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Transcript of DVT
Acute Deep VenousThrombosis: Clinical andDiagnostic Evaluation
byMohammed Salah
Ass .lecturer –vas .surgery departmentAUH-assuit university
Introduction
DVT is one of the most significant public health problems.
Economic impact is very huge .
Early diagnosis of acute DVT is necessary for achieving the best outcomes
Introduction
detection of this disease is challenging as its early stages are frequently subclinical.
To address this challenge, strategies have been developed that include risk assessment as the first diagnostic step.
Adaptation of these strategy make clinical diagnosis of acute DVT is more accurate .
Cost -effectiveness
producing optimum results for the expenditure.
continuous shift toward early treatment of the majority of the patients based on the clinical information, reserving more expensive diagnostic tests for patients who require invasive treatment.
CLINICAL ASSESSMENT
Clinical picture
The clinical manifestations of acute DVT varies greatly.
About 50% of cases may be asymptomatic.
Broad variation is a result of multiple pathologic processes
Such pathological processes include 1.Timing of presentation …… severity 2.Anatomic distribution……degree of occlusion3.Functional state of lymphatic system 4. preexisting venous and lymphatic insufficiency all these factors lead to varieties in C/P from mild
edema to phlegmasia cerulae or venous gangrene.
Signs and symptoms
Common symptoms of DVT include: Leg pain and tenderness Oedema (swelling) Redness
C/P
The most common symptoms and signs of DVT are dull ache or pain in the leg, tenderness, swelling, erythema, cyanosis, and fever.
Edema, cyanosis, and pain are features of phlegmasia cerulea
Venous gangrene is a rare condition that occurs usually in patients with cancer, can occur with heparin-induced thrombocytopenia with thrombosis, and is generally associated with warfarin-mediated protein C depletion
Phlegmasia cerulea dolens Venous gangrene
C/P
The most common symptom of calf pain variable sensitivity and specificity due to high prevalence of the same signs and symptoms in patients without DVT.
Withholding treatment on the basis of clinical evaluation in primary care settings leads to inadequate management of more than 10% of patients with DVT.
High variability and lack of specificity limit the role of clinical examination in patients with suspected DVT
Signs and Symptoms of DVT’s
Recognize and report signs/symptoms of a DVT including:
Unilateral edema Erythema Calf tenderness Pale leg & cool with
diminished arterial pulse
Pratt's test: Squeezing of posterior calf elicits pain.
Homan’s sign (discomfort in the calf muscles on forced foot dorsiflexion w/ knee straight; NOTE: Homan’s sign is neither sensitive nor specific; Present in <1/3 of patients with confirmed DVT; Found in >50% of patients without DVT) (Schreiber, 2009)
DIAGNOSTIC TESTS
D-dimers: what is the role? D-dimer is a product of fibrin proteolysis
by plasmin; therefore, its elevated levels signify that fibrinolysis of complexed fibrin is taking place
In other words D-dimer: degradation product of cross-linked fibrin
The appeal: a simple blood test .
D-dimers
The concentration of D-dimer in plasma has become a widely used marker for the diagnosis of DVT its elevated levels signify that fibrinolysis of complexed fibrin is taking place.
High sensitivity, low specificity• Quantitative D-dimer < 500 ng/ml makes
PE less likely.
D-dimers
Elevated d-dimer common w/o clot - especially as part of the response to injury
1.Pathological as surgery patient , TraumaCancer patient ,patient with thrombotic disorders 2.Physiological as pregnancy
D-dimers
The degree of D-dimer elevation in patients with DVT varies with the size and extent of the thrombus, the time from its onset, and the use of anticoagulation.
Different types for assay most accurate one for DVT is ELISA but most laborious and slow. Rapid point of- care assays are probably the most practical as the results are obtainable within minutes and their sensitivity is comparable to that of the enzyme-linked immunosorbent assay
D-dimers
concentration of D-dimer below the cutoff value indicates a very low probability of DVT, it does not exclude it with sufficient accuracy, especially in cases of distal thrombi, use of anticoagulation, or long duration between the onset of thrombosis and testing
Similar to clinical evaluation, the use of D-dimer as a single diagnostic tool may result in inadequate management of more than 15% of patients with suspected DVT.
