SONO-ANATOMY: Abdominal Vasculature

What ligament divides the liver into right and left?

falciform

Where does the aorta originate?

left ventricular outflow tract in the heart

Where does the aorta terminate?

fourth lumbar vertebra (near the umbilicus); where bifurcation occurs

Where does the IVC originate?

fifth lumbar vertebra (near the umbilicus); where bifurcation occurs

Where does the IVC terminate?

right atrium of the heart

What does the term “trunk” indicate?

branching into 2 or more

What type of structure is the aorta?

retroperitoneal

Where does the aorta bifurcate?

bifurcates into left and right common iliac arteries at the superior portion of the sacrum (or the 4th vertebra or near the umbilicus)

After bifurcation of the inferior abdominal aorta, the common iliac arteries further divide into what?

internal and external iliac arteries

How many branches does the celiac trunk have? What are they?

3; common hepatic, left gastric, splenic

Which artery could be web-like?

superior mesenteric artery

Where does the abdominal aorta supply blood to?

all structures below the diaphragm; abdominal organs, pelvic organs, lower extremeties

What are the major anterior branches of the aorta?

celiac axis/trunk (CA), superior mesenteric artery (SMA), inferior mesenteric artery (IMA)

What are the major lateral branches of the aorta?

left and right renal arteries (LRA & RRA), left and right common iliac arteries (LCIA & RCIA)

What artery of the aorta do you rarely see in ultrasound?

inferior mesenteric artery

What is the most superior branch of the abdominal aorta?

inferior phrenic artery

Where does the inferior phrenic artery supply blood to?

diaphragm

What is the most inferior branch of the abdominal aorta?

median sacral artery

Where does the median sacral artery supply blood to?

sacrum and rectum

What is the first abdominal branch?

celiac axis/trunk/artery

Where is the celiac artery usually on the aorta?

anterior

What does the celiac trunk give rise to?

splenic artery, common hepatic artery, left gastric artery

Where does the common hepatic artery supply blood to?

liver, right side of stomach, parts of the duodenum

What does the common hepatic artery branch into?

gastroduodenal artery and proper hepatic artery

Where does the splenic artery supply blood to?

spleen, pancreas, and left side of the stomach

What direction does the splenic artery come out of the celiac trunk at?

left at a 90-degree angle

What part of the liver does the left hepatic artery supply?

caudate and left lobe

Where does the right hepatic artery supply blood to?

gallbladder via the cystic artery and the liver

Where does the gastric artery supply blood to?

lower third of the esophagus and the upper right of the stomach

What is the largest branch of the celiac trunk?

splenic artery

What can be used as a landmark in locating the celiac trunk?

superior mesenteric artery

How can you differentiate the celiac trunk from the SMA?

“seagull sign”

Where is the distribution of blood of the celiac trunk vessels to?

liver, spleen, stomach, pancreas, and duodenum

How long is the celiac trunk?

approx. 1-2 cm

What is the second branch of the abdominal aorta?

superior mesenteric artery

Where is the SMA located?

1-2 cm inferior to the celiac axis

Where does the SMA supply blood to?

small intestine, ascending colon, and part of the transverse colon

What are the 5 main branches of the SMA?

inferior pancreatic artery, duodenal artery, colic artery, ileocolic artery, and intestinal artery

Where do the branches of the SMA supply blood to?

small bowel; proximal half of the colon (cecum, ascending, transverse) and the small intestine

What is the third branch of the abdominal aorta?

renal arteries

Where do the renal arteries originate?

lateral aspect of the aorta anterior at the level of the 1st lumbar vertebra, inferior to the SMA

How do the renal arteries course compared to the renal veins?

posteriorly

Which renal artery courses posterior to the IVC?

right renal artery

Which renal artery is longer?

right

Which artery courses from the aorta directly into the hilus of the left kidney?

left renal artery

T/F: both renal arteries are best seen in transverse sonograms

true

T/F: the left renal artery is lower than the right

false

Which kindey is more superior?

left

What branches of the abdominal aorta are not usually seen on scans?

gonadal arteries & inferior mesenteric artery

Where do the gonadal arteries originate?

inferior to the renal arteries on the anterior aorta

What are the respective terms of the gonadal artery dependent on gender?

testicular artery (male) & ovarian artery (female)

Where does the IMA originate?

superior to the umbilicus on the anterior aorta

Where does the IMA supply blood to?

transverse colon, descending colon, and rectum

What is the normal diameter of the proximal abdominal aorta?

approx. 2.0 cm

What is the normal diameter of the mid abdominal aorta?

approx. 1.5 cm

What is the normal diameter of the distal abdominal aorta?

approx. 0.8-1.0 cm

What is the normal diameter of the iliac arteries?

