Download Absite-Colon - Open Source Surgery

1/13/2013
Anatomy and Physiology of Colon:
Absite Colorectal http://opensourcesurgery.com
• SMA supplies: – Ascending and Proximal Transverse Colon
• Ileocolic, Right Colic and Middle Colic
• IMA supplies:
– Distal Transverse, Descending, Sigmoid Colon and Upper Rectum
• Left Colic, Sigmoid Branches, Superior Rectal Artery
• Arc Of Riolan – connection between Proximal SMA and Proxima IMA
• External anal sphincter innervated by internal pudendal nerve(inferior rectal branch and perineal
branch).
• Internal anal sphincter innervated by pelvic splanchnic nerves
• Fuel for Colonocytes: Short chain Fatty Acids(Butyric Acid)
– Fuel for enterocytes and cancer cells: Glutamine
– Medium Chain Fatty acids avoid lymph tissue and can be used in chyle leak.
• Guaic Test False Positive: Beef, Vitamin C, Iron, Antacids, Cimetidine.
• Colon Secretes K+ and HCO3
• Sodium is transported against an electrical and concentration
• Layers of the Bowel: – Mucosa ‐ Columnar
– Submucosa
– Muscularis Propria – Circular , Tenia are longitudinal
– Serosa
• Watershed Areas:
– Splenic Flexure – Griffiths Point
– Superior Rectal and Middle rectal junciton ‐ Sudak’s
Point(some doubt as if this has any real clinical implication)
• Rectal
– Superior Rectal – Branch of IMA
– Middle Rectal ‐ Branch of Internal Iliac
– Inferior Rectal – Branch of internal pudendal off internal Iliac.
• Bacteroides makes up ~60% of the bacteria in the colon. Anaerobes are favored 1000 to 1 in the colon.
• Pouchitis: – Disuse: treated with short chain fatty acids
– Infectious: cipro +flagyl
• Treatment of radiation proctitis: formalin fixation(enema).
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• Colonoscopy:
– Average risk: 50 years Then every 10 years till 75
• If polyps found screen every 3‐5 years.
– Moderate risk:
• A first degree relative or 2 second degree relatives
• Screen at a age 40, Screen or 10 years before youngest relative with colon cancer
•
– FAP: First at 10‐12 years, followed by yearly sigmoidoscopy
– Attenuated FAP: Late Teens
– HNPCC: 20‐25 or 10 years younger than youngest relative. Colonoscopy every 1‐2 years.
Q5y exams for people with 1st
degree relatives with CRC or Polyps less than 60, >2 first degree relatives with CRC.
• After Curative Resection:
– Colonoscopy at 1 year, 3 years, and 5 years
• In unprepped previously not screened setting.
– Look for synchronous and metachronous lesions starting at 3 months
• After Polypectomy:
– 5 years if 1 polyp less than 1 cm
– 3 years if mutliple or >1cm
Polyps
• Types:
– Adenomatous: 75% Incidence, 5% invasiveness
– Villous: 10% incidence, 40% invasiveness
– Tubulovillous 15% incidence, 22% invasiveness1
• Risk Factors for cancer: – Greater than 2cm
– Sessile
– Villous lesions
• Transformation of Polyp to Cancer takes 8 years
• FAP:
• T1 on polypectomy. Need 2mm clear margin, as long as well differentiated without lymphovascular invasion.
• Haggitt Classification(T1 polyps):
– Class 0: Limited to Mucosa
– Class 1: Invasion of Submucosa but limited to the head of polyp
– Class 2: Invasion into the Neck
– Class 3: Invasion into the Stalk – Class 4: Invasion into the stalk but above muscularis
propria(after that it is T2).
– Class 3 and 4 need Formal Resections
• Lynch Syndrome:
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Autosomal Dominant
APC Gene on Chromosome 5
Screen at age 10‐12
Prophylactic Colectomy by age 20. Total Abdominal Proctocolectomy with J‐pouch or End ileostomy
– Need surveilance of any rectal mucosa.
– Get duodenal polyps and cancer and can be late cause of death
– Gardner’s syndrome: FAP with Desmoids
• Treat desmoids w/ Sulindac(NSAID) or antiestrogen(tamoxifen)
– Turcot’s: FAP with Brain Tumors
– By age 40 all have cancer.
– Autosomal dominant
– Error involves DNA Mismatch Repair Genes
– Predisposition toward multiple cancers and with a right sided predominance.
– Lynch I – Just colon cancer
– Lynch II – Endometrial and Ovarian, Bladder, Stomach.
– Amsterdam Criteria: 3‐2‐1
• 3 First Degree relatives
• Over 2 generations
• 1 being younger then age 50
– Colonoscopy at age 25, Pelvic exam yearly, q3year endometrial biopsy, – TAH BSO after child bearing years.
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• Juvenile Polyposis
– Juvenile polyps do not have malignant potential but patients with juvenile polyposis have increased cancer risk. – Surveil every 2 years
– TAC if cancer develops.
• Colorectal Cancer
– Symptoms: Bleeding, Anemia, Change in Bowel habits.
– Most common site is sigmoid.
– Can be associated with Strep bovis
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Oncogene K‐Ras, Tumor Supressor APC, P53, DCC, MCC
APC is thought to be an inciter of the process.
Two methods of formation: – Loss of heterozygosity : Somatic mutations of the above genes
– MMR(mismatch repair) pathway: Inherited or somatic loss of mismatch repair genes.
• Colorectal Cancer
• CEA levels not useful for screening but can be followed to determine success or treatment or to tip you off to recurrence.
• Transanal Excision:
• Colon/Rectal Resection
– Spreads to the nodes first and nodes are most important prognostic factor.
– Liver is #1 site of metastasis
– Lung Metastasis is much higher in lower rectal cancer
– Isolated lung and liver mets should be resected.
