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Flashcards in Colon, Rectum, Anal Canal Deck (111)
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Diverticulitis pathophys

- Diverticulosis = mucosal herniations protruding through intestinal layers and smooth muscle along with natural weakness in muscularis mucosa created by nutrient vessels in wall of the colon. These pouches are lined by mucosa and serosa only

- The condition appears to be associated with low fiber diet, constipation, and obesity

- Diverticula can appear anywhere along GI tract, but mostly in colon and most commonly in sigmoid colon where intraluminal pressures are highest

- Diverticulitis is inflammation of the diverticula. Obstruction of neck of diverticula can result in stasis of intralminal fecal material causing bacterial overgrowth and infection. This can cause:
1) Micro/macro perf (may be walled off by pericoloc fat/mesentery)
2) Abscess (and possible rupture leading to peritonitis)
3) Fistula to adjacent organs or skin (most common in men is colovesicular)
4) Recurrent attacks can yeild scar tissue and narrowing/obstructing of colon

- Abscess can be peritoneal or retroperitoneal depending on segment of colon (posterior ascending and descending colon are retroperitoneal)


Prevalence of diverticulitis

Diverticulosis: 5% before age 40
65% before age 85. Usually asymptomatic

15-25% of those with diverticulosis get diverticulitis
- Of these, 75% have just colicky pain and 25% require surgery

20% of patients with diverticulitis are younger than 50

Anatomic prevalence:
- 70% L side of colon
- 75% R sided in Asians


Diverticulitis morbidity/mortality

20-35% with conservatively managed diverticulitis experience recurrence

More severe illness in younger patients, immunocompromised, significant comorbid conditions, and those taking anti-inflammatory meds


Typical history of diverticulitis

#1 symptom = LLQ pain

- can mimic many abdominal conditions due to location variability of the diverticula

- Mild disease = localized abdominal pain, colicky pain, change in bowel habits (usually constipation more than diarrhea)

- After perf = fever, anorexia, nausea,vomiting

- If colovesicular fistula = dysuria (90%), pneumaturia (70%), fecaluria (70%)

- Bleeding more common in simple diverticulosis NOT diverticulitis


Workup for diverticulitis

H&P usually enough

Look for leukocytosis with L shift

If ambiguous, do CT
- Pericolic fat stranding (98%)
- Colonic diverticula (84%) - note this is NOT 100%
- Bowel wall thickening (70%)
- Phlegmon or abscess (35%)

Colonoscopy and contrast enema are contraindicated with possible perforation***


Hinchey classification of acute diverticulitis

Stage 1 = Pericolic abscess

Stage 2 = Distant or remote abscess

Stage 3 = Prurulent peritonitis

Stage 4 = Fecal peritonitis


Tx for diverticulitis

Medical Care
- Liquid diet and 7-10d of oral broad-spectrum antibiotics (cipro/metronidazole)
- Long term care = high fiber and low fat diet


Indications for surgery in diverticulitis

1) Free air perforation with fecal peritonitis

2) Suppurative peritonitis secondary to ruptured abscess

3) Abdominal or pelvic absess (unless CT-guided aspiration is possible)

4) Fistula formation

5) Inability to rule out carcinoma

6) Intestinal obstruction

7) Failing medical therapy

8) Immunocompromised

9) Extremes of age

10) Recurrent episodes of acute diverticulitis


What is the surgical approach for diverticulitis?

- If patient has peritoneal signs, consider 2 stage Hartmann
1) Resect inflamed colon, diverting colostomy, and closure of rectal stump
2) Wait 3-6 months for healing of rectal stump before taking down colostomy and making a final primary anastomosis

- If preop bowel prep is possible then do a simple resection with primary anastomosis


2 ways to remember some presentations of colorectal cancer

1) "Post-menopausal man with Fe deficiency anemia"
- Cancers on the right generally bleed but don't obstruct

2) Alternating bowel habits/pencil thin stools
- Cancers on the left generally obstruct but don't bleed


Prevalence of CRC

#3 most diagnosed malignancy and #2 leading cause of cancer death in men and women


