Gastrointestinal: Luminal, Small Bowel Flashcards
Differential for small bowel dilatation with thin (<3 mm) small bowel folds
- Mechanical obstruction
- Paralytic ileus
- Scleroderma
- Sprue (e.g. Celiac)
Differential for focal/segmental small bowel fold thickening (>3 mm)
- Small bowel ischemia
- Radiation changes
- Bowel hematoma/hemorrhage
- Adjacent inflammation
Differential for small bowel fold thickening (>3 mm) with a diffuse distribution
- Low protein
- Venous congestion
- Cirrhosis
Differential for nodular small bowel fold thickening in a segmental distribution
- Crohns
- Infection
- Lymphoma
- Metastases
Differential for nodular small bowel fold thickening with a diffuse distribution
- Whipples disease (Tropheryma whipplei)
- Lymphoid hyperplasia
- Lymphoma
- Metastases
- Intestinal lymphangiectasia
What are common causes of small bowel loop separation without bowel tethering on small bowel follow through?
- Ascites
- Wall thickening (e.g. Crohns, lymphoma)
- Adenopathy
- Mesenteric tumors
On small bowel follow through you see loop separation with tethering of the small bowel towards the area of separation…
Think carcinoid
Small bowel follow through demonstrates “sand like nodules” (diffuse micronodules in the jejunum)…
- Whipples disease (Tropheryma whipplei infection)
- Pseudo-Whipples (MAC/mycobacterium avium complex infection)
Small (2-4 mm), uniform small bowel nodules…
Think lymphoid hyperplasia
Small bowel follow through demonstrates multiple nodules of varying sizes
Think metastases (e.g. melanoma)
Small bowel follow through demonstrates “cobblestoning” (raised islands of mucosa separated by linear streaks of contrast…
Think Crohns disease
Note: Especially if you also see strictures and/or loop separation (due to fat proliferation).
Small bowel follow through demonstrated “ribbon bowel” (featureless small bowel that is atrophic and appears thickened at turns)…
Think chronic small bowel ischemia (e.g. graft vs host disease)
What is the bowel pattern depicted by the arrows?
Hidebound bowel (narrow separation of normal small bowel folds)
Note: Think scleroderma.
Hidebound bowel is seen in…
Scleroderma
What is the bowel pattern within the oval?
Moulage sign (dilated jejunal loop with complete loss of jejunal folds, making it look like an opacified tube of wax)
Note: Think Celiac disease.
The moulage (tube of wax) sign is seen in…
Celiac disease
Which bowel pattern is shown here?
Fold reversal (the ileum looks like it has more jejunal-type folds than the jejunum, which appears to have less folds than usual)
Note: Think Celiac disease.
Which disease often demonstrates “fold reversal” on small bowel follow through?
Celiac disease
Note: Fold reversal is when the ileum has more bowel folds than the jejunum (the opposite of normal).
Parasitic roundworm infection (Ascaris lumbricoides or Ascaris suum)
Note: Linear defect in the barium column inferiorly.
Black arrows
Smooth, sessile filing defect in the small bowel
Note: This was carcinoid.
White arrows
Multiple ileal diverticula
Small bowel aphthoid ulcers (punctate collections of barium surrounded by radiolucent mounds of edema), consistent with Crohns disease
Barium enema with reflux of contrast into the terminal ileum
Crohn’s disease
Note: This is the string sign due to terminal ileal edema.
Crohns disease
Note: Narrowing of the terminal ileum (large arrow) with multiple ileocolic fistulas (small arrows).
Think chronic small bowel ischemia (e.g. graft vs host)
Note: Tubular narrowing of the small bowel with complete loss of the small bowel folds (ribbon sign).
Bowel separation with bowel tethering, think carcinoid
Differential for a solitary target sign (not multiple as in this picture)
- GIST
- Primary adenocarcinoma
- Lymphoma
- Ectopic pancreatic rest
- Metastasis (e.g. melanoma)
Differential for multiple target signs
- Lymphoma
- Metastases (e.g. melanoma)
Healed duodenal bulb ulcer
Note; This is the clover leaf sign.
Whipples disease
Small bowel infection of Tropheryma whipplei causing marked swelling of the intestinal villi and irregularly thickened mucosal folds (mostly in the duodenum and proximal jejunum)
Pseudo-whipples
Small bowel infection of MAI that occurs in AIDS pts with CD4 < 100 that appears the same as Whipples disease (jejunal micronodules with irregular fold thickening)
Note: Can get an acid fast stain to differentiate (only MAI in pseudo-whipples will be positive).
Intestinal lymphangiectasia
Dilatation of the intestinal and serial lymphatic channels due to obstruction of lymph flow from the small intestine
Causes of intestinal lymphangiectasia
- Primary (lymphatic hypoplasia)
- Secondary (e.g. obstruction of the thoracic duct)
Which organs are most severely affected by graft vs host disease?
