Meckel Diverticulum Flashcards
A 13-month-old child is admitted to the hospital with lower GI bleeding. Which of the following is correct regarding the most common cause of lower GI bleeding in this patient?
A. Heterotopic pancreatic mucosa is likely to be the cause of bleeding.
B. The bleeding source is most commonly found on the mesenteric side of the intestine.
C. The most common location of the bleeding source is in the jejunum.
D. This problem is not likely to be confused with acute appendicitis.
E. It is a result of an incomplete closure of the omphalomesenteric duct.
ANSWER: E
COMMENTS: Meckel’s diverticulum results from an incomplete closure of the omphalomesenteric duct during development, resulting in a true diverticulum, which contains all layers of the intestinal wall.
Meckel’s diverticula account for 50% of lower GI bleeding in the pediatric population.
They are located on the antimesenteric side of the intestine.
There is an equal distribution among genders.
The rule of 2’s states that Meckel’s diverticulum usually presents by the age of 2, is 2 ft from the ileocecal valve, occurs in 2% of the population, and may contain 1 of the 2 types of heterotopic mucosa.
Gastric mucosa is the most common heterotopic mucosa present.
It may lead to ulcer formation just distal to the diverticulum with painless bleeding.
It has been estimated that 80% of bleeding Meckel’s diverticula contain heterotopic gastric mucosa.
Pancreatic mucosa is the next most common; however, it is not as commonly associated with bleeding.
Other manifestations of Meckel’s include an obstruction or intussusception, with the diverticulum acting as the lead point.
Symptomatic Meckel’s should be surgically excised, either with a diverticulectomy or bowel resection and anastomosis.
Diverticulitis within a Meckel’s can mimic acute appendicitis.
During a negative exploration for presumed appendicitis, the small bowel should be run to rule out a Meckel’s diverticulum, other small bowel diverticulosis, and Crohn’s disease.
What is the vitelline duct?
The vitelline duct, also known as the omphalomesenteric duct, is the embryonic structure that connects the extracoelomic yolk sac with the developing midgut.
When does the vitelline/ omphalomesenteric duct regress?
The regression of this embryonic duct occurs between weeks 5 and 9 of fetal development [2].
What are the potential remnants of the vitelline/omphalomesenteric duct if complete regression does not occur?
If complete regression of the vitelline duct does not occur, several different remnants are possible.
These remnants include Meckel’s diverticulum, omphalomesenteric cyst, congenital band, umbilical sinus and omphalomesenteric duct fistula.
If present, they usually occur in isolation; however, case reports of more than one anomaly have been described.
The most common remnant is Meckel’s diverticulum [3].
How do these remnants present in pediatric patients?
Most of these remnants are asymptomatic and remain that way for a lifetime.
If symptoms present, they are directly related to the portion of the vitelline duct that remains.
Meckel’s diverticulum can present with painless bloody stools, abdominal pain mimicking appendicitis, or symptoms of intestinal obstruction.
Omphalomesenteric duct cysts can present with abdominal pain, abdominal wall cellulitis or umbilical drainage.
A congenital band usually presents with symptoms of intestinal obstruction.
Umbilical sinus presents with umbilical drainage or umbilical cellulitis.
In the case of an omphalomesenteric duct fistula, intestinal contents can be noted at the umbilicus in the newborn.
How does intestinal obstruction occur in patients with Meckel’s diverticulum?
There are several different underlying etiologies for intestinal obstruction in Meckel’s diverticula.
In pediatric patients, a congenital band may attach to the Meckel’s which serves as a fixed point around which intestinal volvulus can occur.
An internal hernia may be formed from bands between the Meckel’s and surrounding mesentery.
The Meckel’s can serve as a lead point for intussusception.
More uncommonly, chronic inflammation secondary to diverticulitis may cause an intestinal stricture.
Perforation with adjacent abscesses may also cause obstruction or ileus [4].
A foreign body may be lodged in the Meckel’s or it may become incarcerated in a hernia defect, called a Littre hernia.
What are the “rule of 2′s” as they relate to Meckel’s diverticulum?
In general, Meckel’s diverticula occur in 2% of the population, 2% are symptomatic, they are 2 feet from the ileocecal valve, most are approximately 2 inches in length, they can contain 2 types of heterotopic mucosa (gastric and pancreatic) and most are symptomatic before the age of 2.
