Compression Ultrasound (CUS)

Norm of Compression Ultrasound (CUS)

Negative.

 

Usage of Compression Ultrasound (CUS)

Used in conjunction with rapid ELISA d-dimer testing to assess the probability of existence of venous thrombi. Monitoring for occurrence of deep vein thrombosis in high-risk populations.

 

Description of Compression Ultrasound (CUS)

Compression ultrasound (CUS) is a noninvasive diagnostic tool that has largely replaced venography (phlebography), which is the criterion standard for diagnosis of venous thrombosis. In this procedure, the transducer pressure is applied to collapse the vein being scanned. A normal vessel will collapse completely, whereas a vessel with a thrombosis will not. Although CUS poses less procedural risk than venography, it is most accurate for the detection of proximal deep vein thromboses, which occur in 85% of clients with deep vein thrombosis (DVT), and which are the source of life-threatening pulmonary emboli. However, CUS often does not identify thromboses of the calf vein(s), is unreliable in determining the patency of the pelvic veins and inferior vena cava, and is not sensitive to asymptomatic postoperative DVT. To compensate for its limitations, the CUS is often followed by a color duplex ultrasound. CUS is not indicated in nonhospitalized clients with a low clinical score for risk of DVT, if a negative d-dimer test result has been obtained. For those with moderate or higher clinical risk scores and a negative d-dimer result, the CUS is recommended. Any positive CUS confirms DVT. Michiels et al. (2002) found that “the combination of a negative CUS and a negative rapid ELISA d-dimer test safely excludes DVT in clients with suspected DVT irrespective of the clinical score.” Frequent involvement of both limbs suggests the use of this procedure bilaterally.

Clinical Score (Ambulatory Care Clients)	Risk of DVT	Rapid ELISA D-Dimer Test	CUS	Implications
Low	3%–10%	Negative	N/A	Negative predictive value >99.9% to exclude DVT
Low		Positive <1000 ng/mL	Negative	Negative predictive value >99% to exclude DVT
Moderate	15%–30%	Negative	Negative	Negative predictive value >99.4% to exclude DVT
Moderate	15%–30%	Positive	Negative	Probability of DVT of 3%–5%
				Repeat CUS recommended
High	>70%	Not recommended	Negative	Probability of DVT of 20%–30%
				Repeat CUS recommended

Michiels JJ, Kasbergen H, Oudega R et al: Exclusion and diagnosis of deep vein thrombosis in outpatients by sequential noninvasive tools, Int Angiol 21(1):9–19, 2002.

 

Professional Considerations of Compression Ultrasound (CUS)
Consent form is NOT required.
Preparation

1. This test may be performed at the bedside.
2. Obtain a 3- to 7-MHz (for adults) or a 5- to 7-MHz (for children) linear transducer.

 

Procedure

1. Establish a baseline for comparison by evaluating the asymptomatic extremity.
2. Both noncompression and compression views are taken, beginning at the groin and proceeding distally down the common femoral vein, superficial femoral vein, and popliteal vein. Transverse views are taken both without and with augmentation at each of these vessels, followed by longitudinal views via spectral and color Doppler.
3. Repeat on the affected extremity, adding visualization of the iliac veins and inferior vena cava in the pelvis.
4. Follow with color duplex ultrasonography if further visualization of the pelvic veins and inferior vena cava is needed.

 

Postprocedure Care

1. Cleanse ultrasound gel off of skin.

 

Client and Family Teaching

1. This test is painless and noninvasive.
2. Test takes about 20 minutes to complete.
3. Radionuclide imaging may follow inconclusive tests.

 

Factors That Affect Results

1. CUS results may be positive for up to 6 months after an acute DVT.
2. The skill of the operator affects the accuracy of the results.

 

Other Data

1. The clinical score for determination of probability for DVT is a clinical model of complaints, signs, and symptoms, which has been found to be valid for estimating low, moderate, and high probability.