Colon Flashcards
(39 cards)
Colon (length and fxn)
5 ft long, absorption of water and ions, storage of waste and indigestibles
Colon (blood supply)
Superior mesenteric a. –> right colon
Inf mesenteric a. –> distal transverse and left colon
Rectal and hemorroidal a. –> splenic flexure and rectum (rectosigmoid) (both prone to ischemia)
IBD (info/causes)
immune disorder of small and large intestine
F>M, presents in teens/early 20s, then second peak in 80s
Crohn’s, UC, or BOTH (20%)
IBD (diagnx/treat)
Gold standard: direct visualization and biopsy (crypt architectural distortion)
Treat: steroids acute ONLY, immunomodulators, TNF-a antags, surgery, vitamin supplements, COLON CANCER SCREENING (annual after 7-8 years of dz)
IBD (extraintestinal symptoms)
More common in UC but you get them in both:
eye, skin, liver, joints, bones
IBD (Crohn’s sx)
Diarrhea/weight/loss fatigue
Can be ANYWHERE (from mouth to anus) but USUALLY TERMINAL ILEUM & RIGHT COLON
Periumbilical/mid abd pain
Nausea/vomiting
Fistulae and sinuses
Strictures from transmural inflammation
“skip lesions” (does not unifomrlay involve the bowel - it skips around) –> obstructions
IBD (Crohn’s info)
can progress to colon cancer (related to duration/extent,/family hx/extraintestinal manifestations)
T-helper TYPE 1 mediated response
NOD2 polymorphism (intracellular receptor for microbes)
SMOKING AGGRAVATES CROHN’S (NOT UC)
IBD (Crohn’s Diagnx)
Transmural damage with deep, linear, fissuring ulcerations
Marked fibrosis –> THICKENED wall and strictures
Fistulas
GRANULOMAS (~20-35%) –> DIAGNOSTIC OF CROHN’S (not in UC)
IBD (UC info)
can progress to colon cancer (related to duration/extent,/family hx/extraintestinal manifestations) T-helper TYPE 2 mediated response ECM2 polymorphism (ECM protein) Smoking AMELIORATES (so UC is uncommon is smokers - if they smoke its most likely Crohn's)
IBD (UC sx)
Diarrhea/weight loss/fatigue
LIMITED TO COLON (usually rectosigmoid - surgery potentially curative)
Lower abd pain (LLQ)
Hematochezia and/or mucus in stool
Tenesmus (sense of incomplete evac)
Diffuses from rectum more proximally (SO YOU ALWAYS GET RECTAL INVOLVEMENT but NOT ANAL, unlike Crohn’s - spares rectum but hits the anus)
UC generally spares the ileum
Toxic megacolon
Usually PRIMARY SCLEROSING CHOLANGITIS (liver) (extreintestinal)
IBD (UC diagnx)
PSEUDOPOLYPS (area spared from ulceration form polyps)
Loss of haustra
No fistulas or strictures
Superficial (restricted to mucosa) –> THINNED walls
Microscopic Colitis (info)
50-80, F:M, 15:1
Autoimmune
Salt and water loss in colon
Mild assoc with Celiac, NSAIDs implicated, no major cancer risk
Two subtypes: lymphocytic & collagenous
Microscopic Colitis (pres/diagnx/treat)
Chronic mild secretory diarhhea (non-bloody)
ONLY seen on histology (lymphocytic infiltration of mucosa), thickened subepithelial collagenous band
Treat with antidiarrheals (and lots of others)
Ischemic Colitis (info & triggers)
90% >60 yo
Triggers: vasospasm, dehydrations, hypotension, MI, PEE
Usually in spenic flexure, rectosigmoid (watershed areas)
Ischemic Colitis (pres)
Abrupt onset, crampy lower abd pain, urgent need to poop, no peristalitc sounds with MILD diarhhea
(if severe or bleeding then another diagnx likely)
Ischemic Colitis (diagnx/treat)
Hx, X-ray “thumb print” bowel wall thickening
Colonscopy = gold standard
Muscosal necrosis
Treat the trigger, give IV fluids and Abx (complete recovery in 1-2 weeks)
Other kinds of NON-IBD colitis
Bacterial Infx Colitis but MOST are viral
See later
DiverticuLOSIS (not diverticuLITIS)
> 50% in elderly
Outpouching of colon (usually sigmoid)
Thought to be due to low fiber diet (inc intra-colonic pressure)
DiverticuLOSIS (pres/diagnx/treat)
80% asymptomatic, 20% hemorrhage (bleeding of vasa recta, painless bloody shit, heavy, stops 2-3 days)
Diagnx: CT/MRI, NO infl cells
Treat with high fiber diet
Acute DiverticuLITIS (cause/pres/complications)
Fecolith obstructions of a diverticulum
Most common in sigmoid
ACUTE onset LLQ pain, nausea, fever, NO diarhhea
Complications: obstruction, perforation, absess, bleeding –> risk of septic shock
Hematochezia vs Melena
Red vs Black blood in stool
Acute DiverticuLITIS (diagnx/treat)
CT/MRI, infl cells
Treat: ABX, drain abscess, surgery
Lower GI bleed (Ddx)
Hematochezia more common than melena
+ abd pain or diarrhea: ischemia colitis/IBD
+ weight loss, anemai, constip: cancer
+ sudden onset bleeding, elderly: diverticulosis
+ acute dysentry, tavel, ABX use: infx diarrha
+ microcytic anemia: neoplasm or AVM
+ NSAIDS: drug induced inschemia
Lower GI Bleed (LGIB) (Diagnx/Treat)
Colonoscopy, tagged RBC scan, angiography
Treat: supportive fluids, surgical resection, endoscopic on angiographic therapy
