Meckel diverticulum is the most common congenital abnormality of
the small intestine, occurring in 2% of the population.
In general, Meckel diverticulum follows the rule of twos: affects
2% of the population; most commonly found 2 feet from the
ileocecal valve; 2 types of ectopic tissue are found within the
diverticulum (gastric and pancreatic tissue); and 2% develop
symptoms. In fact, the life-time risk of complications from Meckel
diverticulum has been estimated to be between 4% and 6%.2 Given
the low number of symptomatic diverticula, many Meckel diverticula
are identified incidentally during operations for other pathology. While
most Meckel diverticula are sporadic, there is an association with
Hirschsprung disease, Down syndrome, esophageal atresia, duodenal
atresia, malrotation, and congenital cardiac abnormalities.3 Other
omphalomesenteric duct abnormalities are much less common.
Normal gut development depends on the interactions among the
layers of endoderm (epithelial lining), mesoderm (smooth muscle
formation) and ectoderm (enteric nervous system). Histologically,
a Meckel diverticulum is a true diverticulum, consisting of all
four intestinal layers. The blood supply is a vestige of the primitive
vitelline artery and may be prominent in patients with bleeding presentations (see Fig. 402-1). Murine studies noted formation of
buds at the region of the vitelline duct in approximately 3% of
13.5-day embryos. The tissue from these buds was able to express
albumin; the remainder of the surrounding tissue did not, suggesting
an escape from the inhibitory effects of the mesoderm.4 Further
studies are necessary to delineate the complex pathway leading to
the development of a Meckel diverticulum.
Omphalomesenteric remnants. A: Meckel diverticulum with
diverticulitis. B: Meckel diverticulum with ulceration and hemorrhage. C, D: Bowel
obstruction from volvulus around attachment to the abdominal wall. E: Patent omphalomesenteric
duct. F: Omphalomesenteric sinus and cyst.
and Differential Diagnosis
The most common presentations of symptomatic a Meckel diverticulum
include painless lower gastrointestinal (GI) bleeding, inflammation
with or without perforation, or bowel obstruction from volvulus,
intussusception, or internal hernia (see Fig.
402-1). Such presentations often mimic other pathology requiring
emergent surgery and therefore diagnosis of a Meckel diverticulum
is often made only in the operating room.
GI bleeding is the most common presenting symptom associated with
a Meckel diverticulum, and it is the most common cause of massive
lower GI bleeding in children less than 4 years of age (see Chapter 387). Ectopic gastric mucosa causes ulceration
of the adjacent mucosa with resultant bleeding. Patients typically
present with relatively painless rectal bleeding. The blood loss
can be brisk and associated with significant anemia and hypotension.
This can mimic intussusception as well as other sources of lower
Meckel diverticulitis typically presents with abdominal pain,
fever, and leukocytosis. Signs of peritonitis and sepsis are often
present if diagnosis is delayed. Presentation is often indistinguishable
from acute appendicitis. Bowel obstruction from a Meckel diverticulum
or omphalomesenteric duct remnant presents with abdominal distension
and pain. Most often obstruction is associated with bilious emesis
and absence of stools and flatus. Signs of dehydration due to intravascular
depletion are common. Signs of peritonitis and sepsis are worrisome
for ischemic or necrotic bowel as a consequence of a strangulated
bowel obstruction. Preoperative differentiation from other causes
of obstruction—adhesions, hernias, congenital bands, etc—can
be difficult and is unnecessary.
The approach to evaluation of the child with varies depending
upon the clinical presentation. Meckel diverticulus presents with
inflammation, with or without perforation, pain and possibly signs
of peritonitis associated with a fever and leukocytosis. In this
setting, physical examination may dictate emergent operative exploration without
the need for further diagnostic evaluation. Ultrasonography or computed
tomography of the abdomen and pelvis typically demonstrate signs
of inflammation, free fluid or free air and occasionally an edematous,
inflamed blind ending segment of bowel in the right lower quadrant
of the abdomen to suggest Meckel’s diverticulitis. Theses
findings on ultrasound and computed tomography scan often mimic
that of appendicitis. The approach to the child with bowel obstruction
is discussed in Chapter 389.
