Small Bowel Obstruction Flashcards
What is a small bowel obstruction?
Partial or complete mechanical blockage of small intestine
Most common cause of small bowel obstruction in developed countries ? Other common causes?
Intra-abdominal adhesions (65-70%), followed by hernias, crohns, malignancy, volvulus
Are small bowel obstructions common or uncommon?
Common
What % of emergency surgeries for abdominal pain are due to SBO?
20%
What % of surgical admissions are due to SBO?
12-16%
Is the incidence of SBO higher in men or women?
Similar instance for men and women
What complication significantly increases the mortality of SBO?
Bowel ischemia
Etiologies of SBO?
Processes extrinsic to wall of the small intestine (adhesions, hernia, volvulus)
Diseases intrinsic to wall of small intestine (tumor, stricture, intramural hematoma)
Processes that block an otherwise normal bowel lumen (intussusception, gallstones, foreign body)
Major causes of intestinal obstruction?
Herniation, adhesions, intussusception, volvulus
Risk factors for SBO?
Prior abdominal or pelvic surgery
Abdominal wall/groin hernia
Intestinal inflammation (crohns)
Hx or inc risk for neoplasm
Prior abdominopelvic irradiation
Hx of foreign body ingestion
Symptoms of SBO?
Colicky (crampy) abdominal pain, abdominal distention, nausea/vomiting, obstipation (late finding), decreased PO intake
Physical exam findings for SBO?
Abdominal distention, TTP/rebound, high pitched “tinkling” BS associated w pain, hypoactive BS (late obstruction)
Dehydration/systemic symptoms: tachycardia, hypotension, dry mucous membrane, reduced urine output, AMS (severe), +/- fever
Lab diagnostics for SBO?
CBC w diff, CMP, LFTs/lipase/amylase, Fecal occult blood test (FOBT), ABG, Lactate, Blood cultures
Purpose of CBC w diff for SBO?
Eval for leukocytosis, anemia
Purpose of CMP for SBO?
Evaluate for electrolyte abnormalities, kidney function
Purpose of LFTs, lipase, amylase for SBO?
Eval for liver, gallbladder, pancreas function
Purpose of FOBT for SBO?
Eval for blood in stool
Purpose of ABG in SBO?
Eval for metabolic alkalosis/acidosis
Purpose of Lactate for SBO?
Eval for ischemia/tissue hypoperfusion
Purpose of blood cultures for SBO?
Eval for bacteremia, guide Abx treatment
Imaging diagnostics for SBO?
Abdominal radiograph **preferred, CT abdomen/pelvis (further characterize nature/severity/etiologies of obstruction), US & MRI (typically reserved for pts that can’t tolerate CT)
What may be seen on an abdominal radiograph for SBO?
Dilated bowel loops and air-fluid levels (step-ladder appearance)
What may be seen on CT of abdomen/pelvis for SBO?
Transition zone from dilated loops of bowel w contrast to area of bowel w no contrast
Ddx for SBO?
Anything that can cause N/V, adynamic (paralytic) ileus, intestinal pseudo-obstruction, large bowel obstruction
What are the surgical correctable causes of SBO?
Closed-loop obstruction, volvulus, intussusception, incarcerated hernia, gallstone ileus, foreign body ingestion, small bowel tumor
Management of SBO depends on what?
Etiology, severity, & location of obstruction
Goals of initial management of SBO?
Relieve discomfort, restore fluid volume, acid-base balance, electrolytes
What would warrant immediate surgical exploration for SBO?
Bowel compromise and a surgical correctable cause
How many adhesion related SBOs resolve without surgery?
60-85%, but difficult to predict which pts will fail non-operative management
Non-adhesion related SBOs are usually due to what?
Another intraabdominal process (inflammation, infection), so targeted tx will lead to resolution of symptoms
What % patients are admitted for SBO will eventually require surgery?
25%
Management of SBO?
Admit, surgery consult, NPO, fluids, electrolytes, GI decompression (NG tube), abx (reserved for certain cases), Gastrografin (reserved for certain cases), immediate surgical exploration (reserved for certain cases)
What cases of SBO are abx reserved for?
Bowel compromise, standard peri operative prophylaxis, infectious processes
What cases of SBO is gastrografin reserved for?
Adhesive SBO without bowel compromise, CONTRAINDICATED IN PREGNANCY AND BOWEL COMPROMISE
What cases of SBO is immediate surgical exploration reserved for?
Suspected bowel compromise, surgically correctable causes, signs and symptoms of deterioration
What is paralytic ileus?
Interruption of normal passage of bowel contents due to reduced peristalsis in the absence of a mechanical obstruction
What is one of the most common causes of paralytic ileus?
Postoperative ileus
What does postoperative ileus following abdominal surgery appear to result from (even though pathogenesis is unclear)?
Inflammatory response to manipulation and trauma
As the intestine becomes distended in paralytic ileus, patients experience symptoms similar to what?
Mechanical obstruction, yet no demonstrable mechanical obstruction on diagnostic imaging
Other etiologies of paralytic ileus?
Meds: Opioids, anticholinergics
Electrolyte abnormalities: hypokalemia esp
Medical conditions (DM, stroke, spinal cord injury)
Clinical manifestations of paralytic ileus?
Abdominal distention, bloating, gassiness
Diffuse persistent abdominal pain
N/V
Delayed passing/inability to pass flatus/stool (obstipation)
Inability to tolerate PO
Hypoactive/absent bowel sounds
No peritoneal signs
Diagnostics for paralytic ileus?
Same labs as SBO, abdominal radiograph, CT of abdomen (when combo of Hx, PE findings, plain radiography cannot distinguish ileus from SBO)
What may be seen on an abdominal radiograph of paralytic ileus?
Dilated loops of bowel w no transition zone
What is the sensitivity & specificity of an abdominal CT to distinguish between ileus vs. complete SBO?
90-100%
*however, less reliable from distinguishing from a partial SBO vs. ileus
Management of paralytic ileus?
Correct reversible causes, supportive care - MAINSTAY: pain control, fluids, electrolytes, NGT/bowel decompression, nutritional support (TPN) until able to take/transition to PO, serial abdominal exams
Potentially treatable causes of paralytic ileus?
Abdominopelvic abscess, anastomotic leaks, anticholinergics, antihistamines, appendicitis, cholecystitis, hemoperitoneum or retroperitoneal hemorrhage, hypokalemia, hypomagnesemia, opiates, pancreatitis, sepsis, uremia
Abdominal distention may be present in what conditions?
Paralytic ileus and SBO
Bowel sounds in paralytic ileus vs. SBO?
Ileus: quiet or absent
SBO: high pitched or absent
Obstipation in paralytic ileus vs SBO?
May be present in both
Pain in paralytic ileus vs SBO?
Ileus: mild and diffuse
SBO: moderate to severe, colicky
Peritoneal signs of ileus vs SBO?
Ileus: absent
SBO: may be present
Radiography of paralytic ileus vs SBO?
Ileus: dilated loops of bowel, paucity of colonic gas
SBO: dilated loops of bowel, differential air-fluid levels, paucity or absence of colonic gas
Fever and tachycardia in paralytic ileus vs SBO?
Ileus: absent
SBO: should raise suspicion
Vomiting in paralytic ileus vs SBO?
Ileus: may be present
SBO: may be present, bilious or freculent
Other name for paralytic ileus?
Adynamic ileus
