Small bowel obstruction

Diseases

Highlights & Basics

Key Highlights

Small bowel obstruction is a mechanical disruption in the patency of the gastrointestinal tract.
It is a medical emergency that requires early diagnosis and potential surgical intervention.
It typically presents with the combined symptoms of abdominal pain, bloating, vomiting, and failure to pass flatus or stool per rectum.
Diagnosis is generally based upon clinical and radiographic features.
Treatment involves a combination of nasogastric decompression and intravenous fluids. Surgery may be required, so the diagnosis requires urgent surgical assessment.
Patients who are treated in a timely manner have a very good prognosis. If untreated, it can progress to intestinal necrosis, perforation, sepsis, and multi-organ failure.

Abdominal x-ray showing partial intestinal obstruction

From the collection of Dr David J. Hackam

Quick Reference

History & Exam
- Key Factors
  - constipation/failure to pass flatus or stool
  - abdominal pain
  - vomiting
  - abdominal distention
  - abdominal tenderness
  - peritonitis
  - palpable abdominal mass
- Other Factors
  - nausea
  - fever
  - tachycardia
  - severe lethargy
  - hypotension
  - diarrhea
  - groin swelling
More information...
Diagnostics Tests
- 1st Tests to Order
  - abdominal CT scan
  - CBC
  - BUN
  - electrolyte panel
- Other Tests to consider
  - abdominal x-rays
  - water-soluble contrast study
  - laparotomy
  - laparoscopy
  - abdominal ultrasound
  - abdominal MRI
More information...
Treatment Options
- acute
  - complicated or strangulated SBO: surgical candidate
    - emergency surgery plus fluid resuscitation
    - preoperative antibiotic prophylaxis
    - nasogastric decompression
    - analgesia
    - correction of the underlying cause
More information...

Definition

Small bowel obstruction (SBO) is a mechanical disruption in the patency of the gastrointestinal tract, resulting in a combination of emesis (that may be bilious), absolute constipation, and abdominal pain.

Classifications

According to the nature of the obstruction

Partial (incomplete) bowel obstruction

The situation in which the blockage of the intestine is not complete, resulting in partial passage of flatus and occasionally stool.

Complete bowel obstruction

Blockage of the intestine completely obstructing the lumen of the intestine, resulting in failure to pass flatus and stool. Although previously considered an indication for operative therapy, there is evidence that, although there is a higher rate of requiring bowel resection, a proportion of patients (41% to 73%) may resolve with nonoperative therapy.[1]

Simple bowel obstruction

An intestinal blockage in the absence of intestinal ischemia or peritonitis; may respond to nonoperative therapy.

Complicated bowel obstruction

A surgical emergency in which the obstruction has progressed to intestinal ischemia/gangrene and/or perforation. This is a life-threatening situation that requires urgent resuscitation and surgical intervention.

Vignette

Common Vignette 1

A 27-year-old man presents with crampy abdominal pain of sudden onset, emesis, and failure to pass any gas or stool for 24 hours. The patient has no history of prior surgery. Physical exam reveals peritonitis. Abdominal computed tomography (CT) scan reveals the level of the obstruction.

Common Vignette 2

A 43-year-old woman with a prior history of open cholecystectomy presents with gradual onset of nausea, vomiting, absolute constipation, and abdominal distention. Physical exam does not demonstrate peritonitis. Abdominal CT scan confirms the diagnosis of SBO.

Epidemiology

The lifetime incidence of SBO varies between 0.1% and 5% in patients who have not undergone previous surgery, yet may rise to over 60% in patients who have undergone previous surgery.[2] [3] [4] In patients with Crohn disease, the incidence may be upward of 25%. In children, 1 in 5000 cases are reported at birth and 0.5% in the first 2 years of life.[5]

SBO is a major cause of morbidity and mortality, and it can be fatal in untreated patients if it progresses to intestinal necrosis, perforation, sepsis, and multi-organ failure.

Etiology

Common causes of SBO in adults include:

Adhesions from previous intra-abdominal surgery or previous intra-abdominal infections
Acute incarcerated hernia including, inguinal, femoral, ventral, incisional, umbilical, and parastomal hernias
Crohn disease
Intestinal malignancy.

Common causes of SBO in children include:

Appendicitis

Intussusception
Intestinal atresia
Volvulus.

Rare causes include radiation enteritis, intra-abdominal abscess (from perforated appendicitis/diverticulitis), gallstone ileus, foreign body, and intestinal bezoar.

Pathophysiology

SBO represents an interruption in the patency of the gastrointestinal tract. The proximal dilation of the intestine, together with peristalsis, leads to abdominal cramping (colic), which can become severe. The abdominal pain may also be accompanied by vomiting, while the distal interruption of fecal flow leads to absolute constipation. In acute cases, there can be hyperperistalsis distal to the obstruction, leading to the finding of diarrhea. Obstructed bowel cancer, over time, prevents appropriate venous drainage with the possible result of decreased arterial perfusion. Untreated patients could develop progressive intestinal ischemia, necrosis, and perforation.

Images

Abdominal CT scan showing small bowel obstruction with multiple air-fluid levels, dilated bowel loops and a transition zone in the right iliac fossa. Red arrows indicate the evident transition zone
Abdominal x-ray showing partial intestinal obstruction
Abdominal x-ray showing complete intestinal obstruction

Diagnostic Approach

General approach

SBO is an interruption of the patency of the gastrointestinal tract. The most common symptoms are abdominal pain, bloating, vomiting, and failure to pass flatus or stool per rectum. If untreated, patients may develop progressive intestinal ischemia, necrosis, and perforation. Early diagnosis, monitoring, and intervention are therefore crucial.

Diagnosis should encompass the anticipated urgency for intervention. It is important to consider the cause of the obstruction, whether the patient has a partial or complete SBO, and/or whether the obstruction is simple (i.e., no peritonitis: may not require surgery) versus complicated (i.e., peritonitis is present: surgery definitely required). The distinction between these various diagnostic possibilities can be based upon a combination of physical exam, CT scanning, abdominal x-rays (in selected patients), and blood tests (e.g., white blood cell count).

