- Author: Nafisa K Kuwajerwala, MD; Chief Editor: John Geibel, MD, DSc, MSc, MA more...
A Meckel diverticulum is a vestigial remnant of the omphalomesenteric (vitellointestinal) duct. As a congenital anomaly, it is a true diverticulum that includes all three coats of the small intestine. Generally, a Meckel diverticulum ranges from 1 to 12 cm in length and is found 45-90 cm proximal to the ileocecal valve. It frequently contains heterotropic tissue; when it does, gastric mucosa accounts for 50%. (See the image below.)
Pluripotential cells line the omphalomesenteric duct; thus, gastric, colonic, duodenal, and pancreatic mucosa may be present. The diverticulum may or may not be attached to the umbilicus with a fibrous cord.
Autopsy records show that Meckel diverticulum occurs in about 2% of the general population. The male-to-female ratio is 3:1 for patients with symptomatic diverticula, but it is 1:1 for patients with asymptomatic diverticula.
Anomalies of Omphalomesenteric Duct
Human embryos initially have convex umbilical loops of primitive gut that communicate freely with the yolk sac through the omphalomesenteric duct. As development proceeds, the duct normally becomes occluded and disappears entirely by weeks 8-10 of gestation. The following anomalies are caused by the persistence of the omphalomesenteric duct:
An outpouching diverticulum secondary to persistence of the proximal part of the vitelline duct (Meckel diverticulum), with or without a fibrous cord; Meckel diverticulum is the most common anomaly (see the first image below)
Persistence and patency of the entire tract, leading to a congenital umbilicoileal fistula (see the second image below)
Persistence of the duct near the umbilicus, forming an umbilical sinus (see the third image below)
Fluid-filled cysts (enterocystomas) located either intra-abdominally or just below the umbilical skin because of persistence of the middle portion of the duct (see the fourth image below)
Obliteration of the lumen of the duct but persistence of the duct, forming a fibrous cord (see the fifth image below)
Complications of Meckel Diverticulum
Although most commonly discovered as an incidental finding on laparotomy or laparoscopy, Meckel diverticulum can be associated with life-threatening disease states. Retrospective studies suggest that the onset and frequency of complications decrease during life. The risk of complications ranges from 4% to 25% in various studies. Complications manifest as the following:
In an excellent population-based study by Cullen et al that covered patient data over a period of 42 years, the lifetime risk of developing a complication that requires surgery was estimated to be 6.4%.
Hemorrhage is the most common complication, with an incidence of about 20-30% of all complications. It is more common in children younger than 2 years and in males. The patient complains of passing bright red blood in the stools. Bleeding may range from minimal, recurrent episodes of hematochezia to massive, shock-producing hemorrhage.
The rate of bleeding can be assessed on the basis of the quantity of blood lost in the stools, the appearance of the material passed through the rectum, and the hemodynamic state. Hemorrhage from a Meckel diverticulum may or may not be associated with abdominal pain or tenderness. Patients may also present with weakness and anemia and may have a history of self-limiting episodes of intestinal bleeding.
Characteristics of hemorrhage based on the appearance of stools include the following:
Bright red blood in the stools - Brisk hemorrhage
Tarry stools - The bleeding is probably minor and associated with slow intestinal transit; tarry stools are commonly observed in patients with upper gastrointestinal (GI) bleeding, because transit through the bowel produces alteration of blood
Currant jelly stools - Associated with copious mucus owing to ischemia of the bowel; commonly observed in intussusception
Blood-streaked stools - A sign of fissure-in-ano
The gastric mucosa found in the diverticulum (see the image below) may form a chronic ulcer and may also damage the adjacent ileal mucosa because of acid production. Ectopic gastric mucosa is found in about 50% of all Meckel diverticula; in bleeding Meckel diverticula, the incidence increases to 75%. Perforation may occur, and the patient then presents with an acute abdomen, often associated with air under the diaphragm, best visualized on an erect chest radiograph.
When a patient presents with painless lower GI bleeding, Meckel diverticulum should always be suspected. Panendoscopy helps to exclude disease in the upper GI and colorectal regions, the two most common sites of GI bleeding.
This is another frequent complication; it is observed in 20-25% of patients with symptomatic Meckel diverticulum. The diagnosis of bowel obstruction due to Meckel diverticulum may not be established preoperatively. At exploration, Meckel diverticulum may be identified as the cause of obstruction. (See the image below.)
Various mechanisms of intestinal obstruction occur with Meckel diverticulum as a causative factor. Because the omphalomesenteric duct may be attached to the abdominal wall by a fibrotic band, a volvulus of the small bowel around the band may occur. The diverticulum may also form the lead point of an intussusception and cause obstruction. Infrequently, a tumor arising in the wall of the diverticulum may form the lead point for intussusception. When incarcerated in an inguinal hernia, a Meckel diverticulum is called Littré hernia.
