Tuesday 2/24/04, 11 A.M.
GI-2 #7 Page 1 of 6
Dr. Mobley
Eric Lawrence for Shane Ashford
Abdomen – Plain Film Studies
Dr. Mobley mentioned before lecture that this lecture will give us exposure to
abdominal radiographs and tell how to read them. He also said that if you are
going to buy textbooks on radiography, then buy the thin ones that say
“essentials”, unless you are going into radiography. There will be 3 test
questions from this lecture:
1. **Most common cause of small bowel obstruction is ADHESIONS**
2. **Most common cause of large bowel obstruction is tumor**
3. **Pneumobilia = air in the bowel ducts**
Abdominal Radiographs:
X-Ray Density
Imaging of abdominal structures is possible because of different densities
interfacing: air-fluid, fluid-bone, or fat-water
 Air – darkest area on the film
 Fat – less dark
 Water – soft tissue density
 Bone
Basic Structures
 Bones
 Psoas Margins
 Flank Stripes
 Bowel
 Calcifications
(and organs if you can see them)



Abdominal radiograph includes diaphragm to pubes
o If large person, then may need to get two shots for this area
Abdominal Series = at least 2 views
o Upright AP (anterior to posterior view = direction it’s going through the
patient) and supine AP
Acute Abdominal Series = also includes upright CXR
Normal Structures (see slide #4)
 Psoas margin – can see it because it’s outlined by fat
 Flank stripes – between peritoneal lining and bowel
 Bowel
 Organs – liver, kidneys (sometimes obscured by bowel), cecum, ascending
colon, transverse colon, descending and sigmoid colon, etc.
 Bones
 Normal calcifications
Tuesday 2/24/04, 11 A.M.
GI-2 #7 Page 2 of 6
Dr. Mobley
Eric Lawrence for Shane Ashford
Abnormal psoas (see slide #5 – loss of psoas margin)
 Right psoas obscured– a large retroperitoneal mass due to hemorrhage (most
common cause) if history of trauma, or lymphoma, large renal mass…more
detail in notes
 Right kidney displayed
 follow up with a CT scan to find out what it is
Bowel
Pattern analysis
 Size
 Position
 Large vs Small
 Bowel wall thickness
 Pneumatosis = air in bowel
o Normal = adult has large bowel gas with very little small bowel gas
Organs
• Evaluate size and volume – just compare to adjacent structures
• (See slide #7) – splenic enlargement displacing gastric bubble to the right
• (See slide #8) -- example of asymmetry of kidney; right kidney is a little
smaller than left due to obstruction of right renal vein and it’s infarcted
and the angiogram with catheter seen into abdominal aorta is injecting dye and
can see also that the right renal artery is occluded
Bone
 Evaluate Bone density
o Most common abnormality to see would be osteopenia (general loss of
density of the bone)
 Evaluate for fractures and trauma
o Eg/ slide #9 – fracture of superior pubic ramus (on right), and fracture
through pubic bone with also rupture of the bladder in this patient
Normal Calcifications
 Costochondral – at ribs
 Pelvic phleboliths – in pelvis and have central lucency
Abnormal Bowel
Stomach
 Most common abnormality would be gastrectasis (gastric distention of
stomach)
o slide #12 (left) -- pediatric pt with most common cause being pyloric
stenosis
o Slide #12 (right) -- in adult pt usually d/t ulcerative disease or diabetes
– also see the gaseous distension with contrast
Tuesday 2/24/04, 11 A.M.
GI-2 #7 Page 3 of 6
Dr. Mobley
Eric Lawrence for Shane Ashford
Small bowel
 Normal small bowel not really seen in adults, but more so in pediatrics
 Normal small bowel should not be more than 3 cm and is centrally located
 valvulae conniventes cross entire lumen of small bowel
o eg/ slide #13 - large and small bowel mildly dilated, little feces seen in
rectum, not massively dilated, normal appearance for an ileus
 Things to look for in small bowel:
o Lumen patent
o Dilated small bowel
o Dilated large bowel
 Etiology of small bowel abnormalities:
o inflammation
o recent surgery
o recent trauma
Small Bowel Obstruction
 Distention of small bowel throughout
 See valvulae conniventes throughout that look like a stack of coins throughout
 No large bowel gas
 On upright film – air/fluid levels are uneven – in ileus you can have air/fluid
levels, but they are usually even all the way across
 **Most common cause of small bowel obstruction is ADHESIONS** TEST QUESTION
Gallstone Ileus
o misnomer because it is an obstruction, but not in ileus
 Riglers Triad = symptoms
o Small bowel obstruction
o Pneumobilia
o Ectopic gallstone
 Gallstone erodes in duodenum and travels through small bowel until it gets
lodged
 You see small bowel obstructive pattern with pneumobilia
 You don’t always see the stone (need CT for that)
Intussusception
 Type of closed loop obstruction usually seen in pediatrics
 Seen as a soft tissue mass displacing bowel
o Eg/ slide #16 – Catheter injected air into small bowel and you can see
it comes around and stops at the mass
 Tx: Usually induce until they rupture (which they always do) and then go in
for surgery
Tuesday 2/24/04, 11 A.M.
