Download radiological examination of the digestive canal

RADIOLOGICAL
EXAMINATION OF THE
DIGESTIVE CANAL
DEPARTMENT OF ONCOLOGY AND
RADIOLOGY
PREPARED BY I.M.LESKIV
ANATOMIC AND FUNCTIONAL OF
THE ESOPHAGUS
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The normal functions of the esophagus are simple - the transport
of food from the pharynx to the stomach and the prevention of
reflux of gastric contents. Disease processes that affect either
function may result in profound clinical symptoms.
Some important anatomic features of the esophagus are
illustrated in next sl. The esophagus is a muscular tube that
begins as a continuation of the pharynx at about the level of the
sixth cervical vertebra. It is a relatively mobile structure, fixed
only at its proximal and distal ends. The trachea lies immediately
anterior to the esophagus from its origin in the neck to the
tracheal bifurcation at the level of the fifth thoracic vertebra. The
right and left recurrent laryngeal nerves ascend in grooves
between the trachea and cervical esophagus, where they are
vulnerable to involvement by proximal esophageal tumors. Also
adjacent to the cervical esophagus are the right and left common
carotid arteries and part of the thyroid gland.
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ANATOMIC AND FUNCTIONAL OF THE ESOPHAGUS
Schematic
Barium contrast examination of the normal esophagus reveals an indentation at the
representation of the
level of the fourth thoracic vertebra caused by the arch of the aorta. Just below the
esophagus illustrating
aortic arch, the anterior aspect of the esophagus may be narrowed slightly by the left
some important
main bronchus. Below the left main bronchus, the left atrium lies just anterior to the
esophagus. Because of these intimate anatomic associations, any enlargement of the
anatomic
thyroid gland, carinal lymph nodes, or left atrium or aorta (aneurysm) can be
relationships.
recognized by characteristic impressions on the barium-filled esophagus.
Attempts to correlate the structural features of the distal esophagus with its
remarkable function have resulted in confusion regarding the anatomy of this
segment. While the radiologist and physiologist can recognize a lower esophageal
sphincter (LES), prosectors have searched in vain for a corresponding anatomic
sphincter.
The physiological LES corresponds roughly with the esophageal ampulla observed on
barium contrast examinations. The fluoroscopist recognizes this area both by its
ability to remain contracted at rest and to dilate more than the remainder of the
esophagus when distended with barium. The proximal border of the ampulla is
formed by a band of circular muscle called the upper. A ring or muscular ring. In
some individuals, the radiologist may identify the lower esophageal mucosal ring (also
known as the В ring or Schatzki ring), which marks the distal border of the ampulla.
The muscular coat of the proximal third of the esophagus is comprised predominantly
of striated muscle, while that of the distal two-thirds is largely smooth muscle.
Therefore, the esophagus is vulnerable to diseases affecting either type of muscle.
The vagus nerve innervates both the striated and the smooth muscle portions of the
esophagus. Innervation to the distal esophagus and LES is carried in intramural nerve
plexuses. Because of this intramural innervation, distal thoracic truncal vagotomy has
little effect on distal esophageal function. The esophagus also receives fibers from
cervical and thoracic sympathetic ganglia. The venous drainage of the distal
esophagus is by way of the gastric veins into the portal vein; therefore, esophageal
varices may develop as a consequence of portal hypertension.
Unlike the rest of the gut, the esophagus has no serosal layer. Surgeons claim that this
contributes to the difficulty of esophageal surgery. Lack of a restraining serosa may
also contribute to the local invasiveness of esophageal carcinoma.
CLINICAL ANATOMY OF THE STOMACH
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The size and shape of the stomach vary from moment to moment
depending on the volume of its contents and on body posture. For
clinical purposes, it is useful to divide this distensible organ into
four anatomic regions. The cardia is the portion of the stomach
immediately adjacent to the esophagus; the fundus is the region
that rises above the cardia. The body of the stomach extends
from the fundus to the incisura angularis, an indentation on the
lesser curvature that is best appreciated by barium contrast
examination. The antrum is the region beyond the incisura
angularis where the stomach turns horizontally toward the
pyloric sphincter.
The histologist often can identify the anatomic region from which
a gastric biopsy is obtained by the type of gastric glands present
in the specimen. The cardiac region contains the cardiac glands,
which are predominantly composed of mucous cells. The oxyntic
glands are found in the fundus and body of the stomach and
contain both chief (zymogen) cells, which secrete pepsinogens,
and parietal (oxyntic) cells, which secrete hydrochloric acid and
intrinsic factor. The gastric antrum contains the pyloric glands,
which include endocrine cells that produce gastrin. The surgeon
takes advantage of this relationship between gross and
microscopic anatomy when designing an operation for peptic
ulcer disease. For example, an antrectomy may be performed to
remove the gastrin-secreting mechanism of the stomach.