The approach to a child with gastrointestinal (GI) bleeding is
described in Chapter 387. If a Meckel diverticulum
is suspected, a technetium 99m pertechnetate scintigraphy, also
known as a Meckel scan is used to demonstrate the presence of gastric
epithelium which concentrates the radio-labeled pertechnetate (see Fig. 402-2). This can be
enhanced by the administration of an H2 receptor antagonist and pentagastrin.
The sensitivity of Meckel’s scan is 85%, and specificity
is 95%. The Meckel’s scan has a high false negative
rate even in patients with gastric mucosa demonstrated on pathological
examination.5 The probability of a Meckel diverticulum
as the source of the GI bleeding in a child who presents with a
GI bleed, hemoglobin less than 11g/dL and a negative Meckel’s
scan is 0.26.5 For this reason, as well as the low morbidity
associated with diagnostic laparoscopy, patients with a significant
GI bleed with no source identified following less invasive diagnostic
tests should be considered for diagnostic laparoscopy despite a
negative Meckel’s scan (see eFig. 402.1).
Technetium-99m pertechnatate scintigraphy of Meckel diverticulum.
Radionucleotide signal is seen in the stomach (S), bladder (B),
and the Meckel diverticulum (M).
(Adapted from Sawin RS. Appendix and Meckel’s
diverticulum. In: Oldham KT, Colombani PM, Foglia RP, Skinner MA, eds. Principles
and Practice of Pediatric Surgery. Philadelphia, PA: Lippincott
Williams & Wilkins, 2005:1269-1282.)
Meckel diverticulum as seen through the laparoscope.
The laparoscopic grasper is holding the tip of the Meckel diverticulum
up toward the anterior abdominal wall.
(Picture courtesy of Dr. Casey Calkins).
Management of patients with symptomatic complications of a Meckel
diverticulum or other omphalomesenteric duct remnants is surgical,
and surgical consultation should be sought early in the treatment.6 Removal
of the diverticulum, cyst, or fistula and any associated ectopic
gastric tissue must be ensured in order to prevent recurrent bowel
obstruction, bleeding and/or ulcers, and diverticulitis.
A narrow-based diverticulum and those with gastric tissue at the
tip of the diverticulum may be resected at the base, whereas wide-based
and short diverticula require resection of additional small bowel
in order to ensure removal of all gastric mucosa.
A diverticulectomy, wedge resection, or partial small bowel resection
may be performed open or laparoscopically. Whether the abdomen is
explored via laparotomy or with the laparoscope, evaluating the
terminal ileum and working proximally will identify a Meckel diverticulum
if present. Laparoscopic methods have been described and include
a camera port with 2 to 3 working ports. Alternatively, a single
10-mm trocar placed at the umbilicus and an operative telescope
have been used to grasp the terminal ileum and exteriorize the Meckel
diverticulum through the umbilical incision for resection.7
Controversy exists as to the management of an asymptomatic Meckel
diverticulum found incidentally at the time of a laparotomy. The
risk of development of symptoms in the future is inversely related
to the patient’s age. Most pediatric surgeons would remove
an asymptomatic Meckel diverticulum in an infant or child at the
time of laparotomy unless it may increase the risk of postoperative
complications. Meckel diverticula that contain palpable ectopic mucosa,
appear inflamed, are attached to the umbilicus, or have a narrow
base are more likely to cause symptoms if left in place and therefore
are often removed. In older children and adults, the risk of developing
complications from an unresected Meckel diverticulum appears less
likely, and the risk of future complications if the Meckel diverticulum
is left in place must be weighed on an individual basis against
the risk of complications from resection.
Complications from surgical resection are infrequent with an
incidence of less than 1% to 2%. Patients who
have undergone resection of a Meckel diverticulum typically have
no further problems.