-pregnant women with a similar condition. A pattern of proximal involvement on the left was found, with left common femoral vein (54% versus 28%, P = 0.03) and superficial femoral vein (62% versus 26%, P = 0.006) more often involved in pregnant patients. The average number of vein segments involved was greater on the left than the right (5.3 versus 3.7). Symptoms of chronic venous insufficiency developed in three with deep venous thrombosis (25%) and in three with superficial venous thrombophlebitis (27%). None had recurrence of deep venous thrombosis. It is concluded that venous thrombotic complications associated with pregnancy are not necessarily benign, with the risk of pulmonary embolism and chronic venous insufficiency not limited to patients with deep venous thrombosis only.     

Risk factors for deep venous thrombosis of the upper extremities

BACKGROUND: Hypercoagulable states and triggering factors (surgery, trauma, immobilization, pregnancy, and use of oral contraceptives) are associated with an increased risk for deep venous thrombosis of the lower extremities. In contrast, risk factors for deep venous thrombosis of the upper extremities have not been identified. OBJECTIVE: To evaluate the prevalence of hypercoagulable states and triggering factors in patients with primary deep venous thrombosis of the upper extremities. DESIGN: Frequency-matched case-control study. SETTING: Hemophilia and thrombosis center at a university hospital. PATIENTS: 36 patients who had primary deep venous thrombosis of the upper extremities, 121 patients who had primary deep venous thrombosis of the lower extremities, and 108 healthy controls. Patients who had deep venous thrombosis of the lower extremities and study controls were frequency-matched by age, sex, geographic origin, and social status with patients who had deep venous thrombosis of the upper extremities. MEASUREMENTS: Resistance to activated protein C was evaluated by a clotting method based on the activated partial thromboplastin time. If test results were abnormal or borderline, DNA analysis for substitution in coagulation factor V gene was done. Antithrombin, protein C, protein S, antiphospholipid antibodies, and total plasma homocysteine levels were also measured. RESULTS: Prevalences of abnormalities of the natural anticoagulant system (9%) and hyperhomocysteinemia (6%) in patients who had deep venous thrombosis of the upper extremities were similar to prevalences of both factors in controls (6% and 7%, respectively) but lower than in patients who had deep venous thrombosis of the lower extremities (31% and 14%, respectively). Antiphospholipid antibodies were found only in patients who had venous thrombosis of the lower extremities (7%). The overall prevalence of hypercoagulable states in patients who had thrombosis of the upper extremities (15%) was similar to that in controls (12%) but was significantly lower than that in patients who had thrombosis of the lower extremities (56%). A recent history of strenuous exercise of muscles in the affected extremity was the most frequent triggering factor for patients who had deep venous thrombosis in the upper extremities (33%). CONCLUSIONS: This preliminary study indicates that the prevalence of hypercoagulable states is low in patients who have primary deep venous thrombosis of the upper extremities.     

Diagnosis of venous thrombosis in the legs using 81Krm venography

Contrast venography, the accepted gold standard for the diagnosis of venous thrombosis of the leg, is a painful and invasive procedure with late side effects. There is controversy in literature reports about the sensitivity of 99Tcm-macroaggregated albumin (MAA) phlebography: indeed, using 99Tcm-MAA, poor results are obtained when one has to detect calf vein thrombosis. As with other isotopic procedures requiring a pedal injection of the tracer, the use of an injectable solution of 81Krm is a nonspecific method, based upon the abnormality in flow in the deep venous system which results from a deep venous thrombosis. However, when compared with 99Tcm-MAA, 81Krm offers theoretical advantages for phlebographic studies of the lower limbs. In this work 24 patients were studied both with contrast phlebography and with 81Krm. Although 81Krm provided images of high quality, there was a lack of sensitivity below the knee, where false negative results were observed. This could be explained by the fact that the radionuclide venographic procedures usually visualize only one or, in some cases, two of the three deep veins of the calf. Moreover, accurate differentiation between superficial and deep veins in the calf often appears difficult, even using a tourniquet.     

