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Volume 99, Number 10 >
Pp. 501-505
Reviews |
1 Department of Surgery, Royal Free Hospital, London
2 Department of Orthopaedics, Princess Alexandra Hospital, Harlow, Essex,
UK
3 Department of Surgery, SSG Hospital, Vadodara, India
Correspondence to: Jayesh Sagar E-mail: jsagar_2001{at}yahoo.com
SUMMARY
Meckel's diverticulum is the most common congenital malformation of gastrointestinal tract. It can cause complications in the form of ulceration, haemorrhage, intussusception, intestinal obstruction, perforation and, very rarely, vesicodiverticular fistulae and tumours. These complications, especially bleeding, are more common in the paediatric age group than in adults; however it is not uncommon to miss the diagnosis of Meckel's diverticulum in adults. Here, we reviewed the literature regarding the complications of this forgotten clinical entity in adults with potential diagnostic difficulties and management strategies.
INTRODUCTION
Meckel's diverticulum is the most common congenital malformation of the gastrointestinal tract (present in 2%-4% of population) due to persistence of the congenital vitello-intestinal duct. Bleeding from Meckel's diverticulum due to ectopic gastric mucosa is the most common clinical presentation, especially in younger patients (Figure 1 in colour online), but it is rare in the adult population. The complications in adults include: obstruction; intussusception; ulceration; haemorrhage; and, rarely, vesicodiverticular fistulae and tumours. Due to the rarity of cases in adults, it is still misdiagnosed preoperatively—although with the wide spread use of technetium-99m pertechnate scan and diagnostic laparoscopic approach, the rates of preoperative diagnosis have improved. Here, we review the current literature of this forgotten clinical entity for its clinical diversity, diagnostic difficulties and management controversies.
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METHODS
We used PubMed and Medline search engines for articles containing terms such as Meckel's diverticulum, ectopic gastric mucosa, technetium-99 pertechnate scan, histopathology, treatment and complications, from 1995 to 2005. From the abstracts of those articles we selected relevant articles and reviewed them in detail. We included all the relevant major review articles and trials. We selected articles, which were available in full text English language. We excluded single case report unless they were of exceptional value. Additional articles were identified by a manual search of the references from the reviewed articles.
DISCUSSION
Gastrointestinal bleeding is a major cause of emergency hospital attendance in adults. Nearly 80% of this bleeding in adults originates proximal to the ligament of Treitz. The most common source of the lower gastrointestinal bleeding is colon, with less than 5% of bleeding from small intestine.1 The usual investigations include upper gastrointestinal endoscopy and colonoscopy as well as the usual biochemical and haematological investigations. Endoscopy may not be useful if there is significant blood pool obstructing the visibility. Technetium-bleeding scan and angiography may be used to diagnose rare focal sources of bleeding such as Meckel's diverticulum.
Meckel's diverticulum is the most common congenital malformation of the gastrointestinal tract—most studies suggest an incidence of between 0.6% and 4%. It is also the most common cause of bleeding in the paediatric age group. This is due to the persistence of the proximal part of the congenital vitello-intestinal duct. It is a true diverticulum, typically located on anti-mesenteric border, and contains all three coats of intestinal wall with its separate blood supply from the vitelline artery. The rare mesenteric location of Meckel's diverticulum has been documented in literature (Figure 2 in colour online).2 In some surgical textbooks, it is known by the rule of two: present in 2% population, 2 ft from the ileo-caecal junction and 2 in. long, although many anatomical variations exist.
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Nomenclature and embryology
Meckel's diverticulum was first described in a paper published in 1809 by
the German anatomist, Johann Friedrich Meckel, the younger (1781-1833), who
described it as a remnant of the omphalo-mesenteric
duct,3 although such
an abnormality had been mentioned quite early by Fabricius Hildamus in 1598
and in 1671 by Lavater (who did not recognize its embryological origin).
However, it was not until almost 100 years later that the understanding of
Meckel's diverticulum increased with the discovery of ectopic gastric mucosas
by Salzer and associated ulceration of ileum by
Deetz.1
In the fetal life, the omphalo-mesenteric duct connects the yolk sac to the intestinal tract and usually it obliterates in the 5th to 7th week of life. If obliteration fails, the congenital anomalies develop, leading to the residual fibrous cords, umbilical sinus, omphalo-mesenteric fistula, enterocyst and most commonly, Meckel's diverticulum.
Clinical diversity
Meckel's diverticulum is lined mainly by the typical ileal mucosa as in the
adjacent small bowel. However, ectopic gastric (most common—57%
according to textbooks, but 20% according to recent
data4)—duodenal,
colonic, pancreatic, Brunner's glands, hepatobiliary tissue and endometrial
mucosa may be found, usually near the
tip.1 According to J
F Meckel, the incidence of the complications due to Meckel's diverticulum was
25%, but in the recent literature it ranges from 4%-16%. Its occurrence in
males and females is equal, but incidence of complications is three to four
times greater in males. The most frequent complications in the adults are:
obstruction due to the intussusception or adhesive band (14%-53%); ulceration
(<4%); diverticulitis; and perforation. In children it is the most common
presentation, especially in those younger than 2 years of age (almost 50%).