GI-2 #7 Page 4 of 6
Dr. Mobley
Eric Lawrence for Shane Ashford
Strangulation
 Closed looped obstruction – usually seen in pediatrics
 Small bowel volvulus – usually seen in pediatrics
 Incarcerated hernia – usually seen in adult
 Eg/ slide #17 – mass is the pt scrotum that contains both large bowel and
small bowel
Large bowel obstruction
 Normal large bowel: no larger than 5 cm and cecum no greater than 8 cm
 **Most common cause of large bowel obstruction is tumor** TEST
QUESTION
o Eg/ slide #18 – distended large bowel, transverse and descending
colon, then stops; there’s also a mass on CT scan causing obstruction;
incidental finding on this pt is pneumotosis and distended cecum.
o Could be due to ischemic bowel, but there are multiple benign causes
of pneumotosis
Large bowel volvulus
 Not uncommon, especially in elderly
 Most common type is sigmoid volvulus
o Eg/ slide #19 – classic appearance – bowel twists upon itself and you
get an inverted U
 Also can exist in cecum and transverse colon
Toxic megacolon
 Condition that occurs usually with ulcerative colitis
 Symptoms: fever, diarrhea, and dilated large bowel
 See a massively thick wall of bowel as it displaces small bowel and loss of
haustral markings (typical of bowel inflammatory dz)
o Slide #20 – Also pneumotosis involving right colon (speckled
appearance)
 No barium enemas on these patients because they will rupture
Bowel wall thickening
 Thumbprint sign seen in: (eg/ slide #21)
o Inflammatory bowel disease
o Ischemic bowel
 CT would be much more sensitive
Tuesday 2/24/04, 11 A.M.
GI-2 #7 Page 5 of 6
Dr. Mobley
Eric Lawrence for Shane Ashford
Free Air (2 Key things to look for on plain film: obstruction and free air)
 Most sensitive plain film is:
o Upright CXR
o Left lateral decubitus
 Can see 1 cc of free air in abdomen with pt sitting in upright or left lateral
decubitus for 20 minutes
 Differential Diagnoses:
o Chilaiditi syndrome – supraposition of large bowel over liver and
between diaphragm that gives appearance of free air; differentiate by
seeing haustral markings
o Subphrenic abscess – when right up against the diaphragm it can
mimic free air
 CT would be more sensitive way to determine if you have free air
**Pneumobilia = air in the bowel ducts** TEST QUESTION
 Can see in:
o Gallstone ileus – if also a small bowel obstruction
o Surgery – most common
o ERCP
o Infection -- rarely
Portal venous gas
 See thin lucency around liver usually at periphery of liver – bad sign
 Sign of:
o Intestinal gangrene
o Ischemic bowel
 Also see pneumatosis (speckled bowel) due to dead bowel
 Patients usually don’t survive
Pneumatosis = air in bowel
Speckled look on plain film, but CT is more sensitive
Abnormal Calcifications
Appendicolith
 Symptoms: RLQ of abdomen,  WBC count, fever
 Not always seen – may see loss of psoas margins and sometimes the lumbar
spine will be concaved away from area of appendicitis
 A CT is more sensitive
Ureteral calculi
 On plain film: large chunky calcification, spine is curved, obstruction of left
kidney, no contrast going to ureter
 Eg/ slide #29 – this is a large stone, and probably won’t pass (if > 5 mm)
 Symptoms: flank pain and hematuria  get an IVP
Tuesday 2/24/04, 11 A.M.
GI-2 #7 Page 6 of 6
Dr. Mobley
Eric Lawrence for Shane Ashford
Abdominal Aorta
 Difficult to see on plain films
 Calcifications and faint rim of Ca along the paraspinal tissues
Chronic pancreatitis
 Easy to diagnose on plain film
 Calcifications along margin of pancreas
Dermoid cyst
 Typically a female in reproductive age with vague pelvic pain
 Looks like a tooth in the pelvis
Calcified uterine fibroid
 Large chunky amorphous calcification
Female with Abdominal Pain
 ALWAYS get a pregnancy test before doing an X-ray
 Slide #34 -- see baby in abdomen
Free fluid
 Difficult to see on plain film
 When massive ascites you see:
o Haziness of abdomen
o Loss of psoas margin
o Organs indistinct
o Small bowel floats to center of abdomen
 Can’t see any lumbar
Foreign bodies
Will see this:
 Surgical instruments / sponges
 Ingested objects: coins, objects, etc..
o Will see lots of coins in kids - if coin gets into colon it will pass
 Inserted objects (rectal)
 “Believe it or not” – see slides #36 to end