Diagnostic approach for acute abdomen / using different imaging modules

1. Acute Abdomen - Practical &
Diagnostic Approach
• Presented By
• DR Laith Fadhil Al-hialy
• MBchB PGSR

2. The 'acute abdomen' is a clinical condition characterized by
severe abdominal pain, requiring the clinician to make an
urgent therapeutic decision- surgical or none surgical
Major causes
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Acute appendicitis.
Acute Cholecystitis
Diverticulitis. or Meckel's diverticulitis
Acute pancreatitis.
Ectopic pregnancy.
Peptic ulcer disease, perforated DU ( 80% duodenum , pyloric antrum )
Salpingitis , PID , Expelled IUCCD
Intestinal obstruction, including paralytic ileus (a dynamic obstruction).
Gastroenteritis.
Acute intestinal ischemia/infarction or vasculitis.
Renal colic or renal tract pain , acute urinary retention.
Abdominal aortic aneurysm (AAA).
Gastrointestinal (GI) haemorrhage
Testicular torsion.
Nonsurgical disease, e.g. myocardial infarction, pericarditis, pneumonia, sickle
cell crisis, hepatitis, inflammatory bowel disease, opiate withdrawal, typhoid.

3. acute abdomen includes a wide spectrum of disorders, ranging
from life-threatening diseases to benign self-limiting conditions

4. Radiological strategy
 Before you perform an examination, obtain relevant information from the referring
clinician.
Don't let the clinician simply 'order' a plain X-ray film , sonogram or CT, but discuss
the patient's age and posture, laboratory results and the number one clinical
diagnosis and differential diagnosis.
Based on that information and your own degree of confidence with the modalities
decide for yourself whether to perform plan X-Ray film ,Sonography or CT.
Sonography has the advantage of close patient contact, enabling assessment of
the spot of maximum tenderness and the severity of illness without ionizing
radiation.
In general the diagnostic accuracy of CT is higher than Sonography.
We advocate the following two-step radiological approach of an acute abdomen.
1. Confirm or exclude the most common disease
2. Screen whole abdomen for general signs of pathology

5. Confirm or exclude most common disease
1st step focusing on most common causes
Location of pain determined strategy
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RLQ : Appendicitis
RUQ : Cholecystitis
LLQ : Diverticulitis
LUQ : rare – mostly related to
gastric pathology
• 2nd step is
Screen the whole abdomen for the
pathological signs
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Bowel wall thickening
Ileus ( dilated a tonic loop )
Air ( Pneumoperitoneum )
Fluid ( ascites )
Inflamed surrounding fat
Renal , uretric stone – pathology

6. A plain X-Ray
abdominal film
A normal film does not exclude an
ileus or other pathology and may
falsely reassure the clinician.
An ileus may not be appreciated on
a plain abdominal film if bowel
loops are filled with fluid only
without intraluminal air (figure).
Alternatively if a plain abdominal
film does indicate an ileus than
Sonography or CT are usually
needed to identify its cause.
Thus, a plain abdominal film is
seldomly useful, with the exception
of detection of kidney stones 70 % ,
GS 20 % , fecolith 10 % or a
Pneumoperitoneum.
For all other indications use
Sonography or CT.
LEFT: Plain abdominal film in a patient with an acute abdomen, showing no abnormalities.
RIGHT: Subsequent CT shows distended small bowel loops (arrowheads) that are not seen on
plain abdominal film because they are filled with fluid only and do not contain intraluminal air.

7. RLQ : Appendicitis
Pain in the RLQ, regardless of any
other symptom or laboratory results,
should be considered to be
appendicitis until proven otherwise.
If you are unable to find the appendix
you cannot rule out the diagnosis of
appendicitis unless a good alternative
diagnosis is found.
If you do not find the appendix and
there is no alternative diagnosis call
the results of the examination
indeterminate. Do not call it:' no
appendicitis'.
Inflamed Appendix
An inflamed appendix ( none
compressible tubal lesion ) has a
diameter larger than 6 mm, and is
usually surrounded by inflamed fat.
The presence of a fecolith or
hypervascularity on power Doppler
strongly supports inflammation.

