Small bowel obstruction: Difference between revisions

(Text replacement - "==Treatment==" to "==Management==")
 
(42 intermediate revisions by 11 users not shown)
Line 1: Line 1:
==Background==
==Background==
*SBO without hx of surgery, no hernia is malignancy until proven otherwise
[[File:Blausen 0817 SmallIntestine Anatomy.png|thumb|Small bowel anatomy with surrounding structures.]]
*Small bowel obstruction without history of surgery or hernia is malignancy until proven otherwise
*"Never let the sun rise or set on a small bowel obstruction"
*"Never let the sun rise or set on a small bowel obstruction"


===Causes===
===Causes===
*Adhesions (Hx of previous abdominal surgeries +LR 3.86 and -LR 0.19)
*Adhesions (history of previous abdominal surgeries +LR 3.86 and -LR 0.19)
**Most common cause in developed countries
*Hernia
*Hernia
**Port hernias can occur after laparoscopic surgery
*Malignancy
*Malignancy
*Intraluminal strictures
*Intraluminal strictures
**Crohn's disease
**[[Crohn's disease]]
**Radiation therapy
**Radiation therapy
**Mesenteric ischemia
**[[Mesenteric ischemia]]
*Intussusception (due to lymphoma as lead point)
*[[Intussusception]] (due to [[lymphoma]] as lead point)
*Foreign body (bezoars)
*[[ingested foreign body|Foreign body]] ([[bezoar]]s)
*Trauma (duodenal hematoma)
*[[abdominal trauma|Trauma]] ([[duodenal hematoma]])
*Gallstone ileus
*Gallstone [[ileus]]
*Small bowel [[volvulus]] (3-6% of causes of SBO)<ref>Roline CE and Reardon RF.  Disorders of the Small Intestine.  Rosen's.  Edition 8.  Chapter 92.  2014.  1216-1224.</ref>


==Clinical Features==
==Clinical Features==
*Abdominal pain
*[[Abdominal pain]]
**Colicky
**Colicky
**Periumbilical or diffuse
**Periumbilical or diffuse
**Paroxysms of pain occur q5min  
**Paroxysms of pain occur q5min  
*Vomiting
*[[Vomiting]]
**More common in proximal than distal obstruction
**More common in proximal than distal obstruction
**Bilious (proximal) or feculent (distal ileal)
**Bilious (proximal) or feculent (distal ileal)
*** Abdominal pain relieved with vomiting positively predictive +LR (4.50-2.82) -LR (0.78-0.35)
***Abdominal pain relieved with vomiting positively predictive +LR (4.50-2.82) -LR (0.78-0.35)
*Abdominal distention
*Abdominal distention
**Seen more in distal than proximal obstruction
**Seen more in distal than proximal obstruction
** +LR (16.8-5.64) -LR (0.43-0.34)
**+LR (16.8-5.64) -LR (0.43-0.34)
*Inability to pass flatus
*Inability to pass flatus
**Pts may pass flatus/stool initially
**May pass flatus/stool initially
***Takes 12-24hrs for colon to empty
***Takes 12-24hrs for colon to empty
***History of constipation +LR 8.8 and -LR 0.59
***History of constipation +LR 8.8 and -LR 0.59
*Dehydration
*[[Dehydration]]
*Anorexia
*Anorexia
*Ischemia (increased intraluminal pressure initially leads to venous obstruction, progresses to frank arterial ischemia)
*[[ischemic bowel|Ischemia]] (increased intraluminal pressure initially leads to venous obstruction, progresses to frank arterial ischemia)
**Fever
**[[Fever]]
**Leukocytosis
**[[Leukocytosis]]
* Abnormal Bowel sounds  
*Abnormal bowel sounds  
**Studies suggest that auscultating bowel sounds is not clinically useful to differentiate between normal and pathologic<ref>Felder S, Margel D, Murrell Z, et al. Usefulness of Bowel Sound Auscultation: A Prospective Evaluation. J Surg. 2014; 71(5):768–773.</ref>
**Studies suggest that auscultating bowel sounds is not clinically useful to differentiate between normal and pathologic<ref>Felder S, Margel D, Murrell Z, et al. Usefulness of Bowel Sound Auscultation: A Prospective Evaluation. J Surg. 2014; 71(5):768–773.</ref>


