|ECR 2019 / C-1485|
|Small Bowel Diverticulosis: the great forgotten. Radiologic features and complications|
Findings and procedure details
The cause of this condition is unknown. It is believed that the diverticula develop as the result of abnormalities in peristalsis, intestinal dyskinesis and high segmental intraluminal pressures.
Risk factors related with small bowel diverticulosis is low-fiber and high-fat diet, advanced age, systemic sclerosis, visceral myopathy and neuropathy.
The diverticula emerge on the mesenteric border of the small bowel, in weakened points of the intestinal wall where mesenteric vessels penetrate in the muscular layer. Fig. 1
The real incidence is unknown because they are usually asymptomatic. All extraluminal diverticula, except Meckel´s diverticulum, are acquired. The incidence is closely related with age. The majority of duodenal diverticula are observed in patients aged > 50 years, while jejunoileal diverticula are often observed in patients aged > 60 years.
There is no predilection by race or gender, however there is a preponderance of jejunoileal diverticula in males.
Duodenal diverticula have been reported in 2-5% of patients undergoing barium studies of the upper gastrointestinal tract and in 7% of patients undergoing endoscopic retrograde cholangiopancreatography (ERCP).
Jejunal diverticula have been reported in up to 1-2% of patients in autopsy series.
In one retrospective review of 208 patients with symptomatic small bowel diverticulosis, diverticula were located in the duodenum in 79%, in the jejunum or ileum in 18%, and in all three segments in 3%.
1.- SPECIFIC FEATURES OF DIVERTICULA BASED ON ANATOMIC LOCATION AND TYPE:
A. DUODENAL DIVERTICULUM
Duodenal diverticula usually occur within 2 cm of the ampulla of Vater (juxtapapillary) (75%). Less than 10% of duodenal diverticula are located in the first and fourth part of the duodenum. The vast majority of duodenal diverticula are extraluminal, they vary from a few millimetres to several centimetres and may be multiple. Fig. 2
This anatomic location is of clinical significance because it is associated with increased incidence of biliary stones, pancreatitis, and biliary and pancreatic anomalies Fig. 3 .The incidence increases with age. Fifty percent of cases have associated colonic pseudodiverticulosis. Haemorrhage and pancreatico-biliary disease are the most common complications.
B. JEJUNOILEAL DIVERTICULA
Small bowel diverticula are more common in the jejunum that in the ileum (79% jejunum, 18% ileum y 3% both) and are multiple in 75% of patients Fig. 4 . They associate colon diverticula by up to 61% of cases, duodenal diverticula by up to 30% Fig. 5 and oesophagus diverticulum in 2,3%.
Diverticula usually are multiple and vary from a few millimetres to 10 cm Fig. 6 and are frequently associated with small intestine motility disorders, such as progressive systemic sclerosis, visceral myopathy, and visceral neuropathies. Diverticulitis and perforation are the most common complications of jejunoileal diverticula.
C. INTRALUMINAL DIVERTICULA
Intraluminal diverticula are congenital diverticula resulting from incomplete canalization of duodenal lumen during fetal development. These structures are believed to start as a fenestrated diaphragm that, over time, transforms into a diverticulum as a result of peristalsis. It occurs singly and has duodenal mucosa on both sides. Intraluminal diverticula are usually located in the second part of the duodenum lined on both sides with duodenal mucosa and an eccentric opening is usually proximal in the sac. The intestinal obstruction is the most commonly associated complication.
2.- CLINICAL MANIFESTATIONS
Most of patients with small bowel diverticulosis are asymptomatic but may present abdominal discomfort, rectal bleeding, disorders of intestinal transit, malabsorption, meteorism. Approximately 40% of patients with jejunoileal diverticula present with symptoms of malabsorption due to small intestinal bacterial overgrowth.
In case of mayor complications they may present abdominal pain, fever, distension, nausea, vomiting, peritoneal irritation...
3.- IMAGING STUDIES
In most of cases, diverticula are incidental findings in radiologic studies.
1. PLAIN ABDOMINAL RADIOGRAPHS AND/OR CHEST RADIOGRAPHS: Demonstrate evidence of perforation (free peritoneal air) or intestinal obstruction (bowel dilatation with air-fluid levels).
2. GASTROINTESTINAL FLUOROSCOPIC STUDIES WITH ORAL BARIUM: Demonstrate diverticula by up to 2% of gastrointestinal tract studies with barium. They are useful diagnosing uncomplicated cases, but contraindicated if acute diverticulitis or perforation is suspected. Filling defects in diverticula may represent enteroliths or foreign bodies.