- GI tract (small bowel most severe)
- Skin
- Liver
SMA syndrome
Bowel obstruction caused by compression of the 3rd portion of the duodenum as it passes between the aorta and the SMA, usually secondary to rapid weight loss
Note: The stomach and proximal duodenum should be dilated.
Celiac disease
An immune disorder triggered by gluten
Clinical manifestations of celiac disease
- Diarrhea/weight loss
- Iron deficiency anemia
- Dermatitis herpetiformis (skin rash)
Celiac disease is associated with…
Idiopathic pulmonary hemosiderosis (Lane Hamilton Syndrome if they occur together)
Lane Hamilton Syndrome
- Celiac disease
- Idiopathic pulmonary hemosiderosis
Pts with Celiac disease are at increased risk for…
Bowel wall lymphoma
Gold standard diagnostic test for celiac disease
Biopsy
Pt is positive for tissue transglutaminase (tTG) antibody…
Celiac disease
Small bowel follow through signs of Celiac disease
- Fold reversal (ileum has more folds than jejunum)
- Moulage “tube of wax” sign (dilated small bowel without any mucosal folds)
How does the spleen appear in pts with Celiac disease?
Atrophic
What type of lymphadenopathy is common in pts with Celiac disease?
Cavitary (low density) lymphadenopathy
Pt on chronic dialysis with duodenal mucosal fold thickening…
Normal finding (pts on chronic dialysis can have severely thickened duodenal folds)
Thickening of duodenal folds on upper GI series…
- Duodenal inflammation (e.g. pancreatitis, chocystitis)
- Duodenal Crohns
- Chronic dialysis
Jejunal diverticulosis is associated with…
Small intestinal bacterial overgrowth (SIBO) and malabsorption
Gallstone ileus
A mechanical small bowel obstruction due to a gallstone that entered the small bowel through a fistula between the gallbladder and duodenum
What are the direct signs of bowel trauma?
- Leaked oral contrast
- Active mesenteric bleeding
What are the indirect signs of bowel trauma?
- Fat stranding
- Fluid layering along the bowel
Best CT protocol for penetrating trauma to the abdomen
CT abdomen and pelvis with IV and water soluble oral contrast
Note: No barium contrast.
Diffuse small bowel wall thickening on noncontrast CT where the bowel wall is more dense than the posts muscle…
Think shock bowel
Note: If the bowel wall was more focally/segmentally hyperdense, then you would think about bowel trauma/hematoma.
Imaging features of hypovolemic shock bowel
- Diffuse thickening of bowel walls with mucosal hyperenhancement (small bowel > large)
- Signs of shock (collapsed IVC, hypoenhancing solid organs, bilateral delayed/persistent nephrograms, hyperenhancing adrenal glands)
Elderly pt in ICU for treatment of UTI
Shock bowel
Note: Diffuse bowel wall thickening with mucosal hyperenhacement and collapsed IVC (arrow).
What are some imaging signs of shock?
- Shock bowel
- Collapsed IVC
- Hypoenhancing solid organs
- Bilateral delayed/persistent nephrograms
- Hyperenhancing adrenal glands
Focal bowel wall thickening that is hyperdense to psoas muscle on non contrast CT…
Think bowel trauma/hematoma
What is the most common small bowel cancer in the proximal small bowel?
Adenocarcinoma (most common in the duodenum)
Focal, circumferential thickening of the duodenum with evidence of obstruction…
Think adenocarcinoma
Classic imaging appearance of small bowel lymphoma
Bowel wall thickening (infiltrative, polypoid, multinodular) WITHOUT obstruction
What is the most common location for small bowel lymphoma?
Ileum
Classic imaging appearance of a small bowel carcinoid
Abdominal mass with desmoplastic “starburst” fat stranding and calcifications
Note: This abdominal mass is not actually the primary tumor, but the desmoplastic reaction to the tumor (the primary tumor is often not visible on imaging).
Paroxysmal flushing and diarrhea
Carcinoid (with metastases to the liver inferred due to carcinoid syndrome)
Note: Abdominal mass with desmoplastic “starburst” fat stranding.
Small bowel carcinoid tumors are most common in what pt population?
Young adults
Are liver mets from carcinoid tumors hypovascular or hypervascular?
Hypervascular (usually)
What is the most common primary location for a carcinoid tumor?
Distal ileum
Note: Some older literature says appendix.
Which GI location has the best prognosis for a carcinoid tumor?
Appendix
Complications of small bowel carcinoid tumor
- Carcinoid syndrome (paroxysmal flushing/diarrhea; only if there are liver mets)
- Right-sided heart valve degeneration (classically tricuspid regurgitation)
Which nuclear imaging study is best to identify carcinoid tumor metastases?
Ga-68 DOTATATE
Note: MIBG or Octreotide scans could also be used. You should not use PET/CT as carcinoid tumors are relatively indolent and typically not FDG avid.
Do carcinoid tumors show up on PET imaging?