The large proportion of the rest of the symptomatic Meckel's diverticulum
occurs in those aged 2-8 years. Bleeding from ectopic gastric mucosa,
especially chronic bleeding, is not common in adults although it has been
documented in a 91 year
old.5 Carcinoid
tumour, sarcoma, stromal tumours, carcinoma, adenocarcinoma, intraductal
papillary mucinous adenoma of pancreatic tissue and vesicodiverticular
fistulae are also rare
complications.6,7
Other rare complications include inversion of Meckel's diverticulum, torsion,
volvulus of ileum around Meckel's diverticulum or fibrous cord and
perforation—spontaneously or by foreign body such as fish
bone.8-11
The risk of the complications decreases with increasing age, with no
predictive factors for the development of complications. The main mechanism of
bleeding is the acid secretion from ectopic mucosa, leading to ulceration of
adjacent ileal mucosa. It is possible that the recurrent intussusception may
cause trauma, inflammation, mucosal erosion and bleeding. The pathogenic role
of Helicobacter pylori in the development of gastritis and bleeding
in the ectopic gastric mucosa is still
debatable.12,13
NSAIDs' effect on the ectopic gastric mucosa is yet to be
proved.14 Bleeding
from Meckel's diverticulum can cause the iron deficiency
anaemia,15 but it
may also cause megaloblastic anaemia due to the bacterial overgrowth and
vitamin B12 deficiency as a result of the dilatation and stasis in adjacent
obstructed ileal loop. The presence of bleeding with hypoalbuminaemia and low
feritin due to ongoing slow unrecognized bleeding may lead to the diagnosis of
inflammatory bowel disease. There have been reported cases of active and
chronic inflammatory bowel disease in Meckel's diverticulum. The incidence is
high in diagnosed cases of inflammatory bowel disease: however, the incidence
of ectopic mucosa or Meckel's diverticulum mucosal involvement by inflammatory
bowel disease is very
low.16
In the English literature, Klinvimol et al. reported that out of 1489 patients only 0.27% of the patients had bleeding,16,17 while Leijonmarck et al. recorded only 5% of patients out of 260 having bleeding.18 Higaki et al. suggested that the mechanical stimulation was an additional cause of bleeding due to the presence of the ectopic gastric mucosa of the body type (rather than the fundic type) and submucosal fibrosis (suggesting recurrent chronic ulcerations).19 Although bleeding is one of the most common presentations, its other clinical presentations may suggest various surgical diagnoses and it is imperative to differentiate Meckel's diverticulum from those surgical conditions.
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Other diagnostic methods have been suggested to supplement the Meckel's scan including Tc 99m RBC labelled scan, angiography and barium enema. Angiography is usually negative unless the bleeding rate is >0.5 mL/min.
Management
The treatment of choice for the symptomatic Meckel's diverticulum is the
surgical resection. This can be achieved either by the diverticulectomy or by
the segmental bowel resection and anastomosis, especially when there is
palpable ectopic tissue at the diverticular-intestinal junction, intestinal
ischaemia or perforation. There has been an ongoing debate about the excision
of Meckel's diverticulum when found as an asymptomatic incidental finding.
During an operation, it is usually impossible to determine by inspection or
palpation whether incidentally found Meckel's diverticulum is at increased
risk of the complications or not. Mackey and Dineen have suggested
statistically significant risk factors such as males less than 40 years,
diverticulum longer than 2 cm and that containing ectopic
mucosa.29 However,
Park et al. favoured removal of incidental asymptomatic Meckel's
diverticulum in males, patients younger than 50 years, diverticulum greater
than 2 cm and presence of histological abnormal
tissue.30 Stone
et al. did not recommend removal of incidental asymptomatic Meckel's
diverticulum in
women.31 Onen
et al. recommended its removal in symptomatic as well as in
asymptomatic cases in children younger than 8
years.32 Ueberrueck
et al. proposed that in cases of gangrenous or perforated
appendicitis, an incidentally discovered Meckel's diverticulum should be left
in place, whereas in an only mildly inflamed appendix it should be
removed.33 Soltero
and Bill mentioned a 4.2% lifetime complication risk of Meckel's diverticulum
versus 9% morbidity after incidental resection, and did not favour incidental
diverticulectomy.34
However, most authors do not agree with these figures; postoperative morbidity
after incidental resection varies between 0% and 6%, with significant
morbidity, up to 33% after resection of a complicated Meckel's diverticulum
and the lifetime complication risk estimated to be up to 16%. The definitive
Mayo clinic survey provides good evidence to support the role of prophylactic
diverticulectomy.
CONCLUSION
Meckel's diverticulum is the most common congenital anomaly of gastrointestinal tract. Clinical manifestations arise from complications of this true diverticulum that are most common in males under 40-50 years of age and with a diverticulum longer than 2 cm. Due to the rarity of cases in adults, especially bleeding from the Meckel's diverticulum, the misdiagnosed cases are not uncommonly reported even in developed countries. A preoperative diagnosis of a complicated Meckel's diverticulum may be challenging because of the overlapping clinical and imaging features of other acute surgical and inflammatory conditions of the abdomen. An adequate knowledge of embryological, clinical, pathologic and radiologic characteristics of Meckel's diverticulum will aid the early and accurate diagnosis of complicated cases.
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  W G Donaldson Meckel's diverticulum J R Soc Med, February 1, 2007; 100(2): 69 - 69. [Full Text] [PDF]
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