Exam IV: Abdominal and Pelvic Imaging Flashcards Preview

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Kidney, Ureters and Bladder AP Supine X-ray (KUB)

Most basic x-ray evaluation of abdomen
No contrast given

You should look for: liver, spleen, kidneys, psoas shadows, intestinal gas pattern

Normal small bowel should be 2.5cm or less
2.5cm to 3cm is borderline
Larger than 3cm is dilated


Recognizing GI Structures by their Mucosal Folds

Stomach with rugae
Circular folds of small bowel mucosa
Haustral folds in colon

Narrow, circular folds represent small bowel
Wider, rounded haustrations show colonic involvement


Dilated Small Bowel

Multiple loops of dilated small bowel
Circular folds are clearly visible


Air Filled Colon

Note haustrations and tenia when colon fills with air
Colon can become massively dilated


KUB with Gallstones

Incidental finding
Only about 15% of gallstones are visible on x-ray
Ultrasound is the diagnostic test of choice when biliary pathology is suspected, not KUB
Not all gallstones require surgery


Porcelain Gallbladder

Gallbladder seen in right upper quadrant (RUQ) outlined by calcifications
Rare, premalignant condition in which the wall of the gallbladder becomes calcified
Risk factor for gallbladder cancer
Requires gallbladder removal because if gets cancer there is no cure and spreads so quickly
Absolute indication for cholecystectomy


Radio-Opaque Foreign Body

Will find swallowed coins, missing jewelry, bullets – any dense object
A KUB is also what we order when the surgeon can’t quite figure out where that last instrument has gone


Abdominal Series

Includes three separate X-ray films:
1. AP supine abdomen (KUB)
2. AP upright abdomen
3. PA Chest X-ray

Decubitus position is used when patient cannot stand up
Left side down puts the large, smooth edge of the liver at the top of the image – if there is free air it will be seen there

Looks for:
Bowel dilatation (dilation)
Air-fluid levels in the abdomen
Free air beneath the diaphragm


Supine vs. Upright

Same patient
When supine, fluid forms a uniform layer, not visible
Standing the patient up shows air fluid levels
It is normal for the intestine to contain air and fluid but not in the same place


Contrast Studies

Upper GI series (UGI) or small bowel follow through use barium to coat mucosal surfaces and outline the lumen
Iodinated contrast is used instead of barium if perforation is suspected
Double-contrast UGI series (Enteroclysis) uses barium and air to coat the mucosa and distend the lumen


Upper GI Barium Study

Oral Barium or iodinated contrast
Dynamic flouroscopic examination
NPO overnight
No laxatives or other preparation needed
Includes stomach and duodenum to ligament of Treitz
Barium is visible in the proximal jejunum but it is not included in this study

Ligament of Treitz: filmy layer of tissue on the duodenum; distinguishes from an upper GI and lower GI bleed


Hiatal Hernia

Use Upper GI Barium Study to Dx
Herniation of part of the stomach through the diaphragmatic hiatus
Common - found in up to 20% of population

Two types:
1. Sliding type (most common 95%)
2. Para-esophageal
Both can cause reflux, have similar symptoms but different potential complications


Sliding Hiatal Hernia

Large portion of fundus “pulled up” into mediastinum, gastroesophageal (GE) junction has moved
Herniated portion of the stomach has entrance and exit
Only repaired if severely symptomatic


Paraesophageal Hiatal Hernia

Fundus of stomach has “flipped up” into mediastinum, GE junction has not moved
Fundus forms a pouch, only one opening
Susceptible to strangulation
Routinely repaired
Twisted stomach above the diaphragm can build up harmful bacteria, and if explodes is right next the heart so is very dangerous


Small Bowel Follow Through

Includes jejunum and ileum
May take up to 5 hours to get through the bowel
Difficult to read individual images without watching the study or reading the report
Roll the patient side to side so barium moves and get lots of information