8. DDX of RLQ disease
Mesenteric lymphadenitis.
Mesenteric lymphadenitis is a common
mimicker of appendicitis.
It is the second most common cause of right
lower quadrant pain after appendicitis.
It is defined as a benign self-limiting
inflammation of right-sided mesenteric
lymph nodes without an identifiable
underlying inflammatory process, occurring
more often in children than in adults..
This diagnosis can only be made confidently
when a normal appendix is found, because
adenopathy also frequently occurs with
appendicitis.
Key finding: Lymphadenopathy with a
normal appendix and normal mesenteric fat.
Bacterial ileocecitis
Infectious enter colitis may cause mild symptoms
resembling a common viral gastroenteritis, but it
may also clinically present with features
indistinguishable from appendicitis especially in
bacterial ileocecitis, caused by Yersinia,
Campylobacter, or Salmonella.
Key finding: ileocecal wall thickening without
inflamed fat, adenopathy, normal appendix

9. Right-sided diverticulitis
Right-sided colonic diverticulitis may
clinically mimic appendicitis or
Cholecystitis, though the patient's
history is generally more protracted.
In contrast to sigmoid diverticula,
right-sided colonic diverticula are
usually true diverticula, that is,
outpunching of the colonic wall
containing all layers of the wall.
This may possibly explain the
essentially benign self- limiting
character of right-sided diverticulitis
Salphingitis
Salphingitis is a common mimicker of
both of appendicitis and diverticulitis.
Transvaginal Sonography depicts an
inhomogeneous enlarged inflamed
ovary. ( adenixial mass lesion )

10. Epiploic appendagitis.
Epiploic appendages are small adipose
protrusions from the serosal surface of the
colon.
An epiploic appendage may undergo torsion
and secondary inflammation causing focal
abdominal pain that simulates appendicitis
when located in the right lower quadrant or
diverticulitis when located in the left lower
quadrant.
The characteristic ring-sign corresponds to
inflamed visceral peritoneal lining surrounding
an infracted fatty epiploic appendage. Epiploic
appendagitis has been reported in
approximately 1% of patients clinically
suspected of having appendicitis.
It is very important to make a positive
diagnosis of this characteristic entity since
epiploic appendagitis is a self-limiting
disease.
Both US and CT will depict an inflamed fatty
mass adjacent to the colon.
Key finding: inflamed fatty mass adjacent to
the colon with characteristic ring sign.

11. Urolithiasis
Urolithiasis often causes flank
pain, but an ureteral stone
(arrowhead) may occasionally
present with clinical signs
simulating appendicitis,
Cholecystitis or diverticulitis.
Appendicitis on the other hand
may cause hematuria, pyuria and
albuminuria in up to 25% of
patients because of direct
invaded ureteral inflammation
Note
Renal colic may associated by
paralytic ileus , sever pain air
swallowing commonly lead to
ileus

12. LLQ : Diverticulitis
If the pain is located in the LLQ your
main concern is sigmoid diverticulitis.
In diverticulitis Sonography and CT
show diverticulosis with segmental
colonic wall thickening and
inflammatory changes in the fat
surrounding a diverticulum.
LEFT: Sigmoid diverticulitis. Diverticulum
(arrow) is surrounded by hyper
attenuating fat. The sigmoid wall is
thickened.
RIGHT: Sigmoid carcinoma with limited fat
stranding.
Complications of
diverticulitis such
as abscess
formation or
perforation, can
best be excluded
with CT.

