Role of venous duplex imaging of the lower extremities in patients with fever of unknown origin

Four-extremity venous duplex ultrasound for suspected deep venous thrombosis is an anachronism

BACKGROUND

Duplex ultrasound is the "gold standard" for diagnosis of acute deep venous thrombosis (DVT) because of its high specificity, sensitivity, safety, and portability. However, unnecessary testing epitomizes inefficient use of scarce health care resources. Here we hypothesize that the majority of simultaneous four-extremity duplex ultrasound (FED) examinations are unnecessary. By analyzing clinical factors of patients with acute DVT found on FED, we aimed to identify a subset of high-risk patients who may have a valid indication for four-extremity testing.

METHODS

We retrospectively reviewed all venous duplex ultrasound examinations performed in our Intersocietal Accreditation Commission-accredited vascular laboratory from January 1, 2009, to December 31, 2016. Patients with duplex ultrasound scans of all four limbs were included. DVT risk factors and indication for duplex ultrasound examination were recorded. The primary outcome was finding of acute DVT.

RESULTS

There were 188 patients who met our search criteria, of whom 31 patients (16.5%) had acute DVT (11 upper extremity, 16 lower extremity, and 4 upper and lower extremity). Fever of unknown origin (FUO) was the main indication for requesting FED (53.7%). Patients who underwent FED for FUO had a significantly lower likelihood of DVT (odds ratio, 0.21; P = .01). DVT was rarely the proximate cause (<1% of all cases) as follow-up culture results and clinical course most often revealed other sources of fever. Only patients with an upper extremity central venous catheter (CVC; n = 103) with at least two associated risk factors had an upper extremity DVT, which was usually line associated (93%). Only patients with at least two associated risk factors had a lower extremity DVT.

CONCLUSIONS

FED for FUO is inefficient, given that DVT was rarely the proximate cause of fever. Acute upper extremity DVT was found only in patients with an upper extremity CVC, demonstrating that patients without upper extremity CVC do not benefit from upper extremity duplex ultrasound examination. Upper extremity DVT is usually line associated and dependent on the number of cumulative risk factors present, suggesting that only the extremity associated with the CVC in the right clinical context should be imaged. Lower extremity DVT is also dependent on the number of cumulative risk factors present, and testing should be reserved for patients according to the clinical context. Our results indicate that a restrictive strategy can reduce testing inefficiency and health care cost without compromising patients' safety.

ACCF/ACR/AIUM/ASE/IAC/SCAI/SCVS/SIR/SVM/SVS/SVU 2013 appropriate use criteria for peripheral vascular ultrasound and physiological testing. Part II: Testing for venous disease and evaluation of hemodialysis access

The American College of Cardiology Foundation (ACCF), in partnership with key specialty and subspecialty societies, conducted a review of common clinical scenarios where noninvasive vascular testing (venous ultrasound and physiological testing) is frequently considered. The indications (clinical scenarios) were derived from common applications or anticipated uses, as well as from current clinical practice guidelines and results of studies examining the implementation of the original appropriate use criteria (AUC). The 116 indications in this document were developed by a diverse writing group and scored by a separate independent technical panel on a scale of 1 to 9, to designate appropriate use (A) (median 7 to 9), maybe appropriate use (M) (median 4 to 6), and rarely appropriate use (R) (median 1 to 3).

A Rationale for the Use of F18-FDG PET/CT in Fever and Inflammation of Unknown Origin

This review focuses on the diagnostic value of hybrid F18-FDG Positron Emission Tomography/Computerized tomography (PET/CT) in fever of unknown origin (FUO) and inflammation of unknown origin (IUO). Due to the wide range of possible causes both FUO and IUO remain a clinical challenge for both patients and physicians. In addition, the aetiology of IUO shows the same variation in diseases as the FUO spectrum and probably requires the same diagnostic approach as FUO. There are numerous historically used diagnostic approaches incorporating invasive and non-invasive, and imaging techniques, all with relative high specificity but limited sensitivity. This hampers the generalization of these diagnostic approaches. However, recently published reports show that F18-FDG PET/CT in FUO and IUO has a high sensitivity and a relative non-specificity for malignancy, infection and inflammation. This makes F18-FDG PET/CT an ideal diagnostic tool to start the diagnostic process and to guide subsequent focused diagnostic approaches with higher specificity. In addition, F18-FDG PET/CT has a relative high negative predictive value. Therefore F18 FDG PET/CT should be incorporated in the routine diagnostic work-up of patients with FUO and IUO, preferably at an early stage in the diagnostic process.

