Meckel's diverticulum

INTRODUCTION — Meckel's diverticulum is the most common congenital anomaly of the gastrointestinal tract. It results from incomplete obliteration of the vitelline duct leading to the formation of a true diverticulum of the small intestine [1].

The embryology, clinical features, diagnosis, and treatment of Meckel's diverticulum are reviewed here. The clinical evaluation of various gastrointestinal symptoms (abdominal pain, gastrointestinal bleeding, bowel obstruction) in children and adults is found in separate topic reviews. General considerations for the management of other congenital anomalies of the gastrointestinal tract are reviewed elsewhere. (See "Intestinal malrotation in children" and "Intestinal malrotation in adults".)

ANATOMY AND EMBRYOLOGY — Meckel's diverticulum is a true diverticulum, containing all layers of the small bowel wall. It arises from the antimesenteric surface of the middle-to-distal ileum. The diverticulum represents a persistent remnant of the omphalomesenteric duct, which connects the midgut to the yolk sac in the fetus. The normal development of the intestine is discussed elsewhere. (See "Overview of the development of the gastrointestinal tract".)

The omphalomesenteric duct normally involutes between the fifth and sixth weeks of human gestation as the bowel settles into its permanent position within the abdominal cavity. The persistence of the omphalomesenteric duct beyond fetal development may result in a variety of anatomic patterns (figure 1), including omphalomesenteric cysts, omphalomesenteric fistulas that drain through the umbilicus, and fibrous bands from the diverticulum to the umbilicus (picture 1) that predispose to bowel obstruction [2,3]. The most common form is a diverticulum without additional attachment, commonly referred to as Meckel's diverticulum [4]. The rich blood supply to the diverticulum is provided by the vitelline artery, which is a branch of the superior mesenteric artery (figure 2). The embryological origin of the ectopic tissue frequently found within the walls of the diverticulum is not known.

EPIDEMIOLOGY — Meckel's diverticulum is the most common congenital malformation of the gastrointestinal tract [1]. There is probably no familial predisposition for Meckel's diverticulum, although a few cases of occurrence within the same family have been reported [2,5]. The prevalence of Meckel's diverticulum is increased in children born with major malformation of the umbilicus, alimentary tract, nervous system, or cardiovascular system, in descending order [3].

The prevalence of Meckel's diverticulum depends upon the population studied. The subset of surgical patients undergoing abdominal exploration or diverticulectomy is the most studied population. In a study of 7927 patients (all ages) who underwent appendectomy, Meckel's diverticulum was present in 3 percent of patients [6]. In the general population, the prevalence of Meckel's diverticulum has been estimated to be approximately 0.3 t0 2.9 percent, although a systematic review found a prevalence of 1.2 percent among 31,499 autopsies in seven studies [7].

The "rule of twos" is the classic description of the essential features of Meckel's diverticulum [1,8]. It states that Meckel's diverticulum occurs in approximately 2 percent of the population with a male-to-female ratio of 2:1, is located within two feet from the ileocecal valve, and can be two inches in length, although, in practice, the size of a Meckel's diverticulum can vary [4,6,9]. Approximately 2 to 4 percent of patients develop a complication over the course of their lives, often before the age of two.

Case series have found that 12 to 44 percent of patients with Meckel's diverticula have ectopic tissue within the diverticulum [6,10-13]. A Meckel's diverticulum that bleeds is usually lined by two different types of mucosae: the native intestinal mucosa and a heterotopic mucosa. The most common type of heterotopic mucosa is gastric; pancreatic or colonic heterotopic mucosa have also been reported [14]. Gastric heterotopia is more common in patients with symptomatic versus asymptomatic Meckel's diverticula (43 versus 12 percent) [10,15,16]. Similarly, a Meckel's scan is more likely to be positive in patients who present with bleeding compared with those who present with other nonspecific symptoms (26 versus 2 percent, in one study) [17]. (See 'Bleeding' below.)

NATURAL HISTORY — The natural history of Meckel's diverticulum has been difficult to define. It is thought that the incidence of symptoms from a Meckel's diverticulum decreases with age in the adult patient, although data on this pattern are not conclusive [18].

