Gastrointestinal: Luminal, Large Bowel Flashcards
Age range for Crohn’s disease
Bimodal:
- 15-30 (most common)
- 60-70
“Squaring” of the bowel mucosal folds…
Think Crohns
Note: This is an early manifestation from obstructive lymphedema.
What are “proud loops” in Crohns disease?
Separation of bowel loops due to fat infiltration of the mesentery (creeping fat)
What are the pseudopolyps in Crohns disease?
Islands of hyperplastic mucosa
What is the best location to evaluate if looking for signs of Crohn’s disease?
The terminal ileum
Age range for ulcerative colitis
Bimodal:
- 15-30 (most common)
- 60-70
Note: This is the same as for Crohn’s disease.
What is the best location to evaluate if looking for signs of ulcerative colitis?
The rectum (involved in 95% of cases)
How often is the terminal ileum involved in ulcerative colitis?
5-10% (due to backwash ileitis)
Pt with longstanding ulcerative colitis and a newly enlarged abdominal lymph node…
Suspicious for cancer
Note: Unlike in Crohn’s disease, lymphadenopathy is not common in ulcerative colitis unless a cancer has developed.
Ulcerative colitis is associated with…
- Colon cancer
- Primary sclerosis cholangitis
- Arthritis
Ulcerative colitis
Note: Ahaustral colon with diffusely granular colonic mucosa.
Ulcerative colitis
Note: Diffusely irregular colonic mucosa (no skip lesions) without any haustra.
Gallstones are more common in Crohns/UC
Crohns
Primary sclerosis cholangitis is more common in Crohns/UC
Ulcerative colitis
hepatic abscesses are more common in Crohns/UC
Crohns
Pancreatitis is more common in Crohns/UC
Crohns
Colonic fistulae are more common in Crohns/UC
Crohns
Think toxic megacolon
Note: Gaseous dilatation of the transverse colon with loss of haustra.
Common causes of toxic megacolon
- Ulcerative colitis (most common)
- Crohns
- C. diff colitis (less common)
What should you not do if you are suspecting toxic megacolon?
Barium enema (due to risk of perforation)
Crohns appearance of the bowel in the ileocecal region in a pt with ulcers of the penis and mouth…
Behcets
What vascular complication is associated with Behcets?
Pulmonary artery aneurysm
Behcets
- Ulcers of the mouth and penis
- Crohns appearance of the bowel in the ileocecal region
- Pulmonary artery aneurysms
What is the most common cause of gastrointestinal fistula formation?
Diverticulitis
Epiploic appendagitis
Omental infarction
Which side is epiploic appendagitis more common on?
The left side
Note: Mental infarction is more common on the right.
Best test to evaluate for appendicitis in a pregnant female
MRI without contrast
Common causes of appendicitis
- Obstructing appendicolith
- Obstructing reactive lymphoid tissue
Think appendix mucocele
Appendix ultrasound
Think appendix mucocele
Note: This is the “onion sign” on ultrasound (layering within the cyst).
Appendices mucocele
Dilatation of the appendix with mucous due to a benign (e.g. retention cyst) or malignant (e.g. mutinous cystadenocarcinoma) process
What are the most common mucinous tumors of the appendix?
Mucinous cystadenoma
Note: These look the same as mucinous cystadenocarcinomas and can also lead to perforation and pseudomyxoma peritonei.
What is the most common adult form of colonic volvulus?
Sigmoid volvulus
Note: Cecal volvulus is the next most common and occurs more often in younger pts.
Sigmoid volvulus
Note: “Coffee bean sign”.
Cecal volvulus
Note: Tip of dilated twist points to the LUQ.
Cecal bascule
An uncommon form of cecal volvulus where the cecum folds up over itself without twisting, but can still lead to obstruction (usually isolated cecal/appendiceal dilatation)
Think cecal bascule
What features should make you consider cecal volvulus over sigmoid volvulus?
More common in cecal volvulus:
- Extends to the LUQ
- Haustra are maintained
- Small bowel is dilated
- Distal large bowel is not dilated
Marked dilatation of the entire large bowel without clear transition point…
Think colonic pseudo-obstruction (AKA Ogilvie syndrome, AKA colonic ileus)
Diversion colitis (AKA pouchitis)
Bacterial overgrowth in a blind loop of bowel that no longer passes feces
Note: This classically occurs in pts with pre-existing inflammatory bowel disease.
Colitis cystica
Cystic dilatation of the colonic mucous glands, can be superficial or deep
Think colitis cystica profunda
What are the two types of colitis cystica?
