CHAPTER 36- COLORECTAL.txt

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CHAPTER 36- COLORECTAL.txt
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  1. What does the colon reabsorb and secrete?
    The colon secretes K and reabsorbs Na and water (mostly in right colon and cecum)
  2. What are the layers?
    • 4 layers:
    • 1) mucosa (columnar epithelium)
    • 2) submucosa
    • 3) muscularis propria
    • 4) serosa
  3. Which parts of the colon are retroperitoneal?
    Ascending, descending, and sigmoidmoid are all retroperitoneal

    peritoneum covers anterior upper and middle 1/3 of the rectum
  4. Muscularis mucosa:
    circular/longitudinal interwoven inner layer
  5. muscularis propria
    circular layer of muscle
  6. plicae semilunaris
    transverse bands that form haustra
  7. taenia coli
    3 bands that run longitudinally along colon.

    at rectosigmoid junction, the taeniae become broad and completely encircle the bowel as 2 discrete muscle bands
  8. Anorectal anatomy with important landmarks
    see page 286 (photo)
  9. Vascular supply
    1) Ascending an 2/3 of transverse colon- supplied by SMA (ileocolic, right and middle colic arteries

    2) 1/3 transverse, descending, sigmoid, and upper portion of the rectum- supplied by IMA (left colic, sigmoid branches, and superior rectal artery)

    3) Marginal artery- runs along colon margin, connecting SMA to IMA (provides collateral flow)

    4) Arc of Riolan- short direct connection between IMA and SMA

    - 80% of blood flow goes to mucosa and submucosa

    5) Venous drainage follows arterial except IMV, which goes to the splenic vein- splenic vein joins the SMV to form the portal vein

    6) Superior rectal artery- branch of IMA

    • 7) Middle rectal artery- branch of internal iliac (the lateral stalks
    • during low anterior resection (LAR) or abdominoperineal resection (APR)
    • contain the middle rectal arteries.

    8) Inferior rectal artery- branch of internal pudendal (which is a branch of internal iliac)

    9) Superior and middle rectal veins drain into the IMV and eventually the portal vein

    10) Inferior rectal veins drain into internal iliac veins and eventually the caval system
  10. Lymphatics of rectum:
    • 1) superior and middle rectum- drain to IMA nodal lymphatics
    • 2) lower rectum- drains primarily to IMA nodes, also to internal iliac nodes
  11. Lymphatics of bowel wall
    bowel wall contains mucosal and submucosal lymphatics
  12. Watershed areas
    1) Splenic flexure (Griffith's point) - SMA and IMA junction

    2) Rectum (Sudak's point)- superior rectal and middle rectal junction

    3) Colon is more sensitive to ischemia than small bowel secondary to decreased collaterals
  13. External sphincter-
    • 1) puborectalis muscle
    • 2) under CNS (voluntary) control
    • 3) inferior branch of internal pudendal nerve and perineal branch of S4
    • 4) is the continuation of the levator ani muscle (striated muscle)
  14. Internal sphincter
    • 1) involuntary control
    • 2) is the continuation of the circular band of colon muscle (smooth muscle)
    • 3) is normally contracted
  15. Meissner's plexus
    inner nerve plexus
  16. Auerbach's plexus
    outer nerve plexus
  17. pelvic nerves
    parasympathetic
  18. lumbar, splanchnic, and hypogastric nerves
    sympathetic
  19. Where is the anal canal, rectum, and rectosigmoid junction in relation to the anal verge?
    Anal canal 0-5cm

    Rectum- 5-15cm

    Rectosigmoid junction 15-18cm
  20. What transition point does the levator ani mark?
    levator ani marks the transition point between anal canal and rectum
  21. Crypts of Lieberkuhn
    mucus-secreting goblet cells
  22. colonic inertia
    • 1) slow transit time
    • 2) patient's may need subtotal colectomy
  23. Whats the main nutrient of colonocytes?
    short chain fatty acids
  24. stump pouchitis (diversion or disuse proctitis)
    treatment- short-chain fatty acids
  25. Infectious pouchitis
    treatment- metronidazole (flagyl)
  26. Lymphocytic colitis
    • 1) watery diarrhea and inflammatory bowel symptoms
    • 2) Treatment- sulfasalazine
  27. Denonvilliers fascia (anterior)
    • 1) rectovesicular fascia in men
    • 2) rectovaginal fascia in women
  28. Waldeyer's Fascia (posterior)
    rectosacral fascia
  29. Polyps:
    • 1) Hyperplastic polyps-
    • 1- most common polyp
    • 2- no cancer risk