Double Contrast or Enteroclysis

A tube is placed through the stomach, into the duodenum
Barium coats mucosa, add air to distend/inflate the bowel
Gives excellent detail
Not very comfortable for patient
Constriction of ileum, “apple core” lesion that goes in circular pattern; can be cancer and double contrast will allow you to dx this


Enteroclysis with Filling Defect

Large white mass is overlapping normal bowel
Only tells us that a mass is present on the bowel wall
May or may not be malignant
If no air injected with double contrast, would have missed this
Might not be seen on single contrast study or CT


Barium Enema

Single or double-contrast barium enemas require NPO overnight and colonic cleansing (5 liters of GoLytely®)
Barium enema looks for changes in diameter, intraluminal masses, colon polyps, diverticuli, colon cancer
Dynamic flouroscopic examination
Similar information obtained with colonoscopy

Barium is forced into rectum, all the way around to the cecum
Very dense, shows outline clearly
Patient can be rotated and tilted for different views
Does not show details of mucosa well


Structure of Transverse Colon

Large “apple core” lesion- highly suggestive of malignancy
The cecum receives mostly liquid through it, so the apple core wouldn’t give patient symptoms since it is just fluid going through; barium provided this finding or otherwise cancer would have developed
No proximal dilatation – may not have been symptomatic


Single Colon Polyp on Barium Enema

Single pedunculated (“with stalk”) polyp in the sigmoid colon
Seen as a filling defect within the barium column (minimal detail)


Double Contrast Barium Enema

Enteroclysis for small intestine
Barium followed by air, both per rectum
Excellent mucosal detail
Very uncomfortable for patient


Colonic Polyps on Double Contrast

Multiple small polyps on double contrast barium enema (BE)
Double contrast gives much more detail than simple barium enema
Polyps need to be removed or become cancerous


Diverticulosis on Double Contrast Barium Enema

Diverticulum – an “out-pouching” or herniation of mucosa through the bowel wall
Very common – 50% of people >50yr have diverticulosis
95% of diverticula are in the descending and sigmoid colon
Rectum has neither haustrations nor diverticuli

Diverticulitis- inflammation/infection that can make you sick
Diverticulosis is a benign condition


Redundant Colon

May be extremely long - colon length is variable
Not pathological, just unusual
Would be difficult to pass a colonoscope
Patient needed a barium enema because the colonoscope couldn’t get through all the loops and curves


Abdominal CT

Axial, cross-sectional imaging
Images are viewed “looking from the feet up”
GI tract lumen identified via oral contrast
I.V. contrast provides tissue enhancement, and is excreted by the kidneys
Abdominal CT scan is from dome of liver to perineum, with contiguous “slices” 0.5-1cm thick
Shorter patient- get more info and smaller slices
Taller patient: get less information because larger slices


Basic Rules of Orientation

No matter which imaging method is involved or what part of the body you are looking at, if the image is axial it should be displayed the same way:
The patient’s right side to your left and vice–versa
Anterior is up, posterior is down


Highest Abdominal CT Slice

Highest slice
Patient’s right on your left and vice-versa
Right hemidiaphragm and liver are most superior part of abdomen
Aorta “lights up” - IV contrast has been given
Small portion of lungs visible

Remember relative densities:
Bone and metal are white
Fat below skin is dark grey
Muscle and organs are lighter gray (heart and liver)
Air is black (lungs, esophagus)


Abdominal Descending CT Slices

Stomach and spleen are larger
Large vein within liver is portal vein
Still some lung tissue visible posteriorly

Gallbladder is dark – no contrast going there
Stomach has air and contrast material in lumen – air fluid level
IVC is buried within liver

Muscles are more prominent in lumbar region


Abdominal CT Slices: Vessels

The first time you see a branch of the aorta you know it is the celiac trunk
Left kidney shows up first

Second large branch of aorta is superior mesenteric artery coursing downward
Large diameter vessel crossing over to vena cava is left renal vein

Aorta splits into iliac arteries – What spinal level? (L4) umbilical cord level


Mesentery of the GI Tract

Sheet of tissue with arteries, veins, nerves, lymphatics that covers the GI tract; support system leading to the GI tract and holds it in