In children, especially infants, diagnosis requires the exclusion of intestinal volvulus as a cause for the obstruction. Failure to establish the diagnosis in a timely manner can result in necrosis of the entire midgut and can be fatal if left untreated.

History

A detailed history provides insights into the onset and timing of the abdominal pain, the nature of the vomiting (which may be bilious), and the history of passage of stool/flatus. Past medical history may provide clues to a potential cause of the obstruction (e.g., a history of prior surgery may suggest adhesive disease).[12] Patients may also report a lump or swelling suggesting a hernia.

In cases of simple or partial SBO, patients may have an acute onset of symptoms, but will generally continue to pass gas and stool, although in lower quantities. Fever may be present, but it is likely to be mild. Vomiting is typically, but not always present, and is likely to be bilious.
In complicated SBO, patients report emesis, absolute constipation (no passage of flatus or stool), severe lethargy, and fever with rigors and typically have worse pain.

Patients may or may not experience a prodrome before the onset of full symptoms.

Physical examination

Patients with simple SBO present with abdominal distention, mild diffuse 4-quadrant abdominal tenderness.[12] They may appear sick, with mild dehydration. A mass may be palpated in the abdomen in cases where an underlying malignancy is the cause of the SBO. Patients are also classically described as having high-pitched (tinkling) increased-frequency bowel sounds early in presentation, but bowel sounds may become less frequent in those with late obstruction as a result of intestinal muscular fatigue.[13] [14] However, the accuracy of abdominal auscultation for bowel obstruction has been questioned.[15]
Patients with complicated SBO appear very ill at presentation. They demonstrate tachycardia and tachypnea, reflective of intravascular volume depletion and pain. In advanced stages, these patients may have fever and hypotension. The abdomen is usually distended, due to the obstructed bowel and the presence of ascites that develops in the setting of complete intestinal obstruction.
Clinicians should also examine for the presence of incarcerated/strangulated hernias in the groin, umbilicus or prior incisions; the presence of surgical scars indicative of prior surgery; and manifestations of Crohn disease (e.g., mucositis, rash).

Investigations

When assessing a patient with intestinal obstruction, it is important to determine whether the patient has partial or complete, simple or complicated SBO. In addition to the history and physical exam, the following investigations should be considered:

1. CT scan of the abdomen

A CT scan of the abdomen is the initial imaging investigation in patients with suspected intestinal obstruction.[14] [16] The sensitivity of the abdominal CT scan in detecting intestinal obstruction is 84% to 95%, depending on the degree of obstruction.[17] CT scan has a high (approximately 90%) accuracy in predicting intestinal strangulation and therefore the need for urgent surgery.[18] Contrast-enhanced CT acquisition is sufficient for the assessment of possible SBO; use of unenhanced CT alongside contrast-enhanced imaging does not add diagnostic information and should be avoided.[16] [19]
CT is also useful in diagnosing complications of SBO, including ischemia, strangulation or necrosis.[13] [17][18] [20]
A multidetector CT scanner and multiplanar reconstruction can be used, if available. They aid in the diagnosis and localization of the SBO.[1] [16] [21]
Abdominal CT scan showing small bowel obstruction with multiple air-fluid levels, dilated bowel loops and a transition zone in the right iliac fossa. Red arrows indicate the evident transition zone
Di Saverio S, et al. Gut 2009; 58: 891-2; used with permission

2. Abdominal x-rays

Although CT-scan has a higher sensitivity and specificity than abdominal x-rays, abdominal x-rays may be considered in the initial evaluation of patients with suspected intestinal obstruction, particularly in patients who are hemodynamically unstable or unable to undergo cross-sectional imaging, or who have equivocal clinical findings. They should be performed in the upright (or decubitus if the patient is unable to stand) and supine positions.[14]Images
Abdominal x-rays will not give information about the etiology of obstruction, and findings may be normal in patients with early or proximal obstruction.[14] As such, they could prolong the evaluation period.[16]

3. Laboratory tests

Early in the course of investigation, a basic blood-work panel should be obtained, including complete blood count, to assess for the presence of leukocytosis and anemia. Tests of renal and pancreatic function should also be performed, to assess whether organ dysfunction is present. Electrolytes should also be measured.

Other useful imaging modalities include:

4. Water-soluble contrast study

In patients with acute SBO as a result of adhesions, water-soluble contrast challenge may help estimate whether conservative treatment has been successful. Patients in which the contrast reaches the colon by 24 hours rarely require surgery.[16] [22][23]

5. Magnetic resonance imaging (MRI) of the abdomen

Not generally performed; the procedure adds no information to that from a well-performed CT scan. However, MRI can be useful in some cases, such as in Crohn disease subacute SBO where diagnosis has been difficult, or to avoid recurrent doses of ionizing radiation in young patients.

6.Ultrasound of the abdomen

Rarely performed in adults with SBO unless CT scanning is not available or cannot be performed. However, ultrasound performed by a specialist technician can be a useful diagnostic modality in children.

7. Diagnostic laparotomy/laparoscopy

May be performed in those cases in which it is difficult to distinguish between simple and complicated SBO, or between SBO and some other cause of abdominal pain. This can take place either through an open incision (laparotomy) or via a minimally invasive approach in the hands of experienced individuals (diagnostic laparoscopy).

View diagnostic guideline references

Risk Factors

strong Factors

Expand All

previous abdominal surgery

- Can lead to intra-abdominal adhesions that may cause obstruction. Open abdominal surgery carries a greater risk of intra-abdominal adhesion-related SBO compared with laparoscopic or robotic surgery.[6] [7] [8]

malrotation

- Can lead to midgut volvulus, resulting in the loss of the midgut, necrosis, and death.

