Small Bowel

• Small intestine: nutrient and water absorption
• Large intestine: water absorption

• Bulb (1st): 90% ulcers here
• Descending (2nd): ampulla of Vater (duct of Wirsung) and duct of Santorini
• Transverse (3rd)
• Ascending (4th)

• Descending and transverse: retroperitoneal
• 3rd and 4th: transition point at the angle between the aorta and SMA

• Superior (off the gastroduodenal artery) and inferior (off SMA) pancreaticoduodenal arteries
• Both have anterior and posterior branches
• Many communications

• 100cm
• Long vasa recta
• Circular muscle folds
• Vascular supply from the SMA
• Maximum site of most absorption...
• Terminal ileum: B12, conjugated bile acids, folate
• Ileum: nonconjugated bile acids
• Duodenum: iron

• 150cm
• Short vasa recta
• Flat
• Vascular supply from the SMA

• Maltase
• Sucrase
• Limit dextrinase
• Lactase

• Absorptive cells
• Goblet cells: mucin
• Paneth cells: secretory granules, enzymes
• Enterochromaffin cells: APUD, 5-hydroxytryptamine release, carcinoid precursor
• Brunner's glands: alkaline solution
• Peyer's patches: lymphoid tissue, increased in the ileum
• M cells: antigen presenting cells in intestinal wall

• IgA: released into gut, mother's milk
• Fe: heme and Fe transporters

• Phase I: rest
• PhaseII: acceleration and gallbladder contraction
• Phase III: peristalsis
• PhaseIV: deceleration
• Motilin: regulating hormone

• Broken down b cholesterol esterase, phospholipase A2, lipase, colipase in combination with bile salts
• Converted to FFA and monacylglycerides: micelles
• TAGs are reformed in intestinal cells and released as chylomicrons into the lymphatics via terminal vilious lacteals
• Chylomicrons: 90% TAGs, 10% phospholipid, cholesterol, protein; released into lymphatics
• Long-chain fatty acids: released into lymphatics
• Short and medium chain fatty acids: released into portal vein

• 95% of bile salts are reabsorbed
• 50% of passive absorption (45% ileum, 5% colon)
• 50% active resorption in terminal ileum
• Conjugated bile absorbed only in terminal ileum
• Bile is conjugated to taurine and glycine
• Deconjugated in colon by bacteria
• Primary bile acids: cholic and chenodeoxycholic
• Secondary bile acids: deoxycholic and lithocholic
• Gallstones can form after terminal ileum resection from malabsorption of bile acids

• Dx made on symptoms and not length of bowel
• Sx: diarrhea, steatorrhea, wt loss, nutritional deficiency
• Lose fat, B12, electrolytes, water
• Sudan stain red: check for fecal fat
• Schilling test: checks for B12 absorption
• Need 75cm to survive off TPN, 50cm with competent ileocecal valve
• Tx: restrict fat with diet resumption, H2 blockers to reduce acid, Lomotil

• Causes: gastric hypersecretion of acid, decreased pH, increased intestinal motility, interferes with fat absorption
• Interruption of bile salt resorption: interferes with micelle formation
• Tx: Lomotil, decrease oral (fat) intake, Pancrease, H2 blocker

• Foreign body
• Radiation
• Inflammatory bowel disease
• Epithiealization
• Neoplasm
• Distal obstruction
• Sepsis
• High output: likely with proximal bowel (duodenum or prox jejunum)
• Colonic: more likely to close
• Persistent fever: check for abscess (fistulogram, abdominal CT, UGI with SBFT)
• Cause: iatrogenic
• Tx: TPN, skin protection, NG, stoma appliance, octreotide
• 40% close spontaneously
• Surgery: resect bowel segment with fistula and perform primary anastomosis

• H/O surgery
• Small bowel: adhesions, hernia
• Large bowel: cancer
• Sx: n/v, crampy abdominal pain, obstipation
• ABXR: air fluids levels, distended small bowel, distal decompression
• Bacterial overgrowth from 3rd spacing of fluid in bowel lumen
• Tx: bowel rest, NG tube, IVF
• Surgery: progressive pain, peritoneal signs, fever, increasing WBCs, strangulation, perforation, failure to resolve

• SBO due to gallstone in terminal ileum
• Air in biliary tree
• Fistula between gallbladder and 2nd portion of duodenum
• Tx: remove stone, can leave fistula if pt sick, if not, cholecystectomy and close duodenum

