Meckel s Diverticulum

Transcription

1 January 2007 Meckel s Diverticulum Alex Herrera, Harvard Medical School Year III

2 Meckel s Embryology Patent Duct Remnant of omphalomesenteric (vitelline) duct Complete obliteration normally occurs between week 5 and 7 of gestation Maintains blood supply from remnant of vitelline artery branch of ileal or (less commonly) ileocecal artery Fibrous connection Meckel s Levy AD, Hobbs CM. Meckel diverticulum: Radiologic features with pathologic Correlation. Radiographics Mar- Apr;24(2):

3 Anatomy of Meckel s Blind sac ANTI-mesenteric Usually within cm of ileocecal valve True diverticulum Normal: 5 cm length, 2 cm diameter Levy AD, Hobbs CM. Meckel diverticulum: Radiologic features with pathologic Correlation. Radiographics Mar-Apr;24(2):

4 Epidemiology 2% of population = most common congenital abnormality of GI tract Most patients present before age 2 (~60%) Complications occur in 4-16% 3-4x more frequent in males 4

5 Gastric mucosa Heterotopic tissue 60% of symptomatic pts Pancreatic tissue 6% of symptomatic pts Combined gastric and pancreatic Other (jejunal, duodenal, etc.) Ileal mucosa Gastric mucosa Levy AD, Hobbs CM. Meckel diverticulum: Radiologic features with pathologic correlation. Radiographics Mar-Apr;24(2):

6 Clinical Presentation Meckel s only presents when there are complications! 6

7 Clinical Presentation Children Painless GI bleeding is most common presentation Peptic ulcer from heterotopic gastric mucosa Adults Intestinal obstruction is most common presentation Strangulation of bowel Intussusception Littre s hernia Neoplasms Diverticulitis Gastric acid Enterolith 7

8 Companion Patient 1: Enterolith in Diverticulum on Plain Film Enterolith Dilated Meckel s Levy AD, Hobbs CM. Meckel diverticulum: Radiologic features with pathologic Correlation. Radiographics Mar-Apr;24(2):

9 Companion Patient 2: Inverted Meckel s on SBFT Tubular Filling Defect Turkington JR, Devlin PB, Dace S, Madden M. An unusual cause of intermittent abdominal pain (2006: 5b). Inverted Meckel's diverticulum. Eur Radiol Aug;16(8): Epub 2006 Jun 3 9

10 Companion patient 3: Intussusception of Meckel s on CT Scan Meckel s telescoped into normal bowel Ring of mesenteric fat Turkington JR, Devlin PB, Dace S, Madden M. An unusual cause of intermittent abdominal pain (2006: 5b). Inverted Meckel's diverticulum. Eur Radiol Aug;16(8): Epub 2006 Jun 3 10

11 Possible Imaging Modalities Abdominal plain film Ultrasound CT Barium studies Nuclear medicine scans Meckel s scan GI Bleeding scan Angiography Unreliable for diagnosis of Meckel s 11

12 Abdominal Plain Film and Companion Patient 4 Poor sensitivity Radiographic signs are nonspecific: Intestinal obstruction Enterolith Air/fluid levels Outpouching suggestive of Meckel s Ojha S, Menon P and Rao K. Meckels diverticulum with segmental dilatation of the ileum: radiographic diagnosis in a neonate. Pediatr Radiol Aug;34(8): Epub 2004 Mar

13 Ultrasound and Companion Patient 5 Hypoechoic, fluid-filled, tubular structure in RLQ Can be cystic Hypervascularization on Doppler Can visualize: Diverticulitis Intussusception Hypervasculariztion Ddx: Appendicitis Intestinal duplication M Baldisserotto, et al. AJR 2003; 180:

14 CT and Companion Patient 6 and 7 Non-specific findings unless attached to umbilicus or there is complication Common findings: Pouch containing fluid and air or particulate material Inflammatory changes in surrounding mesenteric fat Mural enhancement Connection to umbilicus Mural enhancement Ectopic pancreatic tissue Bennett GL, Birnbaum BA, Balthazar EJ. CT of Meckel's diverticulitis in 11 patients. AJR Am J Roentgenol Mar;182(3):

15 Possible Imaging Modalities Abdominal plain film Ultrasound CT Barium studies Nuclear medicine scans Meckel s scan GI Bleeding scan Angiography Preferred diagnostic tests for diagnosing Meckel s diverticulum 15

