Transcript Basic Science: Small Bowel Grace Kim, MD June 6, 2007 Basic Anatomy • 270-290 cm from pylorus to cecum – Duo 20 cm – Jejunum 100

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
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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)
Pathology
• 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
• Etiology
– Extrinsic
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Adhesions (#1)
Hernias (#3)
Abscess
Mass
– Intrinsic
• Mass (#2)
• Foreign body (bezoar, gallstone)
Pathophysiology
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Hyperperistalsis
Bowel dilatation
Third-spacing
Decrease in mucosal blood flow
Bacterial translocation
Presentation
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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
Treatment
• 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?
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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
• 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
• 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
• 3-7/100,000
• Highest incidence in N. America and
Europe
• Bimodal distribution (20-30s and 60s)
• Etiology unclear
• Increased risk of developing SB
adenocarcinoma (100x)
Presentation
• 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
Diagnosis
• 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
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Aminosalicylates (Pentasa, Asacol)
Antibiotics (Flagyl, cipro)
Corticosteroids
Immunosuppresive drugs (6-MP, aza)
Anti-TNFα (Infliximab)
Surgery
• 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
• Small bowel resection
• Ileocolic resection
• Strictureplasty
– Take mucosal bx first
Small Bowel Tumors
• 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
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Adenomas
Lipomas
Hemangiomas
Hamartoma
• Usually asymptomatic
• Should be excised or resected
Malignant Tumors
• Metastatic Disease (cervix, ovaries, renal,
stomach, colon pancreas, melanoma)
• Adenocarcinoma
• Carcinoids
• Malignant GIST
• Lymphoma
Adenocarcinoma
• 50% SB tumors
• More frequently proximal SB
• Treatment: Wide resection with 10-cm
margins, ?adjuvant
• Prognosis poor – usually late stage when
diagnosed
Carcinoids
• 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
• Dx: high index of suspicion, urine 5-HIAA,
CT (mesenteric shortening), SBFT,
octreotide scan
• 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?
Carcinoids
• 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…
• Lymphoma
– Ileum
– Risk factors: immunodeficiency, celiac
disease
– Rx: Wide resection with nodes
• GIST
– Jejunum/ileum
– Segmental resection
Vascular
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
• Embolus
– Acute onset without
antecedent sx
– Lodge distal to middle
colic and jejunal
branches of SMA
• Sparing of proximal
jejunum and R colon
• Thrombus
– Antecedent intestinal
angina
– Origin of vessel
• Entire SB and R colon
affected
Nonocclusive Mesenteric Ischemia
(NOMI)
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Optimize fluid resuscitation
Improve CO
Eliminate vasopressors
Selective vasodilatory injection
(papaverine)
• Bowel resection for frankly necrotic bowel
Mesenteric Embolic Disease
• Surgical embolectomy
– Exposure of SMA
– Transverse or longitudinal arteriotomy (vein
patch)
– 3 and 4-Fr Fogarty embolectomy
Acute Mesenteric Thrombotic
Disease
• Bypass
– Antegrade or retrograde
– Conduit: autologous greater saphenous vein
(acute situation)
– Inflow: supraceliac aorta, infrarenal aorta, iliac
artery
Outcome
• Perioperative mortality 62%
– MODS, ischemia/reperfusion insult
• Long-term TPN 31%
Chronic Mesenteric Ischemia
• Chronic post-prandial abdominal pain in a
vasculopath
• Dx: Duplex, angiogram
Management
• Visceral Bypass
– One or two-vessel bypass
– Inflow: supraceliac, infrarenal
– Conduit: Vein or PTFE/Dacron
• Endovascular
– PTA
– *not many studies supporting management
Outcome
• 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.
Enterocutaneous Fistula
• 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
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Resuscitate
Imaging
Consider abx
Nutritional support
Control of fistula drainage
Skin care
Consider somatostatin
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
• Fistulogram (one week later)
– Define anatomy
– Rule out distal obstruction
• Failure of conservative management
– Operate: small bowel resection
Short Gut
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
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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
• Reanastomose
• Gastrostomy over jej
• Intestinal valves (iatrogenic
intussusception
• Reversed segment
• Tapering enteroplasty (Bianchi procedure)
• Intestinal tranplantation