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


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%.


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

DVT

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