CLINICAL ANATOMY OF THE DUODENUM
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The duodenum may also be divided into four anatomic regions. The first portion of the
duodenum extends posteriorly and superiorly from the pylorus to the first duodenal flexure; it is
entirely intraperitoneal and normally assumes a characteristic conical shape when distended
with barium (duodenal bulb). The second portion of the duodenum extends vertically downward
from the first to the second duodenal flexure. Its medial wall is adjacent to the head of the
pancreas, which when enlarged by carcinoma or pancreatitis, produces a tell tale impression on
the barium-filled second duodenal portion.
The ampulla of Vater, the intestinal opening of the major pancreatic duct and common bile duct,
is located in this duodenal segment. The third portion is the horizontal segment situated just
anterior to the inferior vena cava and aorta; the superior mesenteric artery and vein lie anterior
to this duodenal segment. The fourth portion of the duodenum is the ascending segment that
begins just to the left of the aorta. A fibromuscular ligament arising from the right cms of the
diaphragm (ligament of Treitz) attaches to the small intestine at the duodenojejunal flexure,
which delimits the end of the duodenum and the beginning of the jejunum. Except for a small
segment near the duodenojejunal flexure, the second, third, and fourth portions of the duodenum
are entirely retro-peritoneal.
The duodenum is histologically distinguished from the remainder of the small intestine by the
presence of Brunner’s glands in the duodenal submucosa; these glands secrete a viscous, highly
alkaline fluid. The blood supply to the stomach and duodenum is generous. The stomach is
supplied by large vessels arising from all branches of the celiac artery. The duodenum receives
blood from the superior pancreaticoduodenal branches of the gastroduodenal artery and the
inferior pancreaticoduodenal branches of the superior mesenteric artery. Not surprisingly,
bleeding frequently accompanies ulceration of the stomach and duodenum.
The vagal trunks applied to the anterior and posterior surfaces of the distal esophagus provide
parasympathetic innervation to the entire stomach. These vagal trunks also give off hepatic
branches and celiac branches that supply the small bowel and other abdominal viscera. This
anatomic distribution is important to the surgeon who may wish to spare hepatic, celiac, or
pyloric vagal branches when performing a selective or proximal gastric vagotomy for treatment
of peptic ulcer disease.
GENERAL ANATOMIC AND
FUNCTIONAL OF THE SMALL
INTESTINE
The most remarkable feature of the small intestine is its enormous surface area, which is conferred not so
much by its length as by its multitude of circumferential folds, villi, and microvilli. The anatomic regions of the
small intestine, designated as duodenum, jejunum, and ileum, have no clear boundaries with respect to
absorptive cell characteristics; functionally their similarities are greater than their differences. Indeed,
regional specialization exists only with respect to vitamin B12 and conjugated bile salts, which are both
absorbed preferentially in the distal ileum. Although absorption of all other nutrients appears to be greater in
proximal sites, absorption takes place along the entire length of the intestine. In addition, the small intestine
has an enormous reserve capacity and can fully compensate for losses of up to one-half its length. The intestine
is more than a conduit for nutrients. Although most of the enzymatic digestion of carbohydrates, proteins, and
lipids takes place in the small intestinal lumen before their uptake, optimum absorption of both protein and
carbohydrate is closely linked to an ultimate phase of hydrolysis that occurs within the intestinal brush border.
Dietary fat is digested in the lumen and not further hydrolyzed in the intestinal cells. However, within these
cells, absorbed fat is resynthesized to complex lipids and combined with transport proteins for delivery into
the lymph.The major manifestations of small intestinal diseases are malabsorption of nutrients and
abnormalities in water and electrolyte transport.
ANATOMIC AND FUNCTIONAL OF THE COLON
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The ileal effluent entering the colon consists of water, electrolytes, unabsorbed gastrointestinal
secretions, cellular debris, and undigested food residue. The colon has no digestive function per se; its
principal roles are to assist in maintaining the body’s electrolyte and water balance and to excrete the
unabsorbed remains or feces by means of its absorptive, secretory, storage, and excretory functions.
