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]. Meckel's diverticula are uncommon and often clinically silent, particularly in the adult. An asymptomatic Meckel's diverticulum may be discovered during abdominal exploration for the evaluation of unrelated pathology. Less commonly, they are found incidentally on diagnostic imaging. When symptomatic, Meckel's diverticulum may present with abdominal pain or symptoms of gastrointestinal bleeding or bowel obstruction.

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. They arise 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 within the walls of the diverticulum is not known; theories include a local erroneous association between neural crest and endodermal tissue and a missing restrictive mesodermal effect on the local endoderm within the diverticulum.

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]. 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 [5]. In the general population, the prevalence of Meckel's diverticulum has been estimated to be approximately 2 percent, although a systematic review found a prevalence of 1.2 percent among 31,499 autopsies in seven studies [1,6].

The "rule of twos" is the classic description of the essential features of Meckel's diverticulum [1,7]. 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 [4,5,8]. Approximately 2 to 4 percent of patients develop a complication over the course of their lives, often before the age of two. A Meckel's diverticulum that bleeds is usually lined by two different types of mucosa: 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 [9].

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 [10].

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 [10]. 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 [8].

Risk factors for developing symptoms — Meckel's diverticulum can cause symptoms or can remain clinically silent. Asymptomatic Meckel's diverticulum is occasionally identified incidentally on imaging but is more commonly diagnosed during abdominal exploration for an unrelated pathology. (See 'Incidental Meckel's diverticulum' below and 'Asymptomatic Meckel's diverticulum' below.)

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 [11]:

●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 [11]. Although the presence of histologically abnormal tissue is the most important of these factors, whether to obtain an imaging study (ie, Meckel's scan) to identify heterotopic tissue is controversial, since prophylactic removal of Meckel's diverticulum found on imaging alone is generally not supported by the available evidence. (See 'Meckel's scan' below and 'Asymptomatic Meckel's diverticulum' below.)

CLINICAL PRESENTATIONS

Overview — Meckel's diverticulum is usually clinically silent but can be found incidentally or can present with a variety of clinical manifestations including gastrointestinal bleeding or other acute abdominal complaints [1,11-13]. Between 25 and 50 percent of patients with symptoms present under 10 years of age (figure 3) [6,10,11,14]. Meckel's diverticula that contain ectopic gastric mucosa are generally associated with bleeding. Those that do not may remain silent or present with nonhemorrhagic symptoms such as bowel obstruction or diverticular inflammation (ie, Meckel's diverticulitis) with or without perforation. The clinical manifestations and initial approach to the patient with gastrointestinal bleeding or intestinal obstruction are reviewed elsewhere. (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" and "Etiologies, clinical manifestations, and diagnosis of mechanical small bowel obstruction in adults".)

In a single-center pediatric series of 286 patients (aged 1 day to 15 years), 19 percent of Meckel's diverticula were incidentally detected; 35 percent presented with rectal bleeding or melena, 20 percent with Meckel's diverticulitis or perforation, 14 percent with intestinal obstruction, and 12 percent with intussusception [15].

Many of the case series documenting the clinical presentation of Meckel's diverticulum include both pediatric and adult patients, and it is difficult to define any true difference in presenting symptoms between age groups. It is generally thought that children present more often than adults with bleeding and adults more often than children with symptoms of small bowel obstruction [1,4,12,16]. It should be noted that the available data are not conclusive on this point, and some large case series suggest the opposite with respect to presenting symptoms in children and adults [11,14]. Thus, all varieties of symptomatic presentation should be considered in any age group.

Most patients who come to clinical attention have symptoms; however, Meckel's diverticulum is often not the first diagnosis considered in the differential diagnosis for many abdominal complaints. The clinical features (symptoms, laboratory, examination, imaging) of patients with Meckel's diverticulum are nonspecific, but 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.

