What are the diagnosis and treatment options for small bowel obstruction (SBO)?

From the Guidelines

Small bowel obstruction (SBO) should be initially managed with supportive treatment, including intravenous crystalloids, anti-emetics, and bowel rest, as soon as possible, according to the most recent and highest quality study 1. The diagnosis of SBO involves a combination of clinical assessment, laboratory tests, and imaging studies. Patients typically present with abdominal pain, distension, vomiting, and constipation. Diagnosis begins with a thorough history and physical examination, followed by basic laboratory tests including complete blood count, electrolytes, and kidney function tests to assess for dehydration and metabolic abnormalities.

Key Diagnostic Steps

• Abdominal X-rays may show dilated small bowel loops and air-fluid levels
• CT scan with oral contrast is the gold standard imaging modality, offering 90-95% accuracy in identifying the location and cause of obstruction Treatment depends on the severity and cause of the obstruction.

Initial Management

• Bowel rest
• Nasogastric tube decompression
• Intravenous fluid resuscitation with normal saline or lactated Ringer's at rates based on the patient's hydration status
• Correction of electrolyte imbalances
• Pain management with opioids like morphine 2-4mg IV every 4 hours or hydromorphone 0.5-1mg IV every 4 hours may be necessary For partial obstructions or those caused by adhesions, conservative management for 24-72 hours is appropriate, as evidenced by the study 1. However, immediate surgical intervention is required for complete obstruction, strangulation, perforation, or clinical deterioration.

Surgical Intervention

• May involve adhesiolysis, bowel resection, or repair depending on the underlying cause
• Water-soluble contrast agents like Gastrografin can be both diagnostic and therapeutic, potentially resolving some adhesive obstructions while predicting the need for surgery if contrast fails to reach the colon within 24 hours Close monitoring of vital signs, abdominal examination, and output from the nasogastric tube is essential during treatment to detect complications early, as recommended by the study 1. The study 1 suggests that patients with a virgin abdomen could be treated according to existing guidelines for SBO and adhesive small bowel obstruction, which supports the above recommendations.

From the Research

Diagnosis of Small Bowel Obstruction

• The diagnosis of small bowel obstruction (SBO) typically requires imaging, with computed tomography (CT) and ultrasound being reliable diagnostic methods 2, 3.
• Plain radiographs are often ordered but cannot exclude the diagnosis of SBO 2.
• The clinical presentation of SBO includes abdominal pain, nausea and emesis, abdominal distention, and constipation-to-obstipation 3.
• Physical exam may reveal restlessness, acute illness, and signs of dehydration and sepsis, including tachycardia, pyrexia, dry mucous membranes, hypotension/orthostasis, abdominal distention, and hypoactive bowel sounds 3.

Treatment of Small Bowel Obstruction

• Management of SBO includes intravenous fluid resuscitation, analgesia, and determining the need for operative vs. nonoperative therapy 2.
• Nasogastric tube is useful for patients with significant distension and vomiting by removing contents proximal to the site of obstruction 2, 4.
• Surgery is needed for strangulation and those that fail nonoperative therapy 2, 3.
• The use of water-soluble contrast (WSC) has been shown to stimulate bowel function and may reduce hospital length of stay 4.
• A systematic review found that treatment without nasogastric tube decompression may be effective in some patients, but further investigation is needed to determine the best approach 4.

Classification and Etiologies of Small Bowel Obstruction

• SBO can be classified as complete or partial, and complicated or simple, with complete complicated SBO more commonly requiring surgical intervention 2.
• The most common cause of SBO in adults is adhesions, followed by hernias, neoplasms, Crohn's disease, and other etiologies 3.
• The annual incidence of SBO is approximately 340,100 admissions in the US, with a mortality rate of 10% but increasing to 30% with bowel necrosis/perforation 3, 4.

Fluid Resuscitation in Small Bowel Obstruction

• Fluid resuscitation is an important aspect of SBO management, but the choice of fluid (normal saline or lactated Ringer's solution) does not appear to affect outcomes in acute pancreatitis, a related condition 5.
• Further research is needed to determine the optimal fluid resuscitation strategy for SBO patients 5.