Abdominal Vascular Pathologies Flashcards
Aortic Aneurysms
Definition/Description: It is a permanent localize dilation of the artery
Characteristics: Most cases are true aneurisms which involve all three layers and 95% infrarenal.
Signs and symptoms: 30-60% of patients are asymptomatic; Ruptures or enlarges quickly, it can cause back, abdomen, or flank pain. Patients may present with satiety, nausea, and vomiting.
Lab Values: Hematocrit level will drop if aneurism ruptures.
Sonographic findings and their USA: A thrombus within an aneurysm has medium to low level echoes. You may see wall thickening, calcification, different blood flow, soft or
calcified plaque. An aneurysm will measure more than 3 cm. The walls may appear more echogenic due to calcification.
True Aneurysm
Definition/Description: lined by all three layers (intima, media, and adventitia) of the aorta histologically.
Characteristics: The shape of the aneurysms can be fusiform or saccular which helps to identify a true aneurysm.
Signs and symptoms: Same as AAA
Lab Values: If it ruptures then the hematocrit will be low.
Sonographic findings and their USA: A focal dilation of with at least a 50% increase in diameter is considered an aneurysm. You will see a dilation of the normal looking aorta. A thrombus may also be present and it will have medium to low level echoes. Hyperechoic areas may mean a rupture has occurred.
False aneurysm (pseudo- aneurysms)
Definition/Description: occurs when blood escapes through a hole in the intima of the vessel wall, but is contained in the adventitia or surrounding soft tissue.
Characteristics: The risk of rupture is higher than that of a true aneurysm.
Sonographic findings and their USA: With color Doppler, blood can be seen to flow into the protuberance during systole and out during diastole. Color Doppler will show the
communication between artery and vein. Ying yang sign is present.
Dissecting aneurysms
Definition/Description: Blood can enter the medial layer of the aortic wall through a tear or ulcer and track along the media. This forms a blood-filled channel within the wall.
Sonographic findings and their USA: The sonographer should look for a dissection “flap” or recent channel, with or without aneurysmal dilation. The flap is demonstrated with M-mode as a fluttering within the lumen throughout the cardiac cycle. A blood-filled (anechoic) channel along the aortic wall represents the false lumen. Both the true and false lumens will demonstrate flow with the flow rate differing between the channels.
“Pseudo-pulsatile” abdominal masses
Definition/Description: Masses other than aortic aneurysms that can simulate a pulsatile an abdominal mass. Some examples are retroperitoneal tumor, huge fibroid uterus, and para-aortic nodes.
Characteristics: The most common cause (other than an aortic aneurysm) for a pulsatile abdominal mass is enlarged retroperitoneal nodes.
Lab Values: Enlarged nodes could have a high WBC count due to infection.
Sonographic findings and their USA: Retroperitoneal lymph nodes are homogenous masses surrounding the aorta. The aortic wall will be poorly defined because of the close acoustic impedance of the nodes and aorta. The echo density of a retroperitoneal sarcoma depends on the tissue type. Fatty lesions are more echodense than fibrous or myomatous lesions.
Mesenteric ischemia
Definition/Description: a portion of the small intestine does not receive enough blood supply due to injury. This occurs when one or more mesenteric arteries narrows or becomes blocked.
Signs and symptoms: pain in abdomen (middle to upper part
usually) 15-60 minutes after you eat. Weight loss, diarrhea, nausea, vomiting, flatulence, and constipation.
Lab Values: High WBC count and acidosis are common to see in mesenteric ischemia.
Sonographic findings and their USA: Doppler ultrasound will show the blockage of blood vessels. An abnormal reading shows a blunted increase in the peak diastolic velocity. This
indicates stenosis which is a narrowing of the vessel. On an ultrasound we will see this narrowing.
Arteriovenous fistulas
Definition/Description: Abnormal connection between the
artery and vein. It usually occurs in the legs.
Signs and symptoms: low back and abdominal pain, progressive cardiac decompensation, a pulsatile abdominal mass associated with a bruit, and massive swelling of the lower trunk and lower extremities.
Lab Values: Blood gas analysis in the AVF reveals a higher oxygen saturation in the vein; Large AVF’s can lead to low platelet count
Sonographic findings and their USA: Arteriovenous fistulas are not a common finding in ultrasound.
Celiac axis compression syndrome
Definition/Description: median arcuate ligament of the diaphragm compresses the celiac artery
Signs and symptoms: chronic abdominal pain that has lasted several months, abdominal pain after eating, weight loss, sometimes abdominal bruit, or the sound made by blood flowing through an obstruction. This condition can also be asymptomatic.
Sonographic findings and their USA: You will see diameter changes with inspiration and expiration in the celiac axis. Color flow will show turbulence and aliasing as well as
poststenotic reversal of flow. We will see that the celiac axis is compressed.
Endovascular stent graft
Definition/Description: An endovascular stent graft is a tube composed of fabric supported by a metal mesh called a stent. It is used to help prevent an aneurysm from rupturing.
Sonographic findings and their USA: The vessel is anechoic and surrounding the vessel is hypoechoic due to AAA. Once a stent graft is inserted, there is a hyperechoic circle
around the anechoic vessel.
IVC thrombosis
Definition/Description: This is the obstruction of flow through the IVC by a blood clot.
Characteristics: They are categorized as either Bland or Tumor. Bland thrombosis can be an isolated thrombus but is often associated with DVT of lower extremities. Tumor thrombosis is when a neoplastic lesion extends into the IVC. Signs and symptoms: Patients present with leg edema, low back pain, pelvic pain, GI complaints, and liver and renal abnormalities.
Sonographic findings and their USA: On U/S, the IVC is an anechoic vessel. The IVCT appears as a homogenous echo mass and color Doppler can be useful in determining whether the vessel is occluded.
IVC filters
Definition/Description: The IVC filter is a tubular wire mesh that is implanted into the IVC to trap small emboli that may cause problems in the heart or lungs. It is a cone-shaped device.
Characteristics: The preferred location of the filter is in the iliac bifurcation below the renal veins.
Sonographic findings and their USA: A thrombus is a hypoechoic bulge in the anechoic vessel. A filter appears hyperechoic in the vessel.
Portal venous hypertension
Definition/Description: increase in blood pressure within the portal venous system.
Signs and symptoms: GI bleeding in stool or vomit, ascites,
splenomegaly, and encephalopathy or confusion.
Lab Values: Low platelet and WBC levels.
Sonographic findings and their USA: Doppler findings include: low velocity in portal vein, flow is reversed in the portal vein. Ascites