Meckel's diverticulum should be suspected in:

●Children with painless lower gastrointestinal bleeding (see 'Gastrointestinal bleeding' below)

●Children with intussusception, particularly recurrent or atypical intussusception (see 'Intestinal obstruction' below)

●Patients with features of acute appendicitis, particularly when the appendix has already been removed (see 'Acute abdominal pain' below)

●Adults with gastrointestinal bleeding but no source identified with upper endoscopy or colonoscopy (see 'Gastrointestinal bleeding' below)

A definitive diagnosis of Meckel's diverticulum is generally made in one of three ways depending upon the initial clinical presentation: a Meckel's scan, mesenteric arteriography, or abdominal exploration. The clinical features and diagnosis associated with the typical clinical presentations are discussed separately below.

Incidental Meckel's diverticulum — A Meckel's diverticulum is occasionally identified incidentally on imaging studies. Features that may suggest a Meckel's diverticulum on routine abdominal imaging studies are given in the table (table 1) [17-23]. When an asymptomatic Meckel's diverticulum is identified on imaging studies (image 1), there are no data supporting a role for obtaining a Meckel's scan [6]. (See 'Incidental Meckel's on imaging studies' below and 'Asymptomatic Meckel's diverticulum' below.)

Asymptomatic Meckel's diverticula, however, are rarely identified by routine imaging studies. In one study, none of 26 asymptomatic patients had their Meckel's diverticulum identified prospectively on computed tomography (CT) imaging [24].

Meckel's diverticulum is more likely to be discovered incidentally during abdominal exploration performed for another purpose (picture 2). The decision as to whether to remove asymptomatic, incidentally discovered Meckel's diverticulum is discussed elsewhere. (See 'Normal Meckel's found during abdominal exploration' below.)

Gastrointestinal bleeding — Gastrointestinal bleeding related to Meckel's diverticulum 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.

Case series have found that 12 to 44 percent of patients with Meckel's diverticula have ectopic tissue within the diverticulum [5,11,25-27]. Gastric heterotopia is more common in patients with symptomatic versus asymptomatic Meckel's diverticula [6,11,28]. In a systematic review, 43 percent of symptomatic patients compared with 12 percent of asymptomatic patients had heterotopic tissue contained within the Meckel's diverticulum [6]. Although the most common ectopic tissue is gastric in origin, pancreatic and duodenal mucosa has also been identified [29]. Due to the association of gastric heterotopia and gastrointestinal bleeding in the Meckel's patient, 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) [30].

Signs and symptoms — Bleeding from Meckel's diverticulum may be chronic and insidious or acute and massive. Although the incidence of each type of bleeding is poorly reported in the literature, transfusions are uncommonly reported for Meckel's-associated bleeding. 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 [12].

The abdominal examination is typically benign in patients with gastrointestinal 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. Similarly, plain abdominal radiography in patients with gastrointestinal bleeding is nonspecific (table 1). Bleeding diverticula cannot be routinely seen with standard CT.

Adult and pediatric patients with gastrointestinal bleeding are initially evaluated using standard algorithms. Patients who present with gastrointestinal bleeding may undergo routine upper or lower gastrointestinal endoscopy, neither of which can demonstrate a Meckel's diverticulum. However, Meckel's diverticulum has been identified using advanced endoscopy techniques (double balloon enteroscopy, capsule endoscopy), but these studies are not routinely obtained [31,32]. The diagnostic approach to the adult or pediatric patient with gastrointestinal bleeding is discussed in detail elsewhere. (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".)

Diagnosis — The diagnosis of a bleeding Meckel's diverticulum can typically be made using Meckel's scan or mesenteric arteriography, but double-balloon enteroscopy and capsule endoscopy have been described [33]. If diagnostic testing is unrevealing, or the patient is hemodynamically unstable, abdominal exploration (laparotomy or laparoscopy) may be necessary to determine whether a Meckel's diverticulum is the source of bleeding.

