Colon Flashcards
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
Colonic Obstruction (cause)
Cause: malignancy, foreign body, benign (adhesions, strictures, volvulus)
Diagnx: see on xray, confirm with CT
TAKE HOME POINTS
see notes
Colonic Obstruction (pres/treat)
Nausea, vomiting (emesis may be feculent - has feces in it), distended abd, constipation or obstipation
Giardia
parasitic enterocolitis DUODENUM not COLON
cysts are RESISTANT to chlorine so it doesn’t help
Campylobacter Spp
watery diarrhea, contaminated meat
C. jejuni
C. fetus (immunosuppressed)
Salmonella
Typhoid, bloody diarrhea in 2nd week (abd pain, headache, fever, abd rash, leukopenia
Non-typhoid, milder - endoscopy: musosal redness, ulneration, exudates
E. coli
O157:H7
Non-invasive, toxin-producing, contaminated hamburgers
Bloody diarrhea, severe cramps, mild or no fever, sometimes renal failure (HUS)
On endoscopy: edema, erosions, ulcers, hemorrhage (right colon mostly)
Deadly outbreaks
Pseudomembranous Colitis
C. DIFF
After ABX therapy (3rd gen cephs)
Fever, leukocytosis, abd pain, cramps, watery diarrhea
Disrupts normal colonic flora
Pseudomembreanes on histol (layer of infl cells)
Viral Infx
Cytomegalovirus: (mouth - anus)
Herpesvirus (esophagus and anorectum)
Entericviruses: Rotavirus (most common childhood diarrhea)
6-24 months, DEHYDRATION from watery diarrhea, you can die from it, there are 2 vaccines
Parasitic Infx
Protozoa: tropical/subtropical
Entamoeba histolytica (cecum but can disseminate to liver, flask shaped ulcers)
Diagnx by looking at stool samples
Parasitic Infx (Helminths)
Most common, poor santitation
Ingested from soil contaminated with feces
Obstruction, perforation, growth retardation
Worms can grow to 20cm
Ascaris lumbricoides (roundworm)
UC vs Crohn’s overlaps
more common in women than men, Ashkenazi Jews, neither are autoimmune (but is immune dysregulation dz)
UC & Crohn’s (combo of defects)
Results from:
- host interactions with intestinal microbiota
- intestinal epithial dysfxn
- aberrant muscosal immune responses
Appendicitis (info/pres)
7% lifetime risk, M>F
Luminal obstruction by fecalith–> ischemic injury –>inflammatory response
POSITIVE McBurney’s Sign, periumbilical pain that radiates to TLQ
Appendicitis (diagnx/treat)
Mucosal ulceration/transmural infl
High fever, high WBC, sever pain suggest perforation
Treat: appendectomy