Screening for CRC

Start at age 50

Colonoscopy every 5-10 years


double contrast barium enema every 5 years

OR fecal occult blood + flex sig every 5 years


Risk factors for CRC

1) Environment - high fat, low fiber diet and cigarette smoking

2) Crohns and UC

3) Previous colorectal, breast, ovarian, uterine cancer

4) Genetic
- FAP (100% will have cancer by 30s or 40s) so treated with total proctocolectomy. In FAP we also see gastric, duodenal polyps, and periampullary cancers

- Gardners - skull and desmoid tumors

- Turcots - brain tumors

- HNPCC "Lynch" - 80% chance of CRC. Higher risk for endometrial, stomach, and ovarian



Benign: hyperplastic, hamartomas, inflammatory. P-J and juvenile polyps unlikely to become malignant

Malignant potential: adenomatous. Tubular, villous (bad), tubulovillous. Pedunculated. Sessile (bad)


Presenting symptoms for CRC

Blood in stool: Melena if in right colon which can be detected by guaiac. Possible hematochezia is very distal.

Anemic symptoms and labs: Tired, dizzy, microcytic anemia

Weight loss


Ddx for heme-positive blood

1) Diverticular disease

2) Colon carcinoma

3) IBD

4) benign polyps

5) vascular ectasia

6) ischemic colitis

7) rectal ulcers

8) hemorrhoids


Lymphatic drainage for CRC

Found in colonic mesentery, mesorectum and para aortic area

Low lying cancer in anal canal can go to deep inguinal nodes and tumors of the anus may spread to superficial inguinal nodes


Staging for CRC

LFTs to check for liver mets

Rectal exams, abdominal/pelvic CT for finding mets

Endorectal US for staging local tumors and finding out depth of invasion


T1 = submucosa
T2 = muscularis propria
T3 = Subserosa
T4 = other organs

N1 = mets to 1-3 nodes
N2 = 4 or more

Stage 1: T1-2 N0 M0 5yr = 90%

Stage 2: T3-4 N0 M0 5yr = 75%

Stage 3: Any T N1-N3 M0 5yr=50%

Stage 4: Any T Any N M1 5yr 5%

Untreated liver mets have median survival of less than 1 year. If treated surgically there's 30-40% 5 year survival


Surgical tx for CRC

Single lesion - segmental resection with 2cm margin

Synchronous lesion - hemicolectomy or sigmoid colectomy

Role of laproscopy is up in the air

Bowel prep
- mechanical prep (clear liq 24hrs, lyte solution and enema)
- intraluminal antibacterial (neomycin, metronidazole)
- parenteral antibiotics 30mins before incision


Chemo for CRC

Stage 3 patients and some stage 2

6 months 5FU and leucovorin


Radiation for CRC

Stage 2 or 3 rectal cancer


Follow-up for CRC

CEA preOp. Follow it postop to determine recurrence

PET in pts with known recurrent disease to the liver

H&P should be done every 3 months for 2 years then every 6 months for 5 years

CEA q3m x 2yrs then q6m x 5yrs

Colonoscopy 1y postop and 3-5 yrs if negative for polyps


How does the colonoscopy alter follow-up for suspected CRC?

If it finds polyp...get the path

1) benign: Now q5-7yrs (in case you missed one the first time)

2) Carcinoma in situ. Get CT for staging, resect primary, and FOLFOX
- come back for colonoscopy q3-5y

If the scope showed giant fungating mass then get CT for staging, resect primary, and FOLFOX. Scope 1 yr postop and q3-5y after



FOLinic acid (leucovorin)

F = 5FU



Colon embryo

Midgut = up to mid-transverse

Hindgut = rest to prox anus

Ectoderm = distal anus

Dentate line = transition from hindgut to ectoderm


Blood supply to colon

Based on embryo

Midgut = SMA

Hindgt = IMA

Distal anus = internal pudendal branches (branch of internal iliac)

Internal iliac = middle and distal rectum via middle rectal and inferior rectal arteries (branch of internal pudendal)


Widest part of colon

Cecum...narrows progressively after that


Which parts of the colon are retroperitoneal?

Ascending colon, descending colon, posterior hepatic and splenic flexures (all but cecum, transverse and sigmoid)


Watershed areas of colon

Ileocecal area

Junction of descending and sigmoid

Splenic flexure


Lymphatic drainage of colon

Colon, rectum and anus generally follow arterial supply (ileocolic nodes, superior mesenteric nodes, etc)

Anal canal above dentate line = inferior mesenteric node

Lower anal canal = inguinal nodes