acute abdomen poto
TRANSCRIPT
-
8/2/2019 Acute Abdomen Poto
1/17
Acute Abdomen - A Practical Approach
Adriaan van Breda Vriesman and Robin Smithuis
Radiology department of the Rijnland Hospital, Leiderdorp, the Netherlands
Radiological strategy
Clinics, laboratory, and plain abdominal film
Confirm or exclude the most common disease
RLQ : Appendicitis
LLQ : Diverticulitis
RUQ : Cholecystitis Screen for general signs of pathology
Inflamed fat
Bowel wall thickening
Ileus
Ascites Free air
Differential diagnosis
Mesenteric lymphadenitis.
Bacterial ileocecitis
Right-sided diverticulitis
Salphingitis
Epiploic appendagitis.
Urolithiasis
Ruptured Aneurysm
Pancreatitis
back to overview print
Publicationdate:20-10-2005
The 'acute abdomen' is aclinical condition
characterized by severe
abdominal pain, requiring theclinician to make an urgent
therapeutic decision.
This may be challenging,because the differential
diagnosis of an acute abdomen
includes a wide spectrum of
disorders, ranging from life-threatening diseases to benign
self-limiting conditions (Table
1).Indicated management may
vary from emergency surgery
to reassurance of the patientand misdiagnosis may easily
result in delayed necessary
treatment or unnecessarysurgery.Sonography and CT enable an
accurate and rapid triage of
patients with an acuteabdomen.
We present practical
guidelines on the radiologicalapproach of these patients.
Interactive cases are presented
in the menubar to test your
knowledge.
If you encounter printing
problems with the margins ofthe document, try to adjust the
margins or the scale of the
document in the print settings. Radiological strategy
http://www.radiologyassistant.nl/en/42d54f75d111d#p42d553de8211dhttp://www.radiologyassistant.nl/en/42d54f75d111d#p42d54f75db90dhttp://www.radiologyassistant.nl/en/42d54f75d111d#p42d5545a8b234http://www.radiologyassistant.nl/en/42d54f75d111d#a42d578b13f665http://www.radiologyassistant.nl/en/42d54f75d111d#a42d57df09e50bhttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d582119ea2ahttp://www.radiologyassistant.nl/en/42d54f75d111d#p42d5835b5a7d4http://www.radiologyassistant.nl/en/42d54f75d111d#a42d5843991f65http://www.radiologyassistant.nl/en/42d54f75d111d#a42d5874ff161fhttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d58779024fbhttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d6b9eda7330http://www.radiologyassistant.nl/en/42d54f75d111d#a42d6ba05ace63http://www.radiologyassistant.nl/en/42d54f75d111d#p42d6ba283823chttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d6ba4fb90b3http://www.radiologyassistant.nl/en/42d54f75d111d#a42d6ba4fb90b3http://www.radiologyassistant.nl/en/42d54f75d111d#a42d6bb6b907adhttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d6bbf4c965fhttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d6bc280c3dbhttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d6bd031b8c4http://www.radiologyassistant.nl/en/42d54f75d111d#a42d6bd031b8c4http://www.radiologyassistant.nl/en/42d54f75d111d#a42d6be2e7ae1ahttp://www.radiologyassistant.nl/en/42d54f75d111d#a431e5ad7585aehttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d6bea9c3b2ahttp://www.radiologyassistant.nl/en/420cd11061ecdhttp://www.radiologyassistant.nl/en/42d54f75d111dhttp://www.radiologyassistant.nl/en/42d54f75d111d#p42d54f75db90dhttp://www.radiologyassistant.nl/en/42d54f75d111d#p42d5545a8b234http://www.radiologyassistant.nl/en/42d54f75d111d#a42d578b13f665http://www.radiologyassistant.nl/en/42d54f75d111d#a42d57df09e50bhttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d582119ea2ahttp://www.radiologyassistant.nl/en/42d54f75d111d#p42d5835b5a7d4http://www.radiologyassistant.nl/en/42d54f75d111d#a42d5843991f65http://www.radiologyassistant.nl/en/42d54f75d111d#a42d5874ff161fhttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d58779024fbhttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d6b9eda7330http://www.radiologyassistant.nl/en/42d54f75d111d#a42d6ba05ace63http://www.radiologyassistant.nl/en/42d54f75d111d#p42d6ba283823chttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d6ba4fb90b3http://www.radiologyassistant.nl/en/42d54f75d111d#a42d6bb6b907adhttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d6bbf4c965fhttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d6bc280c3dbhttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d6bd031b8c4http://www.radiologyassistant.nl/en/42d54f75d111d#a42d6be2e7ae1ahttp://www.radiologyassistant.nl/en/42d54f75d111d#a431e5ad7585aehttp://www.radiologyassistant.nl/en/42d54f75d111d#a42d6bea9c3b2ahttp://www.radiologyassistant.nl/en/420cd11061ecdhttp://www.radiologyassistant.nl/en/42d54f75d111d#p42d553de8211d -
8/2/2019 Acute Abdomen Poto
2/17
Table 1. Common causes of acute abdomen from life-threatening to
self-limiting.