Meckel’s diverticula occur 2:1 in males versus females.
What imaging modalities are recommended to diagnose Meckel’s diverticula or other vitelline/omphalomesenteric duct remnants?
In addition to a quality physical examination, imaging can be utilized to assist in making the diagnosis of these remnants.
In cases of intestinal obstruction, abdominal flat and decubitus plain films may be the only imaging obtained preoperatively.
CT scan or MRI may assist in diagnosing a vitelline duct remnant as the source of symptoms, but many cases of obstruction are not fully delineated until the operating room.
A Meckel’s scan can assist in diagnosing a Meckel’s diverticulum.
Abdominal ultrasonography can diagnose omphalomesenteric duct cysts [4].
What is a Meckel’s scan?
The Meckel’s scan is a technetium-99m (Tc99m)-pertechnetate scintigraphy study.
Tc99m accumulates in the parietal cells of ectopic gastric mucosa within the diverticulum.
The sensitivity is 85% and specificity is 95% [4].
What pharmacologic adjuncts can be used to improve the sensitivity of the Meckel’s nuclear medicine scan?
Diagnostic accuracy of the Meckel’s scan has been improved with pentagastrin, histamine-2-blockers and glucagon [4].
What is the treatment recommendation for symptomatic Meckel’s diverticula?
Symptomatic Meckel’s diverticula are treated with surgical resection in all cases.
This involves open or minimally-invasive approaches to diverticulectomy versus segmental small intestinal resection.
What is the appropriate operation for a symptomatic Meckel’s?
As mentioned above, symptomatic Meckel’s diverticula require surgical resection.
This resection can be performed in an open or laparoscopic fashion.
In the absence of significant inflammation or intestinal wall thickening, an isolated diverticulectomy stapled or handsewn is sufficient.
It is important to note that in a minority of patients, ectopic tissue may be present in the base of the diverticulum and this area may not feel abnormal.
Segmental small intestine resection may be required if the diverticulum has resulted in significant surrounding inflammation, intestinal thickening at the diverticulum’s base or if there is concern for bleeding ulcerations in the remaining small intestine.
What should be done with an asymptomatic Meckel’s diverticulum discovered incidentally at the time of surgery for a different indication?
Incidental removal of an asymptomatic Meckel’s diverticulum is controversial.
Zani and colleagues noted a low lifetime mortality risk in patients.
Additionally, they noted a higher postoperative complication rate than morbidity rate of Meckel’s diverticulum left in situ.
By their calculations, nearly 800 Meckel’s would need to be removed to prevent one mortality.
Park and colleagues reviewed a large, retrospective series of patients of all ages at the Mayo Clinic with Meckel’s diverticula of which 16% were symptomatic.
They recommend considering selective excision of asymptomatic Meckel’s in patients less than 50 years of age, male patients, diverticula with a length greater than 2 cm or those containing abnormal/ectopic tissue [5, 6].
Regarding presentation of vitellointestinal duct anomalies, the following are false except:
A. Presents as intestinal obstruction when ectopic gastric mucosa.
B. Presents with melena when there is Meckel’s diverticulum with band.
C. Presents with abdominal pain, mass and redcurrant jelly in stool when patent intestinal duct.
D. Presents with shiny, spherical and deep nodule in the depth of umbilical cicatrix, when prolapse of patent vitellointestinal tract.
E. Presents with features of appendicitis, when there is diverticulitis.
E
Ectopic gastric mucosa presents with bleeding, bands presents with intestinal obstruction. Meckel’s diverticulum that leads to intussusception, presents with abdominal pain, mass, and red currant jelly in stool. Patent vitellointestinal duct presents with passage of air and faeces from umbilicus. Shiny, spherical red nodule is a feature of umbilical polyp (ectopic mucosa at umbilicus). Meckel’s diverticulitis presents with abdominal pain, vomiting, and fever. On examination, tenderness in right lower abdomen. These features are the same as appendicitis.
What type of discharge at umbilicus in patent/persistent vitellointestinal duct?
A. Air and faeces.
B. Pus.
C. Blood.
D. Urine.
E. Gastric contents.
A. Air and faces
Blood is noted in umbilical polyp and urine is seen in patient urachus.