Crohn disease

- Can lead to the formation of an inflammatory phlegmon or strictures that may obstruct the intestine.

hernia

- Inguinal, femoral, ventral, incisional, umbilical, and parastomal hernias can lead to incarceration and intestinal obstruction.

appendicitis

- Can lead to obstruction of the intestine due to the formation of an inflammatory phlegmon/abscess.

intestinal malignancy

- Can lead to intestinal blockage as disease progresses, either from primary tumor or from metastases.

intussusception

- Leads to intestinal obstruction as the intestine is "pinched off" during the process of intussusception.

volvulus

- Always causes obstruction as the twisted intestine leads to the total loss of intestinal luminal patency.

intestinal atresia

- Important cause of intestinal obstruction in newborn infants; the failure of intestinal development leads to an interruption of luminal patency.

foreign body ingestion

- Ingested foreign bodies can cause a mass effect in the intestinal lumen and prevent the passage of intestinal contents.

History & Exam

Key Factors

Frequency

Expand All

constipation/failure to pass flatus or stool

common

Due to distal interruption of fecal flow. Constipation is not always absolute. Some patients may still pass flatus and small amounts of stool especially early in the course.[25]

common

abdominal pain

common

Often described as crampy and intermittent; can be severe. May be accompanied by vomiting, and often precedes the onset of vomiting.

common

vomiting

common

May be bilious; occurs after onset of pain.

common

abdominal distention

common

A common finding in patients with SBO. May be less prominent with more proximal obstructions. It is classically associated with high-pitched, increased frequency bowel sounds; however, the accuracy of abdominal auscultation for bowel obstruction has been questioned.[15]

common

abdominal tenderness

common

Moderate to severe tenderness may be associated with intestinal ischemia; a sign of progressive disease and impending tissue necrosis.

common

peritonitis

common

In the setting of intestinal ischemia, necrosis, and/or perforation.

common

palpable abdominal mass

uncommon

A mass may be palpated in the abdomen, suggestive of an underlying malignancy as the cause of the SBO.

uncommon

Other Factors

Frequency

Expand All

nausea

common

This is an early event in the setting of either partial or complete SBO.

common

fever

common

Nonspecific inflammatory response to the presence of obstruction. In cases of simple SBO, fever may be present, but is likely to be mild. In complicated SBO, patients report fever with rigors.

common

tachycardia

common

Reflective of dehydration and pain.

common

severe lethargy

common

Present in complicated SBO or patients with severe dehydration.

common

hypotension

common

May be present in advanced stages of complicated SBO.

common

diarrhea

uncommon

In acute SBO, there can be hyperperistalsis distal to the obstruction, leading to diarrhea.

uncommon

groin swelling

uncommon

May be due to the presence of incarcerated and/or strangulated hernias in the groin.

uncommon

Tests

1st Tests to Order

Result

Expand All

abdominal CT scan

may visualize transition zone, mass, tumor, appendicitis

CT scan of the abdomen is the initial imaging investigation in patients with suspected intestinal obstruction.[14] The sensitivity of abdominal CT scan in detecting intestinal obstruction is 84% to 95%, depending on the degree of obstruction.[17] CT scan has a high (approximately 90%) accuracy in predicting intestinal strangulation and therefore the need for urgent surgery.[18] Contrast-enhanced CT acquisition is sufficient for the assessment of possible SBO; use of unenhanced CT alongside contrast-enhanced imaging does not add diagnostic information and should be avoided.[16] [19]
CT is also useful in diagnosing complications of SBO, including ischemia, strangulation or necrosis.[13] [17][18] [20]
A multidetector CT scanner and multiplanar reconstruction can be used, if available. They aid in the diagnosis and localisation of the SBO.[1] [21]

may visualize transition zone, mass, tumor, appendicitis

CBC

increased WBC, rarely decreased hematocrit

May indicate potential severe intestinal obstruction with necrosis.
A low hematocrit may indicate blood loss caused by an underlying disease.

increased WBC, rarely decreased hematocrit

BUN

increased in the setting of volume depletion

An increase in the urea shows the severity of dehydration/renal failure in complicated SBO.

increased in the setting of volume depletion

electrolyte panel

may show hyponatremia, hypokalemia, metabolic alkalosis, and metabolic acidosis

Electrolyte imbalance is consistent with dehydration.

may show hyponatremia, hypokalemia, metabolic alkalosis, and metabolic acidosis

Other Tests to consider

Result

Expand All

abdominal x-rays

may be normal; may show air-fluid levels, dilated intestinal loops, absence of gas in the rectum (in complete SBO), pneumoperitoneum

Abdominal x-rays may be considered in the initial evaluation of patients with suspected intestinal obstruction, particularly in patients who are hemodynamically unstable or unable to undergo cross-sectional imaging, or who have equivocal clinical findings. It likely will not give information about the etiology of obstruction, and findings may be normal in patients with early or proximal obstruction.[14] As such, they could prolong the evaluation period.[16] Upright and supine x-rays of the abdomen help to determine whether the patient has a partial or complete SBO, and whether obstruction is simple or complicated:[1]
Partial SBO: gas throughout the abdomen and into the rectum.
Complete SBO: no distal gas, and staggered air-fluid levels.
Complicated SBO: free air under the diaphragm suggestive of perforation; thumb-printing of the bowel suggestive of ischemia.

may be normal; may show air-fluid levels, dilated intestinal loops, absence of gas in the rectum (in complete SBO), pneumoperitoneum

water-soluble contrast study

presence or absence of contrast in the colon on abdominal x-ray

In patients with acute SBO as a result of adhesions, water-soluble contrast challenge may help estimate whether conservative treatment has been successful. Patients in which the contrast reaches the colon by 24 hours rarely require surgery.[16] [22][23]
Involves the administration of water-soluble contrast material into the stomach. The subsequent assessment of the degree of passage of this material, using serial x-rays, can provide information regarding the presence and location of the obstruction within the gastrointestinal tract:
In partial SBO, the medium passes into rectum.
In complete SBO, the medium does not pass into rectum and is held up at the site of obstruction.
Also demonstrates the extent of disease in patients with Crohn disease.