A suspicion for Meckel's diverticulum as a source for lower gastrointestinal bleeding should be increased for:

●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 in young adults <40 years of age, with gastrointestinal bleeding but no source identified with standard endoscopic and possibly radiographic evaluation (eg, colonoscopy, CT angiography, small bowel studies, or radionuclide scanning). (See "Evaluation of suspected small bowel bleeding (formerly obscure gastrointestinal bleeding)".)

Arteriography — Conventional contrast mesenteric arteriography may be appropriate if a source of gastrointestinal bleeding is brisk enough to require transfusion and the source has not been identified using other imaging modalities, given that for some lesions (eg, arteriovenous malformation), but not typically Meckel's diverticulum, therapeutic maneuvers may be possible. (See "Evaluation of suspected small bowel bleeding (formerly obscure gastrointestinal bleeding)", section on 'Angiography' and "Approach to acute lower gastrointestinal bleeding in adults", section on 'Angiography'.)

With 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 [34]. 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. In a meta-analysis of 22 studies, it was noted that CT was able to detect bleeding of as little as 0.3 mL/minute [35]. CT angiography can detect active signs of bleeding, such as that from a Meckel's diverticulum (image 2), that may be undetectable when other techniques such as tagged red blood cell scan, colonoscopy, or conventional arteriography are performed. However, CT angiography subjects the patient to ionizing radiation and requires intravenous contrast, which may be less desirable in certain patient populations (eg, children, pregnant women, renal dysfunction, contrast allergy). (See "Approach to acute lower gastrointestinal bleeding in adults", section on 'CT angiography'.)

Single-photon emission computed tomography (SPECT)/CT fusion imaging was also used to diagnose Meckel's diverticulum in a case report [36]. Others have used magnetic resonance enterography (MRE) for obscure gastrointestinal bleeding in children with negative upper and lower endoscopy [37].

Meckel's scan — In hemodynamically stable patients with less severe or intermittent gastrointestinal bleeding and for whom suspicion for Meckel's diverticulum is high, a Meckel's scan should be performed. 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 [38]. Theoretically, the scan should identify only those diverticula that contain ectopic gastric mucosa, which occurs in less than 25 percent of cases [5,11,25,26]. Meckel's diverticula lacking gastric mucosa will not be seen on a Meckel's scan.

Meckel's diverticula that contain ectopic gastric mucosa present earlier in life with gastrointestinal bleeding relative to other clinical manifestations of Meckel's diverticulum. Thus, in children, a Meckel's scan is performed early in the course of the evaluation of gastrointestinal bleeding because it is more likely to be positive compared with adults. In addition, the study is noninvasive, associated with few side effects, and not likely to require general anesthesia. In adults, a Meckel's scan is appropriate in hemodynamically stable patients whenever the evaluation of lower gastrointestinal bleeding has failed to define the source of bleeding.

The Meckel's scan has a sensitivity of 85 to 97 percent in the pediatric patient, but its sensitivity and positive predictive value are lower in the adult at approximately 60 percent each [30,38]. The specificity of a Meckel's scan is approximately 95 percent (pediatric and adult), and false negative studies can occur [30]. False positives can be seen in the presence of small bowel duplication cysts, intussusception, and inflammatory bowel disease.

Agents used in the initial management of gastrointestinal bleeding can affect the uptake of 99m technetium pertechnetate. Uptake by gastric mucosa is independent of luminal acidification. However, aluminum hydroxide, which is found in some anti-ulcer 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 [39,40].

Wireless capsule endoscopy — With the more common use of wireless capsule endoscopy for the workup of gastrointestinal bleeding of uncertain origin, case reports of the endoscopic appearance of normal, ulcerated, bleeding, and inverted Meckel's diverticula can be found in the literature. In a study that identified Meckel's diverticulum as the source of bleeding in 13 patients, wireless capsule endoscopy had a positive predictive value of 84.6 percent for the diagnosis of Meckel's diverticulum associated with gastrointestinal bleeding of uncertain origin [41]. (See "Wireless video capsule endoscopy", section on 'Indications'.)

