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Abstract
Meckel’s diverticulum is the remain of the prenatal yolkstalk(Vitellointestinal duct). The yolk sac of the developing embryo is connected to the primitive gut by the vitelline duct. This structure normally regresses between the fifth and seventh weeks of fetal life. If this process of regression fails, various anomalies can occur. The spectrum of defects includes a Meckel diverticulum, a fibrous cord attaching the distal ileum to the abdominal wall an umbilical-intestinal fistula,a mucosa-lined cyst, or an umbilical sinus. Of these, Meckel’s diverticulum is the most common congenital anomaly of the gastrointestinal tract in humans.
It is located on the antimesentric border of the ileum 45 to 60 cm proximal to the ileocecal valve and is usually 3-5 cm long
It is true diverticulum because it contains all the three layers of the intestinal wall and has its own blood supply from the superior mesenteric artery, which makes it vulnerable to infection and obstruction like appendix
Since cell lining of vitelline duct are pluripotent, we may get heterotopic gastric mucosa (50%), pancreatic mucosa (5%) and less commonly colonic mucosa, endometriosis, hepatobiliary tissue,
The vast majority of Meckel’s diverticula are incidentally discovered during autopsy, laparotomy, or barium studies. The most common clinical presentations of the Meckel’s diverticulum are gastrointestinal bleeding (from chronic acid-induced ulcer in the ileum adjacent to a Meckel’s diverticulum that contains gastric mucosa), intestinal obstruction, and diverticulitis. Incidence of tumours within the Meckel’s diverticulm is 0.5 to 3.2%
Bleeding is the most common presentation in children and is reported in over 50% of cases. Children often present with dark red or maroon stools or stools with blood or mucus, whereas adults usually present with melena and crampy abdominal pain.
Ninety percent of bleeding diverticula contain heterotropic mucosa, most often gastric mucosa.
Intestinal obstruction is the most common complication in adult patients.The most common obstruction was intussusception or invagination, with the Meckel’s diverticulum being the lead point.
Other causes of obstruction include volvulus around fibrous bands adherent to the umbilicus, inflammatory adhesions, Littre’s hernias and diverticular strictures.
The second most common complication in adults appears to be related to an inflammatory process. Diverticulitis and perforation occur at a combined rate of almost 20% and are often indistinguishable from acute appendicitis until visualization in the operating room.
Tumors in Meckel’s diverticulum are very rare occurrences, with incidence of only 0.5% to 1.9%. These tumors can be benign or malignant. Lipoma, Neuromuscular and vascular hamartoma are among the benign group.In the malignant group, carcinoids are the most common tumor occurring with 44% of incidence. Others are mesenchymal tumors (including gastro intestinal stromal tumors, leiomyosarcomas and peripheral nerve sheath tumors, adenocarcinomas ,and Desmoplastic small round cell tumor .
Various imaging techniques have been used for diagnosing Meckel’s diverticulum. Conventional radiographic examination is of limited value and is usually unrevealing. However, it may show enteroliths, findings of bowel obstruction, and the presence of gas or a gas–fluid level in the diverticulum.
Barium studies have been largely replaced by other imaging techniques for evaluation of patients with acute symptoms.
On barium studies, Meckel’s diverticulum appears as a blind-ending pouch arising from the antimesenteric side of the distal ileum. Filling defects in the diverticulum may suggest gastric mucosa or tumor.
High-resolution ultrasonography usually shows a fluid-filled structure in the right lower quadrant having the appearance of a blind-ending, thick-walled loop of bowel, with the typical gut signature and a clear connection to a peristaltic, normal small-bowel loop.
On CT, Meckel’s diverticulum is difficult to distinguish from normal small bowel in uncomplicated cases. However, a blind-ending fluid or gas-filled structure in continuity with small bowel may be seen. CT may also show enteroliths, intussusception, diverticulitis, and small bowel obstruction. A recent innovation of CT enterography has resulted in better visualization of small bowel and consequent higher sensitivity in the diagnosis of Meckel’s diverticulum.
Technetium-99m pertechnetate radioisotope scintigraphy has been utilized universally for the diagnosis of bleeding Meckel’s diverticulum and is at present the investigation of choice in a suspected Meckel’s diverticulum bleeding.
Angiography may be useful in the evaluation of an adult patient with occult or intermittent gastrointestinal bleeding for the localization of the site of bleeding, specific diagnosis, and therapeutic preoperative embolization. A vascular blush may also be identified at the site of the Meckel diverticulum. When active hemorrhage is occurring at the time of angiography, luminal extravasation of contrast material will be present.
The aim of the surgery in case of bleeding is to resect the Meckel’s diverticulum, all ectopic gastric mucosa, and any ulcerated adjacent ileum to prevent recurrent bleeding. During surgery if we find a narrow base without any mass in the lumen, then a wedge resection of the diverticulum with transverse closure of the ileum is the ideal method. We can use linear stapler in this situation to close the ileum. But when the base is wide or mass of ectopic tissue is palpable or when there is inflammation, it is preferable to resect the involved bowel followed by end-to-end ileoileostomy.
Intestinal Obstruction should be treated as an emergency situation warranting immediate exploratory laparotomy after initial resuscitation. During exploration if we get volvulus around a fibrous band, untwisting of bowel along with division of band should be done. In case of intussusception, attempts to reduce such mass may be difficult, warranting resection of intussuscepted mass followed by primary anastomosis. However in Litter’s hernia, Meckel’s diverticulum should be resected after reducing it followed by hernial repair.
Thus in cases of intestinal obstruction, the main aim of surgery is still to remove the culprit i.e. Meckel diverticulum along with correction of associated pathology, independent of the chosen surgical approach being either open or laparoscopic.
If diverticulitis is left untreated, it usually leads to perforation and peritonitis. This condition should be dealt with a surgical approach that can be open or laparoscopic, with resection of diverticulum at its base and closure perpendicular to the axis of intestine to minimize the risk of subsequent stenosis. And if perforation has occurred, thorough peritoneal toileting is done after resection.
Lipoma and other benign tumer can be dealt with simple diverticulectomy. Since Carcinoid is associated with metastasis early in course (in 25% of cases), solitary, localized, asymptomatic nodules less than 1 cm are generally managed with diverticulectomy or segmental resection. Larger or multiple lesions require wide excision of bowel and mesentery, and hepatic resection may be required for metastatic disease.
the treatment of symptomatic Meckel’s diverticulum should be prompt surgical resection of the diverticulum or resection of segment of adjacent ileum bearing the diverticulum. Segmental ileal resection is required for the treatment of patients with bleeding because bleeding site is usually in the adjacent ileum.
The management of Meckel diverticulum found unexpectedly during an abdominal operation remains controversial. Most published reports have included only patients undergoing diverticulectomy or bowel resection through laparotomy.
The decision to perform diverticulectomy for Meckel’s Diverticulum incidentally detected during an abdominal operation is still controversial. Over the past two decades, laparoscopy has been extensively used in the diagnosis and treatment of various abdominal disorders.
The opportunity provided by the laparoscopic approach to perform a complete abdominal exploration may increase the number of incidental findings, and this may again pose a dilemma to the surgeon who is more and more committed to the principles of evidence-based medicine for a better and more cost-effective patient care.
Further studies are needed to be done in order to emphasize the concept of non-incidental clarification of Meckel’s Diverticulum, which is of course in order to assure a better life style and less complications.