• True diverticulum
• 2 ft fom ileocecal valve
• 2% of population
• Presents in 1st 2 yrs of life: with bleeding
• 50% of painless lower GI bleeds in kiddos <2 yo
• Pancreas tissue: most common
• Gastric mucosa: most likely to be sx
• Obstruction: most common presentation in adults
• Incidental: remove if gastric mucosa suspected, diverticulum feels thick or has narrow neck
• Dx: Technetium scan
• Tx: Diverticulectomy; segmental resection for complicated diverticulits or neck >1/3 diameter of the normal bowel lumen or if diverticulitis involves the base

• R/O gallbladder disease
• Observe unless perforated, bleeding, obstructing or sx
• Frequency: dudodenal>jejunal>ileal
• Tx: segmental resection, temporary gastroj for perf

• Intermittent abdominal pain, diarrhea, wt loss, low grade fever
• 15-35 yrs at first presentation
• Ashkenazi Jews
• Extraintestinal manifestations: arthritis, arthralgia, pyoderma gangrenosum, erythema nodosum, ocular diseases, growth failure, megaloblastic anemia from folate and B12 deficiency
• Mouth-anus
• Terminal ileum: most commonly involved segment
• Anal/perianal disease: 1st presentation in 10%
• Tx: Flagyl
• Anal disease most common sx with large skin tags
• Common sites for initial presentation: terminal ileum and cecum (40%), colon (35%), small bowel (20%), perianal (5%)
• Dx: colonoscopyy with biopsies and enteroclysis

Pathology: transmural involvement, skip lesions, cobblestoning, narrow deep ulcers, creeping fat

• 5-ASA, sulfasalazine, steroids, azathioprine, methotrexate, Remicade (infliximab: TNF alpha inhibitor used for abscesses or fistula), loperamide
• No agents affect natural course of the disease
• TPN: may induce remission and fistula closure in small bowel disease
• 90% will need operation

• Obstruction (if partial, treat conservatievely)
• Abscess (may be able to perc drain)
• Megacolon
• Hemorrhage
• Blind loop obstruction
• Fissures (do not do a lateral internal spincteroplasty)
• EC fistula: can tx conservatively first
• Perineal fistula: unroof and rule out abscess, let heal on its own
• Anorectovaginal fistula: rectal advancement flap with colostomy
• Do not need clear margins: 2cm from gross disease
• Perirectal disease: may respond to resection of small bowel
• Diffuse disease of colon and rectum: proctocolectomy and ileostomy
• Incidental finding of IBD in pt with presumed appendicitis: remove appendix if cecum not involved
• Stricturoplasty: if pt has multiple strictures to save small bowel length, not good for pt's 1st operation b/c leaves disease behind, 10% risk of abscess/fistula/leak
• 50% recurrence rate after resection

• Megaloblastic anemia: B12 deficiency
• Diarrhea and steatrorrhea: decreased bile salt uptake
• Ca oxalate kidney stones: decreased oxalate binding secondary to increased intraluminal fat that binds Ca, oxalate gets absorbed in colon and released in urine
• Gallstones: malabsorption of bile acids

• Serotonin: produced by Kulchitsky cells (enterochromaffin cell or argentaffin cell)
• Part of amine precursor uptake decarboylase system (APUD)
• 5-HIAA is a breakdown product of serotonin: measure in urine
• Tryptophan: precursor to serotonin
• Increased use can lead to niacin deficiency and pellagra: diarrhea, dermatitis, dementia
• Bradykinin also released by carcinoid tumors

• Caused by bulky liver mets
• Intermittent flushing and diarrhea
• Asthma type symptoms
• GI symptoms from vasoconstriction and fibrosis (desmoplastic reaction)
• Right heart valve lesions
• If present with small bowel primary, it indicates liver mets
• Octreotide scan can localize tumors not seen on CT
• All pts need abdominal exploration unless unresectable

• Most common site for carcinoid
• 50% of carcinoids arise here
• Next most common: ileum and rectum

Pts at risk for multiple primaries and second unrelated malignancies

• Appendix: <2cm appendectomy, >2cm or involved base right hemicolectomy
• Anywhere else in GI tract: tx like cancer with segmental resection and lymphadenectomy
• Chemo (streptozocin, 5FU): for unresectable disease and carcinoid syndrome
• Octreotide
• Bronchospasm: treat with aprotinin
• Flushing: treat with alpha blockers (phenothiazide)
• False 5-HIAA: fruits
• Pentagastrin can exacerbate symptoms

