Abdominal Sonography Ch. 8 Veins

Describe how Doppler is used to distinguish the presence of absence of flow in a vessel from nonvascular structures.

Doppler ultrasound frequently is used to differentiate vessels from nonvascular structures. For example, to distinguish the common bile duct from the hepatic artery, look for absence of flow in the common duct; to distinguish the hepatic artery from the splenic artery, look for direction of flow; to differentiate aneurysm from pancreatic pseudocyst, look for slow flow in the aneurysm; to differentiate dilated intrahepatic bile ducts and prominent hepatic artery, again look for absence of flow in the bile duct.

Describe the technique that should be used to image the inferior vena cava.

The patient should be instructed to hold his or her breath; this causes the patient to perform a slight Valsalva maneuver toward the end of inspiration, which dilates the inferior vena cava. The inferior vena cava may expand to 3 to 4 cm in diameter with this maneuver.

Explain how to differentiate the inferior vena cava from the aorta.

The pulsatile aorta is easily differentiated from the inferior vena cava because the IVC travels in a horizontal course with its proximal portion curving slightly anterior as it pierces the diaphragm to empty into the right atrial cavity. The aorta, on the other hand, follows the curvature of the spine, with its distal portion lying more posterior, before bifurcating into the iliac vessels.

The portal vein shows a relatively _________ flow at low velocities, which may vary slightly with respirations.

continuous

Nonresistive vessels have a high _______________ component and supply organs that need constant perfusion, such as the internal carotid artery, the hepatic artery, and the renal artery.

diastolic

Resistive vessels have very little or even reversed flow in diastole and supply organs that do not need a constant blood supply, such as the __________ carotid and the iliac and brachial arteries.

external

The ________ veins originate in the liver an drain into the inferior vena cava at the level of the diaphragm.

hepatic

three large veins that drain the liver and empty into the inferior vena cava at the level of the diaphragm

hepatic veins

During rejection, the vascular impedance ___________, resulting in a decrease or even reversal of the diastolic flow.

increases

drains the left third of the colon and upper colon and joins the splenic vein

inferior mesenteric vein

largest venous abdominal vessel that conveys blood from the body below the diaphragm to the right atrium of the heart

inferior vena cava

The ____________ flows from the kidney posterior to the superior mesenteric artery and anterior to the aorta to enter the lateral wall of the inferior vena cava.

left renal vein

leaves the renal hilum, travels anterior to the aorta and posterior to the superior mesenteric artery to enter the lateral wall of the inferior vena cava

left renal vein

The main renal artery has a ___________ impedance (non resistive) pattern with significant diastolic flow--usually 30% to 50% of peak systole.

low

Doppler records accurate velocity patterns only when the beam is _________ to the flow.

parallel

Cavernous transformation of the portal vein demonstrates ____________ collateral channels in patients with chronic portal vein obstruction.

periportal

____________ is a pattern of blood flow, typically seen in large arteries, in which most cells are moving at the same velocity across the entire diameter of the vessel. In other vessels the different velocities are the result of friction between the cells and arterial walls.

plug flow

The _______ vein is formed posterior to the pancreas by the union of the superior mesenteric vein and splenic veins at the level of L2.

portal

formed by the union of the superior mesenteric vein and splenic vein near the porta hepatis of the liver

portal vein

A flow disturbance (increased velocity or obstruction of flow) may result from the formation of an atheroma, AV, fistula, _________, or an aneurysm dilation.

pseudoaneurysm

leaves the renal hilum to enter the lateral wall of the inferior vena cava

right renal vein

Portal veins become _________ as they progress into the liver from the porta hepatis.

smaller

drains the spleen; travels horizontally across abdomen (posterior to the pancreas) to join the superior mesenteric vein to form the portal vein

splenic vein

The ____________ passes anterior to the third part of the duodenum and posterior to the neck of the pancreas, where it joins the splenic vein to form the main portal vein.

superior mesenteric vein

drains the proximal half of the colonnade small intestine, travels vertically (anterior to the inferior vena cava) to join the splenic vein to form the portal veins

superior mesenteric vein

The few pattern of the proximal abdominal aorta above the renal arteries shows a high __________ peak and a relatively low _________ component.

systolic; diastolic

With a recanalized ____________ vein, the main portal vein and the left portal vein show normal flow but the flow in the right portal vein in reversed.

umbilical

collapsible vascular structures that carry blood back to the heart

veins