– Can metastasize to the spine via the valveless venous “batson’s Plexus”
– Rectal ultrasound can be of significant value because it can detect nodal involvement and start neoadjuvant
chemo based on it’s findings
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0‐10cm, <4cm, < 1/3 circumference
Must be T1 lesion with >2mm margin
No Lymphovascular invasion
Must be well differentiated.
If above criteria not met, APR or LAR.
– 2cm Margin
– Follow the blood supply to obtain at least 12 nodes. If less than 12 nodes are obtained they consider it an inadequate sampling and treat them with chemo anyway.
– Stage III/IV Colorectal cancer gets chemotherapy(rectal cancer gets it for stage II):
• 5FU and Levamisole or 5FU and leucovorin and oxaloplatin
– Stage II/III rectal gets neoadjuvant chemo and radiation. Improves local recurrence rates. May allow sphincter preserving therapy
– T3 or Positive nodes after resection get Post op Chemo.
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• What is the Hinchey Classification?
• Carcinoid:
– <2cm at the tip – Appendectomy adequate
– Right Hemi for >2cm or <2cm but at the base.
– I – Pericolonic Abscess
– II – Pelvic Abscess
– III – Purulent Peritonitis
– IV – Feculent Peritonitis
• Diverticulitis
– False Diverticula
– Form at vascular insertion points
– No real consensus on when to perform elective resection:
• 2 attacks of uncomplicated
• 1 attack of complicated.
UC
Crohn’s
Total colon
Frequent
Uncommon
Distal predominance
Almost 100%
Uncommon
SB involvement
Rarely
common
Skip lesions Never
Frequent
Transmural inflammation Rare
Frequent
Granulomas
Rare
Frequent
Crypt abscess
Frequent
uncommon
Rectal Involvement
Nearly all
Cobblestoning
Sparing common
In severe cases
Bloody diarrhea
Perianal disease‐ fissures and fistula’s,
PSC
• Duodenal Crohn’s treated with bypass:
– 1st and 2nd portion is gastrojejunostomy
– 3rd and 4th portion is duodenojejunostomy
• Fistulizing crohn’s: Can treat with inflixumab if no infectious source. Put’s them at risk for TB
• Ulcerative Colitis: proctocolectomy does not help sclerosing cholangitis
• Any dysplasia in ulcerative colitis ‐> Total abdominal proctocolectomy
• If operating for appy and find normal appy
and Crohn's disease(creeping fat of mesentary): take appendix (unless cecum involved in inflammation). Does not incr
fistula rate.
• Toxic megacolon
– Clinical Dx: fever, Tachycardia, distention, Significantly dilated colon on radiology
– Initial Tx: NGT, bowel rest, resuscitation, steroids, TPN, and antibiotics
– Follow response to medical management and abdominal radiographs
– 50% require surgery
– Surgery: TAC w/ ileostomy, leave rectum virgin for takeback, search for signs of crohn’s
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• Lower GI Bleed
• Large Bowel Obstruction
– Sigmoid volvulus: attempt colonic decompression(~80% successful) prep and perform sigmoidectomy.
– Cecal Volculus: Unlikely to reduce, Resect although some say cecopexy I wouldn’t do it in reality.
– Ogilvies: Rule out true obstruction with gastrograffin
enema. Watch for drugs: Narcotics, Tricyclics, Anti‐
depressants, clonidine, parkinsons meds.
– LOCALIZE
• Colonoscopy
• Tagged Red blood cell scan 0.1ml/min
• Arteriography – 0.5ml/min‐1ml/min
– Most common cause is diverticulosis.
• 75% stop on there own, 25% recurrence.
– Angiodysplasia more common on Right. Associated with Aortic Stenosis.
• If cecum less than 10cm conservative management, Colonoscopic decompression or neostigmine.
Hemorrhoids
• Mesenteric Ischemia
– Commonly you’ll see after Aortic surgery. Stent graft covers IMA.
– Can also be embolic or low flow state.
– Endoscopy shows cyanotic edematous mucosa.
– Conservative management unless signs of perforation.
Grade
Treatment
I
Painless rectal bleeding
Dietary modifications
II
Prolapse with defecation (reduce spontaneously)
Diet, banding
III
Prolapse with defecation(reduce manually)
Diet, banding,
hemorrhoidectomy
IV
Irreducible prolapse
Excisional
hemorrhoidectomy
Externa Below dentate line, painfull
l Excisional
hemorrhoidectomy
Post Hemorroidectomy:Most common complication urinary
retention
Post banding MC complication delayed bleeding,sepsis
Fissure
Anal Canal Tumors
90% located posterior, if another location(lateral) r/o crohn’s or STDs, R/O Anal Cancer
Treatment Change in bowel habits, sitz bath, nitroglycerine, botox
Surgery Lateral internal sphincterotomy
1. Epidermoid (SCC) most common
2. Melanoma
Melanoma: poor prognosis, treatment WLE
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SCC(above dentate)
‐Most important prognosis factor: Tumor Size
‐Risk factors:HIV, HPV(16,18), immunosupession
‐Treatment
Nigro (chemoradiation)
5‐fu, Mitomycin C + XRT
If adenocoarcinoma treat like Low rectal cancer
WLE if T1, otherwise will need apr.
Anal Margin Tumors(below dentate) Treated like other skin cancers
‐ Bowen’s: intraepithelial SSC(WLE)
‐ Paget’s disease: Intraepithelial adenoca,asociated
with other malignancies, WLE
‐ Basal Cell Ca: WLE
‐ SCCA : WLE
‐ Verrucous ca: low grade, well diff SCC. Large cauliflower lesion like condyloma, WLE
‐ Kaposi Sarcoma: 6