presence or absence of contrast in the colon on abdominal x-ray

laparotomy

appendicitis, malrotation, tumor mass

To determine the location of the obstruction and diagnosis of the underlying cause.
To identify those cases in which it is difficult to distinguish between simple and complicated SBO, or between SBO and some other cause of abdominal pain.

appendicitis, malrotation, tumor mass

laparoscopy

appendicitis, malrotation, tumor mass

A minimally invasive approach in the hands of experienced, trained individuals. It may be performed in those cases in which it is difficult to distinguish between simple and complicated SBO, or between SBO and some other cause of abdominal pain.

appendicitis, malrotation, tumor mass

abdominal ultrasound

may show a mass, or inflamed/perforated appendix

This test is rarely performed in adult patients with SBO unless the diagnosis of underlying abdominal mass or appendicitis is suspected, and CT scanning is not available or cannot be performed. The dilated loops of bowel filled with gas and fluid invariably obscure any useful detail that may be obtained by ultrasound. However, it is a useful diagnostic modality in children.

may show a mass, or inflamed/perforated appendix

abdominal MRI

may show transition zone at point of obstruction, mass

This test is rarely performed in patients with acute SBO. Can be useful in chronic, recurrent, or subacute cases, such as in Crohn disease or in pregnant women, to aid diagnosis while avoiding ionizing radiation.

may show transition zone at point of obstruction, mass

Differential Diagnosis

Disease/Condition

Ileus
Differentiating Signs/Symptoms
Less crampy abdominal pain; often associated with another cause (e.g., postoperative, systemic infection, medications).
Differentiating Tests
CT scan shows passage of contrast throughout the small bowel and into the large bowel. No transition point identified.
Infectious gastroenteritis
Differentiating Signs/Symptoms
Vomiting, typically nonbilious.
Differentiating Tests
X-ray shows gas throughout abdomen; stool cultures may be positive for viruses or bacteria.
Large bowel obstruction
Differentiating Signs/Symptoms
Very distended abdomen; constipation progressing to absolute constipation.
Differentiating Tests
X-ray shows a dilated colon and may show the cause (e.g., sigmoid volvulus).
Intestinal pseudo-obstruction
Differentiating Signs/Symptoms
Chronic condition; constipation; often associated with administration of neurologic medications (e.g., amitriptyline, imipramine). Rarely, clozapine has been associated with pseudo-obstruction.[26]
Differentiating Tests
X-ray and CT may show dilated small or large bowel, which may be massively dilated.
Appendicitis
Differentiating Signs/Symptoms
Pain in right lower quadrant with nausea; vomiting (nonbilious).
Differentiating Tests
Ultrasound and CT may confirm diagnosis in most cases.
Pancreatitis
Differentiating Signs/Symptoms
Continuous upper abdominal pain radiating through to the back; nonbilious vomiting.
Differentiating Tests
Increased amylase and lipase; CT scan shows inflamed pancreas.

Treatment Approach

In all cases, it is important to note that SBO is a medical emergency. Diagnosis requires immediate resuscitation and management strategies vary depending on the cause. Adhesive or Crohn disease obstruction may resolve nonoperatively, while obstruction due to hernia usually requires reduction of the hernia and/or repair, and urgent surgery is indicated when there is suspected bowel ischemia or complicated SBO.

In general:

Patients with peritonitis or suspicion for bowel ischemia require surgery.
Patients with simple, adhesive SBO may benefit from nasogastric decompression and close observation. Surgery will likely be required if there is a poor response to nonoperative management after 48 to 72 hours.

Patients should initially be treated in the emergency room with fluid resuscitation, bowel decompression, and administration of analgesia. Early surgical consultation with a general surgeon should take place. Operative treatment is indicated in patients with complicated SBO, peritonitis, evidence of strangulation, and those who do not resolve with nonoperative treatment.

Correction of the underlying cause will be required for treatment of the concomitant intestinal obstruction.

All patients

Nonoperative treatment

Fluid resuscitation: placement of intravenous lines and administration of intravenous fluids is indicated in all patients. A Foley catheter may be helpful to monitor urine output.
Bowel decompression: the placement of a nasogastric tube is indicated to decompress air/fluid in the upper gastrointestinal tract, although there is evidence to suggest it may not be needed in all patients.[28] [29] A surgical consultation (general surgeon) is indicated at this stage.
Antiemesis: although patients with complete SBO often have severe nausea, antiemetics are generally not administered as they do not provide significant relief. The most effective antiemetic strategy is nasogastric decompression. For partial SBO an antiemetic may be beneficial, but only if nasogastric aspirates are minimal.[30] Metoclopramide is contraindicated in patients with bowel obstruction.
Analgesia: it is essential to provide adequate analgesia in patients with partial or complete SBO. This can be readily accomplished with morphine.
Antibiotics: there is insufficient evidence that broad-spectrum antibiotics are beneficial in these patients. By contrast, perioperative antibiotic prophylaxis is indicated if surgery is needed.

The administration of intravenous fluids and passage of a nasogastric tube result in the correction of adhesive SBO in approximately 70% to 90% of cases. A water-soluble contrast challenge may be used to help estimate whether conservative treatment has been successful in these patients. If the contrast reaches the colon by 24 hours the patient rarely requires surgery.[16] [23] There is no evidence that the use of oral water-soluble contrast reduces the need for surgical intervention in patients with adhesive SBO.[31] [32] In patients with Crohn disease, medical management of the inflammatory process may be beneficial. However, if there is evidence of bowel strangulation, prompt surgical intervention is crucial. The optimal duration of nonoperative therapy is not completely defined but expert opinion suggests a 72 hour window is safe, unless there are signs and symptoms of developing bowel ischemia.[1] [18]

Correction of the underlying cause will be required for treatment of the concomitant intestinal obstruction. Appropriate specific treatment, such as appendectomy, Ladd procedure for malrotation, tumor resection, and hernia repair, should be performed. The most frequent causes include adhesions, inguinal hernia, or tumor in adults in whom no previous surgery is present.

