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