Double-balloon enteroscopy — Double-balloon enteroscopy (DBE) has also been reported in small case series in patients undergoing evaluation for gastrointestinal bleeding or abdominal pain [42]. Both prograde (per os) and retrograde (per rectum) DBE have been used to confirm the diagnosis of Meckel's diverticulum based upon a suspicion from other imaging studies (eg, CT, Meckel's scan), or to evaluate the distal small bowel directly in patients with negative radiographic studies but in whom a high suspicion of a Meckel’s diverticulum remains. Endoscopy confirms the diagnosis by direct vision but can also identify complications (mucosal ulceration, active bleeding) and, in some cases, permits therapy [43,44]. One retrospective series found that DBE had a higher diagnostic accuracy for Meckel's diverticulum than Meckel's scan in the adult population [45]. (See "Overview of deep small bowel enteroscopy" and 'Resection of symptomatic Meckel's diverticulum' below.)

Differential diagnosis — 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 2 and figure 4 and table 3).

Intestinal obstruction — Intestinal obstruction related to Meckel's diverticulum can result from any of the mechanisms described below. In children, volvulus and intussusception appear to be the most common etiology of intestinal obstruction, whereas in adults, these are uncommon [6,11,29,46].

●Intussusception – Intussusception refers to the invagination of a part of the intestine into itself. Meckel's diverticulum can act as the lead point [29]. Meckel's diverticulum should be considered in the differential diagnosis of intussusception in all patients, but particularly in children who present with recurrent small bowel intussusception. In adults, tumor in a Meckel's diverticulum can serve as a lead point for intussusception. Intussusception in children is discussed in more detail elsewhere. (See "Intussusception in children" and 'Acute abdominal pain' below.)

●Volvulus – The intestine, usually the small bowel, can twist around the fibrous cord or band often associated with Meckel's diverticulum such as those from the tip of the diverticulum to the peritoneal lining of the anterior abdominal wall, or other adhesions [29,47,48]. These patients present with signs and symptoms of a bowel obstruction without a history of prior abdominal surgery and without findings of a hernia on physical examination.

●Torsion – Torsion of the diverticulum alone can result in small bowel obstruction [49,50].

●Abdominal wall hernia – Meckel's diverticulum can incarcerate in an abdominal wall or internal hernia, which is referred to as a Littre's hernia [51-53]. Incarcerated hernias can also present with gastrointestinal bleeding [54]. The anatomic sites of Littre hernia can be inguinal (50 percent), femoral (20 percent), or umbilical (20 percent) [55]. (See "Overview of abdominal wall hernias in adults".)

●Meckel's diverticulitis – Inflammation of the diverticulum or adjacent small bowel can result in reduced intestinal luminal diameter that leads to partial or complete bowel obstruction.

●Inversion of Meckel's diverticulum – A Meckel's diverticulum can also become inverted into the bowel lumen, and this may serve as a point of intermittent obstruction (image 3).

Signs and symptoms — 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".)

In patients with inflammation 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.

Most patients undergo initial laboratory testing for the evaluation of bowel obstruction that includes a complete blood count and electrolytes. These studies may help identify patients who are volume depleted or experiencing complications such as elevated white blood cell count associated with bowel perforation, but do not help establish a diagnosis of Meckel's diverticulum. Certain clinical features on routine imaging studies to evaluate intestinal obstruction may suggest a diagnosis of Meckel's diverticulum, but these findings are usually nonspecific (table 1) [17-23].

Diagnosis — Patients who present with small bowel obstruction often undergo abdominopelvic CT, which can sometimes diagnose Meckel's diverticulum as the cause of bowel obstruction. In one study of 10 patients who were confirmed to have bowel obstruction attributed to Meckel's diverticula at surgical exploration, the correct preoperative diagnosis was made by CT in 50 percent of patients [56].