3. ABDOMINAL COMPUTED TOMOGRAPHY (CT): Small intestine diverticulosis is a rare diagnostic with CT, probably because of a combination of factors that include their similar aspect to the small bowel loops in the axial plane, and the low index of suspicion of a rare entity, asymptomatic in most of cases. Diverticula can be full of air and/or fluid or iodinated contrast and/or debris and the wall is thin and smooth Fig. 7 and Fig. 8 . Some of them can contain enteroliths up to some centimetres of diameter Fig. 9 .
CT provides more information in uncomplicated and complicated cases. We can identify phlegmon, abscess and ascitis in cases of diverticulitis or extraluminal air in cases of perforation.
4. MESENTERIC ANGIOGRAPHY: Mesenteric arteriography is useful in patients with severe/massive bleeding and hemodynamic compromise. Requires bleeding rates > 0,5 ml/min. Allows embolization treatment.
5. BLEEDING SCAN: to identify small bleeding points.
6. ENDOSCOPIC RETROGRADE CHOLEDOCHOPANCREATOGRAPHY demonstrates periampullary diverticula.
7. CAPSULE ENDOSCOPY: should be avoided in acute diverticulitis, perforation, or small bowel obstruction.
4.- MAYOR COMPLICATIONS
Patients with small bowel diverticulosis may occasionally present with symptoms due to a complication. Although the true incidence is unclear, retrospective studies suggest that the risk of complications is higher with jejunoileal diverticula as compared with duodenal diverticula.
Mortality is influenced by the patient age, the kind of complication and the time elapsed before treatment.
These complications include:
Is the most common complication (up to 6,4% of patients with small bowel diverticula) and may associate perforation. As the colonic diverticulitis, they are different grades of severity from inflammatory changes in mesenteric fat, perforation, abscess formation and diffuse peritonitis. Fig. 10 , Fig. 11 and Fig. 12
Clinical presentation is not specific and includes abdominal pain, fever and leukocytosis. The suspected pathology is acute appendicitis, perforated peptic ulcer, acute cholecystitis or acute colonic diverticulitis.
The radiological differentials include intestinal perforation, acute appendicitis, and infectious/inflammatory ileitis (including Crhon´s disease)
B. GASTRONTESTINAL HEMORRHAGE
Diverticular bleeding of the small bowel is rare and occurs primarily in adults aged more than 60 years. Bleeding is more frequent in duodenal diverticula. Caused by the erosion and ulceration of diverticulum mucosa. The clinical presentation may be acute as rectal bleeding, melena or hematemesis, or chronical as anemia.
The differential diagnosis includes small bowel angiodysplasia, tumors, ulcerated lesions (Crhon´s disease, celiac disease)...
Gastrointestinal bleeding scan may be useful in patients with small amounts of active or intermittent bleeding. Mesenteric arteriography is useful in patients with massive bleeding and hemodynamic compromise. Requires bleeding rates > 0,5 ml/min.
C. GASTROINTESTINAL OBSTRUCTION
As a result of a complicated diverticulitis or enterolith formation.
D. ACUTE PERFORATION
Almost always associated to diverticulitis Fig. 13 and Fig. 14 , but perforation may be produced by the impaction of foreign bodies or traumatic perforations. Herrinton described that perforation of diverticula is related with inflammatory necrosis (82%), trauma (12%) and foreign body (6%).
Complications associated with perforations are fistula, pneumoperitoneum and abscesses.
E. PANCREATIC OR BILIARY DISEASE
Juxtapapillary duodenal diverticula appear to be a risk factor for gallbladder stones, bile duct stones and their recurrence.
The common duct may drain directly into a diverticulum at the ampulla of Vater, which can produce bile stasis, stone formation or infection.
Other mechanism of obstruction is due to compression of the intraduodenal portion of the common duct by a diverticulum distended with duodenal contents, which originates adjacent to the ampulla of Vater.
Increased complication rate of endoscopic interventions of the bile duct system, have also being described.
5.- MINOR COMPLICATIONS
Most of small bowel diverticulosis are asymptomatic but some authors relate them with chronic symptoms of malabsortion, abdominal pain, diarrhoea due to perturbation with peristalsis and normal propulsion of the intestinal content.
The ectasia of the intestinal content in diverticula facilitates the bacterial overgrowth associated with steatorrhoea, malabsorption of fat-soluble vitamins and degradation of the B12 vitamin (megaloblastic anemia).
The goal of treatment is based on reducing intestinal spasms with a diet rich in fibbers. Diverticulosis does not require surgical intervention.
However, giant diverticula do require surgical intervention because they are more likely to become infected and perforated.
In cases of diverticulitis conservative treatment can be considered with absolute diet and broad-spectrum antibiotics. Complicated cases require surgical treatment.
Endoscopic treatment is the most common first-line treatment for bilio-pancreatic complications caused by juxtapapillary diverticula and also for bleeding. Conservative treatment of perforated diverticula based on fasting and broad-spectrum antibiotics may be offered in some selected cases when diagnosis is made early in stable patients, or in elderly patients with comorbidities who are poor operative candidates. Surgical treatment is currently reserved for failure of endoscopic or conservative treatment.
