MECKEL'S DIVERTICULUM
DEFINITION
A congenital abnormality in which a functionless remainder of an
embryonic
gut duct persist into adult life, possibly causing problems of
infection,
obstruction, or abnormal secretion into the bowel.
Rules of 2
- located~ 2 feet from the ileocaecal valve
- 1 in 2 contains 1 of 2 types of heterotopic tissue gastric /
pancreatic
- 2x more common in males
- 2% of population
- 2% become symptomatic
- usually within first 2 years of life
- 2 inches in length
- 2 predominant symptoms: bleeding and obstruction
top D I A B M
I M home
INCIDENCE
Congenitally ~2% of people.
M>F 3-5:1.
Symptoms rare after age 10.
top D I A B M
I M home
AETIOLOGY
Congenital
Failure of involution of the vitelline duct (connects lumen of
developing gut to yolk sac).
top D I A B M
I M home
BIOLOGICAL BEHAVIOUR
Anatomy
An ileal diverticulum, typically around 5 cm long, wide mouthed,
contains
ileal layers and often heterotopic pancreas or gastric mucosa (in
50%).
Arises from the antimesenteric border of the ileum, typically 40-50
cm
from
the ileocecal valve (usually less than 100 cm).
May be connected to umbilicus by a fibrous cord or even fistula.
Pathophysiology
Causes illness in three ways:
1. Secreting potent enzymes
- 50% may contain mucosa capable of doing this: ie. gastric (75%) or
pancreatic (15%)
acid/enzymes
- symptoms decrease post-vomiting and come on worse at night when
stomach
empty & secreting ongoing, or when hungry.
- bleeding is a predominant symptom; typically along the mesenteric
border of the ileum a short way distal to the lesion
- this is the most common Meckel-related problem, overall
2. Becoming infected
- routinely indistinguishable from appendicitis
3. Intussuscepting into
ileum and obstructing it; possibly necrosis and
perforation.
- obstruction is most common presentation in adults
Natural History
Lifetime risk of asymptomatic Meckel's is very low
Most will become symptomatic in first 2 years of life, certainly by
age 18
top D I A B M
I M home
MANIFESTATIONS
Symptoms
Local
Secreting
Acid - bleeding most important sign: haematemesis, melaena, anaemia.
Also pain in central abdomen, weight loss.
Infection
Mimics appendicitis.
Infrequently may perforate, with peritonitis.
Obstructed
Symptoms of bowel obstruction.
Signs
As per complication.
Palpate
May be periumbilical tender mass.
Perhaps bowel dilated proximally, if obstruction.
top D I A B M
I M home
INVESTIGATIONS
CT
May be visible with contrast.
Angiography
May be located when looking for a bleeding source
May demonstrate a persistent right
vitelline artery, arising from the SMA,
- or an embryonic ileal artery branching to it.
Isotope scanning
After technetium injection (Tc99 pertechnetate; taken up by ectopic
gastric mucosa).
False positive and false negative results possible.
- depends on skill of radiologist
- may need oblique, lateral or postvoid fills; secretion should
occur at same time as
stomach
Sensitivity ~80% but can be increased by pre-test pentagastrin or
glucagon administration.
top D I A B M
I M home
MANAGEMENT
Asymptomatic
Leave it alone
Incidentally discovered Meckel's in adults should be be left alone
as the risk of resection probably outweighs the risk of leaving it
alone.
- they should be removed
only in young children.
But there are relative indications
- palpable evidence of a mass or ectopic tissue
- evidence of prior diverticulitis
- past unexplained GI haemorrhage or abdo symptoms
- mesodiverticular band
Bleeding
Note that bleeding ulcer source is often on mesenteric side of bowel
under the Meckel, or on the antimesenteric side just distal to it.
Amputation or wedge resection is not enough.
Explore and conduct a small bowel resection.
Infection
Depending on degree of inflammation.
1. Small bowel resection may be most appropriate
2. Else simple stapled amputation or wedge resection of the Meckel.
- pick up Meckels with two babckocks
- lay across an nTLC 75, longitudinally along the bowel, ensure
there is not going to be any narrowing
- fire.
Obstruction
Relieve then resect by wedge resection or amputation.
top D I A B M
I M home