Duplex ultrasonography
Duplex ultrasonography remains the dominant diagnostic test of choice for the detection of DVT.
accuracy, lack of radiation, portability, noninvasiveness, and relative cost-effectiveness. In addition, ultrasound has the ability to distinguish among nonvascular pathologic processes, such as inguinal adenopathy, Baker’s cyst, abscess, and hematoma
Pitfalls of Duplex
Misidentification of veins missing of duplicate venous systems; systemic illness or hypovolemia resulting in decreased venous
distention suboptimal imaging in obese or edematous patients; and areas
not amenable to compression, such as the iliac veins, the femoral vein at the adductor canal, and the subclavian veins.
As with most ultrasound-based imaging studies, the quality of the examination depends on the skill of the technologist performing the study.
diagnostic criteria for DVT
in Duplex Duplex ultrasound diagnostic criteria for DVT 1.increased intraluminal echogenicity, 2. increased venous diameter, 3.inability of the vein to collapse under a moderate
pressure from the transducer, 4.absence of spontaneous blood flow, 5. and absence of flow augmentation with distal
compression
Color duplex scan of DVT
diagnostic criteria for DVT
in Duplex Among these factors, inability to compress
the vein is the most widely used objective criterion for the diagnosis of DVT.
limitation of compression ultrasound is its lack of accuracy in the evaluation of calf veins
evaluation of venous flow with color Doppler and spectral Doppler can improve the accuracy of compression ultrasonography
Plethysmography
Plethysmography is a noninvasive method of estimating changes in volume in an extremity.
Because all other tissues maintain constant volume during the short period of testing, any recorded volumetric differences reflect changes in blood volume.
Plethysmography
Several plethysmographic techniques with different sensors have been used to measure changes in blood volume
strain-gauge plethysmography (SGP) primarily been used in the past for the diagnosis of deep venous thrombosis(DVT),
impedance plethysmography (IPG), Photoplethysmography (PPG), and air plethysmography (APG).
Plethysmography
assess thrombus resolution and recanalization.
Because the occlusive cuff is placed on the thigh, plethysmographic diagnosis of calf DVT is especially problematic.
Limitation of Plethysmography
Successful recordings from SGP require full cooperation from the patient.
It cannot be performed on patients; who are unable to lie flat. Prolonged recumbency, musclewasting, and cardiac failure may result in measurement errors. Patients with limb injuries, bandages, casts, or severe
edemaare unsuitable candidates for SPG
CT VENOGRAPHY
Computed tomographic arteriography is an excellent technique for the diagnosis of pulmonary embolism.
(CTV), has yet to gain traction for the diagnosis of acute DVT in the lower or upper extremities.
The diagnostic capabilities of CTV are remarkable in the thigh and pelvis compared with duplex ultrasound
CT VENOGRAPHY
In addition, when CTV is used in conjunction for evaluation of PE, it adds only 3 to 5 minutes to the examination, making it an attractive option as the sole diagnostic modality for acute lower extremity DVT
CTV has not been well studied for acute calf vein less cost-effective than duplex ultrasound. involves the use of contrast material, and it uses
radiation
Imaging
MRV
Advantages of MRV
MRV is less expensive than contrast venography but more expensive and less operator dependent than duplex ultrasound.
Non–contrast-enhanced techniques include time-of-flight imaging.
Contrast enhanced MRV. such gadolinium.
MRV
MRV used to diagnose acute DVT in larger venous segments, but less sensitivities when smaller diameter veins are evaluated.
vessel wall enhancement can be visualized with acute thrombus, allowing the examiner a crude detection of thrombus age
Disadvantages of MRV
demands a nonmoving patient and long imaging times that, when paired, can be a significant hurdle.
The below-knee segments of venous anatomy are often paired, accounting for significant artifact during post processing of the images
gadolinium can be toxic in patients with renal dysfunction
ConclusionMRV
MRV can be preserved for detection of thrombus in centrally located venous structures not always accessible to duplex ultrasonography.