Color duplex ultrasound in the assessment of primary venous leg ulceration

METHODS: To determine the extent and severelity of venous reflux, color duplex ultrasound was used in 370 limbs of 303 patients with primary varicose veins. The clinical findings were classified according to the CEAP (clinical, etiologic, anatomic, pathophysiologic) clinical classification. RESULTS: Of 370 limbs, 32 showed previously healed ulcer (Class 5) and active ulcer (Class 6). Overall reflux in the superficial venous system was seen in 28 limbs (87.5%), and solitary superficial vein incompetence was detected in 13 (40.6%). Reflux was detected throughout the length of the superficial vein system, and the retrograde peak velocity was greater than 30 cm/second in these limbs. Reflux in the perforating veins was detected in 14 limbs (43.8%), but isolated perforating vein incompetence was seen in only one limb (3.1%). Deep vein incompetence was detected in 12 limbs (37.5%). Concomitant superficial and perforating vein reflux was evident in 4 limbs (12.5%) and 2 limbs (6.3%), respectively, but isolated deep vein incompetence was detected in only one limb (3.1%). The operations indicated were selective stripping of the long saphenous vein in the thigh, high ligation of the short saphenous vein, subfascial ligation of perforating veins, and compression sclerotherapy for varicose tributary veins. Healing of the ulcers was achieved within 1 month after surgery, and the postoperative color duplex scanning revealed correction of deep vein incompetence. CONCLUSIONS: These data suggest that ablation of the superficial vein system and the perforating veins is an appropriate method for the management of patients with primary venous leg ulceration.     

Healing of deep venous thrombosis: venographic findings in a randomized study comparing streptokinase and heparin

Sequential ascending venographic studies were used to assess the healing of deep venous thrombosis in 50 patients randomly assigned to streptokinase or heparin therapy. Various degrees of thrombolysis and/or recanalization were demonstrated by venograms performed on the fourth and tenth days of treatment. Late follow-up studies (mean, 7 months after treatment) showed three basic patterns of resolution: (1) return to normal, (2) complete recanalization, and (3) incomplete recanalization and/or collateralization. Loss of valves or their function was associated with recanalization. The character, speed, and outcome of healing reflected the nature and extent of thrombosis, prior thrombotic disease in the extremity, and the type and timing of treatment. Streptokinase was highly effective and preferable to heparin in patients with deep vein thrombosis when therapy was begun within 4 days of onset of symptoms. In later stages of acute or recurrent deep vein thrombosis, the effectiveness of both drugs was significantly reduced.     

Prospective study of thromboses of the subclavian vein after setting implantable venous access systems in cervico-facial cancerology

Seventy-eight consecutive patients treated by chemotherapy for ENT cancers and having a subclavian catheter for venous access were studied prospectively to assess the prevalence of venous thrombosis. Thrombosis of the subclavian vein was demonstrated clinically in 4 patients and by ultrasonography in 7 patients. The prevalence of thrombosis was 14.1%. No clinical or biological predisposition factor could be identified. Subclavian thrombosis mostly occurred during the second month after implantation (91% of cases). Ultrasonography seems the most useful non-invasive technique for the diagnosis of subclavian thrombosis.     

Clinical diagnosis of deep venous thrombosis after hip replacement surgery

Hip replacement surgery is associated with a high frequency of postoperative deep vein thrombosis. This prospective study was performed in order to investigate if routine bedside questioning and examination by the visiting doctor could reveal deep vein thrombosis in the legs of patients who had received a hip replacement. 258 patients were evaluated. Thromboprophylaxis (dextran-70, low molecular weight heparin and graded elastic stockings) was given during the first week after operation. Bilateral venography was performed in all patients on day seven after operation, and showed an overall deep vein thrombosis incidence of 16%. The visiting doctors had not suspected deep vein thrombosis in any of the patients. This may have been because postoperative painful and swollen legs effectively masked any signs and symptoms of deep vein thrombosis. Our results show that deep vein thrombosis during the first week after hip replacement surgery cannot be discovered by clinical diagnostics. The high subclinical frequency of deep vein thrombosis indicates the importance of improving thromboprophylaxis in order to further minimise the occurrence of deep vein thrombosis and the risk of thromboembolic complications.     