Patients with intestinal obstruction due to Meckel diverticulum present with abdominal pain, vomiting, and obstipation. Radiography of the abdomen may indicate an ileus or frank stepladder air-fluid levels, as observed in dynamic intestinal obstruction.
In cases of intussusception, patients may also present with a palpable lump in the lower abdomen and currant jelly stools.
This condition develops in approximately 10-20% of patients with symptomatic Meckel diverticulum, occurring more often in the elderly population. Patients may present with symptoms of intermittent, crampy abdominal pain and tenderness in the periumbilical area. Perforation of the inflamed diverticulum leads to peritonitis.
Stasis in the diverticulum, especially in one with a narrow neck, causes inflammation and secondary infection leading to diverticulitis. Diverticular inflammation can lead to adhesions, which cause intestinal obstruction.
These occur in up to 10% of patients and consist of fistulas, sinuses, cysts, and fibrous bands between the diverticulum and the umbilicus. A patient may present with a chronic discharging umbilical sinus superimposed by infection or excoriation of periumbilical skin. There may be a history of recurrent infection, sinus healing, or abdominal wall abscess formation. When a fistula is present, intestinal mucosa may be identified on the skin.
Cannulation and injection with radiographic contrast help to delineate the entire tract and aid in planning a surgical approach for cure. A discharging sinus should be approached surgically with a view toward correction. Exploratory laparotomy may be required.
When found at laparotomy, a fibrous band should be excised because of the risk of internal herniation and volvulus.
This is the pathology least commonly associated with Meckel diverticulum and is reported in approximately 4-5% of complicated Meckel diverticulum cases. Of the various types of tumors reported, leiomyoma is the one that is most frequently found, followed by leiomyosarcoma, carcinoid tumor, and fibroma. One case of ectopic gastric adenocarcinoma has been reported. Lipoma and angioma have also been found.[3, 4]
Other reported complications in Meckel diverticulum are vesicodiverticular fistulas, "daughter" diverticula (formation of a diverticulum within a Meckel diverticulum), and formation of stones and phytobezoar in the Meckel diverticulum.
A diagnosis of symptomatic or complicated Meckel diverticulum is difficult to confirm on the basis of traditional history, physical examination, and laboratory testing. It is always considered as a differential diagnosis in cases of intestinal obstruction and intestinal hemorrhage. Painless, profuse hematochezia, especially in a child, should alert a clinician to the possibility of such a diagnosis and should prompt further investigation.
Thus, in a child, the differential diagnosis for right lower quadrant pain includes appendicitis, acute mesenteric lymphadenitis, intussusception, or Meckel diverticulitis. In an adult, Meckel diverticulum should be entertained in the diagnosis for lower GI bleeding, which would also include angiodysplasias, malignancy, arteriovenous malformations, and other causes.
Asymptomatic Meckel diverticulum
Laparoscopy and laparotomy are the most frequent means by which an incidental diverticulum is found. Upper GI series with small bowel follow-through also detects a diverticulum. The diverticulum appears as a smooth, white, globular shadow on the antimesenteric border of the ileum, approximately 50 cm proximal to the ileocecal valve.
Symptomatic Meckel diverticulum
Technetium-99m pertechnate radioisotope scanning
Diagnosis of a bleeding Meckel diverticulum is established by technetium-99m (99m Tc) pertechnetate radioisotope scanning. This isotope, administered intravenously, is readily taken up by the gastric mucosa. Reportedly, 1.8 cm2 of ectopic gastric mucosa in Meckel diverticulum is required for a positive result.
Pentagastrin, which is known to increase the acid production of ectopic gastric mucosa, enhances radioisotope uptake by the cells. Using a histamine-2 (H2) receptor blocker with pentagastrin provides a synergistic effect, in that it blocks intraluminal release and promotes retention of the isotope. The value of99m Tc pertechnate scanning is more specific in children.
The incidence of false-negative results is high, especially in adults; therefore, a negative scan finding does not exclude a Meckel diverticulum. False-positive results are observed in patients with intussusception, volvulus, obstruction of the small intestine, acute appendicitis, carcinoid of the appendix, or carcinoma of the caecum. The use of pentagastrin and an H2 receptor blocker helps minimize the number of false-negative results.
Approximately 30 images may be required (at 1-minute intervals) to demonstrate activity in the terminal ileum.
In September 2014, the Society of Nuclear Medicine and Molecular Imaging (SNMMI) and the European Association for Nuclear Medicine (EANM) issued a practice guideline for the use of scintigraphy for Meckel diverticulum.
Superior mesenteric angiography may be helpful in patients presenting with acute GI bleeding and is effective when blood loss exceeds 0.5 mL/min.
Indications for Surgery
Symptomatic Meckel diverticulum
Absolute indications for resection in Meckel diverticulum are hemorrhage, intestinal obstruction, diverticulitis, and umbilicoileal fistulas.