MRV useful for detection of hypogastric venous thrombosis
a remarkable 27% of patients without a detectable source of thrombus by duplex ultrasound who have sustained a PE had thrombus identified by MRV.
Contrast venography
Contrast venography for the sole purpose of diagnosing DVT is largely of historical interest.
It is expensive and inconvenient compared with other diagnostic modalities and potentially causes patient discomfort.
Complications of the examination include nephrotoxicity,allergy, phlebitis, and the need for intravenous access.
Nevertheless, contrast venography can be useful when other studies have not produced a solid diagnosis, making it important to retain this technology for diagnosis and therapeutics.
Contrast venography
The Rabinov-Paulin technique uses spot film, and the long-leg technique uses cine film.
contrast venography should be used as the “golden backup” when the diagnosis of acute DVT remains in question after a venous duplex examination
Venogram shows DVT
18F-FDG
18F-labeled fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) .18F-FDG is a glucose analogue that is actively and avidly absorbed by tissues and cells with rapid metabolism. Among these are tumor cells, endothelial cells, macrophages, and lymphocytes
18F-FDG PET/CT
18F-labeled fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) has been shown to:
detect acute DVT, to determine thrombus age.
differentiate acute thrombus from tumor thrombus.
DIAGNOSTIC STRATEGIESDIAGNOSTIC STRATEGIES
DIAGNOSTIC STRATEGIES
In the absence of a single reliable, accurate, and inexpensive diagnostic test, stratification of patients based on their risk of DVT substantially enhances clinical decision making.
strategies have been developed that include risk assessment as the first diagnostic step.
The result is a continuous shift toward early treatment of the majority of the patients based on the clinical information, reserving more expensive diagnostic tests for patients who require invasive treatment.
Two-level DVT Wells scoreClinical feature Points
Active cancer (treatment ongoing, within 6 months, or palliative) 1Paralysis, paresis or recent plaster immobilisation of the lower extremities 1
Recently bedridden for 3 days or more or major surgery within 12 weeks requiring general or regional anaesthesia 1
Localised tenderness along the distribution of the deep venous system 1
Entire leg swollen 1Calf swelling at least 3 cm larger than asymptomatic side 1Pitting oedema confined to the symptomatic leg 1Collateral superficial veins (non-varicose) 1Previously documented DVT 1An alternative diagnosis is at least as likely as DVT −2
Clinical probability simplified scoreDVT likely 2 points or moreDVT unlikely 1 point or lessa Adapted with permission from Wells PS et al. (2003) Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. New England Journal of Medicine 349: 1227–35
DIAGNOSTIC STRATEGIES
It is increasingly recognized that the optimal approach to DVT diagnosis includes risk stratification based on the Wells score and D-dimer assay, followed by diagnostic testing in high-risk patients and in patients who require advanced treatment modalities.
In low and intermediate risk patients, the combination of a Wells score and negative D-dimer result reaches a negative predictive value approaching 100%.
DIAGNOSTIC STRATEGIES
Evaluation of patients with a high probability of DVT is more problematic. Negative D-dimer results in these patients are associated with PE rates of up to 15%.
So, treatment should be started before additional testing is completed. When anticoagulation is initiated, delay in definitive diagnostic studies has been shown to be safe.
DVT during pregnancy
The risk of bleeding complications limits the use of anticoagulation to cases with confirmed DVT.
D-dimer levels have been known to increase during the course of a normal pregnancy and are of unproven utility during pregnancy.
For these reasons, ultrasound remains the preferred diagnostic test for detection of DVT in pregnancy.
Thrombophilia screeningFactor V leiden, Prot C/S deficiency
Antithrombin III deficiency
• Idiopathic DVT < 50 years• Family history of DVT• Thrombosis in an unusual site• Recurrent DVT
Patient with suspect symptomatic Acute lower extremity DVT
Venous duplex scan negative Low clinical probability observe
High clinical probability
Repeat scan /Venography
negativepositive
Evaluate coagulogram /thrombophilia/ malignancy
Anticoagulant therapycontraindication
yes IVC filter
No
pregnancy LMWH
OPD LMWH
hospitalisation UFH+ warfarin
Compression treatment