Bowel Obstruction

Functional bowel obstruction (paralytic ileus)

• ↓ peristalsis

• Localized ➔ sentinel loops (dilated loops adjacent to irritation)

  • Appendicitis, pancreatitis, cholecystitis, diverticulitis, ureteral stones

• Generalized (involves large & small bowel) parkinson, DM, or auto-immune (SLE)

  • Post-op ileus (normal response to ABD surgery that resolves without serious sequelae)

  • Prolonged post-op ileus has at least two ssx on POD 4:

    • N/V, can't tolerate PO for 24hrs, no flatus for 24hrs, ABD distention, imaging confirms

Mechanical bowel obstruction (structural barrier)

• SBO: Adhesions from previous ABD surgeries MCC, incarcerated hernia 2nd MCC

• LBO (Sigmoid MC): Neoplasm MCC, diverticulitis

• Partial small bowel obstruction 

  • MC from strictures associated with Crohn disease, adhesions, tumors, radiation strictures

  • Colicky or constant pain, tenderness, post-pranidal pain

• Complete bowel obstruction:

  • Bowel twisting or two points of obstruction ➔ closed loop ➔  obstipation (inability to pass stool or flatus) 

  • Volvulus twisting of bowel (MC sigmoid, 2nd MCC cecal)

• Complicated (MC in complete obstruction)

  • Ischemia/necrosis, perforation ➔ peritoneal ssx (rebound tenderness, rigidity, guarding)

    • Shocky (hypotension, tachy)

    • ± ↑ WBC

Intussusception (peds)

• Proximal bowel invaginates into distal bowel ➔ obstruction

• Idiopathic MC, or abnormalities that mess with bowel ➔  pathological lead point (Meckel diverticulum, adhesions)

• 3mo-1yo MC

  • Can occur up to 5yo (can occur later in pts with cystic fibrosis)

SSX:

• Well looking (not malnourished) infant with acute, cyclic attacks (~every 20 mins)

• Crying, legs drawn in, non-bilious ➔ bilious vomiting

• Sausage shaped mass in RUQ

• Currant jelly (dark red) stool is a late sign

DX:

• ABD US shows target sign (invagination or bowel)

TX:

• NPO, NGT for distension or N/V, IV fluid and electrolyte repletion

• Air enema and observe for 24hrs

• Surgery if sick

Mesenteric arterial embolism MC (thrown clot)

• RF: arrhythmias (AFIB), endocarditis, recent MI, recent invasive cardiac/aorta procedure

Mesenteric arterial > venous thrombosis (thrombotic occlusion)

• Pts with hx of atherosclerosis or PAD

Nonocclusive (intestinal hypoperfusion) 2nd MC

• Hypotension/hypovolemia in sepsis/dehydration, vasoconstrictive drugs

Secondary to

• Adhesions ➔ obstruction/volvulus, tumors, incarcerated/strangulated hernia

• Distention from obstruction ➔ ↑ venous pressure/venous thrombosis

Acute mesenteric ischemia

• Acute inadequate blood flow to small bowel can ➔ infarct of bowel

• Subtherapeutic elderly pt with afib

• Hx/family hx of thrombotic event

SSX:

• Sudden abd pain and tenderness (out of proportion to exam), N/V, bloody diarrhea

  • Venous thrombosis may ➔ insidious onset abd pain

• Prolonged ischemia ➔ ↑ pain

• Advanced ischemia  ➔ transmural necrosis ➔ metabolic acidosis, sepsis, perforation

DX:

• Peritoneal/perforation signs (rebound tenderness, air under diaphragm), shocky/sick ➔ DX in OR

• ABD CT angiography (not PO contrast)

• Conventional arteriography if CTA non-dx

TX:

• Sick pts go right to OR 

  • Open/lap embolectomy/resection of necrotic bowel

• IV fluid and electrolyte repletion, NPO, NGT, pain control

• Heparin only if arterial/venous occlusion, NOT if nonocclusive/hypoperfusion

• Broad spectrum ABX

• Stable pts without advanced ischemia may get endovascular revascularization 

Chronic mesenteric ischemia

• ♀ > ♂ 

• Atherosclerosis (MC) ➔ constant hypoperfusion of small bowel

• ↑ risk of acute mesenteric ischemia (acute on chronic)

SSX:

• "Intestinal angina" - dull, crampy, postprandial abd pain

• Pain with eating ➔ weight loss ➔ delay in DX (looking for other causes)

DX:

• Calcification of mesenteric vessels on plain films may be present

• ABD CT angiography (conventional arteriography if CTA non-dx)

TX:

• Limit progression of atherosclerosis (smoking cessation)

• Revascularization, angioplasty/stenting in severe stenosis

PATHO:

• Enlarged lymphoid follicle (MCC in children), undigested food, or fecalith (MC in adults) ➔ obstruction ➔ bx overgrowth

• Inflammation ➔ ↑ intraluminal pressure ➔ edema ➔ ischemia ➔ necrotic appendix ± perforation 

• Significant inflammation/necrosis ➔ ↑ risk of perforation ➔ localized abscess formation or peritonitis

SSX:

• Anorexia (appendicitis is unlikely if appetite is still present)

• Fever (usually low grade in adults), ↑ WBC, ↑ CRP

• Classically begins as periumbilical pain ➔ RLQ pain (for <2d)

• McBurney point tenderness (RLQ)

• Rovsing sign - RLQ pain from LLQ palpation

• Psoas sign - RLQ pain with pt in LLR position: passive extension of right hip OR Pt supine: active flexion of right hip against resistance

  • Indicates retrocecal appendix

• Obturator sign - RLQ pain with pt supine, hip and knee flexed, passive internal rotation of hip

DX

• Call an adult (surgery)

• CT ABD/pelvis with IV contrast is the preferred imaging in adults (can use ABD US)

• Children with typical appendicitis presentation usually have appendicitis - call surgery prior to imaging

• US first for kids (limit radiation) and call surgery

TX always Surgery 

• ABX instead of appendectomy is not recommended