Children and adults who present with symptoms of bowel obstruction without evidence for an abdominal wall or groin hernia, or adhesions from prior surgery, may have a Meckel's diverticulum as the source of obstruction. A suspicion for Meckel's diverticulum should be higher in children presenting with symptoms of bowel obstruction, particularly in those who have a recurrent intussusception following successful reduction, compared with adults. In children who present with multiple recurrent episodes of intussusception, a pathologic lead point should be suspected. Diagnostic options in this setting include a Meckel's scan or diagnostic laparoscopy to evaluate for a Meckel's diverticulum, or other lead point. (See "Intussusception in children", section on 'Lead point' and "Intussusception in children", section on 'Recurrence' and "Management of small bowel obstruction in adults".)

In adults, 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.

During abdominal exploration for bowel obstruction, the bowel should be evaluated methodically, as it can be easy to miss a short diverticulum or one that is adherent along its length to the antimesenteric border of the ileum, particularly with laparoscopy. (See 'Treatment' below.)

Differential diagnosis — The differential diagnosis of Meckel's diverticulum includes any etiology that can cause bowel obstruction. (See "Etiologies, clinical manifestations, and diagnosis of mechanical small bowel obstruction in adults".)

There are no specific clinical features that can distinguish Meckel's from any of these other causes of bowel obstruction; however, Meckel's diverticula may be suspected based upon the patient's clinical history or clues from routine imaging studies (table 1). The table lists the common causes of small bowel obstruction (table 4).

Acute abdominal pain — Acute abdominal pain related to Meckel's diverticulum can be the result of diverticular inflammation, similar to acute appendicitis, or related to bowel obstruction, or perforation of the Meckel's diverticulum or adjacent bowel leading to peritonitis. 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 [57-59]. The presence of multiple enteroliths within a Meckel's diverticulum leading to obstruction and ischemia of the diverticulum has been reported [60].

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 [61-63]. Obstruction leads to bacterial overgrowth and inflammation similar to acute appendicitis [25]. Meckel's diverticulitis can also result from torsion or incarceration of the diverticulum or from peptic ulceration due to heterotopic gastric mucosa.

The incidence of tumors within a Meckel's diverticulum ranges from 0.5 to 3.2 percent [8,13,25]. The majority of these tumors are benign (lipomas, leiomyomas, angiomas); however, malignancies within a Meckel's diverticulum such as adenocarcinoma, gastrointestinal stromal tumor (GIST), sarcoma, and carcinoid have been reported [26,59,64-66].

Signs and symptoms — The description of abdominal pain and the physical examination of the patient with Meckel's diverticulum are nonspecific. In patients with obstruction or inflammation related to the Meckel's diverticulum, typical physical findings include abdominal tenderness and abdominal 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.

Most patients undergo initial laboratory testing for the evaluation of abdominal pain that includes a complete blood count, electrolytes, and possibly a coagulation test. These studies may help identify patients who are volume depleted or experiencing complications but do not help establish a diagnosis of Meckel's diverticulitis from other sources of intestinal inflammation. Features of Meckel's diverticulum on routine abdominal imaging are given in the table (table 1) [17-23].

Diagnosis — An inflamed Meckel's diverticulum and complications related to a Meckel's diverticulum may be very difficult to distinguish from acute appendicitis on physical examination or preoperative imaging (image 4 and image 5). During abdominal exploration for presumed appendicitis, a finding of a normal appendix should prompt a thorough evaluation of the mid-to-distal ileum to rule out a Meckel's diverticulum as the source of the patient's symptoms. The bowel should be evaluated methodically, since it is easy to miss a short diverticulum or one that is adherent along its length to the antimesenteric border of the ileum, particularly with laparoscopy. (See 'Treatment' below.)

Differential diagnosis — The differential diagnosis of Meckel's diverticulitis includes any etiology that can cause lower abdominal pain. There are no specific clinical features that can distinguish Meckel's diverticulitis from any of these other causes. The tables provided list the causes of acute abdominal pain (table 5 and table 6). (See "Causes of abdominal pain in adults".)

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 [67-69].