Fever of unknown origin: 98 cases from Saudi Arabia

BACKGROUND AND OBJECTIVES

Fever of unknown origin (FUO) is mainly secondary to infectious, neoplastic or inflammatory diseases. To increase the body of knowledge on this diagnosis in the region, we collected information on all patients admitted to our institution with FUO in a 13-year period.

METHODS

We conducted a retrospective chart review of all immunocompetent males and females aged 13 years and older admitted between January 1995 and June 2008 who fulfilled the criteria for FUO. Data collection included demographics, laboratory investigations, imaging studies, procedures and discharge diagnoses. For true FUO, we recorded the duration of follow-up and the outcome.

RESULTS

The 98 patients who met the criteria included 44 males and 54 females with a mean (SD) age of 41.3 (18.5) years and range of 14 to 85 years. The most frequent diagnostic etiology was infectious in 32 (32.7%). Seventeen (17.3%) patients were undiagnosed or had true FUO. Of 9 patients followed up, 8 recovered and 1 expired. The mean duration of follow-up was 20.6 months (range, 0-168 months).

CONCLUSION

Infectious diseases, especially TB, continue to be the leading etiology of FUO in our area. Our data did not identify any predictor of certain FUO diagnoses except for older age and neoplastic etiology. True FUO patients generally did well. Reporting local experience is important in guiding clinicians about the epidemiologic patterns of FUO in their regions.

Do Patients with Acute Deep Vein Thrombosis Have Fever?

The purpose of this study was to determine whether those with lower extremity acute venous thrombosis have fever. During a recent 14.5-month period, 1847 patients undergoing lower extremity venous duplex scanning also had their oral temperature measured using a digital thermometer at the time of duplex examination. Patients were 57.8 ± 17.3 years of age (range, 14 to 99). Temperature was 98.5 ± 1.1° F. Twenty-three patients had acute inferior vena cava thrombosis, 60 had acute iliac vein thrombosis, 138 had acute femoral venous thrombosis, and 131 had acute popliteal venous thrombosis. Calf vein thromboses were present in 102 patients, and 43 patients had superficial venous thrombosis. A total of 228 patients had acute lower extremity venous thrombosis in one or more of these venous segments. Temperature with acute lower extremity venous thrombosis was 98.7 ± 1.05° F versus 98.5 ± 1.10° F in those with no acute thrombosis. Although small, this temperature difference was statistically significant ( P < 0.02). Acute deep venous thrombosis (DVT) was defined as acute popliteal or more proximal femoral, iliac, or vena cava thrombosis. The temperature for the 175 patients with acute DVT was 98.7 ± 1.10° F versus 98.5 ± 1.10° F for those without DVT ( P < 0.035). There was no temperature that served to accurately differentiate those who did from those who did not have DVT. The frequency that patients with DVT had fever, defined as a temperature ≥100° F, was 9.1 per cent (16 of 175) with DVT versus 7.5 per cent (126 of 1678) without DVT (not significant). In the subgroup with a temperature ≥101° F, 4.6 per cent (8 of 175) with DVT had such a fever versus 3.4 per cent (57 of 1672) without DVT (not significant). Those undergoing venous duplex who were found to have acute lower extremity venous thrombosis, including acute DVT, had statistically higher temperatures, but such temperature differences were minimal. The incidence of fever, defined as a temperature ≥100° F or ≥101° F, was not different between those with and those without acute DVT. It appears that the presence of fever may not be a sensitive or specific indicator for the presence of underlying acute DVT.