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Basic Science: Small Bowel. Grace Kim, MD June 6, 2007. Basic Anatomy. 270-290 cm from pylorus to cecum Duo 20 cm Jejunum 100 cm Ileum 150 cm. Studying the SB. UGI and SB follow-through Enteroclysis CT Enteroscopy Push enteroscopy (up to 100 cm past LOT)

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basic science small bowel

Basic Science: Small Bowel

Grace Kim, MD

June 6, 2007

basic anatomy
Basic Anatomy

270-290 cm from pylorus to cecum

Duo 20 cm

Jejunum 100 cm

Ileum 150 cm

studying the sb
Studying the SB
  • UGI and SB follow-through
  • Enteroclysis
  • CT
  • Enteroscopy
    • Push enteroscopy (up to 100 cm past LOT)
    • Double balloon enteroscopy (to TI ideally)
  • Capsule endoscopy (beware: obstruction)
Case: 72 yo man no prior history of abdominal operations presents with nausea, vomiting, and abdominal distention x 5 days. Last BM and flatus 2 days ago. AXR as shown on next slide.
  • DDx?
  • Management?
small bowel obstruction
Small bowel obstruction
  • Etiology
    • Extrinsic
      • Adhesions (#1)
      • Hernias (#3)
      • Abscess
      • Mass
    • Intrinsic
      • Mass (#2)
      • Foreign body (bezoar, gallstone)
  • Hyperperistalsis
  • Bowel dilatation
  • Third-spacing
  • Decrease in mucosal blood flow
  • Bacterial translocation
  • Crampy abdominal pain
  • Nausea
  • Vomiting
  • Obstipation
  • PE: Vitals; Abdominal exam – scars, hernias, bowel sounds, tenderness, peritonitis; Rectal exam
imaging labs
  • AXR
  • +/- CT scan
  • Chem, CBC, lactate
  • Suspicion for strangulation or bowel compromise
    • Resuscitate and operate
  • Simple obstruction
    • Conservative management (NGT decompression, resuscitate, serial exams)
    • Failure or decompensation
      • Operate
  • Operation: Adhesiolysis +/- bowel resection
Case: During a laparotomy for a small bowel volvulus secondary to adhesions, you lyse the adhesions and detorse the small bowel. It appears congested and ischemic immediately after devolvulizing. Should this bowel be resected?
is the bowel viable
Is the bowel viable?
  • Warm saline-soaked lap pads
  • Time and patience
  • Doppler
  • Fluorescein fluorescence
  • Planned second look
Case: 70 yo woman POD#5 from an exploratory laparotomy and lysis of adhesions for SBO secondary to adhesions c/o abdominal distention. She does not tolerate advancement of diet. She has had one flatus since surgery. Labs significant for WBC 13K, K 3.2. She remains on Dilaudid IV PCA and has been minimally ambulatory.
  • Management?
diverticular disease
Diverticular Disease
  • Duodenal diverticula
    • Asymptomatic – no treatment
    • Symptomatic (biliary obstruction, hemorrhage, perforation, diverticulitis, blind loop) – choledochoduodenostomy or choledochojejunostomy vs. resection or duodenal diverticulization
  • Jejunoileal diverticuli
    • Resect if symptomatic (bleeding, perf)
meckel s
  • True diverticulum
  • Rule of 2’s: 2% population, symptomatic in 2%, 2 years of life, 2 feet from ICV
  • Rx:
    • Bleeding: Small bowel resection
    • Diverticulitis: ?SBR vs. diverticulectomy
    • Incidental finding in child: Diverticulectomy
    • Incidental finding in adult: Diverticulectomy if low risk
Case: You are performing a diagnostic laparoscopy for a presumed acute appendicitis in a 20 yo woman. You find thickened, inflamed ileum with extensive fat creeping. The cecum is uninvolved, and the appendix is normal.
  • Diagnosis and management?
crohn s disease
Crohn’s Disease
  • Can involve GI tract from mouth to anus
    • 40% ileocolic, 30% SB only, 30% colon or anorectum only
  • Transmural inflammation, non-caseating granuloma formation
  • Skip lesions