TREATMENT

Treatment approach — Patients with suspected Meckel's diverticulum are initially managed according to their clinical presentation. If Meckel's diverticulum is found to be the source of symptoms, we resect the Meckel's diverticulum. Whether to resect asymptomatic, incidentally discovered Meckel's diverticulum is controversial. Based upon the natural history of Meckel's diverticulum, evidence from systematic reviews, and our clinical experience [1,5,6,8,11,16,26,29,67,68,70-75], we use the following approach to manage asymptomatic Meckel's diverticulum. The evidence supporting this approach is discussed in more detail in the following sections.

●For children and adults with Meckel's diverticulum discovered incidentally on imaging studies, we suggest not performing elective resection.

●For asymptomatic Meckel's diverticulum identified during the course of abdominal exploration:

•We suggest resecting the diverticulum in most children, up to young adulthood (if otherwise healthy).

•We suggest resecting the Meckel's diverticulum in otherwise healthy, young adults (<50 years of age) if there is a palpable abnormality or the Meckel's diverticulum is longer than 2 cm.

•We suggest not resecting the Meckel's diverticulum in patients >50 years of age, unless there is a palpable abnormality associated with the diverticulum.

Initial management — Initial medical management of symptomatic Meckel's diverticulum is directed toward managing the clinical manifestations that brought the Meckel's diverticulum to clinical attention.

●Intravenous lines should be placed and fluid and electrolyte therapy administered, as needed. (See "Maintenance and replacement fluid therapy in adults" and "Treatment of hypovolemia (dehydration) in children" and "Maintenance intravenous fluid therapy in children".)

●Patients with symptoms and signs of bowel obstruction may require nasogastric decompression. (See "Inpatient placement and management of nasogastric and nasoenteric tubes in adults" and "Management of small bowel obstruction in adults".)

●Patients with gastrointestinal bleeding should be initiated on proton-pump inhibitor therapy. The use of proton-pump inhibitors does not alter the sensitivity or specificity of a Meckel's scan. Aluminum hydroxide should be avoided. (See 'Meckel's scan' above and "Approach to acute lower gastrointestinal bleeding in adults" and "Approach to upper gastrointestinal bleeding in children", section on 'Initial assessment and resuscitation'.)

Resection of symptomatic Meckel's diverticulum — Symptomatic Meckel's diverticulum refers to clinical manifestations related directly to the diverticulum, which may include gastrointestinal bleeding related to heterotopic gastric mucosa, bowel obstruction related to intraluminal obstruction, adhesive bands, herniation of the diverticulum (Littre's hernia), and diverticular inflammation (Meckel's diverticulitis). We resect symptomatic Meckel's diverticulum in children and adults to relieve symptoms. (See 'Clinical presentations' above.)

Resection technique — Meckel's diverticulum can be resected by simple diverticulectomy (excision of the diverticulum at its base) or by segmental small bowel resection and primary anastomosis. Endoscopic resection of inverted Meckel's diverticulum has also been reported (simple diverticulectomy) [76]. (See 'Double-balloon enteroscopy' above.)

Surgical procedures can be performed using hand-sewn or stapling techniques via an open or laparoscopic (including both conventional and single incision) approach [77-79]. It is likely that a laparoscopic approach is feasible and safe.

●A 2019 retrospective review of the National Surgical Quality Improvement Program-Pediatric (NSQIP-Ped) database found no differences in operative time, length of stay, postoperative complications, and readmission between open and laparoscopic resection. However, 27 percent of laparoscopic cases required conversion to an open approach [80].

●A 2021 analysis of 681 children using NSQIP-Ped associated the laparoscopic approach with a shorter length of stay and found that conversion did not affect the risk of complications [81].

Diverticulectomy is most easily performed using a linear gastrointestinal stapler applied to the base of the diverticulum. However, we suggest segmental resection if the small bowel lumen is in jeopardy of being narrowed, a palpable abnormality is present at the base of the diverticulum, or the neck of the diverticulum is wide (>2 cm) [82]. Also, a broad-based, short diverticulum (one with a height-to-diameter ratio of less than 2.0) 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 [83].