</=1.0 cm

What are three sonographic appearances of the abdominal aorta?

1. anechoic, tubular structure located slightly left of midline

2. bright, echogenic smooth wall margins

3. high-resistance arterial blood flow

What are the main reasons for imaging the abdominal aorta?

aneurysms, stenosis, & grafts

What are the types of aneurysms?

fusiform, saccular & dissecting

What can be identified using doppler sonography?

stenosis of the CA, SMA, renal artery, and common iliac; grafts can be evaluated for patency and complications

What does anastomosis mean?

a connection or opening between two things that are normally diverging or branching

How is the IVC formed?

anastomosis of the common iliac veins

How does the IVC course?

superiorly

Where is the IVC in respect to the aorta?

right side

Where is the IVC in respect to the spine?

anterior and to the right

After the IVC goes through the diaphragm, where does it go?

immediately empties into the right atrium

What does confluence mean?

two unequal vessels joining together

What are the IVC tributaries?

inferior phrenic veins, hepatic veins, renal veins, gonadal veins, and left & right common iliac veins

How many hepatic veins (HepV) are there?

usually 3, 2-4 sometimes; RHV, MHV, LHV

What are the renal veins of the IVC?

suprarenal; left & right renal

What is a large collapsible vein that returns blood from the abdomen, pelvis, and lower limbs through the system’s major tributaries into the right atrium of the heart?

IVC

What drains the head, neck, thoracic cavity and upper extremeties?

SVC

Why are the walls of the IVC thinner than aortic walls?

pressure of blood flow is lower

T/F: hepatic arteries and veins are seen in ultrasound?

false; only veins visible

What are sonographic appearances of the IVC?

1. anechoic tubular structure located to the right of midline

2. bright, echogenic smooth wall margins

What are 3 normal variants of the IVC?

1. Double IVC

2. Left-positioned IVC

3. Absence of a portion of the IVC (rare)

What is included in the portal venous system?

splenic vein, SMV, IMV, Main portal vein, LT portal vein, RT portal vein

What is the spleno-portal confluence?

union of the superior mesenteric vein and the splenic vein to form the portal vein

Which part of the portal venous system is difficult to recognize on ultrasound because of its anatomic location and small diameter?

inferior mesenteric vein

What are the components of the spleno-portal confluence?

main portal vein, left portal vein (lateral and medial branches), and right portal vein (anterior and posterior branches)

What is the purpose of the portal venous system?

collects blood and nutrients from the intestines and spleen

T/F: the portal venous system delivers deoxygenated blood to the liver

true

Where does the main portal vein enter the liver?

porta hepatis

What does it mean if the main portal vein is extrahepatic?

outside of the liver

How does the main portal vein course?

diagonally; left hip to right shoulder

What happens after the MPV enters the porta hepatis?

divides into right and left portal veins

What branches are on the left portal vein?

lateral and medial

What branches are on the right portal vein?

anterior and posterior

What can the liver be compared to in an airport?

customs; filters blood, collects blood from spleen for antibodies from the spleen

How are the portal vein walls in terms of color?

bright echogenic

T/F: portal veins have thick walls

false

Why is urine yellow?

it has bile in it

What vein drains the large intestine and varies widely as to where it actually joins the portal venous system?

inferior mesenteric vein

What is the region of anastomosis where the SMV and the splenic vein join?

spleno-portal confluence (portal confluence)

What vein courses along the posterior border of the pancreas?

splenic

Explain the course of the main portal vein.

Begins at portal confluence, courses for 5-6 cm (13mm diameter), ends at the porta hepatis of the liver where it bifurcates into LPV and RPV

Where does the right portal vein supply blood?

right lobe

Where does the left portal vein supply blood?

left lobe

What makes up the portal triad?

bile duct, hepatic artery, and portal vein