  • Usually spares rectum
  • Medical and surgical treatment is palliative
  • Highest incidence in N. America and Europe
  • Bimodal distribution (20-30s and 60s)
  • Etiology unclear
  • Increased risk of developing SB adenocarcinoma (100x)
  • Relapsing/remitting abdominal pain and diarrhea with weight loss
  • Extra-intestinal manifestations (30%)
    • Skin lesions (erythema nodosum and pyoderma gangrenosum)
    • Arthritis and arthralgias
    • Uveitis and iritis
    • Hepatitis and pericholangitis
    • Aphthous stomatitis
  • Barium study of small bowel (linear ulcers, transverse sinuses, and clefts)
  • Endoscopy (discrete ulcers,cobblestoning, skip lesions
  • Adjunctive labs: ASCA positive/pANCA negative
medical management
Medical Management
  • Aminosalicylates (Pentasa, Asacol)
  • Antibiotics (Flagyl, cipro)
  • Corticosteroids
  • Immunosuppresive drugs (6-MP, aza)
  • Anti-TNFα (Infliximab)
  • Reserved for complications and failures of medical management (75%)
  • Indications
    • 1 – Obstruction
    • 2 – Fistula
    • 3 – Perforation/Abscess
    • 4 – Perianal disease
    • 5 – Toxic megacolon
“Operative treatment of a complication should be limited to that segment of bowel involved with the complication and no attempt should be made to resect more bowel even though grossly evident disease may be apparent.”
surgical options
Surgical options
  • Small bowel resection
  • Ileocolic resection
  • Strictureplasty
    • Take mucosal bx first
Represent 2% of all GI malignancies
  • Presentation: intermittent or partial SBO, bleeding, pain, perforation, weight loss
    • Malignant lesions usually will cause sx – based on tumor infiltration
    • Benign lesions may/may not cause sx – based on intussusception
  • Dx: SBFT, enteroclysis, CT, enteroscopy
benign lesions
Benign Lesions
  • Adenomas
  • Lipomas
  • Hemangiomas
  • Hamartoma
  • Usually asymptomatic
  • Should be excised or resected
malignant tumors
Malignant Tumors
  • Metastatic Disease (cervix, ovaries, renal, stomach, colon pancreas, melanoma)
  • Adenocarcinoma
  • Carcinoids
  • Malignant GIST
  • Lymphoma
  • 50% SB tumors
  • More frequently proximal SB
  • Treatment: Wide resection with 10-cm margins, ?adjuvant
  • Prognosis poor – usually late stage when diagnosed
  • From Kulchitsky cells – enterochromaffin cells
  • Produce 5-HIAA, chromogranins, neuropeptide K, substance P
  • 80% found within 2’ of TI
    • AIR: Appendix (45%), Ileum (28%), Rectum (16%)
  • 10% have carcinoid syndrome (diarrhea, blushing, bronchospasm, hypotension, endocardial fibrosis – R heart failure)
    • Metastatic carcinoid or tumors that bypass the portal system
  • Fibrotic, desmoplastic reaction in mesentery
Case: You are operating on a 70 yo woman with a SBO presumably from a carcinoid tumor. During induction of general anesthesia, she develops SVT, hypotension, and elevated peak airway pressures.
  • Management?
  • Treatment: Segmental resection
  • Beware: Carcinoid crisis with general anesthesia (Rx: somatostatin, hydrocortisone, antihistamine)
    • prep all patient with preoperative octreotide
  • Adjuvant: doxo, 5-FU, streptozocin, chemoembolization bulky liver disease
  • Palliative for carcinoid syndrome: octreotide
  • Experimental: radionuclide somatostatin agonists “smart bomb”
last two
Last two…
  • Lymphoma
    • Ileum
    • Risk factors: immunodeficiency, celiac disease
    • Rx: Wide resection with nodes
  • GIST
    • Jejunum/ileum
    • Segmental resection
acute mesenteric ischemia
Acute Mesenteric Ischemia
  • Acute-onset pain, out of proportion to exam, fever, Heme (+) stool
  • MI, A-fib, mural thrombus, mitral valve disease
  • Dx: CT scan (good for bowel, large vessels), angiogram, MRA