Many studies have attempted to assess the incidence of symptomatic Meckel's diverticulum, but since there is no simple screening technique to identify Meckel's diverticulum in the general population, population estimates have been used. For adult patients, one study analyzed the incidence of complications from Meckel's diverticulum over a 42-year period in a rural Midwest county in the United States [18]. Using 2 percent as an estimate of the prevalence of Meckel's diverticulum in the general population, the authors estimated a 6.4 percent cumulative incidence of needing surgery to treat complications of Meckel's diverticulum up to 80 years of age. In this study, there was a higher incidence of symptomatic Meckel's diverticulum in the adult male (124 per 100,000 person-years) compared with the adult female (50 per 100,000 person-years). An older population-based study performed over a 15 year period from a single county in the Pacific Northwest region of the United States estimated a 4.2 percent incidence of symptoms over a lifetime due to Meckel's diverticulum [9].

Risk factors for developing symptoms — Meckel's diverticulum can cause symptoms or can remain clinically silent. Clinical features associated with an increased risk of developing symptoms from a Meckel's diverticulum identified on logistic regression in a study of 1476 patients followed over 50 years at a single institution included [10]:

●Age <50 years (odds ratio [OR] 3.5, 95% CI 2.6-4.8)

●Male sex (OR 1.8, 95% CI 1.3-2.4)

●Diverticulum length greater than 2 cm (OR 2.2, 95% CI 1.1-4.4)

●Presence of histologically abnormal tissue (OR 13.9, 95% CI 9.9-19.6)

The proportion with symptomatic Meckel's diverticulum when only one criterion was met was 17 percent. When two, three, or four of these criteria were met, the proportion increased to 25, 42, and 70 percent, respectively [10]. These data can inform which patients should undergo resection of the asymptomatic diverticula incidentally found during abdominal exploration. (See 'Indications for surgical resection' below.)

CLINICAL PRESENTATIONS — Meckel's diverticulum is often clinically silent; only 4 to 6 percent present with gastrointestinal bleeding or acute abdominal symptoms related to bowel obstruction, Meckel's diverticulitis, or perforation [1,10,19-21]. Between 25 and 50 percent of symptomatic patients present at less than 10 years of age [10,15,18,22] (figure 3).

Bleeding — Meckel's diverticula that contain ectopic gastric mucosa are generally associated with usually painless bleeding, which is caused by ulceration of the small bowel due to acid secretion by ectopic gastric mucosa within the diverticulum. The site of mucosal ulceration and bleeding is adjacent to or just downstream from the diverticulum, not from the mucosa or ectopic tissue within the diverticulum. Children often present with dark red or maroon stools, while adults typically present with melena, which may be attributable to slower colonic transit time in adults [19]. The abdominal examination is typically benign in patients with bleeding from Meckel's diverticulum. Bleeding from a symptomatic Meckel's diverticulum can be brisk, and patients can present with profound acute anemia.

Abdominal symptoms — Gastrointestinal and abdominal symptoms that can be caused by complications of Mecke's diverticulum include obstruction, inflammation, or perforation.

●Intestinal obstruction can result from intussusception [23], volvulus [23-25], torsion [26,27], inversion (image 1), herniation [28-32], or inflammation of the Meckel's diverticulum. In children, volvulus and intussusception appear to be the most common etiology of intestinal obstruction, whereas in adults, these are uncommon [10,15,23,33]. (See 'Surgery for intussusception' below.)

●Inflammation or perforation of the Meckel's diverticulum or adjacent bowel can also lead to abdominal pain or even peritonitis. Acute inflammation of the diverticulum (ie, Meckel's diverticulitis) is thought to be due to obstruction of the diverticular opening as a result of an enterolith, inflammatory tissue, food or other foreign body, or tumor [34-36]. Entrapment of a foreign body, such as an enterolith or parasite, within a Meckel's diverticulum is another rare presentation that can lead to diverticulitis or perforation [37-39]. The presence of multiple enteroliths within a Meckel's diverticulum leading to obstruction and ischemia of the diverticulum has been reported [40]. Bleeding into the diverticulum rather than the intestinal lumen can also cause abdominal pain in rare cases [41].

