Small Bowel, Obstruction and Inflammatory Bowel Disease

Albert Einstein College of MedicineMedical Student Lecture Series

Jessica Schnur, MD

Physiology

• Nutrient and water absorption• Absorbs ~ 80% of the 9L of fluid that passes

through daily, leaving approx 1.5 L for the colon• Starch digestion with pancreatic

amylase/hydrolases glucose/galactose/fructose• Protein digestion with pepsins (bile enterokinase trypsinogen trypsin all other pepsinogens)– Glutamine is major source of energy for enterocytes

Physiology continued

• Long-chain fatty acids absorbed via chylomicrons through lymphatics thoracic duct

• Short/medium-chain fatty acids absorbed directly into portal venous system

• Important in control of chyle leaks

Vitamin absorption

• B12 intrinsic factor from stomach• B12+R protein hydrolyzed in duodenum

binds with IF (escapes hydrolysis by pancreatic enzymes)

• B12+IF absorbed in terminal ileum• Which surgeries cause B12 deficiency??

More Vitamins

• Water soluble: vit C, folate, thiamine, biotin• Fat soluble: A, D, E & K• Duodenum major site of absorption of iron

and calcium• T.I. major site of folate absorption

Bile Reabsorption

• 95% reabsorbed• Majority in terminal ileum• Conjugated bile only reabsorbed in the

terminal ileum• Gallstones can form after resection of T.I. due

to malabsorption of bile

Gut Hormones

• Somatostatin: inhibits secretions, motility and splanchnic perfusion– Carcinoid syndrome, post-gastrectomy dumping

syndrome, EC fistulas, variceal hemorrhage• Secretin: stimulates pancreatic/intestinal secretion– Secretin stim test

• CCK: stimulates pancreas/GB emptying; inhibits Oddi contraction – Evaluate GB EF%

Small Bowel Anatomy

• Arterial supply• Layers of small bowel wall

Small Bowel Obstruction

• Most common causes without previous surgery and with previous surgery??

SBO continued

• Other causes: – neoplasms, Crohn’s, volvulus, intussusception,

RTX/ischemia, foreign body, gallstone ileus, diverticulitis, Meckel’s

• Laparotomy: 5% lifetime incidence of SBO; 20-30% chance recurrence

• Presentation: nausea/vomiting, failure to pass gas/stool, crampy abdominal pain

• Diagnosis: obstruction vs. ileus, partial or complete, etiology, strangulation

Treatment

• NGT, IVF, foley, electrolye correction• Indications for surgery?• Serial abdominal exams

Inflammatory Bowel Disease

Crohn’s Disease

• Median age at dx: 30• Affects entire alimentary tract• First degree relatives have 15x risk• Smoking increases risk of relapse and need for

surgery

Ulcerative Colitis

• Peak age of onset 30’s and 70’s• 10-30% prevalence among family members• Disease of mucosa/submucosa: atrophy,

friable mucosa, crypt abscesses, pseudopolyps• Continuous involvement, 90% rectal

involvement; may have backwash ileitis• Spares anus

Crohn’s Pathology

• Transmural inflammation, skipped areas• Aphthous or linear ulcers, granulomas,

fibrosis/strictures, abscess, fistulas, perforation

• Creeping fat

Presentation

• Abdominal pain, weight loss, diarrhea, fever, perianal abscesses, peritonitis

• Extraintestinal manifestations (25%):– Erythema nodosum; pyoderma gangrenosum– Arthritis; ankylosing spondylitis; sacroiliitis– conjuctivitis; uveitis– PSC; steatosis, cholelithiasis– Nephrolithiasis– Thromboembolism; vasculitis; osteoporosis;

pancreatitis; endocarditis

Diagnosis

• Differentiate Crohn’s from UC, IBS, infectious and ischemic etiologies

• Radiography, endoscopy, pathology

Treatment

• Palliation rather than cure in Crohn’s• Medical therapy, surgical therapy, nutritional

support• Medical: abx, steroids, aminosalicylates,

immunomodulators• Surgery: can be curative for UC patients

Outcome for Crohn’s

• Surgery for Crohn’s: 70-80% require once unresponsive to aggressive medical tx or develop complications (obstruction, hemorrhage, cancer, perforation, growth retardation)

• Postop complications 15-30%: wound infections, abscesses, leaks

• 85% endoscopic recurrence by 3 years• Clinical recurrence: 60% by 5 years, 94% by 15 years• 30% need reoperation within 5 years

Outcome for UC

• Risk of colon cancer 1-2% per year starting 10 years after dx

Crohn’s vs. UCCharacteristic Crohn’s Disease Ulcerative Colitis

Transmural inflammation Yes Uncommon

Location Entire alimentary tract Colon (backwash ileitis)

Distribution Skip lesions Contiguous

Rectal involvement 50% 90%

Gross Bleeding 70-75% Universal

Perianal disease 75% Rare

Fistulization Yes No

Granulomas 50-75% No