    • 2) Tubular adenoma-
    • 1- most common (75%) intestinal neoplastic polyp
    • 2- are generally pedunculated

    • 3) Villous adenoma-
    • 1- most likely to produce symptoms
    • 2- generally sessile and larger than tubular adenomas
    • 3- 50% of villous adenomas have cancer
    • 4- >2cm, sessile, and villous lesions have increased cancer risk

    4) polyps have left sided predominance

    5) Most pedunculated polyps can be removed endoscopially

    6) if not able to get all of the polyp (which usually occurs with sessile polyps) --> need segmental resection

    7) 30% of patients >50 years old with guiac positive stool have polyps
  30. High grade dysplasia
    1) basement membrane is intact (carcinoma in situ)
  31. Intramucosal cancer
    • 1) into muscularis mucosa
    • 2) carcinoma in situ; still has not gone through the basement membrane
  32. Invasive cancer
    into submucosa (T1)
  33. Risk Stratification for Colorectal Cancer Screening
    • Average Risk for Colorectal Cancer (must fulfill all criteria below)
    • 1) age 50 years or older
    • 2) No personal history of polyps or colorectal cancer
    • 3) No first-degree releative with polyps or colorectal cancer
    • 4) Fewer than two second-degree relatives with colorectal cancer

    • Moderate Risk for Colorectal Cancer (any criteria below)
    • 1) First-degree relative with colorectal cancer or polyp
    • 2) Two or more second-degree relatives with colorectal cancer

    • Increased Risk for Colorectal Cancer (any criteria below)
    • 1) Gene carrier or at risk for familial adenomatous polyposis
    • 2) Gene carrier or at risk for hereditary nonpolyposis colorectal cancer

    • Surveillance (any criteria below)
    • 1) personal history of colorectal polyps
    • 2) personal history of colorectal cancer
    • 3) personal history of inflammatory bowel disease
    • - - - - - - - - - - - - - -

    Guidelines for Colorectal cancer screening

    Individuals at Average Risk (age >50)

    • 1) Fecal occult blood test (annually)
    • 2) Flexible sigmoidoscopy (every 5 years)
    • 3) Fecal occult blood test and flexible sigmoidoscopy (FOBT annually flexible sigmoidoscopy every 5yrs)- FOBT first, if positive skip sigmoidoscopy and follow with colonoscopy
    • 4) Colonoscopy (every 10 years)
    • 5) Double contrast barium enema (every 5 yrs)

    • Individuals at Moderate Risk
    • 1) First degree relative with colorectal cancer or polyp at age >60 years or >2 or more second-degree relatives with colorectal cancer- Initiate screeing at age 40. Same screening regimens as intervals at average risk

    2) First degree relative with colorectal cancer or polyp at age <60 years or >2 or more first degree relatives with colorectal cancer- Initiate screening at age 40 or 10 years younger than the youngest family member at the time of diagnosis, whichever comes first. You do colonoscopy every 5 years.

    Individuals at increased risk (Colonoscopy only)

    1) Familial adenomatous polyposis; consider genetic counseling and testing; colectomy if genetic testing is positive. Initiate surveillance at age 10-12yrs . Annual sigmoidoscopy, stopping at age 40 if normal.

    2) Attenuated adenomatous polyposis coli. Initiate surveillance in late teens. Annual colonoscopy, no stopping at age 40.

    3) Hereditary nonpolyposis colon cancer. Initiate survaillnce at 20-25yrs or 10 years younger than earliest family diagnosis. Biennial colonoscopy to age 40, then annual.
  34. What will give you a false positive guiac?
    • 1) beef
    • 2) vit C
    • 3) iron
    • 4) antacids
    • 5) cimetidine (H2 blocker)
  35. You dont do a colonoscopy when:
    • 1) recent MI
    • 2) splenomegaly
    • 3) pregnancy if fluoroscopy planned
  36. Polypectomy shows T1 lesion:
    • Polypectomy is adequate if:
    • 1) margins are clear (2mm)
    • 2) is well differentiated
    • 3) has no vascular/lymphatic invasion

    otherwise need formal colon resection
  37. Extensive low rectal villous adenomas with atypia:
    • transanal exision (can try mucosectomy) as much of the polyp as possible
    • - no APR unless cancer is present
  38. Pathology shows T1 lesion after transanal exision of rectal polyp:
    • transanal exision is adequate if:
    • 1) margins are clear (2mm)
    • 2) well differentiated
    • 3) has no vascular/lymphatic invasion
  39. Pathology shows T2 lesion after transanal excision of rectal polyp:
    patient needs APR or LAR
  40. Guidelines for Colorectal Cancer Endoscopic Surveillance:
    1) Following resection of a single <1cm adenoma, initiate surveillance 5 years posypolypectomy. If first colonoscopy is normal, resume average-risk recommendations.

