Diseases of Large Intestine Flashcards
(List of large intestine diseases below)
Review normal large bowel anatomy below (draw it first yourself)
Which artery supplies the ascending colon, hepatic flexure + proximal 1/3 of the transverse colon?
___artery supplies the distal third of the transverse colon, splenic flexure + the descending colon
The ___ artery (branch of the internal iliac artery) supplies the sigmoid colon and rectum
The superior mesenteric artery artery supplies the ascending colon, hepatic flexure + proximal 1/3 of the transverse colon
Inferior mesenteric artery supplies the distal third of the transverse colon, splenic flexure + the descending colon
The hypogastric artery (branch of the internal iliac artery) supplies the sigmoid colon and rectum
The primary function of the ileocecal valve is ___
A pt with a resected ileocecal valve comes to your clinic presenting w/ abdominal pain, diarrhea and severe bloating. The patient notes a history of repeated small bowel bacterial infections. What condition is on your differential?
Ileocecal valve functions:
serves as gate so colonic contents don’t reflux back into small intestine
(small intestinal bacterial overgrowth - pt w/ resected ileocecal valve; bacteria have full access to small intestine; symptoms inclde abd pain, bloating**, diarrhea, altered vitamin B12 and folic acid
Name the functions of the colon (4)
Absorbs water and electrolytes (Na+ and Cl-)
**most water and nutrients are already absorbed by small intestine by the time things hit the colon**
Produces and absorbs vitamins - **colonic bacteria produce vitamin K; B vitamins e.g. biotin are absorbed in colon**
Makes and propels feces to rectum for elimination (the colon is the poop factory, the rectum is the poop pouch)
Defacation - requires coordination of internal and external anal sphincters
See below on colonoscopy
**ileal crohn’s disease – diagnosed thru colonoscopy coming from ileocecal valve*
What is Inflammatory bowel disease?
IBD is a group of disorders in which there is intestinal inflammation - due to excessive immune response to host factors
Includes UC, Crohn’s, indeterminate colitis (pt has an atypical presentation
*crohn’s disease affects anywhere from the mouth to the anus SANS rectum; UC affects only the colon
There are many factors that can contribute to IBD. Name 4.
IBD results from a combo of:
genetic factors
microbiome factors
immune response
enviromental triggers like NSAIDs
Describe the pathogenesis of IBD (hint: involves inflammatory response)
Causative agents (foreign bugs) modify the gut environment/luminal factors >> sensed by macrophages >> activate T cells >> Th1 response mainly to kill whatever the problem agents are via inflammatory cytokine release etc
In IBD, patients don’t dampen this response and undergo repair. Instead, this keeps happening
What are the main symptoms of ulcerative colitis? (2)
Define the following: proctitis, proctosigmoiditis, left sided UC, extensive UC, pancolitis
**Can use lab values do determine if pt has UC vs hemorrhoids for example (pt with UC will likely by anemic, have increased inflammatory markers)**
**proctitis - inflammation of rectum
proctosigmoiditis - inflammation of sigmoid colon
left sided UC - inflammation of just up to splenic flexure;
if it passes the splenic flexure = extensive UC;
if involving ascending colon also = pancolitis
See below for how UC looks on endoscopy
**what do pseudopolyps tell you about a pts GI health?**
Pseudopolyps develop as the pts body is trying to heal. They’re evidence of prior insult, and may/may not carry any cancerous polyps (don’t typically)
**there’s inflammation + exudate, friable mucosa, pseudopolyps**
Describe the grapth below
The most concerning is pancolitis (involves ascending colon
Cancer risk increases/cancer starts to develop 10 years after their diagnosis with UC - pts with pancolitis actually get a colonoscopy every 2 years
How does Crohn’s disease present? (T/F: Presentation depends on location of disease)
In Crohns disease, bloody diarrhea is suggestive of involvement of what part of the GI tract?