Sodium, chloride, and water are absorbed, and potassium and bicarbonate are secreted. The
importance of the colon in sodium absorption is demonstrated by the fact that patients with an intact
intestine can consume a low-sodium diet (10 mEq/day) for months without adverse effects, whereas
individuals with ileostomy on a 10 mEq per day sodium diet develop symptoms and signs of sodium
depletion within 3 to 5 days. Absorption and secretion of electrolytes and water occur principally in
the right half of the colon; the ability of the colon to perform these functions decreases toward the
rectum. The undigested food residue is primarily that portion of plant cells contained principally in
cereals that consists of nonstarch polysaccarides and lignin (an aromatic polymer); the intestinal tract
is devoid of enzymes to digest these substances known as dietary fiber. The nonstarch polysaccarides
are degraded by colonic bacteria to short-chain fatty acids, other products, and gases (e.g., methane,
carbon dioxide, and hydrogen), while the lignin remains practically intact. These products of
bacterial degradation, except for the gases, give bulk to the stool by imbibing water and are laxative
in effect. In the western world, the average normal fecal output is up to 200 gm per day and contains
100 to 150 ml of water, up to 5 mEq of sodium, 7 to 15 mEq of potassium, 2 mEq of chloride, and 3
mEq of bicarbonate. The normal colon has the capacity to absorb about 6 liters of water and about
800 mEq of sodium per day. The storage and excretory functions of the colon depend on coordinated
colonic motor activity. Nonpropulsive, segmental contractions that probably produce the haustra
move the bowel contents forward and backward over short segments of mucosa, thus enhancing
absorption. Periodically, a peristalitic contraction propels the contents forward either for a short
distance or on into the sigmoid colon or rectum. Distention of the rectum induces a desire to defecate,
which can be overcome by voluntary contraction of the internal and external anal sphincters
GAS PATTERNS
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NORMAL ABDOMINAL RADIOGRAPHS
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In the supine abdominal radiograph gas is normally present in the body of the
stomach and in variable amounts in the transverse and other parts of the
colon. It is also present in small amounts in the small intestine of adults.
Normal gas-fluid levels are usually seen in the gastric fundus on erect
radiographs and occasionally in the first part of the duodenum and in the
caecum. In infants and children gaseous distension of the stomach and of the
intestines is a common feature. In infants in particular this is largely due to
swallowed air. Supine abdominal radiographs occasionally show apparent soft
tissue masses in the gastric fundus or duodenal loop; these are well-recognised
‘pseudo-tumours’ and are due to normal fluid collections gravitating to these
dependent areas.
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ABNORMAL GAS PATTERNS
Abnormal gas patterns in abdominal radiographs may be conveniently classified into:
 excessive intestinal gas
 abnormal contour of gas-containing loops
 extraluminal gas.
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Excessive intestinal gas
Causes
Physiological Air-swallowing,
 usually in children
Radiological features
Non-specific gaseous distension. No consistent end-point to
suggest obstruction
Mechanical obstruction
Small bowel, e.g. adhesions,
hernia, Crohn’s disease
Gaseous distension of loops of small bowel which lie
centrally. Valvulae conniventes visible. Short fluid levels
on erect film.
Large bowel, e.g. carcinoma,
diverticular disease with stricture
Distension of peripherally situated large bowel, proximal to
obstruction. Haustra visible. Longer fluid levels than in
small bowel
Volvulus of the caecum, sigmoid
Specific radiological signs. Extremely dilated loops extending
upwards from normal site of these structures to lie in
upper quadrants. Very long fluid levels in erect film
Non-mechanical obstruction (or
pseudo-obstruction).Generalised
ileus, e.g. following surgery,
peritonitis, metabolic disorders
Localised ileus, e.g. appendicitis,
pancreatitis, abscess, ischaemia
Large and small bowel distended. May resemble mechanical
obstruction
Single loop of dilated bowel (sentinel loop). Speckled gas in
abscess
Abnormal contour of gas-containing
loops
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Causes
Radiological features
Crohn’s disease
Affects small or large bowel, or both. Stricture may be visible,
or irregularity of mucosa due to ulceration May show
signs of obstruction or toxic megacolon (see below)
Ulcerative colitis
Narrowed, featureless empty colon. Pseudopolypi may be
visible as filling defects. Gross dilatation - ‘toxic
megacolon’ is a dangerous complication and predisposes
to perforation
Ischaemia
Dilated bowel, thickened wall with areas of oedema ‘thumbprinting’. Ileus, with signs of obstruction
Intrinsic masses
Tumours and intussusception may be outlined by gas
Displaced loops
Large non-alimentary abdominal masses, e.g. enlarged spleen,
may displace or indent gas-filled loops of otherwise
normal bowel
Extraluminal gas
Causes
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Intraperitoneal
Perforation of a hollow viscus
Subphrenic abscess
Radiological features
Variable amounts of gas, from small crescent under diaphragm
(erect film) to gross peritoneal distension
Air-fluid level under diaphragm. Adjacent
consolidation. Confirm with ultrasound
lung
base
Linear streaks of gas in bowel wall. May coalesce or outline
Bowel wall
portal vein radicles
Infarction, necrotising enterocolitis in
infants
Pneumatosis coli
Blebs of gas in colon wall. Symptoms may mimic carcinoma.