- Superficial (small cysts involving the entire colon)
- Deep/profunda (larger cysts involving the pelvic colon and rectum)
Common causes of colitis cystica
- Vitamin deficiency
- Tropical sprue
Think rectal cavernous hemangioma
Note: Numerous phleboliths in the rectal region.
Rectal cavernous hemangioma is associated with…
- Klippel-Trenaunay-Weber
- Blue Rubber Bleb
Gossypiboma (retained surgical sponge)
Bloody diarrhea
Think Entamoeba histolytica
Note: “Coned cecum” appearance with normal appearance of the terminal ileum. Colonic tuberculosis can also appear similar.
Imaging findings of Entamoeba histolytica
- Inflammation of the cecum and ascending colon (sparing the terminal ileum)
- Liver abscess
- Splenic abscess
Imaging findings of colonic tuberculosis
- “coned cecum” with involvement of the terminal ileum
- Fleischner sign (AKA inverted umbrella sign: enlarged, gaping ileocecal valve with narrowing of the terminal ileum)
- Sterling sign (swollen lips of the ileocecal valve allowing for rapid emptying of contrast from the cecum but retained contrast in the terminal ileum)
Enlarged gaping of the ileocecal valve with narrowing of the terminal ileum giving the impression of an inverted umbrella…
Think colonic tuberculosis
Note: This is the “Fleischner sign” or “inverted umbrella sign”.
Swollen lips of the ileocecal valve leading to persistent barium in the terminal ileum despite rapid emptying of the cecum…
Think acute on chronic colonic tuberculosis
Note: This is the “Stierlin sign”.
What pt population gets colonic CMV?
Immunosuppressed
Think C. difficile colitis
Note: This is the “accordion sign” (enhancing edematous mucosa with contrast trapped between mucosal folds).
Think colon inflammation (e.g. ulcerative colitis, C. difficile colitis, etc.)
Note: This is the “thumb printing” sign.
Colonic CMV
A colonic infection that causes deep ulcerations (can lead to perforation)
Typhlitis
Infection limited to the cecum that can occur in pts with neutropenia
Which GI infections like to affect the duodenum and proximal small bowel?
- Giardia
- Strongyloides
Which infections like to affect the terminal ileum?
- Tuberculosis
- Yersinia
Clinical presentation of colon cancer
- Obstruction/stool caliber change (left-sided cancer)
- Anemia/bloody stools (right-sided cancer)
Large bowel intussusception in an adult…
Think colon cancer
How do colon adenocarcinoma mets to liver appear on MRI?
T dark and T2 mildly bright (“evil grey”) with heterogeneous non-progressive enhancement
Where is squamous cell carcinoma most common in the large bowel?
Anus (think HPV infection)
What type of cancer is rectal cancer?
Adenocarcinoma (98%)
What imaging study is used to stage rectal cancer?
MRI
Note: T2 images are most important for staging.
When does a rectal cancer become stage T3?
When the tumor breaks out of the rectum into the perirectal fat
Note: This is crucial to identify because it changes management. For stage 3 rectal cancer they get neoadjuvant chemotherapy.
What location of rectal cancer has a high recurrence rate?
Lower rectal cancer (0-5 cm from the anorectal angle)
Treatment for rectal cancer
- Low anterior resection (high rectal cancer, >5 cm above the anorectal angle)
- Abdomino-Perineal Resection (low rectal cancer),
Note: LAR maintains fecal continence, but APR does not (requires a colostomy).
What is the second most common tumor in the colon?
Colonic lipoma
What is the most common benign tumor of the colon and rectum?
Adenoma
Which type of colonic adenoma has the highest risk for malignancy?
Villous adenoma
McKittrick-Wheelock syndrome
Mucous diarrhea caused by a villous adenoma, leading to severe fluid and electrolyte depletion
80 y/o F with diarrhea, hyponatremia, hypokalemia, and hypochloremia…
McKittrick-Wheelock syndrome due to a villous adenoma
Note: The villous adenoma causes a mucous diarrhea that leads to severe fluid and electrolyte depletion.
At what point does the sigmoid colon become the rectum?
When it stops having mesentery at the level of S3 (the rectosigmoid junction)
At what point does the rectum become the anal canal?
The anorectal angle (created by the puborectalis sling at the level of the coccyx)
What portion of the rectum is retroperitoneal?
The proximal third
Note: The distal third is extraperitoneal.
Which gastrointestinal structures are retroperitoneal?
- Duodenum (2nd and 3rd portions)
- Pancreas (except tail)
- Colon (ascending and descending)
- Rectum (proximal third)
Is the pancreas retroperitoneal?
Yes, except for the pancreatic tail
Which portions of the duodenum are retroperitoneal?
2nd and 3rd portions