    2) Following resection of >1cm or high-risk adenoma, initiate surveillance 3 yrs postpolypectomy. Repeat colonoscopy in 3 yrs; if normal return to average risk recommendations.

    3) Following curative resection for colorectal cancer. Initiate surveillance within 1 year postoperatively. Repeat in 3 years, then every 5 years.

    4) Inflammatory bowl disease. Initiate surveillance within 8 years of diagnosis. Survey for dysplasia every 1-2 years.
  41. Colorectal Cancer
    1) 2nd leading cause of Ca death

    • 2) symptoms:
    • 1- anemia
    • 2- constipation
    • 3- bleeding

    3) Fat --> O2 radicals are thought to have a role

    4) Colon Ca has an association with clostridium septicum infection
  42. What are the main gene mutations in colon Ca?
    • 1) APC
    • 2) DCC
    • 3) p53
    • 4) k-ras
  43. Whats the most common site of primary colon Ca?
    sigmoid colon
  44. Prognostic factors for Primary colon Ca:
    1) Age- patients <40 yo often present with more advanced stage of disease

    2) Symptoms-Symptmatic patients tend to have more advanced stage of disease

    3) Obstruction and perforation-poorer prognosis when present

    4) Location of primary- Rectosigmoid and rectal cancers have lower cure rates compared with cancers elsewhere in the colon

    5) Tumor configuration- exophytic tumors are associated with less advanced stage of cancer compared with ulcerative tumor

    6)Blood vessel invasion- poorer prognosis when present

    7) Lymphatic vessel invasion- poorer prognosis when present

    8) Perineural invasion- poorer prognosis when present

    9) Lymphocytic infiltration- improved prognosis when present

    10) Carcinoembryonic antigen study- poorer prognosis when elevated before primary tumor resection

    11) Aneuploidy- poorer prognosis when present
  45. Disease spread (colorectal Ca):
    • 1) spreads to nodes first
    • 2) nodal status- most important prognostic factor
    • 3) Liver- 1st site of metastasis (portal vein)
    • 4) Lung- 2nd site of metastasis (iliac vein)
    • 5) If liver metastases are resectable and leaves adequate liver function, patients have 25% 5yr survival rate
    • 6) Lung metastases- 20% 5yr survival rate in selected patients
    • 7) Isolated liver and lung metastases should be resected
    • 8) 5% get drop metastases to ovaries
    • 9) Rectal Ca- can metastasize to spine directly via Batson's plexus
    • 10) Colon Ca- typically does not go to bone
    • 11) Colorectal Ca growing into adjacent organs can be resected en bloc with a portion of the adjacent organ (i.e. partial bladder resection)
  46. Lymphocytic penetration-
    patients have an improved prognosis
  47. Mucoepidermoid-
    worse prognosis
  48. Rectal ultrasound-
    good at assessing depth of invasion (sphincter involvement), recurrence, and presence of enlarged nodes

    - need colonoscopy to rule out synchronous lesions
  49. Goals of resection:
    • 1) en bloc resection, adequate margins, and regional adenectomy
    • 2) Most right sided colon CAs can be treated with primary anastomosis without ostomy
    • 3) Rectal pain with rectal Ca- patient needs APR
    • 4) need 2cm margins
  50. Intraoperative ultrasound
    • 1) best method of picking up intrahepatic metastases
    • 2) conventional ultrasound: 10mm
    • 3) abdominal CT: 5-10mm
    • 4) abdominal MRI: 5-10mm (better resolution than CT)
    • 5) Intraoperative ultrasound: 3-5mm
  51. Abdominoperineal resection (APR)
    • 1) permanent colostomy
    • 2) anal canal is excised along with the rectum
    • 3) Can have impotence and bladder dysfunction
    • 4) Indicated for malignant lesions only (not benign tumors) that are not amenable to LAR
    • 5) Need at least a 2cm margin (2cm from the levator ani muscles) for LAR
    • 6) high rate of impotence in men after rectal resection, especially with APR, due to disruption of nerve supply
    • 7) risk of local recurrence higher with rectal Ca than with colon Ca in general
    • 8) Unresectable large liver metastases at time of APR--> may not need APR
    • - if obstructed or nearly obstructed --> place colostomy and mucous fistula
    • - avoid morbidity of APR in patient with terminal Ca
    • - if bleeding was a significant symptom, probably best to proceed with APR
    • - if rectal pain was a significant symptoms, probably best to proceed with APR
    • 9) unresectable large liver metastases during preop workup for colon or rectal Ca --> no resection unless obstructed or nearly obstructed, or unless bleeding is a significant symptom
  52. Preoperative chemotherapy/XRT
    Produces complete response in some patients with rectal Ca; preserves sphincter function in some
  53. TNM staging system for colorectal Ca
    • T1- into submucosa
    • T2- into muscularis propria
    • T3- into serosa or through muscularis propria if no serosa is present
    • T4- through serosa into free peritoneal cavity or into adjacent organs/structures if no serosa is present

