Chapter 43: Small Intestine- SBO Flashcards
What is small bowel obstruction (SBO)?
Mechanical obstruction to the passage of intraluminal contents
What are the signs/symptoms?
- Abdominal discomfort
- cramping
- nausea
- abdominal distention
- emesis
- high pitched bowel sounds
What lab tests are performed with SBO?
Electrolytes, CBC, type and screen, urinalysis
What are classic electrolyte/acid–base findings with proximal
obstruction?
- Hypovolemic
- hypochloremic
- hypokalemia
- alkalosis
What must be ruled out on physical exam in patients with SBO?
Incarcerated hernia (also look for surgical scars)
What major AXR findings are associated with SBO?
Distended loops of small bowel air-fluid levels on upright film
Define complete SBO
Complete obstruction of the lumen
What is the danger of complete SBO?
Closed loop strangulation of the bowel leading to bowel necrosis
Define partial SBO
Incomplete SBO
What is initial management of all patients with SBO?
- NPO
- NGT
- IVF
- Foley
What tests can differentiate partial from complete bowel
obstruction?
CT scan with oral contrast
What are the ABCs of SBO?
Causes of SBO:
- Adhesions
- Bulge (hernias)
- Cancer and tumors
What is superior mesenteric artery (SMA) syndrome?
Seen with weight loss—SMA compresses duodenum, causing obstruction
What is the treatment of complete SBO?
Laparotomy and lysis of adhesions
What is the treatment of incomplete SBO?
Initially, conservative treatment with close observation plus NGT decompression
Intraoperatively, how can the level of obstruction be determined in
patients with SBO?
Transition from dilated bowel proximal to the decompressed bowel distal to the obstruction
What is the most common indication for abdominal surgery in
patients with Crohn’s disease?
SBO due to strictures
Can a patient have complete SBO and bowel movements and
flatus?
Yes; the bowel distal to the obstruction can clear out gas and stool
After a small bowel resection, why should the mesenteric defect
always be closed?
To prevent an internal hernia
What may cause SBO if patient is on Coumadin®?
Bowel wall hematoma
What is the #1 cause of SBO in adults (industrialized nations)?
Postoperative adhesions
What is the #1 cause of SBO around the world?
Hernias
What is the #1 cause of SBO in children?
Hernias
What are the signs of strangulated bowel with SBO?
- Fever
- severe/continuous pain
- hematemesis
- shock
- gas in the bowel wall or portal vein
- abdominal free air
- peritoneal signs
- acidosis (increased lactic acid)
What are the clinical parameters that will lower the threshold to
operate on a partial SBO?
- Increasing WBC
- Fever
- Tachycardia/tachypnea
- Abdominal pain
What is an absolute indication for operation with partial SBO?
- Peritoneal signs
- free air on AXR
What classic saying is associated with complete SBO?
“Never let the sun set or rise on complete SBO”
What condition commonly mimics SBO?
Paralytic ileus (AXR reveals gas distention throughout, including the colon)
What is the differential diagnosis of paralytic (nonobstructive)
ileus?
- Postoperative ileus after abdominal surgery
- (normally resolves in 3 to 5 days)
- Electrolyte abnormalities (hypokalemia is most common)
- Medications (anticholinergic, narcotics)
- Inflammatory intra-abdominal process
- Sepsis/shock
- Spine injury/spinal cord injury
- Retroperitoneal hemorrhage
What tumor classically causes SBO due to “mesenteric fibrosis”?
Carcinoid tumor