• Small bowel or cecal tumors
• Presentation: bleeding or obstruction
• Often has malignant lead point
• Tx: resection

• Rare
• More common than malignancies
• Leiomyomas: most common, usually extraluminal
• Adenomas: most in the ileum, bleeding obstruction (need resection when identified)

• Autosomal dominant
• Jejunal and ileal harmatomas
• Mucocutaneous melanotic skin pigmentation
• Increased extraintestinal malignancies
• Slight increased risk of colon CA in pt with polyps
• Lipomas, neurogenic tumors, and hemangiomas

• Adenomatous polyps
• Familial adenomatous polyposis
• Peutz-Jeghers syndrome
• Leiomyomas
• Neurofibromatosis
• Crohn's
• Celiac sprue
• Immunosupression
• HIV infection
• H. pylori
• EBV

• Rare
• Most common malignant small bowel tumor
• Most in duodenum
• Sx: obstruction, jaundice
• Tx: resection and adenectomy, Whipple if in duodenum

Risks: FAP, Gardner's, polyps, adenomas, von Recklinghausen's

• Usually in jejunum and ileum
• Most extraluminal
• Hard to differentiate compared with leiomyoma (>5mitoses/HPF, atypia, necrosis)
• Tx: resection, no adenectomy

• Usually in ileum
• Increased incidence with Wegener's, SLE, AIDS, Crohn's, celiac sprue
• Posttransplantation: increased risk of bleeding and perforation
• Dx: abdominal CT, UGI, node sampling
• Tx: XRT, chemo, wide en bloc resection, include nodes
• 40% 5 yr survival rate
• Usually NHL B cell type
• Mediterranean variant: young males with clubbing

• Loop ileostomies: 1-2% obstruction rate
• Parastomal hernias: increased with loop colostomies, relocation is the best tx
• Candida: most common infection
• Diversion colitis (Hartmann's pouch): secondary to decreased short chain fatty acids - treat with short chain fatty acid enemas
• Ischemia: most common cause of stenosis of stoma - tx: dilation if mild
• Crohn's disease: most common cause of fistula near stoma site
• Abscesses: underneath stoma site often caused by irrigation device
• Gallstones and uric acid kidney stones: increased in pt with ileostomy

• Anorexia
• Abdominal pain (periumbilical that radiates to RLQ as peritonitis sets in)
• Vomiting
• 20-35 yrs
• Nl WBC possible
• CT: diameter >7mm or wall thickness>2mm (looks like a bull's eye), fat stranding, no contrast in appendiceal lumen (give rectal contrast)
• Midpoint of antimesenteric border: likely to perforate
• Hyperplasia: most common in children
• Fecalith: most common in adults (luminal obstruction>appendiceal distention>venous congestion>thrombosis>ischemia>gangrene necrosis>finally rupture
• Nonoperative: walled off perforated appendix, treat with perc drain and interval appendectomy, consider f/u barium enema or colonoscopy
• Children and elderly: higher risk of rupture due to delayed diagnosis
• Children have more vomiting and diarrhea

• Most common cause of acute abdominal pain in the first trimester
• Most likely to occur in 2nd trimester
• Most likely to perforate in 3rd trimester
• Make incision where pt is having pain (appendix displaced superiorly)
• Sx of RUQ pain in 3rd trimester
• 35% fetal mortality with rupture
• Women with suspected appendicitis need beta-HCG drawn +/- abdominal US to r/o OBGYN causes

• Can be benign or malignant mucous papillary adenocarcinoma, needs resection
• Right hemicolectomy if malignant
• Pseudomyxoma peritonei with rupture
• MCC of death: SBO from tumor spread

• Can mimic appendicitis
• 10% will have Crohn's

n/v/d

• Ruptured ovarian cyst
• Thrombosed ovarian vein
• Regional enteritis not involving cecum
• Still do appendectomy

• Causes: surgery, electrolyte abnormalities, peritonitis, ischemia, trauma
• Dilation is uniform throughout the stomach, small bowel, colon, and rectum without decrompression
• Obstruction with distal bowel decompression

• Rare bleeding/perforation
• Fever
• HA
• Maculopapular rash
• Leukopenia
• Abdominal pain
• Tx: Bactrim