    • N0- nodes negative
    • N1- 1-3 nodes positive
    • N2- >/=4 nodes positive
    • N3- central nodes positive

    M1- distant metastases

    Neoplastic:

    • Stage TNM status
    • I T1-2, N0, M0
    • II T3-4, N0, M0
    • III Any N1 disease
    • IV Any M1 disease
  54. Low rectal T1:
    T1- limited to submucosa

    • Can be excised transanally if:
    • 1- <4cm
    • 2- has negative margins (need 1cm)
    • 3- is well differentiated
    • 4- there is no neurologic or vascular invasion
    • -otherwise pt needs APR or LAR
  55. Low rectal T2 or higher:
    Tx: LAR or APR
  56. Chemotherapy:
    1) stage III and IV colon Ca (nodes positive or distant metastases) --> postop chemo, no XRT

    2) Stage II and III rectal Ca--> preop or postop chemo and XRT

    3) Stage IV rectal Ca --> chemo and XRT +/- surgery (possibly just colostomy)

    4) Stages II (rectal) and III (colon or rectal) - 5FU, leucovorin, and oxaliplatin

    5) Stage IV (colon or rectal) - 5FU and leucovorin
  57. XRT
    1) decreases local recurrence and increases survival when combined with chemotherapy

    2) Postop XRT for rectal Ca- needed for T3 tumors or positive nodes (stage II or higher)

    3) XRT damage- rectum most common site of injury --> vasculitis, thrombosis, ulcers, strictures

    4) Preop XRT and chemotherapy may help shrink tumor, allowing downstaging of the tumor and possibly allowing LAR versus APR
  58. Recurrence
    • 1) 20% of patients have recurrence
    • 2) 50% have recurrence within 6 months
    • 3) 100% have recurrence by 3 years
    • 4) 5% have another primary -main reason for surveillance colonoscopy
  59. Follow-up for Colorectal Ca-
    • 1) history and physical exam- every 6months for 3 years, then annually
    • 2) CEA- every 6months for 3 years, then annually
    • 3) stool guiac - every 6months for 3 years, then annually
    • 4) yearly LFTs, abdominal CT, colonoscopy, CXR
    • 5) these vary and there is no consensus
    • 6) colonoscopy mainly to check for new colon Cas (metachronous)
  60. Familial Adenomatous Polyposis (FAP)
    • 1) autosomal dominant
    • 2) all have cancer by age 40
    • 3) APC gene- chromosome 5
    • 4) 20% of FAP syndrome are spontaneous
    • 5) polyps not present at birth; are present at puberty
    • 6) Do not need colonoscopy for surveillance in patients with suspected FAP --> just need flexible sigmoidoscopy to check for polyps
    • 7) Need total colectomy prophylactically at age 20
    • 8) Also get duodenal polyps --> need to check duodenum for cancer with esophagogastroduodenoscopy every 2 years