In patients with gastrointestinal symptoms related to the Meckel's diverticulum, typical physical findings include abdominal tenderness and distention. Abdominal tenderness is located more toward the midline compared with appendicitis, but the position of the Meckel's diverticulum can vary; thus, the location of pain and tenderness is not particularly helpful. Perforation of Meckel's diverticulum will manifest with signs of peritoneal irritation, usually localized in the lower abdomen. An abscess related to Meckel's diverticulum may produce a palpable mass on abdominal or digital rectal examination, but, again, this finding is not specific to Meckel's diverticulum.

Obstruction related to Meckel's diverticulum presents similarly to other sources of small bowel obstruction, with abdominal distention, nausea, vomiting, and signs of obstruction. (See "Etiologies, clinical manifestations, and diagnosis of mechanical small bowel obstruction in adults".)

DIAGNOSIS — Meckel's diverticulum should be suspected in:

●Children, particularly those less than 10 years of age, who present with painless lower gastrointestinal bleeding without symptoms or signs of gastroenteritis (diarrhea) or inflammatory bowel disease (abdominal pain, diarrhea) (figure 4).

●Adult patients, particularly those <40 years of age, with gastrointestinal bleeding but no source identified with standard endoscopic and possibly radiographic evaluation (eg, colonoscopy, computed tomography [CT] angiography, small bowel studies, or radionuclide scanning). (See "Evaluation of suspected small bowel bleeding (formerly obscure gastrointestinal bleeding)".)

●Children and adults with intussusception, particularly recurrent or atypical intussusception

●Patients with features of acute appendicitis, particularly when the appendix has already been removed

Because the clinical manifestations are nonspecific, a definitive diagnosis of Meckel's diverticulum is generally made on imaging studies or surgical exploration.

DIAGNOSTIC EVALUATION

Bleeding — Laboratory studies obtained in patients with gastrointestinal bleeding may be consistent with volume depletion or anemia but do not help distinguish Meckel's diverticulum from any other source of gastrointestinal bleeding.

Patients with gastrointestinal bleeding are initially evaluated using standard algorithms including upper and lower endoscopy. (See "Approach to acute lower gastrointestinal bleeding in adults" and "Evaluation of suspected small bowel bleeding (formerly obscure gastrointestinal bleeding)" and "Lower gastrointestinal bleeding in children: Causes and diagnostic approach".)

A bleeding Meckel's diverticulum can typically be diagnosed using a Meckel's scan or mesenteric arteriography. A Meckel’s scan is used in hemodynamically stable patients with less severe or intermittent gastrointestinal bleeding and for whom suspicion for Meckel's diverticulum is high. Mesenteric arteriography may be appropriate if the gastrointestinal bleeding is brisk enough to require transfusion.

●Meckel's scan – A Meckel's scan is a nuclear medicine study in which 99m technetium pertechnetate, which has an affinity for gastric mucosa, is first administered intravenously, and subsequently scintigraphy is performed to identify areas of ectopic gastric mucosa [42]. Meckel's diverticula lacking gastric mucosa will not be seen on a Meckel's scan [6,10-12]. A Meckel’s scan is used more often in children because Meckel's diverticula that contain ectopic gastric mucosa present earlier in life with gastrointestinal bleeding [43]. In a 2023 systematic review and meta-analysis of 16 studies with 1115 children, the combined sensitivity and specificity were 0.80 (95% CI 0.73-0.86) and 0.95 (95% CI 0.86-0.98), respectively. The area under the curve was 0.88 (95% CI 0.85-0.90) [44].

Aluminum hydroxide, which is found in some antiulcer medications, limits the mucosal localization of radiotracer. On the other hand, cimetidine promotes retention of pertechnetate in the gastric mucosa and can be used as an adjunct maneuver to augment an initially negative scan by permitting a higher level of radiotracer to be retained in the ectopic mucosa [45,46].

●Mesenteric arteriography – On conventional contrast arteriography, a diagnosis of Meckel's diverticulum can be established based upon the finding of an anomalous superior mesenteric artery branch feeding the diverticulum. The artery feeding the Meckel's diverticulum is long and nonbranching and traverses the mesentery toward the right lower quadrant where it terminates in several small, irregular vessels [47,48]. Active contrast extravasation may be seen in patients with ongoing hemorrhage. In patients with less brisk bleeding, high-resolution CT angiography is increasingly being used (image 2) [49]. However, the vascular anatomy can be variable [50].

