Meckel Diverticulum Flashcards

Question

Regarding the management of Meckel’s diverticulum, which of the following is false? A. After excision of diverticulum, having two layer closure of ileum is preferable. B. The feeding artery should be ligated. C. If carcinoid has developed, there is greater potential for metastasis than for appendicular carcinoid. D. In case of carcinoid development, aggressive surgical management of tumors larger than 5cm is recommended. E. If left intact, the lifetime risk of complication is 2 percent.

Answer 1

E If left intact the lifetime risk of complication of Meckel’s diverticulum is 6.4 percent. Syed/MCQ

Answer 2

The commonly cited “rule of 2s” regarding the diverticulum is: - occurs in 2% of the population - has a 2:1 male-to-female ratio - usually discovered by 2 years of age - located 2 feet (60 cm) from the ileocecal valve - commonly 2 cm in diameter and 2 inches (5 cm) long, and - can contain two types of heterotopic mucosa Gastric is the most common type of heterotopic mucosa, followed by pancreatic. More rarely, it may contain duodenal, colonic, or endometrial tissue.

Answer 3

C The intracoelomic yolk sac forms the gut. The fetal midgut is attached to the yolk sac via the omphalomesenteric duct (also known as vitelline duct or yolk stalk). This regresses at 5–7 weeks’ gestation. meckel’s diverticulum results from failure of proximal duct to obliterate. The right and left vitelline arteries originate from the aorta within the yolk stalk. The left involutes and the right persists as the superior mesenteric artery and terminally supplies the diverticulum. meckel’s diverticulum is a true diverticulum (containing all normal layers of the intestinal wall) located on the antimesenteric border of the small bowel. SPSE 1

Answer 4

E meckel’s diverticulum is the most common vitelline duct (omphalomesenteric duct) abnormality. Abnormal regression of the vitelline duct can also give rise to other abnormalities. ● Persistent vitelline duct: appearing as a draining fistula at the umbilicus. ● Patent vitelline sinus: can be a source of infection with purulent discharge. It can be connected to the meckel’s diverticulum, by a fibrous band around which volvulus can occur. ● Fibrous band connecting the ileum to undersurface of the umbilicus: can cause obstruction or volvulus. ● Vitelline duct cyst: mucosal and muscular lined cyst, which persists after the proximal and distal duct obliterates. ● umbilical polyp: most are independent anomalies, although some can connect with deeper structures. Sometimes they can be mistaken for umbilical granulomas. ● omphaloileal fistula: persistent patency of the vitelline duct with the fetal intestine. A urachus is a fibrous cord that originates from the allantois and extends from the bladder to the umbilicus. Abnormal obliteration and regression of the urachus gives rise to various abnormalities, unrelated to vitelline duct abnormalities. SPSE 1

Answer 5

D The ‘rule of 2s’ is often used as a mnemonic for meckel’s diverticulum: ● occurs in 2% of the population ● twice as common in males as in females ● usually located 2 feet from ileocaecal valve ● 2 inches long ● 2 cm in diameter ● symptomatic by 2 years of age ● contains two types of heterotopic tissue – gastric and pancreatic. male-to-female ratio is almost equal in asymptomatic group, but in symptomatic group males > females. most cases become symptomatic within first 2 years. Approximately 60%–85% of heterotopic mucosa is gastric and 5%–16% is pancreatic. other mucosa like colonic, endometrial and pancreatic islet are quite rare. SPSE 1

Answer 6

E most cases of meckel’s diverticulum are sporadic. There is an increased incidence with other anomalies such as: ● oesophageal atresia ● duodenal atresia ● imperforate anus ● omphalocele ● malrotation ● Hirschsprung’s disease ● Down’s syndrome ● congenital diaphragmatic hernia ● congenital neurologic conditions ● cardiovascular malformations. Concomitant urachal and omphalomesenteric duct anomalies are rare. The presence of meckel’s diverticulum does not justify a search for other anomalies as <5% have associated anomalies. There has been a high incidence of incidental finding of meckel’s diverticulum with Crohn’s disease (6%), but the presence of heterotopic mucosa in these cases is extremely rare. SPSE 1

Answer 7

A most patients with meckel’s diverticulum are asymptomatic. Approximately 4%–16% of patients have related symptoms. The most common signs and symptoms of meckel’s diverticulum are bleeding, obstruction and inflammation. The type of presentation correlates with age. Intestinal obstruction due to volvulus or intussusception is the most typical presentation in newborns. In older infants and younger children, painless lower gastrointestinal bleeding is common. older children usually present with inflammation mimicking appendicitis. Children are more likely to be symptomatic than adults. In adults inflammation and obstructive symptoms are common. Bleeding is generally painless, episodic and sometimes massive. occult bleeding with anaemia is rare. H. pylori is rarely identified in the heterotopic gastric mucosa of a bleeding meckel’s diverticulum. This could be because of the bile salt toxicity, which affects the H. pylori microorganism. SPSE 1

