Introduction
Imagine a 38-year-old woman arriving at the emergency room after enduring a week of abdominal pain, bloody stools, and vomiting. Initial tests suggest a bowel obstruction, but the underlying cause remains elusive even with advanced imaging. This scenario represents a genuine diagnostic challenge in emergency medicine: intussusception in adults caused by a rare combination of anatomical and tissue abnormalities 1 . Unlike childhood intussusception, which often has no clear structural cause, the adult version typically has a identifiable lead point, frequently overlooked during initial assessment.
Rare Condition
Accounts for only 1% of adult bowel obstructions
Diagnostic Challenge
Often misdiagnosed due to nonspecific symptoms
Surgical Solution
Most cases require surgical intervention
This article explores one of medicine's fascinating rarities—ileocaecal intussusception resulting from Meckel's diverticulum containing heterotopic pancreatic tissue. Through the lens of a clinical case, we'll unravel the embryological origins, diagnostic complexities, and treatment approaches for this unusual condition that bridges congenital development and adult abdominal emergencies.
Understanding Meckel's Diverticulum: The Body's Vestigial Remnant
Meckel's diverticulum represents the most common congenital anomaly of the gastrointestinal tract, affecting approximately 2% of the general population 9 . This curious structure is essentially a persistent remnant of the omphalomesenteric duct (vitelline duct), which normally connects the developing embryo's yolk sac to its primitive gut during early gestation 1 . While this connection typically obliterates by the 7th week of fetal development, its incomplete disappearance leaves behind this pouch-like projection from the small intestine.
Key Characteristics
- True Diverticulum: Contains all layers of the intestinal wall
- Strategic Location: Found on antimesenteric border of ileum
- Size Variations: Ranges from 0.4 to 11 cm in length
- Asymptomatic: Remains symptom-free in most individuals
Symptom Patterns by Age Group
| Age Group | Most Common Presentation | Secondary Presentation | Least Common Presentation |
|---|---|---|---|
| Children | Intestinal obstruction (46.7%) | Hemorrhage (25.3%) | Inflammation (19.5%) |
| Adults | Intestinal obstruction (35.6%) | Inflammation (29.4%) | Hemorrhage (27.3%) |
Heterotopic Pancreas: The Body's Misplaced Tissue
Heterotopic pancreas (also called ectopic, accessory, or aberrant pancreas) is defined as pancreatic tissue located outside the normal pancreas, without any anatomical or vascular connection to it 2 . This fascinating tissue anomaly occurs due to embryological displacement of pancreatic tissue during development, potentially during the rotation and fusion of the pancreatic buds in the developing foregut 7 .
Incidence and Locations
The incidence of heterotopic pancreas ranges widely from 0.5% to 14% in autopsy studies, with the most common locations being:
When found in Meckel's diverticulum—which occurs in approximately 6% of cases—it creates a perfect storm for complications 2 .
Classification System
Type 1
Contains all elements of normal pancreas
Type 2
Contains only excretory glands and ducts
Type 3
Contains only excretory ducts 7
Intussusception: The Telescoping Bowel Mechanism
Intussusception is best described as a "telescoping" phenomenon where a proximal segment of the intestine (the intussusceptum) invaginates into an adjacent distal segment (the intussuscipiens) 1 . This process can lead to bowel obstruction, compromised blood flow, ischemia, and eventually necrosis if not promptly addressed 8 .
Pediatric Intussusception
- Common between 3 months and 3 years
- Often idiopathic (no clear cause)
- Acute, dramatic presentation
- Often treated with non-surgical reduction
Clinical Presentation
The clinical presentation of intussusception includes intermittent abdominal pain (sometimes described as "crampy"), nausea, vomiting, and occasionally the passage of bloody mucus—classically described as "red currant jelly" stools 8 . In adults, the symptoms may be more insidious, often leading to delays in diagnosis.
Warning Signs
Abdominal pain + Bloody stools = Medical emergency
The Perfect Storm: A Case Analysis
Let's examine in detail the case of the 38-year-old woman introduced at the beginning of this article, which exemplifies the diagnostic challenges posed by this condition 1 .
Clinical Presentation and Diagnostic Journey
Initial Presentation
The patient arrived with a one-week history of intermittent, cramp-like abdominal pain accompanied by bloody stools and bilious vomiting—classic signs of intestinal obstruction.
Physical Examination
On examination, she had a distended abdomen with diffuse tenderness.