●Advanced endoscopic modalities – Wireless capsule endoscopy and double balloon enteroscopy have diagnosed bleeding Meckel's diverticulum in case reports or small series [51-59], but these studies are not routinely obtained. Common endoscopic findings include a double-lumen sign, a visible diverticular entrance, or ulceration.

Abdominal symptoms — Laboratory findings on patients who present with acute abdominal symptoms are not specific enough to diagnose Meckel's diverticulum. Such patients should undergo contrast-enhanced abdominopelvic CT scan (image 3 and image 4) [60], which may diagnose Meckel's diverticulum as a cause of intestinal obstruction, inflammation, or perforation; exclude alternative diagnosis (eg, appendicitis); and guide surgical therapy.

DIFFERENTIAL DIAGNOSIS — Meckel's diverticulum is often not the first diagnosis considered in the differential diagnosis for many abdominal complaints. The age of the patient, along with clues from the clinical history or abdominal imaging during the evaluation of the primary complaint, may suggest the possibility of a Meckel's diverticulum.

●For patients who present with bleeding, the differential diagnosis of Meckel's diverticulum includes any etiology that can cause gastrointestinal bleeding. There are no specific clinical features that can distinguish Meckel's diverticulum as a cause of gastrointestinal bleeding. The tables provided list the common and rarer causes of gastrointestinal bleeding (table 1 and figure 4 and table 2).

●For patients who present with acute abdominal symptoms, Meckel's diverticulitis is clinically indistinguishable from other more common intra-abdominal inflammatory conditions. Meckel's diverticulitis is frequently confused with acute appendicitis, colonic diverticulitis, or inflammatory bowel disease. A preoperative diagnosis of Meckel's diverticulitis is made in fewer than 10 percent of patients with a Meckel's diverticulum; acute appendicitis is the most common preoperative diagnosis [61-63]. The tables provided list the causes of acute abdominal pain (table 3 and table 4 and table 5).

TREATMENT — When diagnosed, Meckel's diverticulum can be surgically resected or observed.

Indications for surgical resection — Management of Meckel's diverticulum is according to the clinical presentation:

●Symptomatic patients require surgical resection of the Meckel's diverticulum.

●Asymptomatic patients with incidental, imaging-detected Meckel's diverticulum do not require surgical resection. Features that may suggest a Meckel's diverticulum on routine abdominal imaging studies are given in the table (table 6) [64-70]. When an asymptomatic Meckel's diverticulum is identified on imaging studies (image 5), there are no data supporting a role for obtaining a Meckel's scan [15] or proceeding to surgical resection [1,9,10,15,71].

●The management of asymptomatic patients with incidental, intraoperative finding of a Meckel's diverticulum (picture 2) is controversial [1,6,9,10,23,62,71-76]. We decide based on the patient's clinical status, their lifelong risk of Meckel's-related complications, and anatomic features associated with developing symptoms (algorithm 1) [10,72,77]. (See 'Risk factors for developing symptoms' above.)

•In children (≤18 years old), we suggest surgical resection of all incidentally found Meckel's diverticulum during abdominal exploration because of higher risk of complications of Meckel's diverticulum compared with adults [33].

•In all male adult patients who are <50 years old, we suggest surgical resection of all incidentally found Meckel's diverticulum during abdominal exploration because of higher risk of complications of Meckel's diverticulum in males compared with females. In female adults who are <50 years old, we suggest surgical resection only when the diverticulum is longer than 2 cm, has an associated fibrous band, or has palpable abnormality [10,77]. Such risk factors predict complications.

•In patients ≥50 years, we suggest only resecting the diverticulum when there is palpable abnormality because of higher surgical morbidity and mortality risks [15]. Palpable abnormalities within the diverticulum include ectopic tissue, indurated tissue, and ulcerations, all of which can bleed. Additionally, older adults are also more likely to harbor cancer within Meckel's diverticulum than younger patients, although the overall prevalence remains low. (See 'Tumors in Meckel's diverticulum' below.)

Surgical techniques — In general, a Meckel's diverticulum can be resected with one of two techniques:

●Simple diverticulectomy – Diverticulectomy is most easily performed using a linear gastrointestinal stapler applied to the base of the diverticulum.