If surgery is required, laparoscopic adhesiolysis is more favorable than an open laparotomy but may require specific surgical expertise.[13] Systematic reviews and meta-analyses found that the morbidity, mortality, infection rates, and hospital stay were all more favorable in the laparoscopic group when compared with an open laparotomy.[33] [34] [35] Laparoscopic adhesiolysis is associated with similar short term outcomes (postoperative mortality, iatrogenic bowel perforations, length of postoperative stay, severe postoperative complications and early readmission) as open surgery.[36]

In patients with SBO as a result of stricturing secondary to Crohn disease, endoscopic balloon dilation and double-balloon enteroscopy-assisted dilation are safe and effective alternatives to surgery.[37] [38] [39]

Where SBO has resulted from advanced malignancy, the benefits of surgery must be weighed up against the risk of complications and increased morbidity.[40] Such patients may benefit more from palliation of their symptoms through conservative treatment to decompress the bowel if possible, combined with antiemetics, antispasmodics, and adequate analgesia.[13] Nonetheless, surgery may be a necessary part of the palliative treatment to manage the patient's symptoms.[41]

Patients with complicated SBO, peritonitis, strangulation, or failed nonoperative treatment

Operative treatment

The nature of the obstruction determines the type and extent of surgery. An exploratory laparotomy or laparoscopy should be performed in any patient with documented peritonitis or evidence of strangulation; and in patients with SBO who do not respond to nonoperative treatment as manifest by persistent abdominal pain, leukocytosis, worsening air-fluid levels on abdominal x-ray (or demonstration of a gas-less abdomen), or in an inconsolable infant with documented malrotation. In complicated SBO, peritonitis is present (rebound, guarding), which mandates immediate resuscitation and prompt surgical intervention.[1]

Antibiotic prophylaxis

Patients undergoing surgery for SBO will require broad-spectrum antibiotics (e.g., cefotetan, or cefazolin plus metronidazole) as prophylaxis for wound infection.[42]