*bloody diarrhea indicates colonic involvement*
*perianal disease is seen often*
Remember, symptoms depend on where in the gut the disease is
There are 3 primary complication of UC. Describe them
Inflammatory Crohn’s disease - mildest phenotype
Obstructive Crohn’s disease (stenosis of ileaocecal valve due to fibrosis from the repair process
Perforating Crohn’s disease - a fistula (aka false tracts) develops between the ileum and the colon (can occur INDEPENDENT of stenosis; chronic stenosis can also lead to fistula formation (penetration of bowel wall) )
A characteristic feature of Crohn’s disease on endoscopy is ___ appearance (hint: its a type of stone that looks great on castles, but is horrible to drive on)
A characteristic feature of Crohn’s disease on endoscopy is Cobblestone appearance
What is the condition below? (hint this one of the complications of Crohn’s disease)
*one of the worst complications of Crohns disease; pts are more at risk of getting anal skin tags and anal fissures (but anyone can get them*
(perianal skin tags and fissures develop as a way your body repairs itself)
The presence of a ___ confirms diagnosis of Crohn’s disease
The presence of a perianal abscess confirms diagnosis of Crohn’s disease
(pts may have completely normal luminal bowel - isolated perianal Crohn’s disease)
a fistula can sometimes form and the abscess can also burst resulting in purulent drainage
Review the table below on differences between UC and CD
See below for exraintestinal manifestations of IBD
**problems urinating, bubbles in urine, pain w/ urination all suggest formation of fistula between pts bowel and bladder**
*erythema nodosum can occur in the setting of bowel inflammation but pyoderma gangrinosum can occur independent of bowel problems*
Which class of drugs (or drug name) are used for the categories of IBD below?
Mesalamine: no longer used for Crohn’s disease, still used in UC
Immunomodulators: AZA/6-MP, methotrexate (used for moderate disease)
Biologics: anti-TNFs, anti-integrins, anti-IL12/23 (used for severe disease)
**note that now, people are following a top-down approach of using the stronger meds i.e. biologics first to control pt disease**
What are the absolute (4) and relative indications (4) for surgery in IBD?
Absolute: perforation/hemorrhage/cancer (non-resectable)/chronic high grade obstruction
Relative: Medically refractory/complex fistulae or abscess/perianal disease/growth retardation
Describe an ileocecal anastamoses
Why do pts who undergo this procedure develop more frequent bowel movements, B12 deficiency and bile acid diarrhea?
Pts who have the ileocecal valve resected will get an ileosecal anastamosis (more at risk for small intestinal contents going into colon, more frequent bowel movements because that brake is now gone)
Pts can also develop bile acid diarrhea: since the ileocecal valve is gone (important for absorption of bile), bile acid will go into the colon and irritation of the colonic muosa leads to diarrhea
Pts can also develop B12 deficiency because B12 is absorbed in the terminal ileum + ileocecal valve
What is a J pouch (created during IBD surgery)?
It’s basically a new rectum (surgeon does a temporary ileostomy that diverts flow such that you have a pouch shaped like a J. Once the ileoanal anastamoses heals, the J pouch functions as the new rectum)
(also note that these pts have increased bowel movements because they ain’t got no colon no more)
See below for differences between colostomy and ileostomy
What kind of waste would a pt produce following either procedure?
Pts that undergo a colostomy still have a functional colon so they would produce mostly solid waste, vs those who undergo an ileostomy, who would only have liquid waste
___ colitis is characterized by lymphocytic infiltrate and usually affects middle aged men + women, and may be ass’d w/ autoimmune disease
Lymphocytic colitis is characterized by lymphocytic infiltrate and usually affects middle aged men + women, and may be ass’d w/ another autoimmune disease
**note that this and collagenous colitis present w/ watery diarrhea**
See below for list of drugs that can incite microscopic colitis
What is the Rx of microscopic colitis (1st and 2nd line drugs)?
Rx: remove inciting drug/treat any ass’d condition
Drugs: anti-diarrheals (1st line): imodium/lomotil; 2nd line: budesonide (this is the one w/ e first pass metabolism in liver and has minimal systemic absorption)
(note the other therapies on the slide)
___ is a bug that causes severe watery diarrhea, abdominal cramping, fever, leukocytosis and develops a pseudomembrane on GI mucosa seen on endoscopy
Clostridiodes difficile is a bug that causes severe watery diarrhea, abdominal cramping, fever, leukocytosis and develops a pseudomembrane on GI mucosa seen on endoscopy
What are the main risk factors of C. diff infection? (4)
Being on broad spectrum antibiotics
Hospitalization
Advanced age
Severe illness
*note that acid suppression is also a risk factor e.g. being on PPIs*
How do you Dx C diff infection?
(what 2 things do you test for following a presentation w/ diarrhea + risk factors for C. diff?; if one is negative, what else do you do to confirm the Dx?)
See below for info
*test GDH antigen (its an enzyme) and Toxins A/B first; if one is negative, do PCR*