Cockett syndrome. Initial results with percutaneous treatment in 6 patients

Intimal hypertrophy with venous spur formation caused by compression of the left common iliac vein by the right common iliac artery is advanced as the etiology of the higher incidence of deep venous thrombosis involving the left leg. In most cases of left iliofemoral thrombosis no underlying compression syndrome is detected or treated because the left common iliac vein has to be cleared from thrombi before compression can be identified. A series of 6 consecutive retrospectively analyzed patients with acute left iliofemoral thrombosis is presented. In these patients a left iliac vein compression syndrome was detected after percutaneous intraluminal thrombolysis with Actilyse (rt-PA). This compression was successfully relieved by insertion of a wall stent. Percutaneous treatment of Cockett's syndrome seems an attractive alternative for conservative and/or surgical management.     

Coagulation factor V gene mutation increases the risk of venous thrombosis in beh?et's disease

We investigated the prevalence of the coagulation factor V gene G1691A mutation in 64 patients with Beh?et's disease (BD) and in 107 apparently healthy individuals. The mutation was present in the heterozygous state in 37.5% of the patients with a history of deep vein thrombosis (12/32) and in 9.4% of the patients without any thrombotic event (3/32). Eleven healthy individuals were also heterozygous for the mutation (10.3%). The prevalence of the mutation in BD patients with and without thrombosis was significantly different (P = 0.0079). We conclude that the factor V gene mutation may play a major role in the development of venous thrombosis in BD.     

Prevention of venous thrombosis with small, subcutaneous doses of heparin

The effect of low-dose heparin prophylaxis on venous thrombosis and bleeding after major elective surgery was studied in a prospective controlled study of 820 patients. The total incidence of venous thrombosis detected with leg-scanning using fibrinogen labeled with radioactive iodine (125I) was reduced from 16.0% in the control group to 4.2% in treated patients. More important, the incidence of popliteal or femoral vein thrombosis was reduced from 2.9% to 1.0%. Prophylaxis resulted in a slight increase in bleeding-minor wound hematoma, mean volume of blood transfused, and a post-operative hematocrit fall in treated patients. However, increased bleeding was clinically minor, and prophylaxis was well tolerated.     

Treatment of venous thromboembolism

This review provides meta-analytic data of studies aiming at improved treatment of deep vein thrombosis and pulmonary embolism. The introduction of low molecular weight heparin has considerably ameliorated the initial treatment of deep vein thrombosis, and should now be regarded as the treatment of choice for most patients with deep vein thrombosis. Oral anticoagulant treatment is presently considered safe and effective for the long-term treatment of venous thromboembolism, provided that the INR is maintained at 2.0-3.0. However, the optimal duration as well as the optimal intensity of anticoagulation have still to be determined. Patients with submassive pulmonary embolism should presently be treated with adjusted dose unfractionated heparin and coumarins. Studies determining the efficacy and safety of low molecular weight heparin in this condition deserve priority. Thrombolytic therapy should be restricted to patients with massive pulmonary embolism, unless safer methods of thrombolysis have been developed. Surgical embolectomy and catheter fragmentation of emboli seem alternative options but deserve further investigations.     

Endovascular thrombolysis in deep cerebral venous thrombosis

We present two cases of acute thrombosis of the internal cerebral veins, vein of Galen, and straight sinus without sagittal sinus involvement. Both patients had hydrocephalus and severe edema of the basal ganglia and thalami, one with hemorrhagic infarction of the thalamus. Because both patients rapidly deteriorated to a comatose state, endovascular thrombolysis was performed with urokinase infusion of the deep venous structures. Thrombolysis was continued until a patent channel with brisk flow in the venous structures was achieved. Both patients survived with minimal neurologic deficits.     

Frequency of deep vein thrombosis in patients with patent foramen ovale and ischemic stroke or transient ischemic attack