    • 9) Surgery:
    • 1- proctocolectomy
    • 2- rectal mucosectomy
    • 3- ileoanal pouch (j-pouch)
    • -need lifetime surveillance of residual rectal mucosa
    • -following colectomy, most common cause of death in FAP patients is periampullary tumors of the duodenum
    • -total proctocolectomy with end ileostomy is also an option
  61. Gardner's syndrome:
    • 1) patients get colon Ca (associated with APC gene)
    • 2) desmoid tumors/osteomas
  62. Turcot's syndrome
    • 1) patients get colon Ca (associated with APC gene)
    • 2) brain tumors
  63. Lynch Syndromes (Hereditary Nonpolyposis Colon Cancer)
    • 1) 5% of the population
    • 2) autosomal dominant
    • 3) associated with DNA mismatch repair gene
    • 4) predilection for right-sided and multiple cancers
    • 5) Lynch I- just colon Ca risk
    • 6) Lynch II- patients also have increased risk of ovarian, endometrial, bladder, and stomach cancer
    • 7) Amsterdam criteria- "3,2,1"-->
    • - at least 3 first-degree relatives
    • - over 2 generations
    • - 1 with cancer before age 50
    • 8) Need surveillance colonoscopy starting at age 25 or 10 years before primary relative got cancer
    • 9) 50% get metachronous lesions within 10 years; often have multiple primaries
    • 10) women need endometrial biopsy every 3 years and annual pelvic exams; earlier mammograms
    • 11) consider total abdominal hysterectomy and bilateral salpingoophorectomy after childbearing years
    • 12) consider subtotal colectomy with first cancer operation
  64. Juvenile polyposis
    1) hamartomatous polyp- cancer is dependent on adenomatous change in these polyps

    • 2) Symptoms:
    • 1- anemia
    • 2- decreased energy
    • 3- failure to thrive
    • 4- anergy

    3) Colonic surveillance every 2 years; total colectomy probably best option if Ca develops

    4) Juvenile polyps do not have malignant potential, but patients with juvenile polyposis do have increased cancer risk
  65. Peutz-Jeghers Syndrome
    1) GI hamartoma polyposis and dark pigmentation around mucous membranes

    2) Now believed to increase risk of GI Cas

    3) These patients need polypectomy if possible (may be too many polyps to resect)- 2% colon/duodenal Ca risk

    4) increased risk of other cancers- gonadal, breast, and billiary
  66. Cronkite-Canada Syndrome
    • 1) Hamartomatous polyps; get atrophy of nails and hair, hypopigmentation
    • 2) thought to have no malignant potential
  67. Sigmoid Volvulus
    • 1) more common with high-fiber diets (Iran, Iraq)
    • 2) occurs in debilitated, psychiatric patients; neurologic dysfunction, laxative abuse
    • 3) Symptoms- pain, distention, obstipation
    • 4) Causes closed loop obstruction
    • 5) Abdominal X-ray- bent inner tube sign; gastrografin enema may show bird's beak sign (tapered colon)
    • 6) Do not attempt decompression with gangrenous bowel or peritoneal signs --> go to OR for sigmoidectomy
    • 7) Tx: decompress with colonoscopy (80% reduce, 50% will recur), give bowel prep, and perform sigmoid colectomy during same admission
  68. Cecal Volvulus
    • 1) less common than sigmoid volvulus; occurs in 20-30s
    • 2) can appear as an SBO, with dilated cecum in the RLQ
    • 3) Can try to decompress with colonoscopy but unlikely to succeed (only 20%)
    • 4) Treatment- OR --> right hemicolectomy probably best treatment, can try cecopexy if colon is viable and patient is frail
  69. Ulcerative Colitis
    • 1) Symptoms:
    • 1- bloody diarrhea
    • 2- abdominal pain
    • 3- fever
    • 4- weight loss

    2) involves mucosa and submucosa

    3) strictures and fistulae unusual with ulcerative colitis

    • 4) spares anus- unlike Crohn's diease
    • - starts distally in rectum, is contiguous (no skip areas like Crohn's disease)
    • - bleeding is universal and has mucosal friability with pseudopolyps and collar button ulcers
    • - always need to rule out infectious etiology
    • - backwash ileitis can occur with proximal disease

    5) barium enema- with chronic disease see loss of haustra, narrow caliber, short colon, and loss of redundancy
  70. Medical Treatment for Ulcerative Colitis-
    1) Sulfasalazine + 5-ASA (poorly absorbed in gut, act like topical antiinflammatory, decreases inflammatory cells but not an immunosuppresant)

    2) steroids

    3) methotrexate (competitively inhibits dihydrofolate reductase (DHFR), an enzyme that participates in tetrahydrofolate synthesis. Works in S-phase)

    4) azathioprine (Imuran)- a DNA synthesis inhibior, as it is converted to a purine analogue inhibiting the proliferation of cells, esp. lymphocytes.