==Differential Diagnosis==
==Differential Diagnosis==
{{Abdominal Pain DDX Diffuse}}
{{Abdominal Pain DDX Diffuse}}
{{Constipation DDX}}


==Diagnosis==
==Evaluation==
[[File:Upright X-ray demonstrating small bowel obstruction.jpg|thumb|Upright abdominal X-ray demonstrating a small bowel obstruction. Note multiple air fluid levels.]]
[[File:SBO plain.png|thumb|Small bowel obstruction]]
[[File:SBO_Cai_Maurelus.gif|thumbnail|Ultrasound shows dilated, non-compressible loops of bowel with characteristic to-and-fro motion of bowel contents<ref>http://www.thepocusatlas.com/bowel/</ref>]]
[[File:SBO.gif|thumbnail|Ultrasound shows dilated loops of bowel steep precipice and tumbling feces<ref>http://www.thepocusatlas.com/bowel/</ref>]]
[[File:PSBOCT.png|thumb|A small bowel obstruction as seen on CT.]]
===Labs===
===Labs===
*CBC
*CBC
**WBC >20K suggests bowel gangrene, abscess, or peritonitis
**WBC >20K suggests bowel gangrene, abscess, or peritonitis
**WBC >40K suggests mesenteric vascular occlusion
**WBC >40K suggests mesenteric vascular occlusion
*Chemistry - degree of dehydration, evidence of ischemia (acidosis)
*Chemistry - degree of dehydration, evidence of ischemia ([[acidosis]])
*Lactate - Sn (90-100%), though not Sp marker of strangulation
*[[Lactate]] - sensitive (90-100%), though not specific marker of strangulation
 
===Imaging===
===Imaging===
*Use the 3/6/9 rule for bowel imaging
**Upper limit of 3cm for small bowel, 6cm for colon, and 9cm for cecum
*'''Xray'''
*'''Xray'''
**[[Acute Abdominal Series]]
**[[Acute Abdominal Series]]
**Upright chest film: rule out free air
**Upright chest film: rule out free air
**Upright abd film: air-fluid levels: [[File:Peds_SBO.JPG|thumb|Peds SBO]]
**Upright abdominal film: air-fluid levels:  
**Supine abd film: width of bowel loops most visible (estimate of amount of distention)
**Supine abdominal film: width of bowel loops most visible (estimate of amount of distention)
**String of pearls sign (small pockets of gas along the small bowel that are trapped between the valvulae conniventes) is virtually diagnostic<ref>Maglinte DDT, Reyes BL, Harmon BH, et al. Reliability and role of plain film radiography and CT in the diagnosis of small-bowel obstruction. AJR 1996; 167:1451-1455</ref>  
**String of pearls sign (small pockets of gas along the small bowel that are trapped between the valvulae conniventes) is virtually diagnostic<ref>Maglinte DDT, Reyes BL, Harmon BH, et al. Reliability and role of plain film radiography and CT in the diagnosis of small-bowel obstruction. AJR 1996; 167:1451-1455</ref>  
**Small bowel diameter ≥3cm is associated with obstruction
**Small bowel diameter ≥3cm is associated with obstruction
*** Sen 75% Spec 66% +LR 1.6 -LR 0.43
***Sen 75% Spec 66% +LR 1.6 -LR 0.43
***Air in colon or rectum makes complete obstruction less likely (esp if symptoms >24hr)
***Air in colon or rectum makes complete obstruction less likely (esp if symptoms >24hr)
***If patient does not tolerate upright position left lateral decub abd film can substitute
***If patient does not tolerate upright position left lateral decub abdominal film can substitute
*'''CT A/P with IV contrast'''
*'''CT A/P with IV contrast'''
**Consider if plain films are non-diagnostic
**Consider if plain films are non-diagnostic
**Can show closed-loop obstruction, evidence of ischemia
**Can show closed-loop obstruction, evidence of ischemia
**Per American College of Radiology PO contrast is no longer indicated
**Per American College of Radiology PO contrast is no longer indicated
*** Modern CT Scanner (0.75mm slices): Sen 96%, Spec 100%, +LR infinity -LR 0.04  
***Modern CT Scanner (0.75mm slices): Sen 96%, Spec 100%, +LR infinity -LR 0.04  
*** Historical CT scanner meta-analysis: Sen 87%  Spec 81%,  +LR 3.6  -LR 0.18  
***Historical CT scanner meta-analysis: Sen 87%  Spec 81%,  +LR 3.6  -LR 0.18  
*[[Ultrasound: Abdomen|Ultrasound for SBO]]
*[[Ultrasound: Abdomen|Ultrasound for SBO]]
**Sen 97%, Spec 90%, +LR 9.5, -LR 0.04 (four studies, 2 done by EM residents and 2 by radiology residents)
**Sen 97%, Spec 90%, +LR 9.5, -LR 0.04 (four studies, 2 done by EM residents and 2 by radiology residents)
*'''MRI for SBO'''
*'''MRI for SBO''' - Sen 92%, Spec 89% +LR 6.7 -LR 0.11
*** Sen 92%, Spec 89% +LR 6.7 -LR 0.11


