Imaging of Small Bowel and

Colon

Linda Pantongrag-Brown, MD

King Chulalongkorn Memorial

Hospital, Bangkok

Small Bowel

Anatomy

• Longest tubular organ in body, 18-22 feet

• Mesentery: 15 cm long between ligament

of Treitz to IC junction

• Rule of 3’s

– Wall thickness < 3mm

– Diameter < 3 cm

– Air-fluid levels < 3

Normal Bowel Caliber

• Mnemonic: “3-6-9-12”

– 3 cm max size of small bowel

– 6 cm max size of transverse colon

– 9 cm max size of cecum

– 12 cm max size of cecum before it may burst

Case 1

• A 58-year-old man presented with

abdominal pain, nausea, vomiting.

Case 1

• Rigler Triad

– Partial small bowel obstruction

– Gas in biliary tree

– Ectopic calcified gallstone

• Diagnosis: Gallstone Ileus

Case 2

• A 63-year-old man presented with

abdominal pain, nausea, vomiting.

Case 2

• “Stepladder pattern”

• Multiple air-fluid levels (> 3 ), different

height in the same loops

• Dilated small bowel lumen (> 3cm) with

no air in the colon

• Diagnosis: Small bowel obstruction (CA

cecum)

SBO Etiologies

• Adhesion/Fibrosis

• Internal hernia

• Volvulus

• Intussusception

• GS ileus

• Abscess

• Neoplasm

Case 3

• A 45-year-old man presented with

abdominal pain and fever.

Case 3

• Abscess at the RLQ causing partial SBO

• Possible etiologies

– Ruptured appendicitis

– Ruptured diverticulitis

– SB infarction with perforation

– CA colon with perforation

• Diagnosis: SB infarction with perforation

Case 4

• A 26-year-old female presented with

recurrent abdominal pain.

Case 4

• Cluster of small bowel loops at the left-

side abdomen with marked dilatation of

the duodenum suggestive of left

paraduodenal hernia (through fossa of

Landzert)

Case 5

• A 58-year-old female presented with

abdominal pain.

Case 5

• Relatively thickened, regular folds with

minimal nodularity

• This pattern implies relatively even

distribution of submucosal deposition.

• It is usually caused by edema or

hemorrhage.

D/Dx: Regular, smooth

thickened folds

• Edema (Diffuse)

– Hypoproteinemia (cirrhosis, NS, protein losing

enteropathy)

– CHF

– Portal HT

• Hemorrhage (Focal)

– Anticoagulant therapy/coagulopathies

– Ischemia (SMA, SMV thrombosis; hypoperfusion)

– Vasculitis

Case 5

• Thrombus within the SMV

• Diffusely thickened small bowel wall

• Dx: Ischemic bowel, SMV thrombosis

Case 6

• A 58-year-old man presented with

abdominal distension and pain.

Case 6

• “String of pearls” appearance with

relatively absence of air in colon,

indicative of small bowel obstruction

• Site of obstruction is possibly proximal.

SBO Etiologies

• Adhesion/Fibrosis

• Internal hernia

• Volvulus

• Intussusception

• GS ileus

• Abscess

• Neoplasm

Case 6

• Coil-spring appearance, indicative of

intussusception

• Dx: Lymphoma

Case 7

• A 74 year-old man presented with

abdominal pain and fever.

Case 7

• Jejunal diverticula with inflammatory

mass encasing the small bowel loops and

extraluminal air bubbles

• Dx: Rupture jejunal diverticulitis

Case 8

• A 59-year-old man, check up.

Case 8

• A pedunculated polyp with lobulated

contour at the descending colon

• Diagnosis: Tubulovillous adenoma

Colonic Polyp

• Hyperplastic polyp

– Sessile polyp < 5 mm

• Adenomatous polyp

– Tubular adenoma

– Tubulovillous adenoma

– Villous adenoma

Adenoma Size & Incidence of

Malignancy

• < 5 mm, 0.5%

• 5-9 mm, 1%

• 10-20 mm, 5-10%

• > 20 mm, 10-50%

• All polyps > 10 mm should be removed

• Time for adenoma-carcinoma sequence

10-15 years

Case 9

• A 56-year-old man presented with

constipation.

Case 8

• Circumferential mass at rectum with a

small processional node

• Dx: CA rectum, Modified Dukes C

– T3 (servos)

– N1 (1-3 regional l.n.)

– M0 (No distant met)

CA Colon: preop staging by CT (Balthazar, AJR 1988)

CT vs Modified Dukes

• Stage A (limit to colonic wall): 57%

• Stage B (extend to serosa/pericolic fat): 17%

• Stage C (involve regional nodes): 68%

• Stage D (involve adjacent organs, peritoneal seedings, liver met): 81% with 100% positive predictive value.

CA Colon: preop staging by CT (Balthazar, AJR 1988)

• CT is inaccurate in Dukes A, B, C

staging, and do not effect surgical

treatment.

• CT is sensitive with high +ve predictive

value in Dukes D

Should pre-op CT staging be

performed?

• Yes.

• Because its high sensitivity and high +ve

predictive value in detecting advanced

lesions, which may lead to changes in

surgical planning (limited resection

instead of extensive curative procedure),

or preoperative management.

Case 10

• A 60-year-old man presented with melon.

CT Coronagraph

Case 10

• Intriguingly lobulated mass with

relatively thin wall

• Dx: CA rectum, Modified Dukes A

– T2 (muscular propia)

– N0

– M0

2 cm polyp

Case 11

• A 46-year-old man presented with

abdominal pain and distension.

Case 11

• Distended cecum rotates into the LUQ

• Dx: Cecal volvulus

Case 12

• A 55-year-old man presented with fever

and abdominal pain.

Case 12

• Extraluminal air bubbles at LLQ with

evidence of sigmoid diverticulosis

• Dx: Ruptured sigmoid diverticulitis

Case 13

• A 45-year-old man presented with fever

and abdominal pain.

Case 13

• Dilated appendix with air bubbles

dissecting in its wall and rupture into the

peritoneal cavity

• Dx: Rupture acute appendicitis

Case 14

• A 45-year-old man presented with

abdominal distension.

Case 14

• Omental cake

• Implantation with mass effect over the liver and splenic surfaces (scalloping sign)

• Ascites

• Rim calcified cyst at the RLQ

• Dx: Pseudomyxoma peritonei, from ruptured mucocele

D/Dx omental cake

• Peritoneal carcinomatosis

• TB peritonitis

• Pseudomyxoma peritonei

– Rupture mucocele

– Mucinous adenoCA metastasis

• Peritoneal mesothelioma

• Lymphoma

Case 15

• A 57-year-old presented with acute

abdominal pain and diarrhea.

Case 15

• Diffuse thickening of sigmoid colon

• D/Dx:

– Infectious colitis

– Ischemic colitis

– Pseudomembranous colitis

– Inflammatory bowel (UC, Crohn’s)

Case 15

• Dx: Ischemic colitis

Conclusion

• Normal anatomy

• SBO

– Gallstone ileus

– CA cecum

– Abscess (SB infarction with perforation)

– Intusussception (lymphoma)

• Internal hernia

– Left paraduodenal hernia

• SB ischemia (SMV thrombosis)

• Rupture jejunal diverticulitis

Conclusion

• Colonic polyp

• Carcinoma (T3N1, T2N0)

• Cecal volvulus

• Ruptured diverticulitis

• Ruptured appendicitis

• Pseudomyxoma peritonei (ruptured mucocele)

• Ischemic colitis