View treatment guideline references

Treatment Options

acute
Expand All
- complicated or strangulated SBO: surgical candidate
  - - 1st
      emergency surgery plus fluid resuscitation
      Comments
      In patients with complicated or strangulated SBO, peritonitis is usually present, which mandates immediate resuscitation and prompt surgical intervention by exploratory laparoscopy or laparotomy.
      Placement of intravenous lines and administration of intravenous fluid (either Ringer lactate or normal saline) is indicated.
      A Foley catheter should be placed to monitor urine output.
    - plus
      preoperative antibiotic prophylaxis
      Primary Options
      cefazolin
      children ≥1 year of age: 30 mg/kg intravenously as a single dose within 60 minutes of surgery, may repeat dose every 4 hours during surgery, maximum 2000 mg/dose; adults <120 kg body weight: 2000 mg intravenously as a single dose within 60 minutes of surgery, may repeat dose every 4 hours during surgery; adults ≥120 kg body weight: 3000 mg intravenously as a single dose within 60 minutes of surgery, may repeat dose every 4 hours during surgery
      or
      cefotetan
      children ≥1 year of age: 40 mg/kg intravenously as a single dose within 60 minutes of surgery, may repeat dose every 6 hours during surgery, maximum 2000 mg/dose; adults: 2000 mg intravenously as a single dose within 60 minutes of surgery, may repeat dose every 6 hours during surgery
      AND
      metronidazole
      children ≥1 year of age: 15 mg/kg intravenously as a single dose within 60 minutes of surgery, maximum 500 mg/dose; adults: 500 mg intravenously as a single dose within 60 minutes of surgery
      Comments
      Broad-spectrum antibiotics (e.g., cefazolin or cefotetan plus metronidazole) are indicated preoperatively as prophylaxis for wound infection.[42]
      Usually antibiotics are administered for up to 24 hours after surgery.
    - plus
      nasogastric decompression
      Comments
      In cases of complete SBO, the placement of a nasogastric tube is indicated to decompress air/fluid in the upper gastrointestinal tract. It is also a very effective antiemetic strategy.
    - plus
      analgesia
      Primary Options
      morphine sulfate
      children: 0.1 mg/kg intravenously every 3-4 hours when required; adults: 2.5 to 5 mg intravenously every 3-4 hours when required
      Comments
      It is essential to provide adequate analgesia in these patients. This can be readily accomplished with the administration of intravenous morphine.
    - plus
      correction of the underlying cause
      Comments
      Correction of the underlying cause will be required for treatment of the concomitant intestinal obstruction.
      Appropriate specific treatment such as appendectomy, Ladd procedure for malrotation (infants), tumor resection, or hernia repair should be performed.
      The most frequent causes include adhesions, inguinal hernia, or tumor in adults in whom there is no history of previous surgery.
- complicated or strangulated SBO: surgery contraindicated
  - - 1st
      nasogastric decompression plus fluid resuscitation
      Comments
      In cases where surgery is deemed not to be in the patient's best interests (e.g., SBO is due to advanced malignancy) the focus of treatment should be on palliation of symptoms.[13] Placement of a nasogastric tube is indicated to decompress air/fluid in the upper gastrointestinal tract.
      Placement of intravenous lines and administration of sufficient volume of intravenous fluid (either Ringer lactate or normal saline) to resuscitate and maintain hydration is indicated. A Foley catheter should be placed to monitor urine output.
    - plus
      analgesia
      Primary Options
      morphine sulfate
      children: 0.1 mg/kg intravenously every 3-4 hours when required; adults: 2.5 to 5 mg intravenously every 3-4 hours when required
      Comments
      Adequate analgesia should be provided to all patients. This can be readily accomplished with the administration of intravenous morphine.
    - adjunct
      antiemetic
      Primary Options
      ondansetron
      4 mg intravenously every 8 hours when required
      Comments
      Antiemetics can be a useful adjunct to nasogastric decompression for patients with emesis and/or nausea in cases where surgery is contraindicated.
      Metoclopramide is contraindicated in patients with bowel obstruction.
    - adjunct
      antispasmodic
      Comments
      Some guidelines on management of malignant bowel obstruction recommend the use of antispasmodics to reduce abdominal pain or discomfort.[58] [59]
- simple SBO
  - - 1st
      fluid resuscitation plus nasogastric decompression
      Comments
      Typically, conservative therapy may be adopted for 48 to 72 hours in cases of partial SBO before surgery is performed, except in patients with evidence of bowel strangulation, where prompt surgical intervention is crucial.[1]
      Placement of intravenous lines and administration of large volumes of intravenous fluid (either Ringer lactate or normal saline) is indicated in all patients.
      A Foley catheter may be helpful to monitor urine output.
      The placement of a nasogastric tube is indicated to decompress air/fluid in the upper gastrointestinal tract.
      A surgical consultation (general surgeon) is indicated at this stage to determine the best course of treatment.
      Fluid replacement and passage of a nasogastric tube result in the correction of simple adhesive SBO in approximately 70% to 90% of cases. In patients with acute SBO as a result of adhesions, a water-soluble contrast challenge may be used to help estimate whether conservative treatment has been successful. Patients in which the contrast reaches the colon by 24 hours rarely require surgery.[16] [23] There is no evidence that the use of oral water-soluble contrast reduces the need for surgical intervention in patients with adhesive SBO.[31] [32]
    - plus
      correction of the underlying cause
      Comments
      Correction of the underlying cause will be required for treatment of the concomitant intestinal obstruction. Appropriate specific treatment such as appendectomy, Ladd procedure for malrotation (infants), tumor resection, or hernia repair should be performed.
      In patients with SBO as a result of stricturing secondary to Crohn disease, endoscopic balloon dilation and double-balloon enteroscopy-assisted dilation are safe and effective alternatives to surgery.[37] [38] [39]
      There is no evidence that the use of oral water-soluble contrast reduces the need for surgical intervention in patients with adhesive SBO.[31] [32]
    - plus
      analgesia
      Primary Options
      morphine sulfate
      children: 0.1 mg/kg intravenously every 3-4 hours when required; adults: 2.5 to 5 mg intravenously every 3-4 hours when required
      Comments
      Adequate analgesia should be provided to all patients. This can be readily accomplished with intravenous administration of morphine.
  - poor clinical response after 48 to 72 hours
    - plus
      surgery
      Comments
      An exploratory laparotomy or laparoscopy should be performed in patients who do not respond after 48 to 72 hours of nonoperative treatment or sooner if there are signs and symptoms of developing bowel ischemia as manifest by persistent abdominal pain, leukocytosis, worsening air-fluid levels on abdominal x-ray (or demonstration of a gas-less abdomen), or an inconsolable infant with documented malrotation.
      In patients with SBO secondary to adhesions and surgery is required, laparoscopic adhesiolysis is more favorable than an open laparotomy.[13] Systematic reviews and meta-analyses found that the morbidity, mortality, infection rates, and hospital stay were all more favorable in the laparoscopic group when compared with an open laparotomy.[33] [34] [35] Laparoscopic adhesiolysis is associated with similar short term outcomes (postoperative mortality, iatrogenic bowel perforations, length of postoperative stay, severe postoperative complications and early readmission) as open surgery.[36]
    - plus
      preoperative antibiotic prophylaxis
      Primary Options
      cefazolin
      children ≥1 year of age: 30 mg/kg intravenously as a single dose within 60 minutes of surgery, may repeat dose every 4 hours during surgery, maximum 2000 mg/dose; adults <120 kg body weight: 2000 mg intravenously as a single dose within 60 minutes of surgery, may repeat dose every 4 hours during surgery; adults ≥120 kg body weight: 3000 mg intravenously as a single dose within 60 minutes of surgery, may repeat dose every 4 hours during surgery
      or
      cefotetan
      children ≥1 year of age: 40 mg/kg intravenously as a single dose within 60 minutes of surgery, may repeat dose every 6 hours during surgery, maximum 2000 mg/dose; adults: 2000 mg intravenously as a single dose within 60 minutes of surgery, may repeat dose every 6 hours during surgery
      AND
      metronidazole
      children ≥1 year of age: 15 mg/kg intravenously as a single dose within 60 minutes of surgery, maximum 500 mg/dose; adults: 500 mg intravenously as a single dose within 60 minutes of surgery
      Comments
      Broad-spectrum antibiotics (e.g., cefazolin or cefotetan plus metronidazole) are indicated preoperatively as prophylaxis for wound infection.[42]
      Usually antibiotics are administered for up to 24 hours after surgery.
    - plus
      correction of an underlying cause
      Comments
      Correction of the underlying cause will be required for treatment of the concomitant intestinal obstruction. Appropriate specific treatment such as appendectomy, Ladd procedure for malrotation (infants), tumor resection, or hernia repair should be performed.
    - adjunct
      antiemetic
      Primary Options
      ondansetron
      4 mg intravenously every 8 hours when required
      Comments
      For partial SBO an antiemetic may be beneficial, but only if nasogastric aspirates are minimal.[30]
      Metoclopramide is contraindicated in patients with bowel obstruction.

Prevention

Primary Prevention

Although there is no reliable strategy to prevent the occurrence of intra-abdominal adhesions (the most common cause of SBO) after abdominal surgery, best surgical practice may minimize their formation.[9] There are also a variety of agents designed to limit the extent of adhesion formation,[10] although their efficacy remains controversial. The diagnosis and correction of malrotation can significantly prevent the development of SBO due to intestinal volvulus.[11] Treatment of Crohn disease and surgical correction of hernias can also limit its development. One of the potential advantages of laparoscopic surgery compared with open colorectal surgery is a reduction in postoperative bowel obstruction events. A meta-analysis showed that laparoscopic surgery for colorectal disease reduces overall early postoperative bowel obstruction, including ileus, as well as early bowel obstruction in subgroups of patients having surgery for cancer and diverticular disease.[6]

Follow-Up Overview

Prognosis

SBO is a medical emergency. Patients treated in a timely manner have a very good prognosis. In untreated patients, obstruction could progress to intestinal necrosis, perforation, sepsis, and multi-organ failure.