==Management==
==Management==
 
===[[Volume resuscitation]]===
===Volume Resuscitation===
*IV fluid resuscitation with [[electrolyte repletion]]
*IV fluid resuscitation with [[electrolyte repletion]]
*Assessment of need for operative vs nonoperative management
*Assessment of need for operative vs nonoperative management
===Nonoperative Management===
 
*Sometimes successful in patients with partial SBO (must rule-out strangulation first)
===[[Nasogastric tube]]===
*If increasing pain, distention, or peristent high NGT output, consider surgery
====NG tube====
*14 French
*14 French
**Intermittent low wall suction
**Intermittent low wall suction
*Nasogastric fluid losses can be replaced w/ NS + KCL (30-40 meq)
*Nasogastric fluid losses can be replaced with NS + KCL (30-40 meq)
====Contrast====
*There is some evidence to suggest nasogastric tube decompression was not associated with decreased bowel ischemia or need for surgery<ref>Berman, DJ et al. Nasogastric decompression not associated with a reduction in surgery or bowel ischemia for acute small bowel obstruction. Am J Emerg Med. 2017 Dec;35(12):1919-1921.PMID: 28912083</ref>
 
===Oral Contrast===
*Both diagnostic and therapeutic (draws water into the bowel stimulating peristalsis)
*Both diagnostic and therapeutic (draws water into the bowel stimulating peristalsis)
*Associated with decreased hospital stay, more rapid resolution of symptoms
*Associated with decreased hospital stay, more rapid resolution of symptoms
*Repeat CT scan may be helpful to detect early signs of bowel ischemia
*Repeat CT scan may be helpful to detect early signs of bowel ischemia
**Repeat plain films are not helpful (only detect perforation)
**Repeat plain films are not helpful (only detect perforation)
===Operative Management===
 
*25% of patients admitted for SBO require surgery. Surgery is indicated for patients withh:
====Gastrografin PO====
*Complete SBO
*Alternative to operative management if early obstructive process
*Closed-loop obstruction (incarcerated hernia)
*Gastrografin through NG or OG decreases bowel wall edema and increases bowel motility<ref>Assalia A, Schein M, Kopelman D, et al. Therapeutic effect of oral Gastrografin in adhesive, partial small-bowel obstruction: A prospective randomized trial. Surgery 1994; 115: 433-437.</ref>
*[[Fever]], leukocytosis, peritonitis
**Diagnostic and therapeutic<ref>Chen SC, Lin FY, Lee PH, et al. Water-soluble contrast study predicts the need for early surgery in adhesive small bowel obstruction. Br J Surg 1998; 85: 1692-1694.</ref>
**100 cc of gastrografin through NG tube
**Transit may be observed through serial radiographs
***Contrast within the large bowel within 24 hrs suggest partial SBO
***Contrast failing to reach large bowel within 24-48 hrs suggests complete obstruction, requiring laparotomy
**Therapeutic, may reduce necessary operative rate by ~75%<ref>Choi HK et al. Therapeutic Value of Gastrografin in Adhesive Small Bowel Obstruction After Unsuccessful Conservative Treatment: A Prospective Randomized Trial. Annals of Surgery. 2002;236(1).</ref>
*Avoid barium as it becomes inspissated in bowel, causing complete obstruction<ref>Choi HK et al. Therapeutic Value of Gastrografin in Adhesive Small Bowel Obstruction After Unsuccessful Conservative Treatment: A Prospective Randomized Trial. Annals of Surgery. 2002;236(1).</ref>
**Gastrografin is water-soluble and relatively safer if perforation occurs
 