To evaluate the additional value of transesophageal (TEE) compared with transthoracic (TTE) echocardiography and the role of patent foramen ovale (PFO) and deep vein thrombosis in the work-up of embolic events, patients with presumed cardiac embolic stroke or transient ischemic attack (neurovascular etiology was excluded) were prospectively studied by transthoracic and transesophageal contrast echocardiography. If PFO was detected echocardiographically, PFO size was assessed semiquantitatively and phlebography of both legs was performed. Two hundred forty-two consecutive patients (153 men, 60 +/- 15 years) were studied. In 197 patients, neuroimaging showed evidence of embolic infarction. TEE identified 138 potential cardiac sources of embolism in 111 patients, compared with 69 by TTE (p <0.01) in 59 patients. TEE detected potential cardiac sources in 52 patients with negative TTE examination and was significantly superior compared with TTE for identifying left atrial thrombi, spontaneous echo contrast, PFO, atrial septal aneurysm, and atheroma of the ascending aorta. In patients with a positive TTE, additional diagnostic information by TEE was found in only 6 patients and did not change therapy. Phlebography was performed in 53 patients with PFO and revealed deep vein thrombosis in 5 patients (9.5%); all had medium or large PFOs. Thus, in patients with cerebral ischemia of suspected cardiogenic origin and a normal TTE examination, TEE detects potential causes of embolism in 31% of patients and is therefore of diagnostic relevance. Conversely, in the presence of a diagnostic TTE an additional TEE confers only marginal diagnostic benefit. Deep venous thrombosis was detected in nearly 10% of patients with PFO as the sole identifiable cardiac risk factor. Given that in 4 of 5 patients deep vein thrombosis was clinically silent, phlebography should be performed in patients with medium or large interatrial shunts if paradoxical embolism is suspected.     

Recurrent sinopulmonary disease in a young adult

In 50 patients aged 60 +/- 4 operated for colorectal carcinoma simultaneous combined radionuclide phlebography (RNP) and pulmonary perfusion scintigraphy (PPS) using 99Tcm labeled macroaggregates of the human serum albumin (MAHSA) were performed within 20 postoperative days aiming to detect deep vein thrombosis (DVT) and pulmonary thromboembolism (PTE). The aim of the study was to determine the incidence and segmental DVT localization as well as incidence, localization and clinical characteristics of developed pulmonary perfusion disorders. Deep vein thrombosis was detected in 33 (66%) patients with rather uniform distribution in vein segments. According to their scintigraphic characteristics the findings suggested recent thrombosis in almost all cases (only two of them had signs of chronic thrombosis). Of patients with detected DVT 17 (52%) had pulmonary perfusion disorders of which 10 (59%) were unilateral (7 right and 3 left) and 7 (42%) bilateral. Characteristics and extent of perfusion defects suggested very probable PTE in 11 (65%) patients and less probable in 6 (35%). It has been concluded that patients operated for colorectal carcinoma were highly exposed to DVT and PTE development which necessitates all measures contributing to their prevention.     

Patterns of venous reflux in limbs with skin changes associated with chronic venous insufficiency

The distribution of venous reflux in patients with skin changes associated with chronic venous insufficiency presenting to a specialist clinic was assessed. A total of 300 limbs in 153 patients were examined by Doppler ultrasonography with colour-flow imaging for the presence of venous reflux in superficial veins, deep veins and medial perforating veins, both above and below the knee. Ninety-eight limbs had skin changes, which included hyperpigmentation, lipodermatosclerosis, atrophie blanche and ulceration. Of this group, 2 per cent had no evidence of venous reflux on duplex scanning, 39 per cent had deep vein incompetence, 57 per cent had superficial vein incompetence and 2 per cent had isolated medial perforating vein reflux. Of 25 limbs with ulceration, 13 had superficial and 12 deep vein reflux. A total of 202 legs, which included 20 normal control limbs, had no skin changes; 22.3 per cent of these had no venous reflux, 8.4 per cent had deep vein incompetence, 65.3 per cent had superficial incompetence and 4.0 per cent had isolated medial calf perforating vein incompetence.     

The risk of a diagnosis of cancer after primary deep venous thrombosis or pulmonary embolism