●Segmental resection – This involves resection of the small bowel segment containing the diverticulum followed by primary small bowel anastomosis. (See "Bowel resection techniques".)

We perform a segmental resection if the small bowel lumen is in jeopardy of being narrowed with a diverticulectomy, a palpable abnormality is present at the base of the diverticulum, or the neck of the diverticulum is wide (>2 cm) [78]. Also, a broad-based, short diverticulum (one with a height-to-diameter ratio of less than 2) with features warranting resection is best addressed by a formal small bowel resection rather than a simple diverticulectomy due to the risk of leaving behind ectopic tissue at the base [79].

Surgical procedures can be performed using hand-sewn or stapling techniques via an open or laparoscopic (including both conventional and single-incision) approach [80-82]. There is evidence that a laparoscopic approach is feasible and safe [83,84].

Special considerations

Surgery for bleeding diverticulum — When gastrointestinal bleeding is the primary clinical manifestation, it is likely that both segmental small bowel resection and simple diverticulectomy are effective surgical approaches. Although segmental resection removes the gastric mucosa within the diverticulum as well as the mucosal ulceration located in the adjacent small bowel, there are no definitive data demonstrating superiority of segmental resection over diverticulectomy. Diverticulectomy alone has been used in the setting of bleeding and appears to be safe with a low incidence of complications [73,85,86].

Surgery for intussusception — In children who present with multiple recurrent episodes of intussusception, Meckel's diverticulum should be suspected as a pathologic lead point. In adults with intussusception, malignancy is more often the lead point and surgical reduction of the intussusception is not recommended; rather, the affected small intestine should be resected en bloc for pathologic examination. Meckel's diverticulum may be identified in the resected specimen. (See "Intussusception in children" and "Etiologies, clinical manifestations, and diagnosis of mechanical small bowel obstruction in adults", section on 'Intussusception'.)

Tumors in Meckel's diverticulum — The incidence of tumors within a Meckel's diverticulum ranges from 0.5 to 3.2 percent [9,11,20]. The majority of these tumors are benign (lipomas, leiomyomas, angiomas); however, malignancies within a Meckel's diverticulum such as adenocarcinoma, gastrointestinal stromal tumor, sarcoma, and carcinoid have been reported, especially in older adult patients [12,39,87-89].

In a retrospective study of 163 cases of Meckel's diverticulum cancer and 6214 cases of ileal cancer not related to Meckel's diverticulum between 1973 and 2006 from the Surveillance, Epidemiology, and End Results database, incidence increases with age, with a mean age at diagnosis of 60.6 (±15.1) years [90]. Adjusted risk of cancer in the Meckel's diverticulum was at least 70 times higher than any other ileal site. The study authors advocated for resection of incidental Meckel's diverticulum for its oncologic benefits.

Perioperative morbidity and mortality — In contemporary practice, death related specifically to the resection of Meckel's diverticulum is rare, with an estimated incidence of 0.001 percent [8,15]. The anticipated complication rate for Meckel's resection is overall approximately 5 percent [6,10,12,18], and the most common complications are surgical site infection, prolonged postoperative ileus, and anastomotic leak, which are essentially those of any small bowel surgery. (See "Bowel resection techniques".)

The risk of perioperative morbidity and mortality from surgical resection of symptomatic Meckel's diverticulum is likely higher than that of an incidentally diagnosed, asymptomatic diverticulum. However, the incidence of complications is difficult to estimate in patients who have undergone resection for incidental, asymptomatic diverticula during the course of another procedure. Population-based studies have estimated a 2 to 20 percent complication rate from resection of an asymptomatic Meckel's diverticulum, but few of these complications (apart from rare anastomotic leaks) could be directly attributed to resection of the diverticulum. In a systematic review, the perioperative morbidity was 12 percent for resection of symptomatic Meckel's, and the cumulative risk of long-term postoperative complications was 7 percent [18]. By comparison, the complication rate for elective Meckel's resection was 2 percent.