Usually elderly patient with airways obstruction
Branching gas pattern in liver (bile ducts). Usually lie centrally
Biliary tree
in liver; gas in portal vein radicles extends more
After sphincterotomy or anastomosis
peripherally
between biliary tree and bowel
Erosion of gallstone into small bowel; Small bowel obstruction (‘gallstone ileus’) and opaque calculus
may be visible in intestine with gas in biliary tree. Other
erosion of duodenal ulcer into biliary
causes listed do not cause intestinal obstruction
tree; pancreatic neoplasm; gas-forming
infection
Gas may outline urinary bladder, ureters and collecting
Genitourinary tract
systems. Differential diagnosis: gas-forming infection in
Fistula, e.g. trauma, postoperative,
diabetic patients
Crohn’s disease
ABDOMINAL CALCIFICATION
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Many structures in the abdomen calcify, especially in
older subjects; most of these are of no clinical
significance. They include the walls of blood vessels,
lymph nodes and costal cartilages. Calcification may
also occur in pathological states but may be
discovered coincidentally. Gallstones and prostatic
calcification fall into this category. Those that are
often associated with symptoms include calcified
urinary calculi, pancreatic calcification in chronic
pancreatitis, and calcification occurring in abdominal
tumours
RADIOLOGICAL EXAMINATION OF THE GASTROINTESTINAL
TRACT
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Contrast studies of the gastrointestinal tract and endoscopic diagnostic techniques play
complementary roles in the investigation of alimentary tract symptoms. How these different methods
are deployed in different hospitals depends to a large extent on the availability and accessibility of
endoscopy. Hospitals with comprehensive endoscopy facilities and ‘open access’ policies tend to use
this technique as the first-line investigation in patients with gastrointestinal symptoms. This has been
accompanied by a decline in the numbers of barium studies carried out in the same hospitals. In
general, patients complaining of dysphagia can be investigated using either endoscopy or radiology:
dyspepsia is investigated by endoscopy; colonic symptoms are investigated using barium techniques,
followed by colonoscopy for further clarification and biopsy; upper gastrointestinal bleeding
(haematemesis and melaena) is investigated with endoscopy; the small bowel is examined by means of
a specialised barium technique. There will be many local variations in the way that some of these
investigations are used.
BARIUM EXAMINATIONS
Barium sulphate suspensions are specially formulated for use in different parts of the alimentary
tract. Whether they are taken orally or introduced through simall bowel or rectal tubes, they are
accompanied by gas (carbon dioxide) releasing agents or air insuflation to produce what is known as
air contrast or double contrast. This allows detection of small mucosal lesions as well as improving
the accuracy of these techniques in detecting masses, polyps, strictures, infiltrations and surface
erosions and ulceration.
All barium examinations are carried out under fluoroscopic control to optimise mucosal barium
coating and gaseous distension. Assessment of gut distensibility and motility can also be made during
fluoroscopy. Biopsy techniques have been used in conjunction with barium studies of the oesophagus
but have not gained widespread acceptance. Endoscopic ultrasound techniques are becoming
established and have been shown to be useful in the oesophagus, stomach and rectum. Contrast
examination of the small bowel will be discussed in a later section in this lecture.
In this section it is appropriate to discuss radiology of the alimentary tract according to the clinical
presentation - dysphagia, dyspepsia, bleeding, symptoms suggesting small bowel disease, and large
bowel disorders.
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DYSPHAGIA
This is a common symptom. Its radiological assessment often requires a rapid sequence of radiographs or video
recording during fluoroscopy, so that the swallowing function can be studied in detail from the oropharynx to the
gastric cardia. The common causes of dysphagia and their radiological features are summarised in Table
Causes
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Radiological features
Post-cricoid carcinoma
Irregular narrowing; mass displacing larynx forwards
Pharyngeal diverticulum
Variable size, arising posteriorly
Oesophageal web
Characteristic appearance; associated with iron-deficiency anaemia
Malignant stricture
May be primary oesophageal cancer or invasion by bronchial or
mediastinal tumour. Characteristic appearance - irregular
narrowing, ‘shouldering’, partial or complete obstruction
Stricture secondary to Reflux shown during fluoroscopy; mucosal ulceration, hiatus hernia;
reflux oesophagitis and
strictures tend to be smooth but may mimic carcinoma
hiatus hernia complex
Achalasia
Miscellaneous causes:
corrosive strictures
Generalised motility defect with dysfunction of cardia causing
obstruction and sometimes gross dilatation of oesophagus, with food
and liquid residue
Severe ulceration initially. Tendency to perforate
moniliasis, herpes infection
Opportunistic infection. Severe ulceration and pain
systemic sclerosis
Impaired peristalsis
neurological disorders
Swallowing difficulties with aspiration into lungs
Dyspepsia
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This term is used to describe upper abdominal symptoms arising from a variety of
different conditions. Epigastric pain, with or without a relationship to food, is an
extremely common symptom. Peptic ulceralion, hiatus hernia with gastro-oesophageal
reflux, gastric neoplasm and diseases of the biliary tract (e.g. gallstones) and pancreas
(e.g. chronic pancreatitis, carcinoma) all tend to cause similar symptoms. It is possible to
distinguish between these conditions to some extent on the basis of symptom complexes,
particularly their relationship to meals. Persistence of symptoms despite adequate
medical treatment, weight loss, vomiting, blood loss (haematemesis and melaena),
persistent pain with radiation away from the typical site of peptic ulcer or gallstone pain
are all features that give cause for concern. In this situation the patient should be
investigated intensively, using endoscopy as the first investigation. If endoscopy is
negative, radiological techniques, including plain abdominal radiographs, upper
gastrointestinal barium studies and ultrasonography, are used, depending on the
symptom complex. Ultrasonography is useful for the detection of biliary and pancreatic
disease; CT may be added to complete the investigations by outlining areas not
demonstrated by ultrasonography, e.g. the retroperitoneal planes.Uncomplicated
dyspepsia which is short lived is usually managed conservatively (particularly in young
adults) using one of the many anti-dyspepsia drug regimens. The decision to investigate
this common problem depends on the availability of endoscopy services. There is,
however, some debate about the appropriateness of the current widespread use of
endoscopy in this particular clinical circumstance.
