ESSENTIAL FEATURES
Proximal Obstruction
• Vomiting
• Abdominal discomfort
• Abnormal PO contrast x-rays
Mid or Distal Obstruction
• Colicky abdominal pain
• Vomiting
• Abdominal distention
• Constipation-obstipation
• Peristaltic rushes
• Dilated small bowel on x-ray
EPIDEMIOLOGY
• The most common surgical disorder of the small intestine
• Common causes of obstruction:
–Adhesions: The most common cause of mechanical small bowel obstruction
–Neoplasms: Intrinsic or extrinsic
–Hernia: Due to incarceration of bowel
–Intussusception: Common in children
–Volvulus: Often results from congenital anomalies or acquired adhesions
–Foreign bodies: Luminal blockage
–Gallstone ileus: Passage of a large gallstone through a cholecystenteric fistula
–Inflammatory bowel disease: Lumen is
narrowed by inflammation or fibrosis
–Stricture-luminal narrowing
–Cystic fibrosis: Partial obstruction of the distal ileum and right colon
–Hematoma
–Paralytic ileus: Neurogenic
CLINICAL FINDINGS
SYMPTOMS AND SIGNS
• Vomiting
• Cramping abdominal pain
• Obstipation
• Distention
–Minimal in proximal obstruction
–Pronounced in distal obstruction
• Mild abdominal tenderness
• Audible rushes (borborighmi) and high-pitched tinkles (metallic sounds)
Strangulation Obstruction
• Shock
• High fever
• Abdominal pain: Severe and continuous
• Vomitus may contain blood
• Abdominal tenderness and rigidity
LABORATORY FINDINGS
• Hemoconcentration
• Leukocytosis
• Electrolyte abnormalities that depend on the level of obstruction and the severity of dehydration
• Serum amylase is often elevated
Strangulation Obstruction
• Marked leukocytosis not accounted for by hemoconcentration
• Metabolic acidosis
IMAGING FINDINGS
• Abdominal x-ray
–Dilated bowel
–Air-fluid levels (minimal in early, proximal, or closed loop obstruction)
• The colon is often devoid of gas
• Intraperitoneal air indicates perforation
• Contrast upper GI series: Assesses completeness of obstruction
• CT scan
–Intraperitoneal free fluid
–Dilated bowel proximal and decompressed distal to the obstruction
–Point of obstruction may be visualized
• Gas within the bowel wall or portal vein may be seen in strangulation
• Intraperitoneal free air or air-fluid levels indicate perforation
DIAGNOSTIC CONSIDERATIONS
• Classification of small bowel obstruction
• Functional (failure of peristalsis to propel intestinal contents) or mechanical (a physical barrier impedes aboral progress of intestinal contents)
• Complete or partial
• Simple (occludes the lumen only) or strangulated (impaired the blood supply leading to necrosis of the intestine)
• Open loop (the lumen is occluded in 1 place) or closed loop (the lumen is occluded in at least 2 places)
• 33% of strangulation obstructions are unsuspected before operation
RULE OUT
• Acute appendicitis
• Obstruction of the large intestine
• Acute gastroenteritis
• Acute pancreatitis
• Mesenteric vascular occlusion
• Pseudo-obstruction associated with scleroderma, systemic lupus erythematosus, amyloidosis, drug abuse, or radiation
• Intrinsic dysmotility
WORK-UP
• Abdominal x-ray
• CBC
• Serum electrolytes
• ABG measurements (if strangulation suspected)
• Serum lactate
• Serum amylase and lipase
• Contrast upper GI series or CT scan if diagnosis is in doubt or further information needed
WHEN TO admit
• All cases of acute small bowel obstruction
TREATMENT AND MANAGEMENT
• Partial obstruction can be treated expectantly as long as there is continued passage of stool and flatus; successful in 90% of such patients
• NG decompression
SURGERY
• Details of the operative procedure vary according to the cause of obstruction
Indications
• Persistent incomplete obstruction
• Complete obstruction
• Closed loop obstruction
• Strangulation
Contraindications
• Paralytic ileus
• Abdominal carcinomatosis (relative)
• Inflammatory bowel disease (relative)
MEDICATIONS
• Fluid and electrolyte replacement
• Antibiotics if strangulation is suspected
TREATMENT MONITORING
• Serial abdominal exams
• Serial abdominal x-rays
Complications omplications
• Perforation
• Shock
Prognosis
• Mortality rate in cases of nonstrangulating obstruction is about 2%
• Mortality rate in cases of strangulation obstruction is approximately 8–25%
RESOURCES
REFERENCES
• Jenkins JT. Secondary causes of intestinal obstruction: rigorous preoperative evaluation is required. Am Surg. 2000;66:662.
• Miller G et al. Natural history of patients with adhesive small bowel obstruction. Br J Surg. 2000;87:1240.
• Beck DE et al: A prospective, randomized, multicenter, controlled study of the safety of Seprafilm adhesion barrier in abdominopelvic surgery of the intestine. Dis Colon Rectum 2003;46:1310.
• Fevang BT et al: Long-term prognosis after operation for adhesive small bowel obstruction. Ann Surg 2004;240:193.
• Jenkins JT: Secondary causes of intestinal obstruction: rigorous preoperative evaluation is required. Am Surg 2000;66:662.
• Lazarus DE et al: Frequency and relevance of the “small-bowel feces” sign on CT in patients with small-bowel obstruction. Am J Roentgenol 2004;183:1361.
• Miller G et al: Natural history of patients with adhesive small bowel obstruction. Br J Surg 2000;87:1240.
• Ryan MD et al: Adhesional small bowel obstruction after colorectal surgery. ANZ J Surg 2004;74:1010.
• Scaglione M et al: Helical CT diagnosis of small bowel obstruction in the acute clinical setting. Eur J Radiol 2004;50:15.
• Zalcman M et al: Helical CT signs in the diagnosis of intestinal ischemia in small-bowel obstruction. Am J Roentgenol 2000;175:1601.