BACKGROUND: Several small studies have indicated an association between deep venous thrombosis or pulmonary embolism and a subsequent diagnosis of cancer, but the subject is controversial. METHODS: We conducted a nationwide study of a cohort of patients with deep venous thrombosis or pulmonary embolism that was drawn from the Danish National Registry of Patients for the years 1977 through 1992. The occurrence of cancer in the cohort was determined by linkage to the Danish Cancer Registry. The expected number of cancer cases was estimated on the basis of national age-, sex-, and site-specific incidence rates. RESULTS: A total of 15,348 patients with deep venous thrombosis and 11,305 patients with pulmonary embolism were identified. We observed 1737 cases of cancer in the cohort with deep venous thrombosis, as compared with 1372 expected cases (standardized incidence ratio, 1.3; 95 percent confidence interval, 1.21 to 1.33). Among the patients with pulmonary embolism, the standardized incidence ratio was 1.3, with a 95 percent confidence interval of 1.22 to 1.41. The risk was substantially elevated only during the first six months of follow-up and declined rapidly thereafter to a constant level slightly above 1.0 one year after the thrombotic event. Forty percent of the patients given a diagnosis of cancer within one year after hospitalization for thromboembolism had distant metastases at the time of the diagnosis of cancer. There were strong associations with several cancers, most pronounced for those of the pancreas, ovary, liver (primary hepatic cancer), and brain. CONCLUSIONS: An aggressive search for a hidden cancer in a patient with a primary deep venous thrombosis or pulmonary embolism is not warranted.     

Expanding eligibility for outpatient treatment of deep venous thrombosis and pulmonary embolism with low-molecular-weight heparin: a comparison of patient self-injection with homecare injection

BACKGROUND: The outpatient treatment of patients with deep vein thrombosis and pulmonary embolism using low-molecular-weight heparin has the potential to reduce health care costs, but it is unclear if most patients with deep vein thrombosis and pulmonary embolism can be treated as outpatients. In the published studies, more than 50% of patients were excluded from outpatient treatment for reasons such as comorbid conditions, short life expectancy, concomitant pulmonary embolism, and previous deep vein thrombosis, and many patients were not treated entirely at home. We sought to determine if expanding patient eligibility for the outpatient treatment of deep vein thrombosis and pulmonary embolism affects the safety and effectiveness of the treatment, and to determine if patient self-injection compared with injections administered by a homecare nurse affected these outcomes. PATIENTS AND METHODS: We treated as outpatients all patients with deep vein thrombosis and pulmonary embolism, except for those with massive pulmonary embolism, high risk for major bleeding or an active bleed, phlegmasia, and patients hospitalized for reasons that prevented discharge. We compared 2 models of outpatient care to determine feasibility, safety, and efficacy. Both models involved nurse managers who provided daily patient contact and ongoing treatment; however, in one model the patients were taught to inject themselves and in the other model homecare nurses administered the injections. We expanded the population of patients eligible for outpatient treatment by including many patients not treated at home in previous studies. Most patients in our study were treated with dalteparin sodium, 200 U/kg every 24 hours, for a minimum of 5 days. Therapy with warfarin sodium was started on the day of diagnosis or the following day. Patients were followed up for 3 months to determine rates of recurrent venous thromboembolism, bleeding, and death. RESULTS: In this study, 194 (83%) of 233 consecutive patients were deemed eligible and treated as outpatients. Of the 39 patients who did not receive home therapy, 20 had concomitant medical problems responsible for their admission or were already inpatients, 6 had massive pulmonary embolism, 6 refused to pay for the dalteparin therapy, 4 had active bleeding, and 3 had phlegmasia cerulea dolens, which required treatment with intravenous narcotics for pain control. More than 184 (95%) of the 194 patients were treated entirely at home. There was no significant difference (P>.99) in the rate of recurrent venous thromboembolic events between the patients who were injected by homecare nurses (3/95 [3.2%]) and those who injected themselves (4/99 [4.0%]). Combining the 2 models, the overall recurrent event rate was 3.6% (95% confidence interval, 1.5%-7.4%). Similarly, there were no significant differences in rates of major hemorrhage (2/95 vs 2/99; P>.99), minor hemorrhage (8/95 vs 2/99; P = .06), and death (6/95 vs 8/99; P = .63). The overall rate of major hemorrhage was 2.0% (95% confidence interval, 0.6%-5.2%). CONCLUSIONS: We demonstrate that more than 80% of patients at our tertiary care hospital could be treated at home using 1 of the 2 models of care we describe. Our results demonstrate that patients can safely and effectively perform home self-injection under the supervision of a hospital-based nurse. Injections at home by a homecare nurse are similarly effective. Our overall rates of recurrent venous thromboembolism, bleeding, and death are at least as favorable as those previously reported despite using 1 dose per day of dalteparin for most patients.