Ultrasound of the inferior vena cava and hepatic veins

Ultrasound anatomy

The inferior vena cava is located to the right of the spine, passing through the diaphragm and draining into the right atrium. The main tributaries visualized by Doppler ultrasound are the iliac veins, the renal vein, and the three hepatic veins, which drain into the inferior vena cava just below the diaphragm. More than three hepatic veins may be found when the caudate lobe of the liver drains through a separate vein.

Methodology for performing ultrasound examination of the inferior vena cava and hepatic veins

Ultrasound Dopplerography of the inferior vena cava system is usually performed on the inferior vena cava in color mode in two planes along its entire length. When anomalies are detected, Doppler spectra are recorded for quantitative assessment.

Normal ultrasound image of the inferior vena cava and hepatic veins

Blood flow in the inferior vena cava and hepatic veins has a clear dependence on the cardiac cycle. The movement of the cardiac valve cusps towards the apex creates a pronounced suction effect inside the atrium, causing a rapid inflow of blood to the heart. When the right atrium is filled by the beginning of diastole, venous inflow decreases or even a certain period of reverse blood flow can be determined. When the atrioventricular valves open, blood enters the ventricles, and venous inflow into the atrium can again occur. Towards the end of diastole, the atrium contracts. Since there are no valves between the terminal veins and the atrium, this contraction causes a transient outflow from the heart. Closure of the atrioventricular valves at the end of diastole sometimes leads to the formation of a small notch on the spectrum line.

Right ventricular failure may alter the pattern of spectral waves, with decreased blood flow to the heart. Tricuspid valve insufficiency results in abnormal backflow through the inferior vena cava during systole. Flat, ribbon-like spectra may be recorded in patients with advanced liver cirrhosis.

In B-mode, thrombosis of the inferior vena cava is manifested by the inability to compress the vein, loss of pulsation and hypoechoic dilation, which is still somewhat more echogenic than in the echo-negative lumen. In color mode, a color void is determined in the area of the affected segment, which is caused, for example, by extended thrombosis of the left common iliac vein. The right common iliac vein gives residual blood flow in the inferior vena cava in the form of a crescent).

Filters in the inferior vena cava reduce the risk of embolization from the veins of the pelvis and lower extremities, but complications are common. Metal filters installed intraluminally can shift or thrombose and become a source of emboli. Doppler ultrasound is a method for monitoring and determining the location of the filter.

Narrowing of the inferior vena cava lumen may have other causes besides thrombosis, such as postoperative complications, stenosis, intraluminal tumor growth, or external tumor compression.

Thrombosis may affect individual small hepatic veins (veno-occlusive disease) or the main venous trunks (Budd-Chiari syndrome), sometimes with damage to the inferior vena cava. When individual veins or venous segments are thrombosed, the absence of blood flow on ultrasound Dopplerography may be combined with intersegmental collateralization and a Doppler spectrum in the form of a strip.

Intrahepatic lesions, such as angioma, can displace and narrow the hepatic veins, reaching significant sizes.