Patients with previous surgery are most likely to have intestinal adhesions as a cause of the SBO. Such patients are at risk of recurrent SBO due to the formation of recurrent adhesions despite adequate adhesiolysis.
Patients without prior surgery may have an underlying malignancy, inguinal hernia, congenital band, or Crohn disease as the cause of the obstruction, and their outcome will be determined by the response to the underlying condition.

Monitoring

After surgery, patients should be monitored for recurrence of their symptoms (e.g., crampy pain, abdominal distention, vomiting).

Following discharge, patients should be seen annually for routine medical care by their primary care physician. Evidence of crampy abdominal pain or food intolerance should lead to additional investigations by an upper gastrointestinal x-ray with small bowel follow-through and/or a computed tomographic scan of the abdomen, to assess for disease recurrence, particularly in the setting of malignancy. The frequency of follow-up and monitoring should be determined by the underlying disease.

Complications

Medium Likelihood

Timeframe

Expand All

intestinal necrosis

short term

As obstruction progresses, intestinal perfusion may decrease, resulting in ischemic change and necrosis. This is heralded by the onset of peritonitis, leukocytosis, dehydration, and prerenal acute kidney injury.[20][61] [62]

short term

sepsis

short term

Patients who develop intestinal necrosis are at risk of developing intestinal perforation with sepsis and multi-organ failure. This leads to death in many patients.

short term

multi-organ failure

short term

Patients who develop intestinal necrosis are at risk of developing intestinal perforation with sepsis and multi-organ failure. This leads to death in many patients.

short term

intestinal perforation

variable

Patients who develop intestinal necrosis are at risk of developing intestinal perforation with sepsis and multi-organ failure. This leads to death in many patients.

variable

Low Likelihood

Timeframe

Expand All

intra-abdominal abscess

short term

In cases of intestinal obstruction with perforation, patients may develop intra-abdominal infection with abscess formation. This requires treatment by either open surgery or image-guided drainage.

short term

short bowel syndrome

long term

If correction of the SBO requires resection of a large amount of small intestine, patients may develop short bowel syndrome. This condition is characterized by the functional or anatomic loss of extensive segments of the small intestine resulting in inadequate absorption of enteral nutrition.
These patients require supplemental nutrition, either via the enteral or the parenteral route. Definitive treatment involves intestinal transplantation in severe cases.

long term

Citations

Key Articles

Maung AA, Johnson DC, Piper GL, et al; Eastern Association for the Surgery of Trauma. Evaluation and management of small-bowel obstruction: an Eastern Association for the Surgery of Trauma practice management guideline. J Trauma Acute Care Surg. 2012 Nov;73(5 suppl 4):S362-9.[Abstract][Full Text]
Jackson P, Vigiola Cruz M. Intestinal obstruction: evaluation and management. Am Fam Physician. 2018 Sep 15;98(6):362-7.[Abstract]
American College of Radiology. ACR appropriateness criteria: suspected small-bowel obstruction. 2019 [internet publication].[Full Text]
Li Z, Zhang L, Liu X, et al. Diagnostic utility of CT for small bowel obstruction: systematic review and meta-analysis. PLoS One. 2019;14(12):e0226740.[Abstract][Full Text]
Ten Broek RPG, Krielen P, Di Saverio S, et al. Bologna guidelines for diagnosis and management of adhesive small bowel obstruction (ASBO): 2017 update of the evidence-based guidelines from the World Society of Emergency Surgery ASBO Working Group. World J Emerg Surg. 2018 Jun 19;13:24.[Abstract][Full Text]

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26. Medicines and Healthcare products Regulatory Agency. Clozapine: reminder of potentially fatal risk of intestinal obstruction, faecal impaction, and paralytic ileus. Oct 2017 [internet publication].[Full Text]
27. American College of Radiology; Society for Pediatric Radiology. ACR-SPR practice parameter for the performance of a contrast small bowel examination. 2023 [internet publication].[Full Text]
28. Klingbeil KD, Wu JX, Osuna-Garcia A, et al. Management of small bowel obstruction and systematic review of treatment without nasogastric tube decompression. Surg Open Sci. 2022 Nov 7;12:62-7.[Abstract][Full Text]
29. Fonseca AL, Schuster KM, Maung AA, et al. Routine nasogastric decompression in small bowel obstruction: is it really necessary? Am Surg. 2013 Apr;79(4):422-8.[Abstract]
30. Chen SC, Lee CC, Yen ZS, et al. Specific oral medications decrease the need for surgery in adhesive partial small-bowel obstruction. Surgery. 2006 Mar;139(3):312-6.[Abstract]
31. Koh A, Adiamah A, Chowdhury A, et al. Therapeutic role of water-soluble contrast media in adhesive small bowel obstruction: a systematic review and meta-analysis. J Gastrointest Surg. 2020 Feb;24(2):473-83.[Abstract]
32. Scotté M, Mauvais F, Bubenheim M, et al. Use of water-soluble contrast medium (gastrografin) does not decrease the need for operative intervention nor the duration of hospital stay in uncomplicated acute adhesive small bowel obstruction? a multicenter, randomized, clinical trial (adhesive small bowel obstruction study) and systematic review. Surgery. 2017 May;161(5):1315-25.[Abstract]
33. Sajid MS, Khawaja AH, Sains P, et al. A systematic review comparing laparoscopic vs open adhesiolysis in patients with adhesional small bowel obstruction. Am J Surg. 2016 Jul;212(1):138-50.[Abstract]
34. Wiggins T, Markar SR, Harris A. Laparoscopic adhesiolysis for acute small bowel obstruction: systematic review and pooled analysis. Surg Endosc. 2015 Dec;29(12):3432-42.[Abstract]
35. Quah GS, Eslick GD, Cox MR. Laparoscopic versus open surgery for adhesional small bowel obstruction: a systematic review and meta-analysis of case-control studies. Surg Endosc. 2019 Oct;33(10):3209-17.[Abstract][Full Text]
36. Krielen P, Di Saverio S, Ten Broek R, et al. Laparoscopic versus open approach for adhesive small bowel obstruction, a systematic review and meta-analysis of short term outcomes. J Trauma Acute Care Surg. 2020 Jun;88(6):866-74.[Abstract]
37. Navaneethan U, Lourdusamy V, Njei B, et al. Endoscopic balloon dilation in the management of strictures in Crohn's disease: a systematic review and meta-analysis of non-randomized trials. Surg Endosc. 2016 Dec;30(12):5434-43.[Abstract]
38. Baars JE, Theyventhiran R, Aepli P, et al. Double-balloon enteroscopy-assisted dilatation avoids surgery for small bowel strictures: a systematic review. World J Gastroenterol. 2017 Dec 7;23(45):8073-81.[Abstract][Full Text]
39. Bettenworth D, Bokemeyer A, Kou L, et al. Systematic review with meta-analysis: efficacy of balloon-assisted enteroscopy for dilation of small bowel Crohn's disease strictures. Aliment Pharmacol Ther. 2020 Oct;52(7):1104-16.[Abstract]
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Guidelines

