Small Bowel Diverticula


Small Bowel Diverticula

  1. Meckel’s Diverticulum
    • found in 2% of the population
    • true diverticulum containing all four bowel wall layers
    • usually occurs within 100 cm of the ileocecal valve
    • majority contain heterotopic gastric or pancreatic mucosa
    • results from failure or incomplete vitelline duct obliteration

    Meckel's Diverticulum
    1. Clinical Manifestations
      • asymptomatic unless complications occur

      1. Bleeding
        • most common complication in the pediatric population
        • rare complication in older patients
        • results from an ileal ulceration adjacent to acid-producing heterotopic gastric mucosa located within the diverticulum

      2. Obstruction
        • most common complication in adults
        • may occur as a result of intussusception with the diverticulum acting as a lead point
        • volvulus may occur if there is a fibrous band attaching the diverticulum to the umbilicus

      3. Diverticulitis
        • clinically indistinguishable from appendicitis

    2. Diagnosis
      • in a bleeding pediatric patient, a Meckel’s radionuclide scan is 90% accurate in identifying a Meckel’s diverticulum
      • in symptomatic adults, the majority are identified during laparoscopy or laparotomy

    3. Surgical Management
      1. Symptomatic Patients
        • bleeding patients should have a segmental resection, including the ileal ulceration
        • segmental resection will also be required if the base of the diverticulum is inflamed or perforated
        • diverticulectomy may be possible in patients with obstruction from intussusception

      2. Incidentally Found Meckel's Diverticulum
        • most surgeons do not perform prophylactic diverticulectomy
        • however, any bands attaching the diverticulum to the abdominal wall should be lysed to prevent a future volvulus

  2. Duodenal Diverticula
    • false diverticula, only containing the mucosa and submucosa
    • majority are located near the ampulla on the medial wall of the duodenum and may involve the pancreas
    • detected on 5% - 27% of ERCPs

    Periampullary Diverticulum
    1. Pathophysiology
      • acquired defect
      • results from herniation through the bowel wall at sites where large vessels enter
      • dysmotility from increased intraluminal pressures may also play a role

    2. Clinical Manifestations
      • majority are asymptomatic
      • rarely, may cause bleeding, biliary obstruction or recurrent pancreatitis
      • may cause technical challenges during ERCP for choledocholithiasis

    3. Management
      • asymptomatic diverticula should be left alone
      • symptomatic lateral wall diverticula can be managed with diverticulectomy
      • symptomatic medial wall diverticula should be managed endoscopically if possible

  3. Jejunal/Ileal Diverticula
    • majority are false diverticula
    • usually multiple and localized to the proximal jejunum
    • often associated with intestinal dysmotility

    Jejunal Diverticula
    1. Clinical Manifestations
      • most are asymptomatic
      • some patients develop bacterial overgrowth: bloating, malabsorption, steatorrhea, vitamin B12 deficiency
      • additional complications include bleeding, obstruction, diverticulitis

    2. Management
      • bacterial overgrowth and diverticulitis are treated with antibiotics
      • bleeding will require identification of the bleeding site, which may require tagged RBC bleeding scans and/or angiography
      • surgical management of bleeding or obstruction will require segmental resection

Chronic Radiation Enteritis

  1. Pathophysiology
    • Radiation therapy for pelvic cancers may result in a progressive occlusive vasculitis that leads to chronic ischemia and fibrosis of the small bowel
    • These changes can result in strictures, abscesses, and fistulas
    • Terminal ileum is the most frequently involved segment

  2. Clinical Manifestations
    • Most patients become symptomatic within 2 years of treatment, although in some patients symptoms do not develop until many years later
    • Partial small bowel obstruction is the most common presentation – crampy abdominal pain, nausea, and vomiting
    • Complete small bowel obstruction, lower GI bleeding, and abscesses and fistulas are less common presentations

  3. Diagnosis
    • Contrast studies will show luminal narrowing, loss of mucosal folds, and ulceration
    • CT scanning is neither sensitive nor specific for radiation enteritis, but it is valuable to rule out recurrent cancer

  4. Indications for Surgery
    • Obstruction that does not resolve with conservative therapy
    • Perforation
    • Intra-abdominal abscesses
    • Fistulas
    • Hemorrhage

  5. Surgical Management
    • Goal is a limited resection with primary anastomosis between healthy bowel segments
    • Limited resection, however, is often difficult because of diffuse fibrosis and dense adhesions
    • Distinguishing between normal and irradiated bowel can also be challenging at times
    • Anastomoses between irradiated segments have a leak rate of 50%
    • Mortality rate is 10%
    • If a limited resection is not feasible, then an intestinal bypass procedure may be the best option







References

  1. Schwartz, Principles of Surgery. 10th ed., Pgs 1162 - 1167
  2. Sabiston, Textbook of surgery. 20th ed., Pgs 1280 - 1286, 1290 - 1291