Laboratory Findings
Initial laboratory studies revealed leukocytosis (elevated white blood cells suggesting inflammation) and surprisingly elevated lipase levels, though without pancreatic inflammation on imaging.
Imaging Results
A contrast-enhanced CT scan of her abdomen and pelvis demonstrated a long-segment intussusception in the distal ileum with proximal small bowel dilation—clear evidence of mechanical obstruction. However, the scan couldn't definitively identify the specific lead point causing the telescoping 1 .
Surgical Intervention and Findings
Surgical Procedure
Given the clear evidence of bowel obstruction with a structural lead point, the patient underwent exploratory laparotomy. The surgical team discovered an extensive ileo-ileal intussusception approximately 80% of which they could reduce through manual pressure. However, a segment remained irreducible, necessitating segmental small bowel resection with end-to-end anastomosis 1 .
Pathological Findings
Examination of the resected specimen revealed the culprit: a Meckel's diverticulum that had served as the lead point for the intussusception. Further histopathological examination delivered the final surprising discovery—the diverticulum contained heterotopic pancreatic tissue without evidence of malignancy or ectopic gastric mucosa 1 .
Diagnostic Modalities and Their Effectiveness
| Diagnostic Method | Utility | Limitations |
|---|---|---|
| CT Scan | Excellent for identifying bowel obstruction and intussusception; can show target lesion | Often fails to specifically identify Meckel's diverticulum as the lead point |
| Meckel's Scan (Technetium-99m) | Detects ectopic gastric mucosa (sensitivity enhanced with pharmacologic agents) | Limited value when only pancreatic ectopic tissue present; false negatives common |
| Ultrasound | Can show "doughnut" or "bull's eye" sign of intussusception | Operator-dependent; less effective in obese patients or with excessive bowel gas |
| Double Balloon Enteroscopy | Allows direct visualization and potential biopsy | Invasive; not universally available |
| Capsule Endoscopy | Non-invasive visualization of small bowel | Cannot obtain biopsies; risk of retention in obstruction |
The Scientist's Toolkit: Key Research Reagents and Diagnostic Solutions
Understanding this complex condition requires specialized tools and reagents that enable precise diagnosis and histological confirmation.
| Tool/Reagent | Primary Function | Application in This Condition |
|---|---|---|
| Technetium-99m Pertechnetate | Radioactive tracer | Taken up by ectopic gastric mucosa in Meckel's diverticulum; helps pre-operative identification |
| H&E Staining | Basic histological staining | Visualizes tissue architecture and confirms presence of all intestinal wall layers in diverticulum |
| Immunohistochemistry Markers | Tissue-specific protein identification | Confirms pancreatic acinar cells (trypsin, lipase) or endocrine cells (chromogranin, synaptophysin) |
| CT with Contrast | Cross-sectional imaging | Identifies bowel obstruction, intussusception pattern, and potential lead points |
| Laparoscopic Equipment | Minimally invasive surgical visualization | Allows direct inspection and resection without large laparotomy incision |
Research Limitations and Future Directions
The comprehensive understanding of Meckel's diverticulum with heterotopic pancreas causing intussusception faces several research challenges:
Future Research Directions
Future research directions include developing better preoperative identification methods, potentially through advanced nuclear medicine techniques or improved endoscopic approaches. Additionally, larger multicenter studies might help establish clearer guidelines for managing incidentally discovered diverticula based on specific risk factors.
Conclusion: A Rare Condition with Important Clinical Lessons
The case of an adult with ileocaecal intussusception due to Meckel's diverticulum containing heterotopic pancreatic tissue represents a remarkable convergence of multiple rare gastrointestinal phenomena. This condition highlights several crucial clinical principles:
Silent Anomalies
Congenital anomalies can remain silent for decades before manifesting in adulthood
Unusual Diagnoses
Consider unusual diagnoses when common conditions have been ruled out
Histopathological Value
Critical value of histopathological examination for definitive diagnoses
For surgeons and gastroenterologists, this condition serves as a reminder that Meckel's diverticulum, while rare in adults, should remain in the differential diagnosis for small bowel obstruction and intussusception—even when initial imaging doesn't specifically identify it. The presence of heterotopic pancreatic tissue further complicates the clinical picture by creating additional secretory potential within the diverticulum.
As medical science advances, perhaps future clinicians will have more tools at their disposal to identify these anomalies before they cause complications. Until then, this case stands as a testament to the diagnostic challenges and therapeutic precision required in managing complex abdominal emergencies that bridge embryological development and adult pathology.