===Non-operative Management vs. Operative===
*75% of patients are amenable to non-operative management
 
====Operative Management====
*25% of patients admitted for SBO require surgery
*Surgery is indicated for patients with:
**Increasing pain, distention, or peristent high NGT output
**Necrotic bowel
**Closed-loop obstruction (incarcerated hernia, small bowel volvulus, cecal volvulus)
**[[Fever]], leukocytosis, peritonitis
 
===[[Antibiotics]]===
===[[Antibiotics]]===
Indicated if evidence of ischemia or infection
*Not typically indicated, unless evidence of concurrent ischemia or infection
{{Peritonitis Antibiotics}}
*See [[Peritonitis#Management|peritonitis antibiotics]]


==Disposition==
==Disposition==
Line 102: Line 132:


==Prognosis==
==Prognosis==
===Pallatiave Medicine===
*In the context of advancing malignancy with widespread peritoneal metastases, bowel obstruction is common and often indicates a poor prognosis
*In the context of advancing malignancy with widespread peritoneal metastases, bowel obstruction is common and often indicates a poor prognosis
*A less interventional and more comfort based approach to treatment may be appropriate
*A less interventional and more comfort based approach to treatment may be appropriate

Latest revision as of 11:43, 23 April 2022

Background

Small bowel anatomy with surrounding structures.
  • Small bowel obstruction without history of surgery or hernia is malignancy until proven otherwise
  • "Never let the sun rise or set on a small bowel obstruction"

Causes

Clinical Features

  • Abdominal pain
    • Colicky
    • Periumbilical or diffuse
    • Paroxysms of pain occur q5min
  • Vomiting
    • More common in proximal than distal obstruction
    • Bilious (proximal) or feculent (distal ileal)
      • Abdominal pain relieved with vomiting positively predictive +LR (4.50-2.82) -LR (0.78-0.35)
  • Abdominal distention
    • Seen more in distal than proximal obstruction
    • +LR (16.8-5.64) -LR (0.43-0.34)
  • Inability to pass flatus
    • May pass flatus/stool initially
      • Takes 12-24hrs for colon to empty
      • History of constipation +LR 8.8 and -LR 0.59
  • Dehydration
  • Anorexia
  • Ischemia (increased intraluminal pressure initially leads to venous obstruction, progresses to frank arterial ischemia)
  • Abnormal bowel sounds
    • Studies suggest that auscultating bowel sounds is not clinically useful to differentiate between normal and pathologic[2]

Differential Diagnosis

Diffuse Abdominal pain

Constipation

Evaluation

Upright abdominal X-ray demonstrating a small bowel obstruction. Note multiple air fluid levels.
Small bowel obstruction
Ultrasound shows dilated, non-compressible loops of bowel with characteristic to-and-fro motion of bowel contents[3]
Ultrasound shows dilated loops of bowel steep precipice and tumbling feces[4]
A small bowel obstruction as seen on CT.

Labs

  • CBC
    • WBC >20K suggests bowel gangrene, abscess, or peritonitis
    • WBC >40K suggests mesenteric vascular occlusion
  • Chemistry - degree of dehydration, evidence of ischemia (acidosis)
  • Lactate - sensitive (90-100%), though not specific marker of strangulation

Imaging

  • Use the 3/6/9 rule for bowel imaging
    • Upper limit of 3cm for small bowel, 6cm for colon, and 9cm for cecum
  • Xray
    • Acute Abdominal Series
    • Upright chest film: rule out free air
    • Upright abdominal film: air-fluid levels:
    • Supine abdominal film: width of bowel loops most visible (estimate of amount of distention)
    • String of pearls sign (small pockets of gas along the small bowel that are trapped between the valvulae conniventes) is virtually diagnostic[5]
    • Small bowel diameter ≥3cm is associated with obstruction
      • Sen 75% Spec 66% +LR 1.6 -LR 0.43
      • Air in colon or rectum makes complete obstruction less likely (esp if symptoms >24hr)
      • If patient does not tolerate upright position left lateral decub abdominal film can substitute
  • CT A/P with IV contrast
    • Consider if plain films are non-diagnostic
    • Can show closed-loop obstruction, evidence of ischemia
    • Per American College of Radiology PO contrast is no longer indicated
      • Modern CT Scanner (0.75mm slices): Sen 96%, Spec 100%, +LR infinity -LR 0.04
      • Historical CT scanner meta-analysis: Sen 87% Spec 81%, +LR 3.6 -LR 0.18
  • Ultrasound for SBO
    • Sen 97%, Spec 90%, +LR 9.5, -LR 0.04 (four studies, 2 done by EM residents and 2 by radiology residents)
  • MRI for SBO - Sen 92%, Spec 89% +LR 6.7 -LR 0.11