Diagnostic

ACR-SPR practice parameter for the performance of a contrast small bowel examination [27]
Summary
These guidelines are designed to assist practitioners in providing appropriate radiologic care for patients.
Published by
American College of Radiology; Society for Pediatric Radiology
Published
2023
ACR appropriateness criteria: suspected small-bowel obstruction [16]
Summary
These guidelines provide recommendations on the selection of appropriate radiologic imaging procedures for evaluation of patients with suspected SBO.
Published by
American College of Radiology
Published
2019
Evaluation and management of small-bowel obstruction [1]
Summary
Consensus guidelines addressing the evaluation of SBO.
Computed tomographic scan of abdomen and pelvis should be considered in all patients with SBO, as it can provide incremental information over plain ﬁlms in differentiating grade, severity, and etiology of SBOs that may lead to changes in management.
Published by
Eastern Association for the Surgery of Trauma
Published
2012
Bologna guidelines for diagnosis and management of adhesive small bowel obstruction (ASBO): 2017 update [18]
Summary
Includes an algorithm for the diagnosis of adhesive SBO.
Published by
World Society of Emergency Surgery
Published
2018

Treatment

Dynamic practice guidelines for emergency general surgery: small bowel obstruction [60]
Summary
Recommendations for the management of SBO.
Published by
Canadian Association of General Surgeons
Published
2018
Evaluation and management of small-bowel obstruction [1]
Summary
Consensus guidelines for the management of SBO.
Published by
Eastern Association for the Surgery of Trauma
Published
2012
Bologna guidelines for diagnosis and management of adhesive small bowel obstruction (ASBO): 2017 update [18]
Summary
In the absence of signs that require urgent surgical exploration (i.e., peritonitis, strangulation, or bowel ischemia), nonoperative management is the treatment strategy of choice for adhesive SBO.
Published by
World Society of Emergency Surgery
Published
2018

Credits

Authors

Topic last updated: 2025-05-09

Adrian Maung, MD, MBA, FACS, FCCM

Associate Professor of Surgery

Division of General Surgery, Trauma and Surgical Critical Care, Department of Surgery

Yale School of Medicine

New Haven

[disclosures]

Acknowledgements:

Dr Adrian Maung would like to gratefully acknowledge Dr John T. Jenkins, Dr Edward T. Pring, Dr George Malietzis, Dr Frances J. McNicol, and Dr David J. Hackam, previous contributors to this topic.

[disclosures]

Peer Reviewers

Steven D. Wexner, MD, FACS, FRCS, FRCS (Ed)

Chief Academic Officer

Emeritus Chief of Staff (1997-2007)

Chairman Department of Colorectal Surgery

Professor of Surgery Ohio State University

Affiliate Professor Department of Surgery

Division of General Surgery

University of South Florida College of Medicine

Cleveland Clinic Florida

[disclosures]

Patient Instructions

Patients should be advised to seek medical attention for symptoms suggestive of recurrent intestinal obstruction (e.g., crampy pain, abdominal distention, and vomiting), particularly if there is evidence of prior intestinal necrosis.

Diseases

Highlights & Basics

Quick Reference

Definition

Classifications

Vignette

Epidemiology

Etiology

Pathophysiology

Images

Diagnostic Approach

General approach

History

Physical examination

Investigations

Risk Factors

previous abdominal surgery

malrotation

Crohn disease

hernia

appendicitis

intestinal malignancy

intussusception

volvulus

intestinal atresia

foreign body ingestion

History & Exam

constipation/failure to pass flatus or stool

abdominal pain

vomiting

abdominal distention

abdominal tenderness

peritonitis

palpable abdominal mass

nausea

fever

tachycardia

severe lethargy

hypotension

diarrhea

groin swelling

Tests

abdominal CT scan

CBC

BUN

electrolyte panel

abdominal x-rays

water-soluble contrast study

laparotomy

laparoscopy

abdominal ultrasound

abdominal MRI

Differential Diagnosis

Ileus

Infectious gastroenteritis

Large bowel obstruction

Intestinal pseudo-obstruction

Appendicitis

Pancreatitis

Treatment Approach

All patients

Patients with complicated SBO, peritonitis, strangulation, or failed nonoperative treatment

Treatment Options

complicated or strangulated SBO: surgical candidate

complicated or strangulated SBO: surgery contraindicated

simple SBO

Prevention

Primary Prevention

Follow-Up Overview

Prognosis

Monitoring

Complications

intestinal necrosis

sepsis

multi-organ failure

intestinal perforation

intra-abdominal abscess

short bowel syndrome

Citations