    5) Infliximab (remicade)- monoclonal antibody against TNF-alpha

    6) loperamide- opiod-receptor agonist and acts on the mu-opiod receptors in the myenteric plexus of the large intestine. Doesn't effect the CNS system like other opiods

    5-ASA and sulfasalazine have been shown to maintain remission in ulcerative colitis
  71. Toxic Megacolon
    • Clinical Dx:
    • -fever
    • - increased HR
    • - bloating
    • - abdominal radiographs -> dilated colon

    • Initial treatment-
    • 1- NG tube
    • 2- fluids
    • 3- steroids
    • 4- bowel rest
    • 5- TPN
    • 6- antibiotics
    • - all the above will treat ~50% adequately; the other 50% will require surgery
    • - follow clinical response and abdominal radiographs

    Indications for Surgery:

    • Absolute:
    • 1- pneumoperitoneum
    • 2- diffuse peritonitis
    • 3- localized peritonitis with increasing abdominal pain and/or colonic distention >10cm
    • 4- uncontrolled sepsis
    • 5- major hemorrhage

    • Relative
    • 1- inability to promptly control sepsis
    • 2-increasing megacolon
    • 3- failure to improve within 24-48hrs
    • 4- increasing toxicity or other signs of clinical deterioration
    • 5- continued transfusion requirements
  72. Where are perforations most likely in ulcerative colitis and in Crohns?
    Ulcerative Colitis- transverse colon more common

    Crohns- distal ileum most common
  73. Surgical Indications (Ulcerative Colitis)
    • 1) hemorrhage
    • 2) toxic megacolon
    • 3) acute fulminant ulcerative colitis (occurs in 15%)
    • 4) obstruction
    • 5) dysplasia
    • 6) cancer
    • 7) intractibility
    • 8) systemic complications
    • 9) failure to thrive
    • 10) long standing disease (>10yrs) as prophylaxis against colon Ca
  74. Emergent/urgent resections (ulcerative colitis)-
    - total proctocolectomy and bring up ileostomy

    - perform definitive hookup later
  75. Elective resections-
    1) Ileoanal anastomosis- rectal mucosectomy, J-pouch, and ileoanal (low rectal) anastomosis; not used with Crohn's disease

    • - protects bladder and sexual function
    • - needs lifetime surveillance of residual rectal area
    • - many ileoanal anastomoses need resection secondary to cancer, dysplastic changes, or refractory proctitis
    • - need temporary diverting ileostomy (6-8wks) while pouch heals

    Leak- most common major morbidity after surgery- can lead to sepsis

    Infectious pouchitis- Tx: flagyl

    APR with ileostomy can also be performed
  76. Whats the cancer risk in ulcerative colitis?
    1) cancer risk is 1-2% per year starting 10 years after initial diagnosis

    2) cancer is more evenly distributed throughout the colon

    3) needs yearly colonoscopy starting 8-10 years after diagnosis
  77. Extraintestinal manifestations of ulcerative colitis:
    1) most common intestinal manifestation requiring total colectomy- failure to thrive in children

    • 2) Do not get better with colectomy:
    • 1- primary sclerosing cholangitis
    • 2- ankylosing spondylitis

    • 3) Get better with colectomy:
    • 1- most ocular problems
    • 2- arthritis
    • 3- anemia

    4) 50% get better --> pyoderma gangrenosum

    5) HLA B27- sacroiliitis and ankylosing spondylitis

    6) can get thromboembolic disease

    7) Pyoderma gangrenosum- Tx steroids
  78. Carcinoid of the Colon and Rectum:
    • 1) represents 15% of all carcinoids; infrequent cause of carcincoid syndrome
    • 2) metastases related to size of tumor
    • 3) 2/3 of colon carcinoids have either local or systemic spread
    • 4) Low rectal carcinoids- <2cm --> wide local excision with negative margins; >2cm or invasion of muscularis propria--> APR
    • 5) Colon or high rectal carcinoids- formal resection with adenectomy
  79. Colonic obstruction
    • 1) Colon perforation with obstruction- most likely to occur in cecum
    • - Law of LaPlace: tension = pressure x diameter

    • 2) Closed-loop obstructions- can be worrisome; can have rapid progression and perforation with minimal distention
    • - competent ileocecal valve can lead to closed-loop obstruction

    3) Colonic obstruction- #1 cancer, #2 diverticulitis

    4) Pneumatosis intestinalis- air on the bowel wall, associated with ischemia and dissection of air through areas of bowel wall injury; most often indication for surgery

    4) Air in the portal system- usually indicates significant infection or necrosis of the large or small bowel; often an ominous sign
  80. Ogilvie's Syndrome:
    1) pseudoobstruction of colon

    • 2) associated with:
    • 1- opiate use
    • 2- bedridden or older patient's recent surgery
    • 3- infections
    • 4- trauma