Acute onset without antecedent sx

Lodge distal to middle colic and jejunal branches of SMA

Sparing of proximal jejunum and R colon


Antecedent intestinal angina

Origin of vessel

Entire SB and R colon affected

nonocclusive mesenteric ischemia nomi
Nonocclusive Mesenteric Ischemia (NOMI)
  • Optimize fluid resuscitation
  • Improve CO
  • Eliminate vasopressors
  • Selective vasodilatory injection (papaverine)
  • Bowel resection for frankly necrotic bowel
mesenteric embolic disease
Mesenteric Embolic Disease
  • Surgical embolectomy
    • Exposure of SMA
    • Transverse or longitudinal arteriotomy (vein patch)
    • 3 and 4-Fr Fogarty embolectomy
acute mesenteric thrombotic disease
Acute Mesenteric Thrombotic Disease
  • Bypass
    • Antegrade or retrograde
    • Conduit: autologous greater saphenous vein (acute situation)
    • Inflow: supraceliac aorta, infrarenal aorta, iliac artery
  • Perioperative mortality 62%
    • MODS, ischemia/reperfusion insult
  • Long-term TPN 31%
chronic mesenteric ischemia
Chronic Mesenteric Ischemia
  • Chronic post-prandial abdominal pain in a vasculopath
  • Dx: Duplex, angiogram
  • Visceral Bypass
    • One or two-vessel bypass
    • Inflow: supraceliac, infrarenal
    • Conduit: Vein or PTFE/Dacron
  • Endovascular
    • PTA
    • *not many studies supporting management
  • Mortality 8%, morbidity 30% (includes acute)
  • Primary patency 89% at 72 months
  • 5-yr survival 64%, 3-yr symptom-free rate 81%
  • Endovascular approaches promising – more recent studies: similar symptom-free rate with lower morbidity and mortality
Case: You perform a small bowel resection in a 80-yo woman who presented with an SBO secondary to a strangulated incisional hernia. She is slow to regain bowel function. On POD#6, her wound appears erythemaous. You open it at the bedside, and purulent, feculant material is returned.
Prevention: preoperative nutritional status, good technique, perioperative hemodynamics, bowel prep
  • Disability
    • Electrolyte imbalance
    • Malnutrition
    • Sepsis
  • Low-output <200cc/ 24 hr versus high >200 cc/24 hr
initial management
Initial Management
  • Resuscitate
  • Imaging
  • Consider abx
  • Nutritional support
  • Control of fistula drainage
  • Skin care
  • Consider somatostatin
impediments to closure
Impediments to closure
  • High output (>500 mL/24 hr)
  • Severe disruption of intestinal continuity (>50% of bowel circumference)
  • Active inflammatory bowel disease of bowel segment
  • Cancer
  • Radiation enteritis
  • Distal obstruction
  • Undrained abscess cavity
  • Foreign body in the fistula tract
  • Fistula tract <2.5 cm in length
  • Epithelialization of fistula tract
secondary management
Secondary Management
  • Fistulogram (one week later)
    • Define anatomy
    • Rule out distal obstruction
  • Failure of conservative management
    • Operate: small bowel resection
short bowel
Short bowel
  • Less than 200 cm healthy small intestine
  • Downside of TPN
    • Liver failure
    • Cholelithiasis
    • Line sepsis
    • Venous thrombosis
  • Adaptive response: 1-2 years
medical therapy
Medical Therapy
  • Diarrhea: Immodium, lomotil, opiods
  • Bile salt-induced diarrhea: cholestyramine
  • Electrolyte losses: replete IV/PO
  • Hypergastrinemia: H2 blocker or PPI
  • Vitamin/Mineral deficiencies: Monitor and replete
  • Bacterial overgrowth: Flagyl, tetracycline
  • Enteral nutrition with supplemental TPN
surgical therapy
Surgical Therapy
  • Reanastomose
  • Gastrostomy over jej
  • Intestinal valves (iatrogenic intussusception
  • Reversed segment
  • Tapering enteroplasty (Bianchi procedure)
  • Intestinal tranplantation