Dyspepsia
Cause
Radiological features
Oesophageal
disease hiatus hernia
complex
Superfici.il mucosal ulceration in the oesophagus indicates oesophagitis.
Reflux may be detected but barium studies are less sensitiv e than
endoscopy or pH studies. Strictures may develop and may be
indistinguishable from malignant strictures
Gastric
abnormalities
ulceration
Barium collection in crater. Radiating folds of mucosa to edge of crater.
Surrounding deformity and oedema. Heal to form distinctive scars. May be
malignant from outset. Careful endoscopic follow-up necessary, with
biopsies
Polip(s)
Multiple polyps in body of stomach form part of chronic gastritis spectrum
- usually hyperplastic in nature, and benign. Adenomatous polyps, usually
in antrum, may be premalignant lesion(s). Should be removed. Other types
of polyps may be part of familial polyposis syndromes
Cancer
Characteristic signs in advanced disease. Either ulcerating or polypoid, or
mixture of both. Early or superficial cancers resemble benign ulcers but
with specific signs such as ‘clubbed’ mucosal folds and geographical areas
of very superficial ulceration
Non-mucosal
tumours
Usually large and may have surface ulceration or excavation. Exogastric
extension. May be leiomyoma, sarcoma or lymphoma
Duodenal
Characteristic ulcer craler(s) in first part of duodenum, with deformity.
disease:e.g. alceration Atypical signs in Crohn’s disease and Zollinger-Ellison syndrome
BARIUM MEAL
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The standard double-contrast study of the upper gastrointestinal tract includes views of
the oesophagus, stomach and duodenum. The examination is carried out following a
period of starvation; peristalsis is temporarily abolished using an injection of glucagon
or an atropine-like agent. This enhances mucosal coating with barium suspension and
allows detection of small mucosal lesions, e.g. erosions and polyps. The radiographs
obtained are examined for evidence of ulceration, deformity, infiltration, stricture
formation, external compression or displacement, and obstruction. Some of the
radiological abnormalities that may be found are summarised in Table 5.
The major advantage of endoscopy in the investigation of alimentary disorders is the
ability of the operator to obtain biopsies of lesions or suspicious mucosal abnormalities.
Sources of bleeding can also be identified accurately. Endoscopy is not without
complications and it has been claimed that good barium studies are as accurate as
endoscopy in the detection of significant lesions.
What has become apparent over recent years is that many benign and malignant
diseases of the gastrointestinal tract cause similar or identical radiological signs, and
that some benign lesions become, or harbour, malignant disease. Disorders such as
achalasia, peptic and corrosive strictures of the oesophagus, gastric ulcers and certain
non-epithelial sub-mucosal tumours, such as leiomyomas, predispose to, or undergo,
malignant transformation into malignant tumours. Therefore direct inspection of the
lesions, obtaining biopsies where necessary, is an accepted way of following up some
lesions such as gastric ulcers. It is also known that malignant ulcers undergo cyclical
healing changes and may therefore mimic benign ulcers.
Finally, benign ulcers may cause marked localised fibrosis and deformity when they
heal. This change is usually permanent and should not be the sole justification for
further follow-up using barium studies.
GASTROINTESTINAL BLEEDING
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Bleeding may be the first manifestation and presenting feature of gastrointestinal disease. The clinical
picture may vary from severe haematemesis to anaemia due to occult blood loss (e.g. cancer of the stomach
or colon), melaena or frank rectal bleeding. Careful questioning may pin-point other symptoms, and clinical
examination may reveal signs that help lo localise the cause of the bleeding. Very occasionally no cause is
found after exhaustive investigation and these patients may require exploratory operations.
