Diagnosis of Iliac Vein Obstruction With Duplex Ultrasound

Criteria used during duplex ultrasound examination to identify iliac vein obstruction.

By Prof. Nicos Labropoulos
 

Venous obstruction most often occurs due to thrombosis, extrinsic compression, or when both conditions are present. Obstruction of the iliac veins has a significant impact because it is responsible for the highest outflow resistance, venous claudication, and higher deep vein thrombosis recurrence. It also causes more prevalent and severe postthrombotic symptoms, impairing the quality of life of the patients, and poses a marked financial burden to society. Therefore, prompt and accurate diagnosis is necessary to facilitate the management of patients.

Obstruction is a dynamic entity associated with increased resistance to outflow due to energy loss when blood travels from one area to another. Most often, symptoms are present when the patient is walking; however, diagnosis of obstruction may be controversial because all imaging tests are performed with the patient in the supine position, which only shows morphologic but not dynamic changes. Venous pressure measurements at rest and during exercise are better indicators of the hemodynamic impact but may underestimate the chronic effect of somewhat compensated obstruction. All tests are patient and operator dependent, but duplex ultrasound may be the most. More importantly, formal training for ultrasound detection of obstruction is lacking, and rigorous training and experience are necessary to perform accurate evaluation. The exam starts at the common femoral vein (CFV) union and finishes with the inferior vena cava (IVC). Diagnosis with duplex ultrasound is based on specific direct and indirect criteria listed in Table 11-9 and detailed in the sections that follow.

DIRECT CRITERIA

Planimetric evaluation and luminal changes are very important because they allow direct imaging and evaluation of the obstruction. Stenosis and occlusion can be differentiated this way. Additionally, the diameter of the veins can be measured, luminal material indicating previous thrombosis with partial or no recanalization can be seen, and extrinsic compression and the type of compression producing the stenosis or occlusion can be assessed. Acute and recurrent thrombosis and extrinsic compression and thrombosis can be directly assessed. When present, the velocity ratio is important because it indicates > 50% diameter stenosis and has been validated by three studies using intravascular ultrasound. However, the absence of the velocity ratio cannot exclude obstruction, as the vein may be occluded, have long stenosis, or be partially recanalized. When velocities or diameters are being measured, it is very important that the pressure applied by the ultrasound transducer does not affect the measurements, as too much pressure may lead to disease overestimation.

INDIRECT CRITERIA

When indirect signs are detected, they always indicate some form of obstruction. However, they cannot differentiate between stenosis and occlusion, extrinsic compression, or luminal changes. Therefore, direct imaging of the affected veins is important. The presence of phasic flow and good augmentation cannot exclude obstruction.

DISCUSSION

Our group and others have identified many patients with obstruction, sometimes with occlusion of iliac vein still having normal CFV phasicity and flow augmentation. Imaging of the inflow and the IVC are important, as this information is needed for proper patient management. The inflow veins, including the femoral, deep femoral, and CFV, are examined for patency because adequate inflow is necessary before stent placement to relieve iliac vein obstruction. Evaluation of the IVC is performed to determine patency. When present, the type of obstruction and anatomic variations such as aplasia, hypoplasia, left-sided cava, and duplication are reported because they are also important for the treatment plan. Understanding the vein anatomy and the surrounding structures is paramount. The areas of vein compression are listed in Table 2.

Figure 1. Compression of the left common iliac vein (CIV) by the right common iliac artery (CIA) over the fifth lumbar vertebra (A). The vein velocity ratio is 5.8. Narrowing of the CIV is apparent with mosaic color due to aliasing from the high velocity. No flow is seen in the left CIV, whereas normal flow is observed in the right CIV (B). This is a less common type of compression where both the right and left CIA compress the left CIV.