    3) get massively dilated colon

    4) Check electrolytes; discontinue drugs that slow the gut, such as morphine

    5)Treatment: colonoscopy with decompression and neostigmine (parasympathomimetic which acts as a reversible acetylcholinesterase inhibitor), cecostomy if that fails
  81. Amoebic Colitis
    1) 10% become carriers of Entamoeba histolytica; from contaminated food and water with feces that contain cysts

    • 2)Primary infection- occurs in colon;
    • Secondary infection- occurs in liver

    • 3)Risk factors:
    • 1- travel to mexico
    • 2- EtOH

    4) fecal oral transmission

    • 5) Symptoms:
    • 1- similar to ulcerative colitis (dysentery)
    • 2- chronic more common form (3-4BMs/day, cramping, fever)

    • 6) Diagnosis:
    • 1- endoscopy --> ulcerations, trophozoites, 90% have antiamebic antibodies

    • 7) Treatment:
    • 1- flagyl
    • 2- diiodohydroxyquin
  82. Actinomyces
    1) can present as a mass, abscess, fistula, or induration, suppurative and granulomatous

    2) cecum most common location

    • 3) Treatment:
    • 1- tetracyclin or penicillin
    • 2- drainage
  83. Lymphogranuloma Venereum
    • 1) Chlamydia; homosexuals
    • 2) causes proctitis, tenesmus, and bleeding; may produce fistulas
    • 3) Treatment: doxycycline, hydrocortosone
  84. Diverticula
    1) herniation of mucosa through the colon wall at sites where arteries enter the muscular wall

    2) thickening of circular muscle adjacent to diverticulum with luminal narrowing

    3) Caused by straining (increased intraluminal pressure)

    • 4) More diverticula occur on left side (80%) in the sigmoid colon
    • -Bleeding is more likely with right-sided diverticula (50% of bleeds occur on right)
    • - Diverticulitis is more likely to present on the left side

    5) Present in 35% of the population
  85. Lower GI bleeding
    • 1) stool guiac can stay positive up to 3 weeks after bleed
    • 2) Hematemesis- pharynx to ligament of Treitz
    • 3) Melena- passage of tarry stools; need as little as 50ccs
    • 4) Azotemia after GI bleed- caused by production of urea from bacterial action on intraluminal blood (increased BUN, total bilirubin)
    • 5) Arteriography- bleeding must be > 0.5cc/min
    • 6) Tagged RBC scan- bleeding must be > 0.1cc/min
  86. Look at chart on pg 303 on lower GI hemorrhage diagnostic steps
  87. Diverticulitis
    1) result of perforations in the mucosa in the diverticulum with adjacent fecal contamination

    2) denotes infection and inflammation of the colonic wall as well as surrounding tissue

    3) LLQ pain, tenderness, fever, increased WBCs

    4) Diagnosis: CT scan is needed only if worried about complications of disease

    5) Need follow-up barium enema to rule out cancer

    6) 25% of patients will have a complication, most likely abscess formation which can usually be percutaneously drained

    7) Signs of complication- obstruction symptoms, fluctuant mass, peritoneal signs, temperature >39, and WBCs >20

    • 8) uncomplicated diverticulitis-
    • Treatment: flagyl and TMP/SMX (bactrim)
    • bowel rest for 3-4 days

    • 9) Surgery for:
    • 1- recurrent disease (2nd attacks associated with 50% recurrence rate)
    • 2- significant emergent complications (obstruction, perforation, or abscess formation not amenable to percutaneous drainage)
    • 3- inability to exclude cancer

    • - some say that patients with any complicated diverticulitis (i.e. abscess formation) or if young should undergo sigmoidectomy with 1st time diverticulitis.
    • - need to resect all of the sigmoid colon up to the superior rectum
  88. Right sided diverticulitis:
    • 1) 80% discovered at the time of incision for appendectomy
    • 2) Treatment: right hemicolectomy
  89. Diverticulitis:
    Colovesicular fistula
    • 1) fecaluria, pneumonuria
    • 2) Occurs in men, women are more likely to get colovaginal fistula
    • 3) cystoscopy is more likely to identify
    • 4) Treatment: close bladder opening, resect involved segment of colon, and perform reanastomosis, diverting ileostomy
  90. Diverticulosis Bleeding
    1) most common cause of lower GI bleed

