L8: Bowel Obstruction Flashcards
Bowel obstruction pathophysiology
Obstruction→ bowel dilatation and retention of fluid within lumen proximal to obstruction, distal to obstruction bowel decompresses
Further distention→ from accumulation of swallowed air and gas from fermentation
Edematous bowel wall→ fluid sequestration→ volume depletion
Excessive dilatation→ compromised vascular supply→ poor perfusion→ ischemia→ necrosis→ perforation
Causes of bowel obstruction
Extrinsic/Extra-luminal
external to bowel
Intrinsic
within wall of bowel
Intraluminal
defect that prevents passage of GI contents
Why would adults get intussusception
It’s rare, and usually due to tumor
3 types of intestinal strangulation
Strangulated hernia
Volvulus
Intussusception
Blood supply to the small bowel
Superior mesenteric artery
Subdivisions of the small bowel and their role
Duodenum
Jejunum
Ileum
Digestion and absorption
Red flags in presentation/on exam of SBO
Obstipations
fever
tachycardia
hypotension
shock
Mild/moderate distress, lying motionless?
Peritoneal signs: guarding, rigidity, rebound tenderness
Etiology and risk factors for SBO
Adhesions (~ 65-75%)
Prior abdominal/pelvic surgery
Hernia (~10-20%)
Abdominal wall/groin hernia
Neoplasm (~10-20%)
Primary or metastatic tumor
Intestinal inflammation /Intra-abdominal abscess Strictures Inflammatory, Radiation, Ischemic, Anastomotic FB ingestion Intussusception, Volvulus
SBO presentation
+/- fevers/chills
Abdominal Pain
Initially may be periumbilical, intermittent, “cramping”
Focal and constant pain→ peritonitis (bad sign)
Abdominal bloating/distention
N/V/A/C
+/- hematochezia
Obstipation - inability to pass flatus or stool
Indications for surgical exploration of SBO
Complicated bowel obstruction (ischemia, necrosis, perforation)
→ worsening abdominal pain, fever, tachycardia, leukocytosis, metabolic acidosis, peritonitis
Intestinal Strangulation
Worsening symptoms or unresolved symptoms with NG tube and bowel rest
Exam of SBO
+/- fever, tachycardia, hypotension, shock
Mild/moderate distress, lying motionless?
+/- decreased skin turgor, dry mucous membranes
Abdominal Exam:
Inspection: note distention, scars, hernias
Auscultation: High pitched “tinkling” bowel sounds (early phase) or hypoactive/absent (late phase) (bad sign)
Percussion: Tympany
Palpation: Diffuse or localized abdominal tenderness, mass?
Peritoneal signs: guarding, rigidity, rebound tenderness
DRE: gross or occult blood, fecal impaction or rectal mass?
SBO Labs
CBC \+/- Increased H/H (hemoconcentration), +/- Leukocytosis, +/- anemia CMP \+/- Elevated BUN/Cr (dehydration), +/- lyte abnormalities Amylase/Lipase UA \+/- elevated specific gravity (dehydration) Lactate/LDH (tissue destruction) Plain Abdominal Films→ Supine + Upright Dilated loops of bowel, air fluid levels Proximal bowel dilation, distal bowel collapsed
SBO imaging
CXR→ free air from perforation
CT Scan with oral contrast
Location (transition point), severity (partial vs. complete), etiology , complications
Dilated proximal bowel with distal collapsed loops
Bowel wall thickening >3 mm
Submucosal edema
If X-ray and CT are contraindicated or there is need for further assessment consider:
Abdominal US
CT/MR enterography
UGI+SBFT
If you really know it’s SBO, what’s the best imaging?
Call the surgeon and let them decide
SBO is a surgical emergency when
Strangulated bowel leading to ischemia nad necrosis
Hypomotility of GI tract in absence of mechanical bowel obstruction
Ileus
Causes of ileus
Postoperative abdominal surgery (> risk open & lower GI)
From inflammatory response to intestinal manipulation & trauma
→ Physiologic: benign, self-limited
→ Pathologic: no return
of bowel function 4-6 days post op
Nonsurgical causes Hypomotility agents: opioids, antispasmodics,anticholinergics
If a patient comes in with: Abdominal pain Distention Bloating Gassiness N/V Inability to tolerate PO Think...
Ileus
Ileus on exam
Distention
Tympany
Variable reduction in bowel sounds
Mild tenderness
Imaging for ileus
Supine/upright films→ dilated loops of bowel but air still present in both small bowel & colon. No air fluid levels
Unsure→ CT
Ileus management
Supportive care with IV fluids Lyte replacement NSAIDs, avoid narcotics Bowel rest (NPO/CL diet +/- nutrition support) Persistent N/V → Bowel decompression with NG tube Serial abdominal exams Ambulate
Anatomy of the large intestine
Large intestine subdivided: Cecum, Ascending,
Transverse, Descending, Sigmoid Colon, Rectum
Vascular supply: SMA + IMA
Role: Right colon→ Absorbs water and
electrolytes, Left colon→ stores feces
Etiology of LBO
Adenocarcinoma→ commonly colon + rectum Stricture due to diverticulitis/ischemia Volvulus→ Sigmoid + Cecal IBD Fecal Impaction Foreign bodies
Presentation of LBO
\+/- fever/chills Crampy abdominal pain Bloating, distention Constipation/Obstipation \+/- N/V Normal to quiet bowel sounds Abdominal tenderness \+/- peritoneal signs Hematochezia DRE→ occult blood, impaction, rectal mass?