Endoscopic techniques are the preferred method of investigation because the sources of bleeding, both in
the upper gastrointestinal tract and in the colon, can be identified.
Barium studies may show the causal abnormality but may also show unrelated diseases, which may cause
confusion. Barium persisting in the alimentary tract may preclude the use of more effective investigations,
such as isotope-labelled red blood cell scans or selective coeliac and mesenteric angiography, to localise sites
of bleeding beyond the reach of diagnostic endoscopy, or when the latter is ‘negative’. Table 6 lists some
causes of upper gastrointestinal bleeding and their radiological features. It is important to remember that
bleeding may arise in the small bowel or in the caecum; these areas are not easily accessible during
endoscopy. Further more, bleeding may be intermittent, and may vary in severity from sub-clinical to
catastrophic and life threatening. All diagnostic methods are more accurate during active bleeding.
Angiography must be carried out when bleeding is brisk (a rate of over 5 ml/min is often quoted); isotopelabelled red blood cell scans may detect slower rates of bleeding but are anatomically less precise.
Selective coeliac and mesenteric angiography is time consuming and is rendered more difficult and
hazardous if the patient’s general condition is deteriorating due to the rate of blood loss. The technique may
show a vascular lesion or demonstrate extravasation of contrast medium into the bowel lumen.
In a patient with portal hypertension it may be important to demonstrate the patency of the portal vein if
shunt procedures are being considered. Delayed radiographs will demonstrate the venous phase of an
angiogram and will outline draining and collateral veins. This technique has superseded the hazardous
direct approach of splenoportography which involved direct needle puncture of the spleen.
One cause of rectal bleeding, particularly in childhood, is a Meckel’s diverticulum. Because this contains
gastric mucosa which ulcerates and bleeds, it is readily detectable using a technetium isotope scan. The
ectopic gastric mucosa is shown as a localised area of increased isotope activity, usually lying centrally in
the abdomen.
Upper gastrointestinal bleeding
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Cause
Radiological features
 Oesophagus
Varices due to portal hypertension
Serpiginous filling detects on barium studies
of the lower oesophagus
Mucosal tear following vomiting (MalloryWeiss lesion)
Tears rarely shown radiologically. Endoscopy
preferred
Oesophagitis, .ill causes
 Stomach
Endoscopy more sensitive. Barium studies
may show ulceration
Erosions
Characteristic multiple ‘target’ lesions. Acute
or chronic gastritis
Ulcer, tumour, varices
 Duodenum
Characteristic appearances. Varices here
usually accompanied by varices in the
oesophagus, though not invariable
Ulceralion, invasion from adjacent tumour
Characteristic findings in duodenal
ulceration; signs of malignant infiltration
also characteristic
THE SMALL INTESTINE
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The usual indications for investigating the small intestine are:
 abdominal pain, weight loss, diarrhoea symptoms suggesting inflammatory disease;
 colicky abdominal pain, distension, vomiting - symptoms suggesting obstruction,
which may be intermittent;
 anaemia, malabsorption - caused by a variety of small bowel disorders.
Abdominal radiographs may show signs of small bowel obstruction but the cause may
not be apparent. Evidence of inflammatory disease in the colon is helpful (Table 2).
Small bowel contrast studies may be a continuation of a barium meal (a ‘follow-through’
study) although the high density barium contrast agent used specifically for doublecontrast studies of the oesophagus, stomach and duodenum may give poor images of the
small bowel. F:or the small bowel a large volume of relatively low density (semitransparent) barium suspension is more appropriate.
A more detailed study of the small bowel may be indicated if a follow-through
examination is inconclusive; this consists of administering the barium suspension via a
catheter introduced through the mouth into the proximal small intestine (small bowel
enema, or enteroclysis). This method has some well-documented advantages but is more
invasive. Fluoroscopy is used to determine the optimal infusion rate of contrast agent
and allows ‘spot films’ of areas of interest to be obtained during the infusion.
The radiological features of some common small bowel disorders are summarised in
Table .