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SUMMARY AND RECOMMENDATIONS

●Anatomy and embryology – Meckel's diverticulum is the most common congenital anomaly of the gastrointestinal tract. Meckel's diverticulum is a true diverticulum that arises from the antimesenteric surface of the mid-to-distal ileum that results from incomplete obliteration of the vitelline duct. (See 'Introduction' above and 'Anatomy and embryology' above.)

●Epidemiology – The rule of twos is the classic description of the essential features of Meckel's diverticulum. Meckel's diverticulum occurs in approximately 2 percent of the population with a male-to-female ratio of 2:1, is found approximately two feet from the ileocecal valve, and is approximately two inches long. Approximately 2 percent of patients develop a complication over their lifetime, typically before the age of two. Symptomatic Meckel's diverticula most often contain two types of tissue: both native intestinal and heterotopic gastric mucosa. (See 'Epidemiology' above.)

●Clinical presentations – Meckel's diverticulum is often clinically silent; only 4 to 6 percent present with gastrointestinal bleeding or acute abdominal symptoms related to bowel obstruction, Meckel's diverticulitis, or perforation. Between 25 and 50 percent of symptomatic patients present at less than 10 years of age. (See 'Clinical presentations' above.)

●Diagnosis – Meckel's diverticulum should be suspected in patients with the following clinical features (see 'Diagnosis' above):

•Children with painless lower gastrointestinal bleeding

•Adults with gastrointestinal bleeding but negative upper endoscopy and colonoscopy

•Patients with features of appendicitis, particularly when the appendix has already been removed

•Children and adults with recurrent intussusception

A definitive diagnosis of Meckel's diverticulum is generally made on imaging studies or surgical exploration.

●Diagnostic evaluation – A suspicion for an intermittent bleeding Meckel's diverticulum can be investigated with a Meckel's scan, which identifies the presence of ectopic gastric mucosa within the diverticulum. A conventional or CT mesenteric arteriogram can be used to diagnose Meckel's diverticulum with more brisk bleeding. Other abdominal symptoms are best investigated with a contrast-enhanced abdominopelvic CT scan. (See 'Diagnostic evaluation' above.)

●Differential diagnoses – The differential diagnosis of Meckel's diverticulum includes any etiology that can cause gastrointestinal bleeding, small bowel obstruction, or acute abdominal pain. There are no specific clinical features that reliably distinguish symptomatic Meckel's diverticulum from other causes (figure 4 and table 1 and table 2 and table 3 and table 4 and table 5). (See 'Differential diagnosis' above.)

●Treatment – Patients with Meckel's diverticulum are managed according to their clinical presentation (see 'Treatment' above):

•Symptomatic patients – Symptomatic patients require surgical resection of the Meckel's diverticulum.

•Asymptomatic patients with image diagnosis – For children and adults with asymptomatic Meckel's diverticulum identified on imaging studies, we suggest not performing elective resection (Grade 2C).

•Asymptomatic patients with intraoperative diagnosis – For patients with a normal-appearing Meckel's diverticulum identified on abdominal exploration, we suggest the following selective approach (algorithm 1) (see 'Indications for surgical resection' above):

-For most children ≤18 years of age, we suggest resection of the normal-appearing Meckel's diverticulum (Grade 2C). Children have an increased lifelong risk for complications than adults.

-For adults <50 years of age, we suggest resection of the normal-appearing Meckel's diverticulum in males or if there is a palpable abnormality, the Meckel's diverticulum is longer than 2 cm, or is associated with a fibrous band (Grade 2C). These features are associated with a greater risk for developing symptomatic Meckel’s diverticulum. (See 'Risk factors for developing symptoms' above.)

-For adults ≥50 years of age, we suggest not resecting the normal-appearing Meckel's diverticulum, unless there is a palpable abnormality associated with the diverticulum (Grade 2C). The morbidity and mortality rate associated with the procedure is higher in older adults.

-For adults ≥50 years of age and a palpable abnormality, we suggest resecting the normal-appearing Meckel's diverticulum (Grade 2C). In this population, a palpable abnormality may contain ectopic, indurated, or ulcerated tissue that can bleed, or a tumor.

-For adults ≥50 years of age and no palpable abnormality, we suggest not resecting the normal-appearing Meckel's diverticulum (Grade 2C). The morbidity and mortality rate associated with the procedure is higher in older adults.