THE ACUTE ABDOMEN
• Patients with an acute abdomen comprise
the largest group of people presenting as
a general surgical emergency.
• In most acute abdominal conditions,
following the history and clinical
examination, plain film radiographs have
traditionally been the first & most useful
methods of further investigation.
Plain abdominal radiographs
• In most acute abdominal conditions the
radiological diagnosis depends on gas
patterns .
• A supine abdomen and an erect chest is
regarded as the basic standard
radiographs.
Chest X-ray
This is an essential examination in any patient with
acute abdomen because:
1-It is the best radiograph to show the presence of
a small pneumoperitoneum.
2-A number of chest conditions may present as an
acute abdominal pain : pneumonia (particularly
lower lobe), MI, … .
3- Acute abdominal conditions may be
complicated by chest pathology: pleural effusion
frequently complicate acute pancreatitis.
4-Even when the chest radiograph is normal it
acts as a valuable baseline.
Small
amount
Abdominal radiographs
– The supine abdominal radiograph is probably the single
most useful film. It allows the distribution of gas and the
caliber of bowel to be determined and may show
displacement of bowel by soft tissue masses.
– An erect abdominal radiograph is usually taken to show
the air fluid levels; three or more small bowel fluid levels
longer than 2.5 cm are abnormal, and indicate dilated
small bowel loops with stasis.
Pneumoperitoneum
• In over 90% of cases the cause of
pneumoperitoneum will require emergency
surgery.
Pseudo-Pneumoperitoneum:
• These are important because failure to
recognize them may lead to an unnecessary
laparotomy in search for a perforated viscus.
• The commonest cause for this are: Chiladiti
syndrome, subdiaphragmatic fat & curvilinear
pulmonary collapse .
Intestinal obstruction:
• Gastric dilatation : could be
– Part of paralytic ileus
(functional).
– Mechanical : usually
caused by peptic
ulceration or a carcinoma
of the pyloric antrum ,
often lead to massive fluid
filled stomach which
occupy most of the upper
abdomen.
Small bowel obstruction
• The commonest cause is adhesions due to previous surgery .
• The main value of plain film is in assessing the degree &
severity of the obstruction (not the cause).
• On plain film, changes in small bowel obstruction may appear
after 3-5 hours if there is complete obstruction and marked
after 12 hours.
• Radiologically, complete obstruction of the small bowel usually
causes small bowel dilatation with accumulation of both gas &
fluid and a reduction in caliber of the large bowel, if dilated gas
filled loops of small bowel will be readily identified on the
supine radiograph, multiple fluid levels are present on erect
film.
if fluid filled loops
• The dilated small bowel loops
appears as a sausage, oval
or round soft tissue densities
that change in position in
different views, sometime with
small gas bubbles trapped in
rows between the vulvulae
conniventes on horizontal ray
films; this is known as 'string
of beads' sign which is
virtually diagnostic of small
bowel obstruction and does
not occur in normal people.
Gall stone ileus
•
This is a mechanical obstruction
caused by the impaction of one or
more gall stones in the intestine,
usually in the terminal ileum, but
rarely in the duodenum or the
colon.
The commonest radiological signs to
be observed are :
1- A gas shadow within the bile ducts
and/ or the gall bladder.
2- Complete or incomplete intestinal
obstruction.
3- An abnormal location of an already
observed gall stone.
Large bowel obstruction
• The commonest cause is
carcinoma, of which about 60% are
situated in the sigmoid colon.
The radiological appearance of large
bowel obstruction depends on the
state of competence of the ileocecal
valve :
- TYPE 1A:the ileocecal valve is competent
leading to dilated gas filled colon with its
haustral markings and a distended thinwalled cecum but no distension of small
bowel., this can lead to massively distended
cecum, which is in then at a higher risk of
perforation secondary to ischemia
( transverse cecal diameter of 9 cm had
been suggested as the critical point above
which the danger of perforation exists).
• As this type progresses, small
bowel distention occur (type 1B),
with a radiological appearance
identical to that of paralytic ileus .
• In TYPE II obstruction, the
ileocecal valve is incompetent
and the cecum and ascending
colon are not distended, but the
back pressure from the colon
extends into the small bowel
which may simulate small bowel
obstruction.
Cecal volvulus
(Right colon volvulus)
• This account for less than 2%
of adult intestinal obstruction
( young age group).
• The diagnosis of acute cecal
volvulus is rarely made on
clinical ground alone, and so
radiological diagnosis become
much more important & it is
usually comprises a distended
lower abdominal viscus with
one or two haustral markings,
concomitant small bowel
dilatation & a collapsed left half
of the colon.
• Note: identification of gas filled
appendix confirm the diagnosis.
Sigmoid volvulus
• This is the classic volvulus,
occurring in old, mentally
subnormal patients.
• It is usually chronic with
intermittent acute attacks.
• Radiological signs :
– inverted U shaped
distended loop which is
devoid of haustra
(ahaustral).
– Liver or left flank overlap
signs.
– Apex of the volvulus
above T10.
– Air fluid ratio greater than
The distinction between small &
large-bowel dilatation
Small bowel
1. vulvulae conniventes
2. number of loops
3. distribution of loops
4. haustra
5. diameter
6. radius of curvature
7. solid feces
present in jejunum
many
central
absent
3-5 cm
small
absent
large bowel
absent
few
peripheral
present
5 cm +
large
*present
haustra may be completely absent from the descending & sigmoid colon.