When gastrointestinal bleeding is the primary clinical manifestation, it is likely that both segmental small bowel resection and simple diverticulectomy are effective surgical approaches. 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 [16,84,85].

Asymptomatic Meckel's diverticulum — Asymptomatic Meckel's diverticulum may rarely be identified on imaging, but more commonly an asymptomatic, normal Meckel's diverticulum is found during the course of abdominal exploration (open or laparoscopic).

Incidental Meckel's on imaging studies — In patients with Meckel's diverticulum discovered incidentally on imaging, we suggest not performing elective resection. The bulk of evidence, which consists primarily of retrospective reviews [1,6,8,11,70], does not support elective resection of asymptomatic Meckel's diverticulum. The lifetime risk of developing complications related to Meckel's diverticulum is overall low (4 to 6 percent). A large number of elective Meckel's resections would need to be performed to prevent a single death related to complications from a Meckel's diverticulum [6,8]. In one study, to prevent one death would require removing approximately 800 asymptomatic Meckel's diverticula, unnecessarily exposing these patients to the risk of surgical complications [8]. (See 'Natural history' above.)

Normal Meckel's found during abdominal exploration — Management of a normal-appearing Meckel's diverticulum identified during abdominal exploration is controversial. Although this issue has been evaluated in multiple case series and systematic reviews [1,5,8,11,16,29,68,70-74], there are no definitive prospective data supporting resection over no resection. Since most published studies combine adult and pediatric populations, it is difficult to define an appropriate algorithm for resection based solely upon age. Comparisons are further complicated by the varying definition of "child" used by various authors. Some authors suggest leaving incidentally detected Meckel's in situ regardless of age [5,8,71,86]. Others advocate resection of all incidentally detected Meckel's diverticula because gastric heterotopia in the resected Meckel's specimen is a common finding [10,69,70].

When asymptomatic Meckel's diverticulum is identified during abdominal exploration, we do not routinely resect all Meckel's diverticula; rather, we take into consideration the patient's clinical status, their lifelong risk of Meckel's-related complications, and anatomic features associated with developing symptoms [11,73,75]. A risk score has been used by some to guide decision making [73]. (See 'Risk factors for developing symptoms' above.)

We suggest a selective approach resecting the Meckel's diverticulum in otherwise healthy, young adults (<50 years of age) with anatomic risk factors (length >2 cm, palpable abnormality, fibrous bands) associated with Meckel's complications [11,75]. Patients without these features should not undergo Meckel's resection. Older patients (>50 years) and those with medical comorbidities should not undergo resection of incidental Meckel's, unless there is a palpable abnormality. This selective approach is further supported by a systematic review that compared complication rates of patients with resected asymptomatic Meckel's diverticulum with those of patients who did not undergo resection [6]. Mortality associated with Meckel's resection was overall low, but, among those who died, 94 percent were older than 44 years of age. The incidence of perioperative complications was significantly higher in those who underwent resection of the Meckel's compared with those who did not (5.3 versus 1.3 percent). In four studies, 91 patients were followed for a variable period of time after an incidental Meckel's diverticulum was left in situ; no patient developed clinical manifestations.

The risk of complications of Meckel's diverticulum may be higher for children compared with adults. In a review of 74 children, the risk of Meckel's-related complications in children under two years and between two and eight years of age was significantly higher compared with children older than eight years [46]. Thus, some authors have suggested removal of all asymptomatic diverticula in children younger than eight years of age. Our practice is to resect Meckel's diverticulum incidentally identified on abdominal exploration in most children. The Meckel's diverticulum can remain in place for selected children with medical comorbidities provided risk factors associated with complications of Meckel's diverticulum are not present. (See 'Risk factors for developing symptoms' above.)

Counseling asymptomatic patients — Patients with asymptomatic Meckel's diverticulum that remains in situ should be counseled regarding potential future symptoms. If symptoms do develop, the Meckel's diverticulum will require resection. (See 'Clinical presentations' above and 'Resection of symptomatic Meckel's diverticulum' above.)