Answer 8

E The most common cause of intestinal obstruction secondary to meckel’s diverticulum is intussusception. meckel’s diverticulum acts as a pathological lead point and should be suspected in all cases of intussusception occurring in older children (>5 years). Pneumatic reduction in these cases is usually unsuccessful and the meckel’s diverticulum is identified at the time of bowel resection. other mechanisms of intestinal obstruction include volvulus, inflammation, meckel’s diverticulum incarcerated in an inguinal hernia (littre’s hernia) and, rarely, prolapse through a patent vitelline duct. Volvulus can occur because of persistent vascular or vitelline remnants from the bowel or diverticulum attached to the abdominal wall allowing twisting, kinking or herniation. A giant meckel’s diverticulum can also cause volvulus in newborns. Ectopic gastric mucosa seen with meckel’s diverticulum usually causes bleeding and ulceration. SPSE 1

Answer 9

E Approximately 5% of patients with symptomatic meckel’s diverticulum present with umbilical abnormalities. They could manifest as an umbilical polyp, a persistent umbilical sinus connecting to the meckel’s diverticulum or an omphaloileal fistula. Rarely foreign bodies, stones and parasitic infections such as ascariasis or schistosomiasis have been reported within a meckel’s diverticulum. These can cause inflammation or can perforate through the diverticulum. Carcinoid tumours are more often seen in adults and are relatively aggressive. Tumours larger than 5 mm have a significant risk for metastasis. Carcinoid syndrome can also occur with meckel’s diverticulum. SPSE 1

Answer 10

E The lifetime risk of complications developing from an incidentally diagnosed meckel’s diverticulum ranges from 4.2% to 6.4%. The incidence of complications decreases with advancing age. Factors associated with increased likelihood of complications include age younger than 40 years, male sex, presence of heterotopic mucosa and diverticular length >2 cm. most cases of meckel’s diverticulum associated with Crohn’s disease are incidental findings at the time of hemicolectomy for Crohn’s disease. The incidence of heterotopic mucosa seen with patients with Crohn’s disease is very rare. SPSE 1

Answer 11

B 99m Tc pertechnetate scintiscan is useful when meckel’s diverticulum is complicated with episodes of bleeding. Because this scan is specific for gastric mucosa (in the stomach or ectopic) and not specifically diagnostic of meckel’s diverticulum, positive results can occur in other conditions where ectopic gastric mucosa is present. Duodenal ulcers, small intestinal obstruction, intestinal duplications, ureteric obstruction, aneurysms and angiomas of the small intestine yield false positive results. False-negative results can occur when gastric mucosa is very slight or absent in the diverticulum, if necrosis of the diverticulum has occurred or if meckel’s diverticulum is superimposed on the bladder. The sensitivity is 80%–90%, specificity is 95% and accuracy is 90% for meckel’s diverticulum. Pentagastrin, histamine blockers and glucagons may enhance the accuracy of scanning. likewise fasting, nasogastric suction and bladder catheterisation may increase the yield of scanning. Barium study has a low diagnostic yield and is not routinely used. If performed, it should never precede 99m Tc scintiscan, because barium may obscure the hot spot. Selective arteriography may be helpful in patients in whom the results from scintiscan and barium studies are negative. They can detect a meckel’s diverticulum even in the absence of bleeding. SPSE 1

Answer 12

C The treatment for meckel’s diverticulum is either a simple diverticulectomy or small-bowel resection with end-to-end anastomosis. Incidental appendicectomy is usually performed. The definitive treatment of complicated meckel’s diverticulum such as bleeding is by excision of the diverticulum along with adjacent ileal segment either using a stapling device of by hand-sewn anastomosis, which can also be accomplished laparoscopically. The ectopic gastric mucosa may extend along the adjacent ileum as well, on the mesenteric side opposite the ileum. Hence, in cases of bleeding, resection of a segment of adjacent ileum with end to-end anastomosis is a safer option. A persistent right vitelline artery supplying the diverticulum is sometimes found during operation and must be identified and ligated. The role of elective removal of asymptomatic meckel’s diverticulum is still controversial. The most common complication following elective removal of meckel’s diverticulum is adhesive bowel obstruction in 5%–10% of cases. In cases of intussusception secondary to meckel’s diverticulum, complete reduction with pneumatic or contrast enema is attempted followed by elective excision of meckel’s diverticulum. However, complete reduction is usually unsuccessful, and the diverticulum is often detected at the time of bowel resection. SPSE 1

Answer 13

E management of asymptomatic meckel’s diverticulum is controversial. In the past, if meckel’s diverticulum was encountered in patients undergoing abdominal surgery, many surgeons recommended its removal. This has now been questioned given the overall likelihood of developing complications around 4.2%–6.4% and a decreasing risk with increasing age. A large number of meckel’s diverticulums would have to be excised to prevent one death. On the other hand, some authors argue that the resection of meckel’s diverticulum is a simple operation, and the management of its complications is associated with high morbidity and mortality. Elective resection is recommended in cases with a palpable thickening suggestive of heterotopic mucosa, in those with unexplained abdominal pain, and in cases with abdominal wall attachment. In general, removal of incidental meckel’s diverticulum is indicated in children less than 8 years old, because infants and young children are at a greater risk for complications. SPSE 1

Answer 14

E Elective excision of incidental meckel’s diverticulum is not recommended in cases highly susceptible to sepsis. It is generally contraindicated in immunocompromised patients, those undergoing insertion of a prosthetic material and babies with gastroschisis, owing to the presence of a thickened serosal peel or prosthetic patch. SPSE 1