Small bowel disorders
Cause
Radiological features
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Crohn’s disease
Signs of bowel inflammation - characteristic fissuring or
‘rose-thorn’ ulcers, nodular or ‘cobble-stone’ mucosa,
strictures, thickened bowel wall, adherence of adjacent
loops, fistulae to adjoining structures, ‘skip’ lesions,
dilated and obstructed loops of bowel, involvement of
stomach, duodenum and colon. Terminal ileum is
commonly affected, but disease may be extensive
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Obstruction due to causes
other than inflammation
Small bowel contrast studies usually localise site of
obstruction provided proximal loops are not too
distended. Adhesions produce characteristic deformities
of affected loops, especially when using small bowel
enema technique
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Malabsorphion problems, Coeliac syndrome causes non-specific dilatation of small
other than those caused by.
bowel loops in severe cases but small bowel biopsy is
inflammatory disease
much more specific. Jejunnl diverticulosis , blind loops,
fislulae and strictures may all cause malabsorption and
are detectable on contrast studies
THE LARGE INTESTINE
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Symptoms such as alterecd bowel habit, rectal bleeding, abdominal pain, weight
loss and anaemia may indicate serious colonic disease. Colonoscopy and barium
studies are complementary and equally useful but their deployment depends to a
large extent on the availability of colonoscopy services. Many clinicians use the
barium enema as the first-line diagnostic investigation and either combine this with
flexible fibreoptic sigmoidoscopy or reserve a full colonoscopy for those instances
where a barium study is inconclusive or where a lesion shown radio-logically
requires further direct examination and biopsy.
Barium studies require full bowel preparation using one of a variety of cleansing
techniques (faecal residue may mimic polyps or tumours). A double-contrast
technique involves inflation of the colon using air or carbon dioxide, and peristaltic
activity is temporarily abolished using a short-acting atropine-like pharmacological
agent.
Colonoscopv provides direct access to lesion- or suspicious areas of mucosa for
biopsy: small polypoid lesions may be amenable to removal during the same
diagnostic procedure. The examination may not be complete because in a
significant proportion (10-30%) the caecum is not reached and there are also ‘blind’
spots at points of angulation of the colon. Advanced diverticular disease produces
deformity and narrowing that is difficult to assess both in barium studies and during
colonoscopy.
Colonoscopy has a significantly higher risk of complications than barium enema,
and the procedure is more time consuming.
Table 8 summarises the radiological features of common disorders of the large
intestine
Common disorders of the large
intestine





Carcinoma: Most are irregular strictures with ‘shouldering’. Destroyed
mucosal pattern, proximal dilatation and obstruction. Invasion of adjoining
tissues and organs. May appear as polyp, usually more than 2 cm with
complex surface pattern. Long-standing ulcerative colitis and familial
polyposis coli are predisposing conditions.
Diverticular disease: Multiple diverticula particularly in sigmoid region,
but may be widespread. Narrowing and deformity. Common, so may
coexist with cancer. May bleed or perforate, or form fistulae, e.g. with
bladder.
Ulcerative colitis: Diffuse, uniform fine ulceration; loss of haustra, giving
featureless tubular colon. Toxic megacolon and carcinoma are
complications. May only involve distal colon or rectum in some cases.
Crohn’s disease: Areas of narrowing, deep ulceration, strictures. Perianal
disease is common. Prone to form fistulae. Coexists with small bowel
disease often.
Ischaemic colitis: Cause of profuse bleeding and acute abdominal pain.
Narrowing of lumen, often affecting localised segment, with mucosal
oedema (‘thumb-printing’). Occasionally difficult to distinguish from
Crohn’s disease
Normal oesophagus, (a) Full of barium to show the smooth outline and
indentation made by the aortic arch (arrow), (b) Film taken after the main
volume of barium has passed, to show the parallel mucosal folds.
Carcinoma of the oesophagus.
The carcinoma is shown as a mass around the lumen of the oesophagus (arrow).
Subcarinal nodes (N) are also present. Ao, descending aorta; RPA, right pulmonary
artery . There is an irregular stricture with shouldering (arrow) at the upper end.
Peptic stricture due to gastro-oesophageal reflux in a patient with a hiatus
hernia. There is a short smooth stricture at the oesophagogastric junction with
an ulcer crater within the stricture (arrow).
Achalasia. The very dilated oesophagus containing food residues
shows a smooth narrowing at its lower end.
Leiomyoma
There is an intramural filling defect
in the eosophagus below the aortic
arch (arrows). The sharp angle this
makes with the wall of the
oesophagus indicates that the filling
defect is due to a mass arising in the
wall of the oesophagus
.
There is a large filling defect in the stomach with smooth borders
(outer arrows). An ulcer crater (central arrow) is present within the
filling defect - a characteristic feature of a leiomyoma
Oesophageal varices. Tortuous,
worm-like filling defects are seen
in the lower half of the oesophagus.
Pharyngeal pouch (Zenker's
diverticulum). The pouch is
lying behind the oesophagus
which is displaced forward.
Duodenal diverticulum arising
from the second part of the
duodenum (arrows)
Normal stomach and duodenum: double-contrast barium meal. On this supine
view barium collects in the fundus of the stomach. The body and the antrum of
the stomach together with the duodenal cap and loop are coated with barium
and distended with gas. Note how the fourth part of the duodenum and
duodenojejunal flexure are superimposed on the body of the stomach
Carcinoma. There are a number of large filling defects in the antrum and body
of the stomach
Benign ulcer, (a) In profile the ulcer (arrow) projects from the lesser curve of
the stomach, (b) En face the ulcer (arrow) is seen as a rounded collection of
barium.