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 [6,7]. The anticipated complication rate for Meckel's resection is overall approximately 5 percent [5,10,11,26], 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 [10]. By comparison, the complication rate for elective Meckel's resection was 2 percent.

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Meckel's diverticulum (The Basics)")

SUMMARY AND RECOMMENDATIONS

●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.)

●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 both native intestinal and heterotopic gastric mucosa. There is no familial predisposition for Meckel's diverticulum, but the prevalence is increased in children with major malformations of the umbilicus, alimentary tract, nervous system, or cardiovascular system. (See 'Epidemiology' above.)

●Meckel's diverticulum is often clinically silent, particularly in the adult. Incidental Meckel's diverticulum is most commonly identified during abdominal exploration for an unrelated pathology. When symptomatic, Meckel's diverticulum can present with gastrointestinal bleeding or acute abdominal pain 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. Specific anatomic factors related to the Meckel's diverticulum (length >2 cm, palpable abnormality) increase the risk of developing symptoms. (See 'Clinical presentations' above and 'Risk factors for developing symptoms' above.)

●Meckel's diverticulum is often not the first diagnosis considered for many abdominal complaints. A diagnosis of Meckel's diverticulum should be suspected in patients with the following clinical features:

•Children with painless lower gastrointestinal bleeding

•Children and adults with intussusception, particularly children with recurrent small bowel intussusception

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

•Adults with gastrointestinal bleeding but negative upper endoscopy and colonoscopy

●Certain features on routine imaging studies (eg, plain abdominal films, ultrasound, computed tomography) obtained to evaluate abdominal pain or intestinal obstruction may suggest a diagnosis of Meckel's diverticulum, but these findings are usually nonspecific. In patients without immediate indications for abdominal exploration (eg, perforation), a suspicion for a bleeding Meckel's diverticulum can be investigated with a Meckel's scan, which identifies the presence of ectopic gastric mucosa within the diverticulum. A Meckel's scan should be obtained earlier in the evaluation of gastrointestinal bleeding in children compared with adults. Meckel's diverticula without ectopic gastric mucosa will not be visible on a Meckel's scan. Abdominal exploration will be needed to establish the diagnosis. 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 2 and table 3 and table 4 and table 5 and table 6).

●Symptomatic Meckel's diverticulum should be resected in all patients (children and adults) to relieve symptoms. Whether an incidentally discovered, asymptomatic diverticulum should be removed is controversial in children and adults. For children and adults with asymptomatic Meckel's diverticulum identified on imaging studies, we suggest not performing elective resection (Grade 2B). For patients with a normal-appearing Meckel's diverticulum identified on abdominal exploration, we use a selective approach that takes into consideration the patient's clinical status, their lifelong risk of Meckel's-related complications, and anatomic features associated with developing symptoms. (See 'Normal Meckel's found during abdominal exploration' above.)

•For most children to young adulthood, we suggest resection of the normal-appearing Meckel's diverticulum given an increased lifelong risk for complications (Grade 2C).

•For otherwise healthy, young adults (<50 years of age), we suggest resection of the normal-appearing Meckel's diverticulum if there is a palpable abnormality or the Meckel's diverticulum is longer than 2 cm (Grade 2C).

•For patients >50 years of age, and patients with significant comorbidities, we suggest not resecting the normal-appearing Meckel's diverticulum, unless there is a palpable abnormality associated with the diverticulum (Grade 2C).

●For patients undergoing resection of a symptomatic Meckel's diverticulum due to gastrointestinal bleeding, it is likely that both segmental small bowel resection and simple diverticulectomy are effective surgical approaches, although there are no high-quality data to compare the two techniques. (See 'Resection technique' above.)

●Death related to resection of Meckel's diverticulum is rare. The anticipated complication rate for Meckel's resection is overall approximately 5 percent. The most common complications are surgical site infection, prolonged postoperative ileus, and anastomotic leak, which are essentially those of any small bowel surgery. (See 'Perioperative morbidity and mortality' above.)