Figure 2. Reverse flow is seen in the left internal iliac vein (A) in a patient with tight stenosis of the ipsilateral CIV (B). The internal iliac vein has the same color as the internal iliac artery. The Doppler waveform demonstrates flow in the same direction in both vessels. The left CIV diameter measures only 2 mm at the site of compression, whereas the distal part of the vein measures 14 mm.

Many types of compression are observed and do not include other types from tumors, aneurysms, or hematomas. Several duplex ultrasound images are displayed to make an informed diagnosis of iliac vein obstruction. Figure 1 and Figure 2 demonstrate examples of patients with vein compression, and Figure 3 and Figure 4 show patients with different forms of vein occlusion.

Figure 3. Left external iliac vein compression by the left external iliac artery and chronic vein occlusion, with the diameter measuring 7 mm (A). The patient had chronic iliofemoral obstruction with edema, pain, and skin damage. The ipsilateral CIV was patent, filling from the left internal iliac vein. A large pelvic collateral vein is seen with nonphasic, high-velocity flow (> 100 cm/s) (B).

Figure 4. Normal femoral veins are seen in a patient without vein obstruction (A–C). The CFV has phasic flow with good augmentation (phasic flow cannot exclude obstruction). The CFV is easily compressed. The distal CFV, femoral, and deep femoral veins in the contralateral side are normal. There is low nonphasic flow with poor augmentation in the CFV (D–F). This patient has an IVC filter with chronic occlusion that extends into the iliac veins (F).

CONCLUSION

Ultrasound is a great method for diagnosing venous obstruction. It is practical, cheap, has no side effects, can be easily repeated, and some dynamic testing is possible. It offers direct imaging as well as indirect criteria, which are very useful for detecting obstruction. However, it is the most operator-dependent imaging method, and there is a lack of formal, rigorous training worldwide. Furthermore, there are no robust diagnostic criteria for defining hemodynamically significant obstruction in a great number of patients. Further, work is needed to establish and also translate such findings with the clinical improvement of the patients.

1. Labropoulos N, Borge M, Pierce K, Pappas PJ. Criteria for defining significant central vein stenosis with duplex ultrasound. J Vasc Surg. 2007;46:101-107.

2. Labropoulos N, Jasinski PT, Adrahtas D, et al. A standardized ultrasound approach to pelvic congestion syndrome. Phlebology. 2017;32:608-619.

3. Mousa AY, Broce M, Yacoub M, AbuRahma AF. Iliac vein interrogation augments venous ulcer healing in patients who have failed standard compression therapy along with pathological venous closure. Ann Vasc Surg. 2016;34:144-151.

4. Metzger PB, Rossi FH, Kambara AM, et al. Criteria for detecting significant chronic iliac venous obstructions with duplex ultrasound. J Vasc Surg Venous Lymphat Disord. 2016;4:18-27.

5. Kayılıoglu SI, Köksoy C, Alaçayır I. Diagnostic value of the femoral vein flow pattern for the detection of an iliocaval venous obstruction. J Vasc Surg Venous Lymphat Disord. 2016;4:2-8.

6. Sumner DS, Lambeth A. Reliability of Doppler ultrasound in the diagnosis of acute venous thrombosis both above and below the knee. Am J Surg. 1979;138:205-210.

7. Lensing AW, Levi MM, Büller HR, et al. Diagnosis of deep-vein thrombosis using an objective Doppler method. Ann Intern Med. 1990;113:9-13.

8. Bach AM, Hann LE. When the common femoral vein is revealed as flattened on spectral Doppler sonography: is it a reliable sign for diagnosis of proximal venous obstruction? AJR Am J Roentgenol. 1997;168:733-736.

9. Lin EP, Bhatt S, Rubens D, Dogra VS. The importance of monophasic Doppler waveforms in the common femoral vein: a retrospective study. J Ultrasound Med. 2007;26:885-891.

Prof. Nicos Labropoulos
Professor of Surgery and Radiology
Stony Brook University Medical Center
Stony Brook, New York
nlabrop@yahoo.com
Disclosures: None.

 

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