13. As DDX of LLQ lesion
Ruptured Aneurysm
Most abdominal aortic aneurysms rupture
into the left retro peritoneum (4).
Clinically this may simulate sigmoid
diverticulitis or renal colic due to
impingement of the hematoma on
adjacent structures.
However most patient will present with
the classic triad of hypotension, a
pulsating mass and back pain.
Continuous leakage will lead to rupture
into the peritoneal cavity and eventually
death.
Sonography is a quick and convenient
modality, but it is much less sensitive and
specific for the diagnosis of aneurysmal
rupture than CT.
The absence of sonographic evidence of
rupture does not rule out this entity if
clinical suspicion is high

14. RUQ : Cholecystitis
Cholecystitis occurs when a calculus
obstructs the cystic duct. The trapped
bile causes inflammation of the
gallbladder wall.
As gallstones are often occult on CT,
Sonography is the preferred imaging
method for the evaluation of
Cholecystitis, Some gallbladders happen
to be small and others are large. The
imaging appearance of Cholecystitis
consists of an enlarged hydropic
(meaning non-compressible)
gallbladder with a thickened wall in
the region of maximum tenderness
(the so-called 'Murphy sign‘)

15. Epigastric or upper
abdominal pain
Pancreatitis
CT depicts fat-stranding
(arrowheads) surrounding the
primary focus of the inflammation:
the pancreas
BY US focal edema on the pancreatic
fat , enlarge hypoechoic texture
pancreas
By X-ray , duodenal ileus , Lt plural
effusion , obliteration Lt poses shadow

16. Screen the whole abdomen for general signs of pathology
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Bowel wall thickening
Air ( Pneumoperitoneum )
Ileus ( dilated a tonic loop )
Fluid ( ascites )
Renal , uretric stone and
pathology
6. Inflamed surrounding fat
Bowel wall thickening
Thickening of bowel wall indicates inflammation or
tumor, and has an extensive differential diagnosis.
Thickening of small bowel loops usually indicates
regional inflammation, as small bowel tumors
(carcinoid, lymphoma, GIST) are relatively
infrequent.
In patients with local colonic wall thickening a
carcinoma is a prime concern.

17. Free air
The presence of free
intraperitoneal air is proof of
bowel perforation, and indicates
a surgical emergency.
A Pneumoperitoneum has only
two frequent causes:
- Perforation of a duodenal ,
gastric ulcer 80%
- Perforation of colonic
diverticulitis
Free air is usually not seen in
perforated appendicitis).
Always examine the images in
lung setting for better detection
of free intraabdominal air
(figure).

18. Ileus
Pathologic distention of bowel loops may be caused by obstruction or
paralysis.
Firstly determine which parts of the gut are affected: small bowel, large bowel, or
both. Look for normal non distended bowel loops, which, if present, strongly suggest
an obstructive cause for the ileus
Causes of paralytic Ileus
• post operative
• Peritonitis
• Inflammation ( appendicitis ,
cholecystis , pancreatitis )
• Trauma
• CHF , Uremia
• Hypokalaemia
• Pneumonia
•Drugs – morphine
•Renal colic
Causes of SBO
• adhesion 70-80 %
• Hernia
• volvulus
• intussusception
• GS Ileus
• tumor – lymphoma
• mesenteric ischemia
Causes of LBO
• Ca 60% - mostly sigmoid
• volvulus
• diverticulitis
• fecal impaction
• IBD - toxic mega colon

19. Distinction between small and Large bowel dilation
• No. of loops
• distribution of loops
• diameter
• Sold feces
• structure
• Radius of curvature
• Many
• Central
• 3-5 cm
• absent
• valvule
conniventes
• small
• Few
• peripheral
• 5 cm +
• present
• haustra
• large

20. Ascites
Asymptomatic person do not
have a detectable amount of
free intraperitoneal fluid, with
the exception of an incidental
drop of fluid in Douglas in
fertile women.
The presence of ascites is a
nonspecific sign of abdominal
pathology, indicating that
'something is wrong'.
You may want to perform a
US-guided diagnostic puncture
of the ascites, in order to
investigate whether it is
sterile reactive fluid, pus,
blood, urine, or bile.