Colonic Diseases Flashcards
What is the anatomical division of the colon from proximal to distal?
- Ileocecal valve
- Cecum
- Ascending colon
- Hepatic flexure
- Transverse colon
- Splenic flexure
- Descending colon
- Sigmoid colon
- Rectum
- anus
Why are the splenic flexure and rectum considered watershed areas of the large bowel?
- The receive blood from terminal branches of their respective arteries
- IMA for the most of the descending colon
- Rectum gets terminal branches from exterinal and internal iliac arteries, the inferior rectal and hemorrhoidal arteries
- These are somewhat easily “shut off” in cases of global hypo-perfusion and thus the splenic flexure and rectum can experience ischemic injury in septic cases or anything else that really drops blood pressure or volume
Even though the colon’s main job is water reabsorption, does it do a lot of it?
- Normally, it doesn’t need to
- The small intestine does the majority of absorption, and usually the colon plays a minor physiological role
- It’s when small intestine motility or volume is ramped up that the colon has to suck back some water before it’s too late
What are the bacterial colonies of normal flora in the colon supposed to do?
• They ferment non-absorbed nutrients and produce trophic factors that maintain a healthy mucosa and motility
How does the colon reabsorb water?
• Na, Cl and K are reabsorbed through trasport systems
○ Very similar to kidney
• Water follows passively
What is meant by indeterminant colitis?
- In 20% of cases the presenting colitis will have features of both chron disease and ulcerative colitis and you can’t further differentiate
- At this point you call it indeterminant colitis
Is there a cause, or at least some risk factors for IBD?
• There is a genetic component because risk goes up in a family of cases
○ HLA-B27 is a genetic risk factor
• No real good cause yet
• Risk factors ("environmental triggers")
○ Bacterial infection
○ Tobacco exposure
○ Diet
○ climateCompare and contrast the two IBDs in terms of where they affect the GI tract
• UC is limited to the colon
• Crohn’s disease is “tongue to bung” or anywhere in GI tract
• UC usually involves rectosigmoid
○ 50% of cases are pan-colonic
• UC can be fully managed by colectomy but CD may be only modified by it
• CD is usually in terminal ileum and right colon
○ Jejunal invlolvment is infrequent
○ Anything above jejunum is downright RARE
• Smoking is protective in UC and a risk factor for CD
Why might Crohn’s patients have a bowel obstruction?
- Because the disease is transmural it carries a greater risk of fibrotic strictures in the small bowel
- These focal strictures may cause obstruction
What is different between the IBD’s in terms of mucosal penetration of inflammation?
- CD can be completely transmural
- UC is limited to mucosa, and in severe cases can be in submucosa
- CD is transmural enough to spread beyond strict GI tract
- CD can cause fistula formation due to complete transmural inflammatory injury
Describe the landscape of the affected bowel as seen endoscopically in CD vs. UC.
• CD has skip lesions
○ Relative sparing of mucosa in between lesions
○ Less mucosa affected, but deeper inflammation
• UC has linear or focal ulceration
○ Diffuse inflammation that is friable, edematous, and bloody
○ Punctate ulcerations
○ Sometimes Has pseudopolyps, which are islands of spared mucosa
What are the intestinal signs and symptoms (clinical manifestations) of crohn’s disease vs. ulcerative colitis?
• Both - diarrhea or abdominal pain
○ Usually small-volume, 4-6 times per day
○ Often tenesmus = extreme urgency to defecate
○ Often sense of incomplete evacuation
○ Weight loss
§ Increased catolism, loss of nutrients in stool or decreased PO intake
○ Hematochezia and anemia in severe disease
• Crohn’s
○ Lower abdominal pain consistent with colitis or mid-abdominal (perumbilical) pain more consistent with small bowel disease
○ Ileitis or jejunitis - diarrhea may occasionally be large-volume, foul smelling and/or associated with steatorrhea (might indicate malabsorption)
○ Nausea and vomiting more common here but still a bit on the rare side
○ Small bowl obstruction
○ Fistula formation
• UC
○ Almost always localized to the lower quadrants, LLQ more frequently than RLQ
§ Consistent with sigmoid and rectal involvement
○ Visible mucus in stool
What are the extra-intestinal clinical manifestations of crohn’s vs. ulcerative colitis?
• More common in UC than crohn’s but rare overall
• Eye, skin, bile ducts and joint inflammatory symptoms
• Don’t follow the course of IBD, meaning IBD may be well controlled but these pop up anyway
○ Except erythema nodosum
• Uveitis
• Pyoderma gangrenosum
• Erythema noddosum
• Ankylosing spondylitis
• Primary sclerosing cholangitis
What is up with primary sclerosing coholangitis in IBD?
• PSC - fibrosing condition of the intra and extra hepatic bile dcuts
• Can progress to cirrhosis or cause cholestasis alone
• ERCP is usually required for dx and treatment
• Liver transplant may be necessary
○ Also a risk factor for neoplasm
What is up with ankylosing spondylitis in IBD?
- Stiffness and pain in the lumbar spine
- Typically in young males
- May be severe and disabling
What is up with erythema nodosum in IBD?
- Characterized by painful nodules arising within an erythodermous patch
- Dermatologic condition
- Usually follows course of IBD and goes away with well controlled IBD
What is up with pyoderma gangrenosum in IBD?
• Large, painful, impressive ulcerative condition that usually occurs all over the lower extremities
What is up with Uveitis in IBD?
- Also scleritis or episcleritis
- Eye pain and redness, can be severe
- Opth consultation is usually necessary
- Use topical steroids to provide relief
Describe the treatment paradigm for inflammatory bowel disease
• Complex - depends on type, severity, location of disease and the type of previous therapy used
• Glucocorticoids may help induce remission
○ New disease or acute flare
○ Don’t use for chronic management
• Chronic treatments
○ Sulfasalazine
○ 5-aminosalicylates
○ Topical steroids - budenoside
○ Immunomodulators - azathioprine and 6-mercaptopurine
○ TNF-alpha antagonists - infliximab, adalimumab, certolizumab
• Surgery
○ Fistula treatment
○ Subtotal colectomy
○ Partial small bowel or colon resection
○ Structuroplasty
○ UC - may be curative
What are the long-term management issues of IBD patients?
• Carry a higher risk of colorectal cancer
○ 5-7 fold higher risk
○ Associated with disease duration and severity
○ Surgical indications more radical with biopsy results showing dysplasia
• Screen for osteoporosis
○ IBD even without steroid use can cause osteopenia and osteoporosis
• Malabsorption? Screen for fat-soluble vitamin deficiency
○ ADEK and B12
• Immunomodulators or immunosupression? Think infection
○ Lymphoma, fungal and mycoplastic infections
○ Also CNS disease
○ Need TB test before starting therapy
• Pregnancy considerations
○ Higher risk of flare up during pregnancy, and immunomodulators might be terotogenic
○ Patients should probably reconsider pregancy during treatment
What is microscopic colitis?
• Autoimmune, inflammatory condition of the colon associated with mild to moderate diarrhea
• Presumed cause is inflammation to colonic mucosa with associated malabsorption of water and sodium
• 2 major variants only differentiated by histology
○ Lymphocytic colitis
○ Collagenous colitis
• Intraluminal bacteria or dietary components are presumed to TRIGGER
○ Etiology is unknown
• Could also be associated with bile acid-related irritation of the colon (in sensitized individuals)