Malignant ulcer. The ulcer (arrow) does not project from the lumen of the
stomach. Note how the mucosal folds do not reach the ulcer crater. The
stomach is narrowed by an extensive carcinoma converting it to a rigid tube
with obliteration of mucosal folds.
Gastric outlet obstruction. A carcinoma is causing narrowing of the antrum
(arrow). The speckled appearance in the fundus of the enlarged stomach is due
to food residues
Erosive gastritis. The erosions appear on this double-contrast barium meal as
many small collections of barium, some of which are arrowed, surrounded by a
radiolucent halo of oedema.
Hiatus hernia, Sliding: the fundus of the stomach and the gastro-oesophageal
junction (arrow) have herniated through the oesophageal hiatus and lie above
the diaphragm (dotted line)
(a)
Normal barium follow-through. The small intestine, ascending and transverse
colon are filled with barium. The jejunum in the left side of the abdomen has a
much more marked mucosal fold pattern than the ileum which is lying in the
pelvis. When a peristaltic wave contracts the bowel the mucosal folds lie
longitudinally (arrows). Note the way of measuring the diameter of the bowel. In
the pelvis the loops overlap and details of the bowel become hidden, (b) Normal
terminal ileum
Normal small bowel enema. This
technique gives good mucosal detail.
The arrow points to the terminal
ileum. Note that a tube has been
passed through the stomach into the
jejunum
Dilatation from small bowel
obstruction. The diameter of the
bowel is greatly increased. The
feathery mucosal pattern is lost and
the folds appear as thin lines
traversing the bowel, known as
valvulae conniventes (arrows).
Mucosal abnormality with infiltration
of the bowel, in this case from
oedema. The mucosal folds become
thickened. Some of the thickened
folds are arrowed
Ulceration. Abnormal loops of
bowel in Crohn's disease
showing the ulcers as outward
projections (arrows).
Narrowing. There is a long irregular stricture
(arrows) in the terminal ileum due to Crohn's
disease. There is an abnormal mucosal pattern in
the remainder of the terminal ileum. Note the
contracted caecum - another feature of the
disease
Displacement. The small bowel is
displaced around enlarged
abdominal lymph nodes from a
metastatic teratoma of the testis.
Malrotation. The small bowel is situated
in the right side of the abdomen. Later
films showed the colon on the left side.
Crohn's disease
Diverticulosis. A number of diverticula of varying size are arising from the
small bowel. Some of these are arrowed multiple small bowel diverticula a
dilated loop cut off from the main stream of the bowel in which there is
delayed filling and emptying (blind loop)
Stricture. A short circumferential narrowing is seen in the sigmoid colon
(arrow) from a carcinoma.
Extrinsic compression. A narrowed
length of sigmoid colon is seen
caused by compression by an
adjacent ovarian
Extrinsic compression. An appendix
abscess is compressing and
narrowing the caecum.
Filling defects. Lumps of faeces have caused
smooth filling defects surrounded by barium.
However, in the sigmoid colon there is a large
filling defect with ill-defined edges (arrow). This
is a carcinoma. A clean colon is essential for a
satisfactory barium enema.
Muscle hypertrophy and diverticula.
Muscle hypertrophy gives the sigmoid
colon a serrated appearance. Two small
diverticula are arrowed
Ulceration, (a) Single contrast. (b) Double contrast. In this case of ulcerative
colitis the ulceration causes the normally smooth outline of the colon to be
irregular.
Ulcerative colitis. With long-standing disease the haustra are lost and the colon
becomes narrowed and shortened coming to resemble a rigid tube. Reflux into
the ileum through an incompetent ileocaecal valve has occurred.
A). Crohn's disease. The mucosal pattern has a 'cobblestone' appearance due to
criss-crossing fine ulceration. B). Crohn's disease - strictures. A long stricture is
present in the transverse colon (between curved arrows) and a shorter one in
(hesigmoid colon (between small arrows). In this case the outline of the strictures
are irregular, due to ulceration. C). These two abnormal segments with normal
intervening bowel are an example of skip lesions' - an important diagnostic feature
of Crohn's
a
b
c
Diverticular disease. Numerous
diverticula are seen as out-pouchings
from the sigmoid colon
Diverticular disease. A stricture is
present (arrow). Although there is
recognizable diverticular disease at
both ends of the stricture, it is
impossible to exclude definitely a
carcinoma
Polyps within the colon may be demonstrated as radiolucent filling defects
displacing the contrast substance. Note stalk, which is well seen.