16 Barium Studies: SBFT and Enteroclysis Triradiate (surrounding bowel is collapsed) Triangular Plateau (surrounding bowel is patent) Eisenberg RL. GI Radiology: A Pattern Approach, 2nd edition. Philadelphia: Lippincott, Unreliable for detection of Meckel s Findings: Blind ending pouch Filling defect (inverted) Mucosal pattern: Triradiate Triangular plateau Limitations: Stenosis of neck Intestinal contents Peristalsis Small size 16

17 Companion patients 8 and 9: Mucosal Pattern of Meckel s on SBFT Triangular plateau Triradiate pattern Eisenberg RL. GI Radiology: A Pattern Approach, 2nd edition. Philadelphia: Lippincott, Meckel diverticulum: Radiologic features with pathologic Correlation. Radiographics Mar-Apr;24(2):

18 Enteroclysis Preferred by some radiologists Continuous distension of abnormal loops Frequent flouroscopy Limitations: Discomfort Side effects Increased radiation exposure 18

19 Meckel s Scan 99m Tc-Pertechnetate concentrates in mucussecreting cells of gastric mucosa Uptake in stomach and Meckel s simultaneous within 10 minutes of administration Pharmacologic enhancement (pentagastrin, cimetidine, glucagon) Advantages: Highly sensitive and specific (>90%) in children Disadvantages: Less sensitive and specific in adults 99m Tc-Pertechnetate concentrates in areas of increased blood flow 19

20 Limitations of Meckel s Scan False Positive Fake-outs Intestinal duplication Hemangiomas/AVMs Neoplasm (e.g. carcinoid) IBD and small bowel inflammation (hyperemia) False Negatives Absence of gastric mucosa Impaired vascular supply Brisk hemorrhage 20

21 Companion Patient 10: Meckel s Scan Anterior View Focus of Tc uptake in RLQ Stomach Meckel s typically appears in RLQ, but can present on either side of midline 21

22 GI Bleeding Scan 99m Tc-labeled autologous RBC accumulate in bowel at sites of active hemorrhage Sensitive for bleeding Meckel s, but not specific Specificity ~100% if subsequent Meckel s scan is positive Advantages: Can detect intermittent bleeding High sensitivity for low bleeding rate Bleeding rate of only 0.1 cc/sec required for detection 22

23 Companion Patient 11: GI Bleeding Scan Posterior View Meckel s usually present as increased activity in RLQ Can appear more superiorly or on either side of midline Area of increased activity PACS, BIDMC 23

24 Angiography Indications: Active GI bleeding High suspicion for Meckel s with negative Meckel s scan and barium studies Technique: Superselective SMA or ileal arteriography Positive findings: Extravasation = at least 0.5cc bleeding/sec Persistent vitelline artery supplying tubular structure in RLQ 24

25 Companion Patient 12: Selective SMA and Ileal Arteriography SMA Ileal artery Vascular blush Vitelline artery Mitchell AW, Spencer J, Allison DJ, Jackson JE. Meckel's diverticulum: angiographic findings in 16 patients. AJR Am J Roentgenol May;170(5):

26 Suggested Meckel s Work-up Barium stuides can be helpful, but Most sensitive and specific test is a Meckel s scan! If setting of acute GI bleeding, GI bleeding scan and/or angiography is indicated Meckel s scan may be falsely negative 26

27 Radiologic Work-up Algorithm Acute abdomen Findings suggestive of Meckel s on KUB, Barium, CT, or U/S Self-limited GI bleed prompts suspicion of Meckel s Acute GI hemorrhage Indeterminate EGD/Colonoscopy Meckel s Scan - + Surgery - + GI Bleeding Scan Angiography 27

28 Patient Presentation, 8/22/04 JD is a 20 year old male who presents to an OSH with: 10 episodes of blood per rectum over 24 hours He becomes pale and diaphoretic after having another bloody stool while waiting in the ED No history of aspirin or NSAID use PMH: non-contributory PE: significant for tachycardia to 122, BP 99/49, and gross blood on rectal exam. No abdominal tenderness or external hemorrhoids noted. 28

29 OSH Hospital Course Significant labs: Hct 24.2, WBC 13.5, normal PT, PTT, INR Diagnostics: Colonoscopy showed dark red blood throughout colon without active bleeding site EGD normal to 2 nd portion of duodenum 99m Tc GI bleeding scan showed small focus of increased activity at region of terminal ileum Meckel s scan showed possible uptake at L5 level Therapeutics: JD received IV fluids and 7 units of PRBCs over the course of his stay 29