Usually not, carcinoid tumors are relatively indolent and usually not FDG avid
Note: Nuclear imaging with Ga-68 DOTATATE is excellent.
What is the most common primary when there is small bowel metastases?
Melanoma
Note: You can also get small bowel metastases in breast cancer, lung cancer, and Kaposi sarcoma.
Spigelian hernia
Lateral ventral abdominal hernia that occurs at the semilunar line (lateral border of the rectus muscles)
Note: “S”pigelian hernias happen at the “S”emilunar line. These most commonly occur at the arcuate line.
What is the arcuate line?
A horizontal line across the lower abdomen at the lower limit of the posterior layer of the rectus sheath
Note: Above this line the lateral body wall aponeuroses split anterior and posterior to the rectus muscles, but below the line the lateral body wall aponeuroses all travel anterior to the rectus muscles.
What are the two types of lumbar hernias?
- Superior lumbar or Grynfeltt-Lesshaft (more common)
- Inferior lumbar or Petit
What is the anatomic triangle that a superior lumbar (Grynfeltt-Lesshaft) hernia travels through?
Superior lumbar triangle:
- 12th rib
- Internal oblique
- Quadratus lumborum
What is the anatomic triangle that an inferior lumbar (Petit) hernia travels through?
Inferior lumbar triangle:
- Latissimus dorsi
- External oblique
- Iliac crest
Superior lumbar hernia
Note: At the inferior border of the 12th rib.
Inferior lumbar hernia
Note: At the superior border of the iliac crest.
Spigelian hernia
Note: At the lateral border of the rectus muscle.
Littre hernia
A hernia containing a Meckel diverticulum
Amyand hernia
A hernia containing the appendix
Richter hernia
A hernia containing only one bowel wall (not an entire loop of bowel)
Note: These are less likely to obstruct, but have a higher risk of strangulation.
Obturator hernia
Note: Between the right obturator and pectinous muscles.
Obturator hernias are more common in what pt populations?
- Elderly pts
- Pts with increased intra-abdominal pressure (ascites, chronic coughing in COPD, pregnancy)
Elderly female with parenthesis along the inner thigh down to the knee…
Think obturator hernia
Note: This is the Howship-Romberg sign due to compression of the obturator nerve.
What are the major types of inguinal hernias?
- Indirect (most common)
- Direct
- Femoral (elderly females)
How can you differentiate direct and indirect inguinal hernias?
Indirect inguinal hernias are lateral to the inferior epigastric artery
Direct inguinal hernias are medial to the inferior epigastric artery
How can you differentiate femoral inguinal hernias from other types of inguinal hernias?
Femoral inguinal hernias occur below the pubic tubercle
Direct and indirect inguinal hernias occur above the pubic tubercle
Indirect inguinal hernias occur due to…
A failure of the processus vaginalis to close
Direct inguinal hernias occur due to…
A defect in Hesselbach’s triangle
Femoral inguinal hernias often have mass effect on…
The femoral vein (may appear concave)
Note: There is often associated engorgement of collateral veins.
Which inguinal hernias often cause compression of the inguinal canal contents?
Direct inguinal hernias
Note: Compression of the inguinal canal is what causes the lateral crescent sign (the crescent is the compressed inguinal canal).
Direct inguinal hernia on the left
Note: Lateral crescent sign (compression of the inguinal canal).
Which type of inguinal hernia is covered by internal spermatic fascia?
Indirect inguinal hernia
What is the most common type of internal hernia?
Paraduodenal hernias
Postprandial abdominal pain that improves after massaging their abdomen…
Think internal hernia with intermittent obstruction
What are the two major types of paraduodenal hernias?
- Left-sided, occurring through the fossa of Lanzert (75%)
- Right-sided, occurring through the fossa of Waldeyer
Note: L for Left and Lanzert.
Where is the defect that a left-sided paraduodenal hernia travels through?
The fossa of Lanzert in the descending colon mesentery (LLQ)
Where is the defect that a right-sided paraduodenal hernia travels through?
The fossa of Waldeyer in the ascending colon mesentery (RLQ)
Left-sided paraduodenal hernia
Note: Cluster of bowel in the left anterior pararenal space.
What is the major risk factor for right-sided paraduodenal hernias?
Malrotation
Right-sided paraduodenal hernia
Note: Cluster of bowel on the right below the duodenum and pushing the SMA anteriorly.
What are the common locations for an internal hernia?
- Paraduodenal (most common)
- Lesser sac/foramen of winslow
- Pericecal
- Sigmoid mesocolon
- Small bowel mesentery
- Post gastric bypass surgery
You see a single segment of bowel dilatation on an abdominal radiograph…
Think sentinel loop (focal reactive ileus in response to an adjacent inflammatory process)
Note: If the dilated loop is central, think pancreatitis, and if in the RLQ, think appendicitis.
Gasless abdomen on radiograph…
Nonspecific finding, but can be seen in diarrhea and obstruction (look at the clinical history)
