Chapter 12, part 3 Flashcards
Pseudomembranous colitis
Overgrowth of C. diff (happens after abx use)
Transmission of pseudomembranous colitis
Fecal oral route
What are the two endotoxins that C. diff produces?
Enterotoxin
Cytotoxin
Cause mucosal damage resulting in exudative pseudomembrane on scope
Dx of pseudomembranous colitis
ELISA (and PCR if necessary)
GDH
Tx of pseudomembranous colitis
Initial: oral metronidazole or oral vanc (chosen in more severe cases)
In the case of septic shock, subtotal colectomy with end ileostomy
Causes of bloody diarrhea
Shigella C. jejuni Enterohemorrhagic E. coli (EHEC) E. histolytica Certain salmonella
E. histolytica and bloody diarrhea
Causes amebic colitis
Amoebic colitis sx
Mimics IBD (crampy abd pain and bloody diarrhea)
Dx of amoebic colitis
Stool studies
Antigen testing
Endoscopy (ulcerations and trophozites)
Tx of amoebic colitis
Metronidazole + luminal agent (paromomycin)
Shigella and bloody diarrhea
Fecal-oral route or through contaminate food and water
Dx of shigella
Stool culture
Tx of shigella
Self-limiting, but can give FQ to reduce duration
EHEC
Fecal contamination of foods
MC sx of EHEC diarrhea
Hemorrhagic colitis
Tx of EHEC
Supportive
What is a major potential sequela of EHEC infection?
HUS (hemolytic uremic syndrome)
5-10 days after diarrhea
Acute renal failure, thrombocytopenia, and microangiopathic hemolytic anemia
Salmonella
Gastroenteritis caused by nontyphoidal strains= MC
Sx of salmonella bloody diarrhea
Abdominal pain
Fever
Vomiting 1-3 days after exposure
Tx of salmonella bloody diarrhea
Self-limiting, supportive
C. jejuni
Same sx and tx as salmonella
Cytomegaloviral colitis
Presents similar to appendicitis (tx with ganciclovir)
Neutropathic enterocolitis
MC affects cecum
Immunosuppressed pts undergoing chemo
Presents like appendicitis
Tx: bowel rest and IV abx
What is the MC site of bowel ischemia and why?
Colon
Usually d/t prolonged hypoperfusion secondary to hemodynamic instability
What is the MC site of the colon for ischemia
Watershed areas (splenic flexure)
S/sx of ischemia of the colon
Worsening abdominal pain (out of proportion to the exam)
Bloody diarrhea
Abdominal distention
Lab findings for ischemia of the colon
Lactic acidosis
Leukocytosis
Rads for ischemia of the colon
CT:
Bowel wall edema or pneumatosis of intestinal wall
Sigmoidoscopy or colonoscopy:
Patchy hemorrhagic areas with dusky mucosa
Tx of ischemia of the colon
If full thickness necrosis or perforation: urgent segmental resection and creation of stroma
Partial thickeness: abx, bowel rest, and correction of hypoperfused state
Where can Crohn’s be found?
Anywhere in GI tract (mouth to anus)
Terminal ileum is MC
What type of involvement occurs in Crohn’s?
Patchy involvement
What components does Crohn’s affect?
Transmural inflammation
Gross appearance of Crohn’s
Segments look grossly inflammed with thickened mesentery and creeping serosal fat
What is seen on colonoscopy in Crohn’s?
Long longitudinal ulcers and erosions of the submucosa: cobblestoning
Path of Crohn’s
Transmural infiltration with deep penetrating fissures through muscularis propria and non-caseating granulomas
Presentation of Crohn’s
Crampy abdomainl pain
Diarrhea +/- bleeding
Fever
Weight loss
Dx of Crohn’s
Colonscopy and imaging of the small bowel
Granulomas on hx
Colonscopy q1-2 yrs beginning 10 years after dx
Tx of Crohn’s
Sulfasalazine, immunosuppresives and biologics
Pts with highly symptomatic focal dz may benefit from early interventions
Fulminent colitis (doesn’t respond to therapy in 5-6 days): total abdominal colectomy and end ileostomy
Total proctocolectomy is contraindicated in Crohn’s
If obstructive sx present: surgery is recommended
What are the hallmark of Crohn’s?
Fistulas: 1/3 will develop internal fistula = SB to SB or SB to colon
Enterocutaneous fistulas in Crohn’s
Low output <500 mL/day
High output >500 mL/day
Bowel rest, TPN and aggressive tx of the Crohn’s
Refractory: operation and resection
Where can UC be found?
Rectum and progresses proximally (does not involve the small bowel)
What type of involvement occurs in UC?
Contiguous
What components does UC affect?
Only affects the mucosa
Gross appearance of UC
Nl
Colonoscopy findings of UC
Extremely friable mucosa
Path of UC
Nl muscularis propria
Presentation of UC
Frequent bloody diarrhea
Crampy abd pain
Tenesmus and urgency resulting in fecal incontinence
Dx of UC
Stool studies for ova and parasites
Stool cultures
Colonoscopy and hx
Extracolonic fistulas and UC
Pyoderma gangrenosum- destructive inflammatory ulcerative dz of the skin commonly found around ostomy sites
Primary sclerosing cholangitis: obliterating inflammatory dz of the small and large bile ducts = MC noninfectious indication for liver transplant
Tx of UC
Moderate dz: sulfasalazine
Severe cases: azathioprine and 6-mercaptopurine
-Steroids during exacerbation
Surgery fro those pts refractory to meds= MC indication
What is the risk of UC pts having colon CA?
33% lifetime risk
Colonoscopy starting 10 yrs after dx
What cures UC?
Surgical therapy at removing all mucosa
Total proctocolectomy with ileal pouch and anastamosis
Total proctocolectomy with IPAA
Entire colon and rectum mobilized and removed
J. pouch constructed using the terminal ileum
Pouch anastamosed to the remnant of the distal rectum and anus
Temporary diverting loop ileostomy may be done
May do rectal mucosectomy to remove remaining mucosa
What is the 3rd MC cancer in the US?
Colorectal
Adenocarcinoma
Adenoma leads to dysplasia leads to invasive carcinoma
What is the MC neoplastic polyp?
Adenoma
Precursor for all colorectal CA
Adenoma
Can be pedunculated or sessile (no stalk, so automatically level 4)
Tubular, villous, tubovillous
If they are >2 cm, villous, and sessile: higher risk of CA
Hagitt criteria level 0
Carcinoma in situ. No invasion
Hagitt criteria level 1
Head of polyp
Hagitt criteria level 2
Head + neck of polyp at junction of adenoma and stalk
Hagitt criteria level 3
Into the stalk
Hagitt criteria level 4
Into submucosa of bowel but above muscularis propria
Tx of malignancies
Polypectomy if malignancy well differentiated
May need resection if not defined lesions
What are the MC neoplasms?
Benign
Classified into hyperplastic, juvenile, and inflammatory
Parameters of benign neoplasms
<3 mm
No malignant potential
Juvenile polyp
Hamartomas seen throughout the GI tract
Associated with polyposis syndromes, no malignant potential, but often bleed
Inflammatory polyp
Result from repetitive mucosal ulceration and regeneration