    2) usually causes significant bleeding

    3) 75% stops spontaneously; recurs in 25%

    4) caused by disrupted vasa rectum; creates arterial bleeding

    • 5) Diagnosis:
    • - colonoscopy 1st or angio 1st if massive bleed --> these can be therapeutic and will localize the bleeding should surgery be required
    • - go to operating room if hypotensive and not responding to resuscitation --> subtotal colectomy if bleeding source has not been localized
    • - tagged RBC scan for intermittent bleeds that are hard to localize
    • - NG tube to rule out upper GI source

    • 6) Treatment:
    • -with colonoscopy can coagulate bleeder
    • - with arteriography can use vasopressin or highly selective coil embolization
    • -vasopressin can allow time for resuscitation
    • - may need segmental colectomy or even subtotal colectomy when bleeding is not localized and not controlled

    7) patients with recurrent diverticular bleeds should have resection of the area if it can be localized or they may need subtotal colectomy if the area cannot be localized
  91. Angiodysplasia bleeding:
    • 1) increased on right side of colon
    • 2) bleeds are usually less severe than diverticular bleeds but are more likely to recur (80%)
    • 3) causes venous bleeding
    • 4) soft signs of angiodysplasia on angiogram- tufts, slow emptying
    • 5) 20-30% of patients with angiodysplasia have aortic stenosis (Heyde's Syndrome)- coincidence of aortic valve stenosis and bleeding from angiodysplasia. In this disorder, vWF is proteolysed due to high shear stress in the highly turbulent blood flow around the aortic valve. vWF is most active in vascular beds with high shear stress, including angiodysplasias, and deficiency of vWF increases the bleeding risk from such lesions).
  92. Ischemic colitis
    • 1) Symptoms:
    • 1- abdominal pain
    • 2- bright red bleeding

    • 2) Can be cause by:
    • 1- a low-flow state
    • 2- ligation of the IMA at surgery (ie AAA repair)
    • 3- embolus or thrombosis of the IMA
    • 4- sepsis
    • 5- MI

    3) Splenic flexure and descending colon most vulnerable to low-flow state

    4) Griffith's point- SMA and IMA junction

    5) Sudeck's point- superior rectal and middle rectal artery junction

    • 6) Diagnosis:
    • - made by endoscopy--> cyanotic edematous mucosa covered with exudates
    • -lower 2/3 of the rectum is spared--> supplied by the middle (off the internal iliac) and inferior (off the internal pudendal) rectal artery
    • - if gangrenous colitis is suspected (peritonitis), no colonoscopy and go to OR--> sigmoid or left heicolectomy usual
  93. Pseudomembranous colitis (C.difficile colitis)
    1) symptoms: watery, green, mucoid diarrhea; pain and cramping

    2) Can occur up to 3 weeks after antibiotics; increased in postop, elderly, and ICU patients

    3) Carrier state is not eradicated; 15% recurrence

    4) Key finding- PMN inflammation of mucosa and submucosa

    5) pseudomembranes, plaques, and ringlike lesions

    6) Most common in distal colon

    • 7) Diagnosis:
    • 1- fecal leukocytes
    • 2- stool cultures for C.diff + C. diff toxin
    • 3- only 1/3 of patients with C. diff colitis are positive for fecal leukocytes with each test
    • 4- if tests are negative at first, need to repeat if your suspicision is high or just treat empirically

    • 8) Treatment- oral vancomycin or flagyl; IV-flagyl
    • -lactobacillus can also help; stop other antibiotics or change them
  94. Neutropenic Typhlitis (enterocolitis)
    • 1) follows chemotherapy when WBCs are low
    • 2) can mimic surgical disease
    • 3) can often see pneumatosis on plain film
    • 4)Treatment: antibiotics; patients will improve when WBCs increase
  95. Other causes of colitis:
    • 1) salmonella
    • 2) shigella
    • 3) campylobacter
    • 4) CMV
    • 5) yersinia (can mimic appendicitis in children)
    • 6) other viral infections
    • 7) giardia
  96. TB enteritis-
    1) presents like Crohn's disease (stenosis)

    • 2) Treatment:
    • 1- INH
    • 2- rifampin
    • 3- surgery with obstruction
  97. Yersinia
    can mimic appendicitis; comes from contaminated food (feces/urine)

    Treatment: tetracycline or bactrim
  98. Megacolon-
    1) propensity for volvulus; enlargement is proximal to nonperistalsing bowel

    - Hirschsprung's disease- rectosigmoid most common. Dx: rectal biopsy

    - Trypanosoma cruzi- most common acquired cause, secondary to destruction of nerves

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