MCQ - Colon ischemia, Lower GI bleeding, Anatomy

• ColonQ
• MC site of ischemic colitis: Splenic flexureQ
• Rectum is relatively spared because of its rich collateral circulationQ

• Unlike small bowel ischemia, colonic ischemia is rarely associated with major arterial or venous occlusionQ.
• Most colonic ischemia appears to result from low flow and/or small vessel occlusionQ

• Abdominal X-ray: Thumb printingQ (due to mucosal edema and submucosal hemorrhage)Q.
• CT scan: Nonspecific colonic wall thickening and pericolic fat stranding

• • Majority of patients with ischemic colitis can be treated medicallyQ.
• • Bowel rest and broad-spectrum antibiotics are the mainstay of therapy (80% of patients recoverQ with this regimen)

• • Failure to improve after 2 to 3 days of medical managementQ
• • ProgressionQ of symptoms
• • Deterioration in clinical conditionQ

IMA is assessed for backbleeding. If there is strong backbleeding (stump pressure >40 mm Hg), the IMA is ligated close to the aorta or oversewn from within the sac. Poor backbleeding from the IMA is a sign of insufficient collateral circulation to the sigmoid colon, and reimplantation of the IMA with a patch of the aorta into the aortic limb is warrantedQ.

ClindamycinQ

• Mild disease
• −−Oral metronidazole (10-day course): Drug of choice
• −−Oral vancomycin: Second-line agent, used in metronidazole allergy or in recurrent diseaseQ
• Severe disease: Bowel rest, IV hydration, and IV metronidazole or oral vancomycinQ

• Kocher’s Maneuver - Used for mobilization of duodenumQ
• Extended Kocher’s Maneuver - Recommended for drainage of infra-mesocolic hematomaQ
• Mattox Maneuver - Recommended for drainage of central supra-mesocolic hematomaQ
• Cattel-Braasch Maneuver - Good option for exposure of the infrapancreatic segmentQ

• Heyde’s syndrome is a triad of aortic stenosis, an acquired coagulopathy and anemia due to bleeding from intestinal angiodysplasiaQ.
• It is due to the induction of von-Willebrand disease type IIA by the valvular stenosisQ.

• Large bowel bleed (95%) – Diverticular disease (40%), Anorectal disease (15%)
• Small bowel bleed (5%)

Vascular ectasiaQ – it is an acquired condition

Vascular ectasiaQ

• Almost always occur in the cecum or the proximal ascending colonQ
• Usually multiple, are <5 mmQ in diameter
• Rarely identified with gross inspection or routine pathologic examination
• Diagnosed with colonoscopy or angiography
• Angiography: Slow emptying of veinQ and dilation of submucosal vesselsQ

Defined as a bleeding from a site distal to the ligament of TreitzQ.

HemorrhoidsQ (Rarely massive bleeding)

Diverticular disease (overall)Q

AngiodysplasiaQ

Vascular ectasiaQ (angiodysplasia)

Bacteroide

Escherichia coli

• Complete bowel obstruction
• Free perforation

• Polyethylene glycol solution (PEG) Q - electrolyte imbalances in patients with impaired renal functionQ
• Sodium phosphate solutionQ

• Epicolic - Located along the bowel wall and in the epiploicaeQ
• Paracolic - Located adjcent to the marginal arteryQ
• Intermediate - Located along the main branchesQ of the large blood vessels
• Primary or terminal - Located on the superior or inferior mesenteric

• Colon and proximal two thirds of the rectum - Para-aortic nodal chain, which empties into the cisterna chyliQ
• Distal rectum and anal canal - either to the para-aortic nodes or laterally, through the internal iliac system, to the superficial inguinal nodal basin

• At birth - intestine is sterile
• In the breastfed children - Lactic acid streptococci and LactobacilliQ
• In normal adults, the stomach acidity keeps the number of microorganism at minimum, unless obstruction at the pylorus favors the proliferation of gram positive cocci and bacilli.
• • As the pH of intestinal contents becomes alkaline, the resident flora gradually increasesQ.
• Bacteria are most metabolically active in cecumQ

• Right colon - Antiperistaltic, or retropulsive wavesQ generate retrograde flow of colonic contents back to the cecum.
• Left colon - Antegrade tonic contractionsQ

• Auerbach – Peristalsis
• Meissners – Secretion

ButyrateQ – Supplied by colonic bacteria

Complex carbohydrates: starches and nonstarch polysaccharides (NSPs), also known as dietary fiberQ.

• • Lignin is not fermented by human colonic flora and attracts waterQ, thus producing bulk.
• • Celluloses are only partially fermentedQ.
• • Fruit pectins are completely fermentedQ.

• Water-insoluble fibers (Lignin) - Used for the treatment of constipationQ
• Water-soluble NSPs (Pectin) - Used to treat diarrheaQ

• • Early diagnosis (within 4-6 hours)Q
• • Absence of prolonged shock or hypotensionQ
• • Absence of gross contaminationQ of the peritoneal cavity
• • Absence of associated colonic vascular injuryQ
• • Less than 6 units of blood transfused
• • No requirement for the use of meshQ to permanently close the abdominal wall

• Low-risk penetrating colonic injuries: Primary closure or resection and primary anastomosisQ
• High-risk colon injuries or those associated with severe injuries: Resection and colostomyQ.

• Short chain fatty acids are produced in the colon by bacteria and absorbed from itQ.
• SCFAs: Acetate (60%), Propionate (25%), ButyrateQ (15%)

It is a collateral branch that connects the proximal MCA to the LCA and runs in the transverse mesocolon parallel to the left branch of the MCA.

Splenic flexure, where the vascular arcades connecting the MCA and LCA are often absent

Inconsistent marginal artery at the junction of the lowest sigmoid branch and the superior hemorrhoidal artery

Adhesion from the right abdominal wall to the anterior taenia of the ascending colon.

A mucosal fold covering the appendiceal orifice.

Inferior ileocecal fold (does not contain any vessel, referred as the bloodless fold of Treves). Fold of Treves is the only antimesenteric epiploic appendage normally found on the small intestine and marks the junction of the ileum and cecumQ

CecumQ

SigmoidQ

CecumQ

Water, NaClQ; secretes K+, HCO3 and mucusQ

Splenic flexure

• Length of cecum: 7.5 cm (x=7.5 cm)
• Length of Ascending colon: 15 cm (2x)
• Length of Transverse colon: 45 cm (6x)
• Length of Descending colon: 22.5 cm (3x)
• Length of Sigmoid colon: 30 cm (4x)