Management

Volume resuscitation

  • IV fluid resuscitation with electrolyte repletion
  • Assessment of need for operative vs nonoperative management

Nasogastric tube

  • 14 French
    • Intermittent low wall suction
  • Nasogastric fluid losses can be replaced with NS + KCL (30-40 meq)
  • There is some evidence to suggest nasogastric tube decompression was not associated with decreased bowel ischemia or need for surgery[6]

Oral Contrast

  • Both diagnostic and therapeutic (draws water into the bowel stimulating peristalsis)
  • Associated with decreased hospital stay, more rapid resolution of symptoms
  • Repeat CT scan may be helpful to detect early signs of bowel ischemia
    • Repeat plain films are not helpful (only detect perforation)

Gastrografin PO

  • Alternative to operative management if early obstructive process
  • Gastrografin through NG or OG decreases bowel wall edema and increases bowel motility[7]
    • Diagnostic and therapeutic[8]
    • 100 cc of gastrografin through NG tube
    • Transit may be observed through serial radiographs
      • Contrast within the large bowel within 24 hrs suggest partial SBO
      • Contrast failing to reach large bowel within 24-48 hrs suggests complete obstruction, requiring laparotomy
    • Therapeutic, may reduce necessary operative rate by ~75%[9]
  • Avoid barium as it becomes inspissated in bowel, causing complete obstruction[10]
    • Gastrografin is water-soluble and relatively safer if perforation occurs

Non-operative Management vs. Operative

  • 75% of patients are amenable to non-operative management

Operative Management

  • 25% of patients admitted for SBO require surgery
  • Surgery is indicated for patients with:
    • Increasing pain, distention, or peristent high NGT output
    • Necrotic bowel
    • Closed-loop obstruction (incarcerated hernia, small bowel volvulus, cecal volvulus)
    • Fever, leukocytosis, peritonitis

Antibiotics

Disposition

  • Admit

Prognosis

  • In the context of advancing malignancy with widespread peritoneal metastases, bowel obstruction is common and often indicates a poor prognosis
  • A less interventional and more comfort based approach to treatment may be appropriate
  • See Malignant bowel obstruction for details

See Also

References

  1. Roline CE and Reardon RF. Disorders of the Small Intestine. Rosen's. Edition 8. Chapter 92. 2014. 1216-1224.
  2. Felder S, Margel D, Murrell Z, et al. Usefulness of Bowel Sound Auscultation: A Prospective Evaluation. J Surg. 2014; 71(5):768–773.
  3. http://www.thepocusatlas.com/bowel/
  4. http://www.thepocusatlas.com/bowel/
  5. Maglinte DDT, Reyes BL, Harmon BH, et al. Reliability and role of plain film radiography and CT in the diagnosis of small-bowel obstruction. AJR 1996; 167:1451-1455
  6. Berman, DJ et al. Nasogastric decompression not associated with a reduction in surgery or bowel ischemia for acute small bowel obstruction. Am J Emerg Med. 2017 Dec;35(12):1919-1921.PMID: 28912083
  7. Assalia A, Schein M, Kopelman D, et al. Therapeutic effect of oral Gastrografin in adhesive, partial small-bowel obstruction: A prospective randomized trial. Surgery 1994; 115: 433-437.
  8. Chen SC, Lin FY, Lee PH, et al. Water-soluble contrast study predicts the need for early surgery in adhesive small bowel obstruction. Br J Surg 1998; 85: 1692-1694.
  9. Choi HK et al. Therapeutic Value of Gastrografin in Adhesive Small Bowel Obstruction After Unsuccessful Conservative Treatment: A Prospective Randomized Trial. Annals of Surgery. 2002;236(1).
  10. Choi HK et al. Therapeutic Value of Gastrografin in Adhesive Small Bowel Obstruction After Unsuccessful Conservative Treatment: A Prospective Randomized Trial. Annals of Surgery. 2002;236(1).