Early surgery is the treatment of choice for patients with intestinal perforation.
7. MECKEL´S DIVERTICULUM
The Meckel´s diverticulum was named after the German anatomist Johann Friedrich Meckel in 1808 established its embryonic origin and pathological characteristics, but, previously, it was described by Fabricus Heldanus in 1650 and reported by Levator in 1671 and by Ruysch in 1730.
This embryonic remnant is caused by the incomplete obliteration of the onphalomesenteric duct between the 5th and 7th week of gestation.
Is the only true diverticulum containing all layers of the bowel wall and arises from the antimesenteric border of the small bowel.
Is the most common congenital anomaly of the small bowel, occurring in 2% of the population, according to autopsy reviews.
The male:female ratio is 2:1.
The average of length is 3 cm but 90% of cases range between 1 and 10 cm. Large diverticula are more susceptible to complications. Fig. 15
The Meckel´s diverticulum is typically found within 100 cm of the ileocecal valve, with an average distance in adults of 67 cm and in children under 2 years of 34 cm.
Approximately 60% of Meckel´s diverticula contain heterotopic mucosa, of which over 60% consist in gastric mucosa. Pancreatic mucosa (5%), colonic mucosa, endometriosis and hepatobiliary tissue, can also be found.
C.- CLINICAL MANIFESTATIONS
The clinical diagnosis of Meckel´s diverticulum is rarely impossible, because symptoms are not specific and its presentation commonly mimics such disorders as appendicitis, peptic ulcer disease and Crhon´s disease. Only 10% are diagnosed preoperatively. The rest are incidental findings during laparotomy for other causes, such as acute appendicitis.
D.- IMAGING STUDIES
Radionuclide scintigraphy will detect 85% of Meckel´s diverticulum if gastric mucosa is present in it. Fig. 16
Gastrointestinal tract studies with barium may also detect a smaller percentage of diverticula. The diverticulum can be identified as a sacular structure in the antimesenteric border of the ileum, usually in the right lower quadrant or pelvic region. Fig. 17
With CT, Meckel´s diverticulum is difficult to distinguish from normal small bowel in uncomplicated cases. We can see a blind-ending structure filled with fluid or air in continuity with the small bowel Fig. 18 - Fig. 19 - Fig. 20 - Fig. 21 ). Abdominal CT is used for complicated cases.
The lifetime risk of complications of a Meckel´s diverticulum is approximately 4 to 6%. Most of them are diagnosed in the first 2 years of life, and the probability of becoming symptomatic decreases with age.
Gastrointestinal bleeding is the most frequent complication (about 20-30% of all complications) and it is the most frequent clinical presentation in children, mainly due to the presence of heterotopic acid-secreting gastric mucosa in the diverticulum. Bleeding may range from minimal, recurrent episodes of hematochezia to massive, shock-producing hemorrhage.
When a patient presents with painless lower gastrointestinal bleeding, Meckel´s diverticulum should always be suspected. Fig. 22
2. INTESTINAL OBSTRUCTION
Observed in 20-25% of patients with symptomatic Meckel´s diverticulum, intestinal obstruction is the most frequent clinical presentation in adults, mainly due to intussusception Fig. 23 or intestinal volvulus, and more rarely due to diverticulitis, diverticular torsion, Littré´s hernia (abdominal wall hernia that involves the Meckel´s diverticulum) or enterolith.
This condition develops in approximately 10-20% of patients with symptomatic Meckel´s diverticulum. Mimics acute appendicitis and should be considered in the differential diagnosis of a patient with right lower quadrant pain. The inflammation may be precipitated by the obstruction of the diverticulum by a foreign body or enterolith or by peptic ulceration-related inflammation and scarring. Fig. 24 - Fig. 25 - Fig. 26 - Fig. 27
Commonly results from progressive diverticulitis. Also reported secondary to a calculus and fish thorn.
Retroperitoneal abscess formation has been reported as a rare complication of Meckel´s diverticulum perforation.
Tumors of Meckel´s diverticulum are very rare and the most common tumors are leiomyoma, leiomyosarcoma and carcinoid tumor.
6. UMBILICAL ANOMALIES
These occur in up to 10% of patients and consist of fistulas, sinuses, cysts, and fibrous bands between the diverticulum and the umbilicus. Patients can present with a chronic discharging umbilical sinus superimposed by infection or excoriation of periumbilical skin. Cannulation and injection with radiographic contrast help to delineate the entire tract and aid in planning a surgical approach for cure.
Surgical resection is considered the treatment of choice for the symptomatic Meckel´s diverticulum. Whether an asymptomatic diverticulum should be resected is controversial topic.
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ECR 2019 / C-1425
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