Colon Flashcards
Mg vs. Calcium antacids
Mg antacids- cause movements (diarrhea). Calcium antacids- cause constipation
What if patient is hemoccult + and complains of rectal bleeding-
refer to colonoscopy
What if patient is 45 or older with positive hemoccult test but denies rectal bleeding-
refer for colonscopy, and give trial of fiber supplementation
What are studies of pelvic floor function
balloon expulsion test, defacography, anorectal manometry
Diagnostic studies for constipation
Colon transit study and studies of pelvic floor function
Tx for constipation- general
minimize constipation causing meds, lifestyle changes, treat hypothyroidism, treat diabetes, increase fluid and fiber intake, regular exercise
pharmacologic therapy for constipation
ONSES- osmotic laxatives (mag citrate), non-absorbable sugars, saline laxatives (MOM), emollient laxatives, stimulant laxatives
What is a consequence of excessive stimulant laxative use in tx of constipation?
melanosis coli- inner lining of colon turning brown
Rescue meds for acute constipation tx
stimulant and osmotic laxatives, and enemas (avoid soap studs)
tx of fecal impaction
manual disimpaction
Colonic pseudoobstruction and dilation of colon seen in..
Ogilve’s syndrome
Cause of ogilve’s syndrome related to..
electrolyte abnormalities
Tx of ogilve’s syndrome
bowel rest, IVF, electrolyte replacement
cause of diverticulosis
pulsion, d/t increased colonic pressure
What part of colon is spared in diverticulosis?
Rectum spared
pathogenesis of diverticulosis
- Hypermotility- high colonic pressure, affects mostly sigmoid colon. 2. Simple massed diverticulosis- occurs throughout colon, d/t weak muscular wall from CT disorder like Marfan’s or Ehlers-Danlos
complications from diverticulosis
bleeding and infection(diverticulitis)
tx of uncomplicated diverticulosis
high fiber diet
Which diagnostic imaging tests are contraindicated in acute diverticulitis?
Barium enema and colonoscopy
Patient presents with colicky abdominal pain, severe pain in LLQ, constipation, diarrhea, pain relieved by defecation, N/V, abdominal distension. Also see colovesical fistula. Dx?
Probably diverticulitis
What is colovesical fistula?
most common type of fistula from colon to bladder in diverticulitis
Tx of diverticulitis
outpatient abx or IV hospitalize if necessary
Should you perform colonoscopy in diverticulitis?
NO. Wait 6-8 weeks after resolution to perform to r/o cancer
After 3-4 episodes of diverticulitis…consider
elective colectomy
When would you need to emergently perform surgery in diverticulitis
If free perforation, causing pneumoperitoneium and fecal peritonitis. Surgery involves removal of colon and formation of an ostomy (Hartman procedure). Takedown ostomy in 2-3 months and bowel is reconnected
Hartman procedure
removal of rectosigmoid colon and formation of ostomy- surgery used in colon cancer and complicated diverticulitis
Ischemic colitis cause
mesenteric vascular occlusion (inferior mesenteric artery often)
Patient presents with LUQ abdominal pain, bloody diarrhea. Is hypotensive and dehydrated. You suspect..
Ischemic colitis
Watershed area
areas perfused by 2 arteries- splenix flexure in colon - this is why ischemic colitis usually presents with LUQ pain
ischemic colitis- how do diagnose?
colonscopy
Patient presents with RUQ pain, fever, watery or bloody diarrhea, distenstion, nausea. Areas most affected are right colon, including cecum. You suspect..
Neutropenic colitis or typhlitis
Diarrhea in toxic megacolon can either by bloody or no movement- why?
if bloody diarrhea- early toxic megacolon. if no movement- late due to lack of contractility.
Most common causes of toxic megacolon
C. Diff colitis, or U. Colitis
C. Difficile infection often follows…
antibiotic use
What does C. difficile cause
pseudomembraneous colitis (accordion sign). also a cause of gastritis and peptic ulcers
“Accordion sign” -
Pseudomembranous colitis (caused by C. diff)
Tx of c diff infection
oral and IV abs
tx for toxic megacolon
surgery
Xray finding characteristic of colon cancer
apple core lesion
95% of colon cancers are…
adenocarcinomas
3-4% of patients with colorectal cancer have a genetic susceptibility syndrome, like…
HNPCC or FAP (autosomal dominant, highly penetrated)
hereditary polyposis diseases
Juvenile polyposis, Peutz-Jegher’s syndrome, HNPCC, FAP
4 types of juvenile polyposis
Juvenile polyposis syndrome, Cronkhite-Canada syndrome, Bannayan-Riley-Ruvalcaba syndrome, and Cowden disease
Extracolinic manifestations in juvenile polyposis syndrome
None
manifestations besides polyps in colon in cronkhite-canada syndrome
ectodermal lesions
manifestations besides polyps in colon in bannayan RR syndrome
macrocephaly and genital hyperpigmentation
manifestations besides polyps in Cowden disease
facial trichilemmomas, thyroid goiter, and cancer, breast cancer
mode of inheritance in Peutz-Jeher’s syndrome
autosomal dominant
Peutz Jegher’s syndrome characterized by…
multiple hamartomatous polyps and melanotic pigmentation of the skin, lips, and gums. Lifetime risk of colorectal cancer
Difference in R vs. L sided tumors in colon cancers in Stools
R sided tumors present with bleeding- stool on R is liquid. L sided tumor stools are solid and cause obstruction (alternating constipation and diarrhea)
How fast does colon cancer spread?
Doubling time is 130 days. Takes 5 years to produce tumor large enough to produce any symptoms. Slow growing!
Persistent rectal bleeding in patient
workup for colon cancer!
Steps in diagnosis of colon cancer
Hx of unrelenting rectal bleeding or abdominal pain in patient, Hemoccult positive- order colonoscopy. One diagnosis is made, CT scans of chest, abdomen, and pelvis to stage disease
CEA
Carcinoembryonic angigen- useful in detecting recurrences of colon cancer after resection, but not specific
complications of colon cancer
obstruction, perforation, and direct extension
tx of colon cancer
partial colectomy usually with anastomosis- laparoscopic or open
Primary vs. metastatic colon cancer tx
primary- chemo agents, antimetabolites. Metastatic- (MAb to VEGF)- Bevacizumab, Topoisomerase I inhibition (irinotecan), MAb to EGFR- cetuximab
adjuvant vs. neoadjuvant
adjuvant- meds given AFTER sx. neoadjuvant- meds given BEFORE sx - to make tumor smaller for surgery
F/U with colon cancer colonoscopy
colonoscopy 3 months after emergency resection. And then every 1-3 years for screening.