Incidentally discovered Meckel diverticulum
When a Meckel diverticulum is incidentally discovered at laparoscopy or laparotomy, the surgeon must decide whether to resect. Most surgeons generally do not resect a diverticulum with a wide mouth. However, a diverticulum with a narrow neck, which may obstruct or twist, can be easily resected at the neck without the need for segmental resection. A diverticulum deemed abnormal because of inflammation, thickening, or intramural pathology should be resected, with a decision for local or segmental resection based on the pathology.
In 1976, Soltero and Bill reported that the lifetime risk of complications from Meckel diverticulum is 4.2%, with the risk decreasing with age. Their data indicated that 800 asymptomatic diverticula would have to be removed to save the life of 1 patient. On that basis, they opposed surgical excision.
Miltiadis et al stated that resection of incidentally found Meckel diverticulum protected patients from future surgery caused by complications of Meckel diverticulum. This strategy could help reduce morbidity and mortality, especially in elderly patients.
Cullen et al reported that prophylactic diverticulectomy is warranted to eliminate the possibility of future deaths. As a result, they advocated diverticulectomy for asymptomatic disease even in the older age group.
Overall, selected cases of incidentally discovered diverticulum in adults and most asymptomatic diverticulum found in children may be removed. Resection is recommended in the following cases:
Patients younger than 40 years
Diverticula longer than 2 cm
Diverticula with narrow necks
Diverticula with fibrous bands
Suspected ectopic gastric tissue
Inflamed, thickened diverticula
Removal of a healthy diverticulum in the presence of peritonitis, Crohn disease, ulcerative colitis, or any other complication that would militate against resection is not advised.
Resection of Diverticulum
Surgical dissection and excision depend on the evident pathology. In asymptomatic Meckel diverticulum, excision is generally performed if the neck of the diverticulum is narrow or if stasis is present. Tangential excision with suture closure of the base is performed. In complicated cases, the diverticulum must be resected. (See the image below.)
Four possible surgical procedures are as follows:
Diverticulectomy with suture closure of the base
Wedge resection of the intestinal wall containing the diverticulum with suture closure
Segmental resection of the intestine, including the diverticulum, and end-to-end anastomosis
Division of the fibrous band, with or without diverticulectomy
Preoperative, intraoperative, and postoperative management of Meckel diverticulum follows the general principles of abdominal surgery and includes the use of perioperative antibiotics. Surgical considerations also include the following:
Hemorrhage - In cases of hemorrhage, wedge or segmental resection ensures adequate excision of the part containing gastric and ulcerated ileal mucosa
Intestinal obstruction - In cases of intestinal obstruction, the viability of the bowel wall delineates the extent of excision
Segmental resection - This is advised in children with broad-based diverticula in whom the risk of ileal stenosis is greater if diverticulectomy or wedge resection is performed
Umbilical sinus and fistula - These may necessitate excision of the umbilicus
Meckel diverticulitis - Because Meckel diverticulitis often mimics appendicitis, examine the distal ileum for diverticulitis when the appendix is discovered to be normal during exploration for suspected appendicitis
Surgical principles include ensuring adequate blood supply to the resectional margins, recognition of bowel viability, suture line tension, and potential for intestinal stenosis due to narrowing.
Handsewn technique versus stapling
All procedures are carried out either by handsewn technique or by stapling, depending on the preference of the surgeon. Stapling enables faster resection of a Meckel diverticulum without opening the bowel's lumen, avoiding potentially septic and postoperative complications. Meckel diverticulum, which fits well into the stapling device, is easy to remove and has a low complication rate, especially when it has been found incidentally.
Laparoscopic techniques are increasingly being used for Meckel diverticulectomy and intestinal resection.[8, 9] With advancements in technology, therapeutic interventions, such as intracorporeal resection or laparoscopic-assisted extracorporeal resection, can easily be performed. At present, laparoscopic management of Meckel diverticulum is largely limited to symptoms of abdominal pain and GI bleeding. For symptoms of obstruction, diagnostic laparoscopy is not recommended, because of difficulties in establishing pneumoperitoneum.
How best to manage a Meckel diverticulum in an asymptomatic patient is controversial. The risk of postoperative complications following excision of an incidental diverticulum has been reported to be as high as 8%.
Symptomatic patients have a 10-12% incidence of early postoperative complications, such as ileus, suture line or intestinal anastomotic leak, intra-abdominal abscess, and pulmonary embolism.
Late postoperative complications occur in 6-8% of patients and consist of small bowel obstruction due to intestinal adhesions. The reported mortality for surgery in symptomatic patients is 2-5%.
In incidental diverticulectomy for asymptomatic disease, the morbidity is 2%, the late postoperative complication rate is 2%, and the mortality is 1%.
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