Meckel’s Diverticulum

  1. Anatomy and Physiology
    1. Is a congenital abnormality that occurs in about 2% of the pediatric population
    2. Is caused is a bulge in the lower portion of the small intestine and a congenital defect. Essentially it is a left over form the umbilical courd
    3. Usually found in the antimesenteric side of the small bowel and approximately 46 to 67 cm from the ileocecal valve
    4. Ranges between 1 to 12 cm in size
    5. Approximately 25% of the time it contains gastric mucosal cells
    6. Pain and GI bleeding is usually associated with this abnormality
    7. Patient is usually asymptomatic
    8. Bleeding is caused by HCl and pepsin secreted from ectopic gastric mucosa causing ulceration to the adjacent tissue

  2. Rules of 2s
    1. Occurs in 2% of the population
    2. Is usually within 2 feet of the ileocecal valve
    3. Average length is 2 inches
    4. Patient is usually symptomatic by the age of 2
  3. Pathophysiology of the radiopharmaceutical
    1. 99mTcO4- is used
    2. Pertechnetate has an affinity for mucosal cells
    3. If Meckel's is present, when pertechnetate is injected a hot spot in the lower abdomen is seen
  4. Procedure
    1. Patient should be NPO 12M
    2. Patient is placed in the supine position
    3. Camera/Computer setup
      1. 256 x 256 matrix
      2. Collimator – LEHR or LEGap
      3. Five minute acquisitions
    4. Place the camera head in the anterior projection over the abdomen
    5. Inject 200 μCi/kg of 99mTcO4- IV
    6. Take 1 image every 5 to 10 minutes for an hour
    7. Display data
    8. Pharmacologic intervention can further enhance detection
      1. Glucagon promotes pooling and prevents pertechnetate from moving down the GI track (dose – 50 to 100 μg)
      2. Pentagastrin – increases pertechnetate uptake (dose – 6 μg/kg)
      3. Cimetidine – as a histamine antagonist and blocks secretion of pertechnetate from the gastric mucosal cells (dose – 300 mg QID for 1 – 2 days)
      4. Ranitidine – just like cimetidine, however, there are fewer side effects (dose – 1 mg/kg given IV over 20 minutes: start the procedure 1 hour post dose)
  5. Case Review
    1. Case 1

        2. mecklesnormal.jpg - 31849 Bytes

      1. The above example is of a normal Meckel’s scan taken over 60 minutes
      2. Note the distribution of pertechnetate
        1. Stomach becomes very intense with activity – why?
        2. Significant background is seen throughout the body – why?
        3. Notice how the myocardium initially appears very intense, but decreases in activity over time – why?
    2. Case 2

        3. mecklesabn.jpg - 24597 Bytes

      1. The above is an example of an abnormal study
      2. Notice that over time an increase of activity is seen in the lower right quadrant of the abdomen (red arrow)
      3. This is the location of the Meckel’s Diverticulum
  6. Sensitivity/Specificity
    1. Sensitivity is 85% or greater
    2. Specificity is 95%
    3. Main reason for a false negative exam is the lack of gastric muscosal cells in the diverticulum

Meckel’s Diverticulum Procedure
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