30 Transfer to BIDMC, 8/30/04 JD was transferred to the BIDMC for further work-up. On 8/31, JD underwent a Meckel s scan and a GI bleeding scan. 30

31 Our Patient JD: Meckel s Scan 8/31/04 Anterior View Negative Scan Bladder PACS, BIDMC 31

32 JD: GI Bleeding Scan 8/31/04 Posterior View Spleen Negative Scan PACS, BIDMC 32

33 Discharge On 9/01, colonoscopy, EGD, and capsule endoscopy were negative. JD was stabilized and discharged on 9/2 without a clear etiology for his GI bleeding. 33

34 Differential Diagnosis The differential diagnosis based on his course included: Meckel s diverticulum AVM or angiodysplasia IBD Infectious ileitis/colitis Neoplasia 34

35 14 months later, 11/12/05 JD, now 21 years old, is admitted directly to the medical ICU with massive GI bleeding. A GI bleeding scan is performed on the same day 35

36 Our patient JD: GI Bleeding Scan 0-60 min 11/12/05 Posterior View min min PACS, BIDMC Bleeding in terminal ileum 36

37 Findings and Differential Diagnosis Tracer activity in center of pelvis at 90 minutes, corresponding to terminal ileum Extends antegrade into ascending colon DDx for terminal ileum hemorrhage: AVM or angiodysplasia Meckel s Colonoscopy was performed to localize and potentially treat (if found to be AVM) the lesion 37

38 JD: Colonoscopy, 11/12/04 A clot and then fresh blood was seen coming from the ileocecal valve Old blood was pooled throughout the colon Angiography recommended to localize lesion and embolize possible AVM PACS, BIDMC 38

39 JD: SMA Arteriogram 11/13/05 Negative arteriogram Selective ileal arteriogram recommended PACS, BIDMC 39

40 Selective Ileal Arteriogram 11/14/05 Persistent vitelline artery PACS, BIDMC 40

41 Conclusion JD underwent successful surgery to remove the Meckel s diverticulum seen on ileal arteriography. Pathology demonstrated a 3cm Meckel s diverticulum with diffuse gastric heterotopia. 41

42 Summary Meckel s diverticulum commonly presents as GI bleeding in the pediatric population Meckel s presents less commonly in adults, usually as obstruction or diverticulitis 99m Tc-Pertechnetate scan is the best test for diagnosing a Meckel s diverticulum For active GI bleeding, GI bleeding scan and/or angiography can aid diagnosis 42

43 References Rossi P, Gourtsoyiannis N, Bezzi M, Raptopoulos V, Massa R, Capanna G, Pedicini V, Coe M. Meckel s Diverticulum: Imaging Diagnosis. AJR Am J Roentgenol Mar;166(3): Bennett GL, Birnbaum BA, Balthazar EJ. CT of Meckel's diverticulitis in 11 patients. AJR Am J Roentgenol Mar;182(3): Baldisserotto M, Maffazzoni DR, Dora MD. Sonographic findings of Meckel's diverticulitis in children. AJR Am J Roentgenol Feb;180(2): Mitchell AW, Spencer J, Allison DJ, Jackson JE. Meckel's diverticulum: angiographic findings in 16 patients. AJR Am J Roentgenol May;170(5): Pantongrag-Brown L, Levine MS, Buetow PC, Buck JL, Elsayed AM. Meckel's enteroliths: clinical, radiologic, and pathologic findings. AJR Am J Roentgenol Dec;167(6): Eisenberg RL. GI Radiology: A Pattern Approach, 2 nd edition. Philadelphia: Lippincott, Levy AD, Hobbs CM. Meckel diverticulum: Radiologic features with pathologic Correlation. Radiographics Mar-Apr;24(2): Turkington JR, Devlin PB, Dace S, Madden M. An unusual cause of intermittent abdominal pain (2006: 5b). Inverted Meckel's diverticulum. Eur Radiol Aug;16(8): Epub 2006 Jun 3. Ojha S, Menon P and Rao K. Meckels diverticulum with segmental dilatation of the ileum: radiographic diagnosis in a neonate. Pediatr Radiol Aug;34(8): Epub 2004 Mar 12. Nagi B, Kochhar R, Malik AK. Inverted Meckel diverticulum shown by enteroclysis. AJR Am J Roentgenol May;156(5):

44 Acknowledgements I would like to thank: Jacques Tham, MD Anthony Parker, MD, PhD Pamela Lepkowski Larry Barbaras 44