Before you perform an
examination, obtain relevantinformation from the referring
clinician.
Don't let the clinician simply'order' a sonogram or CT, but
discuss the patient's age and
posture, laboratory results andthe number one clinical
diagnosis and differential
diagnosis.
Based on that information andyour own degree of
confidence with the modalities
decide for yourself whether to
perform sonography or CT.Sonography has the advantage
of close patient contact,enabling assesment of the spot
of maximum tenderness and
the severity of illness withoutionizing radiation.
In general the diagnostic
accuracy of CT is higher than
sonography.In patients with inconclusive
US-results, CT can serve as an
adjunct to sonography, andvice versa.
We advocate the following
two-step radiological approachof an acute abdomen.
1. Confirm or exclude the
most common disease
2. Screen for general signs ofpathology
You have to be familiar with
all the diagnoses listed inTable 1 to be able to recognize
them.Clinics, laboratory, and plain
abdominal film
-
8/2/2019 Acute Abdomen Poto
3/17
The clinical presentation of
patients with an acute
abdomen is often nonspecific.Both surgical and nonsurgical
diseases may present with a
similar clinical history andsymptoms.
Laboratory findings (leucocyte
count, erythrocytesedimentation rate, CRP) are
equally nonconclusive.
Findings may be normal in
patients who need emergencysurgery (such as appendicitis)
and may be abnormal in
patients without a surgical
disease (like salpingitis).A plain abdominal film has a
limited value in the evaluationof abdominal pain.
A normal film does not
exclude an ileus or otherpathology and may falsely
reassure the clinician.
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.
An ileus may not be
appreciated on a plainabdominal film if bowel loops
are filled with fluid only
without intraluminal air(figure).
Alternatively if a plain
abdominal film does indicatean ileus than sonography or
CT are usually needed to
identify its cause.
Thus, a plain abdominal filmis seldomly useful, with the
exception of detection of
kidney stones or apneumoperitoneum.
For all other indications use
sonography or CT.
Confirm or exclude the mostcommon disease
-
8/2/2019 Acute Abdomen Poto
4/17
Many disorders may cause an
acute abdomen, but
fortunately only a few of theseare common and clinically
important.
Focus on confirming orexcluding these frequent
disorders:RLQ : Appendicitis
Pain in the RLQ, regardless of
any other symptom or
laboratory results, should beconsidered to be appendicitis
until proven otherwise.
If you are unable to find theappendix you cannot rule out
the diagnosis of appendicitisunless a good alternative
diagnosis is found.If you do not find the
appendix and there is no
altermative diagnosis call theresults of the examination
indeterminate. Do not call it:'
no appendicitis'.
Normal appendix : Longitudinal (A) sonogram depicts a blind-
ending tubular structure (arrowheads) with 'gut-signature', with amaximum outer diameter of 6 mm, with noninflamed surrounding
fat. On an axial view (B) the appendix can be compressed crossingthe iliac vessels.
Normal Appendix.
Your first task is to identify
the appendix.At sonography and CT theappendix is seen as a blind-
ending nonperistaltic tubular
structure arising from the baseof the cecum.
Do not mistake a small bowel
loop for the appendix.Secondly determine if the
appendix is normal or
inflamed.
The outer-to-outer diameter ofthe appendix is the most
important imaging criterium.
Although an overlap ofappendiceal diameters in
normal and inflamed
appendices can incidentally befound, a threshold value of 6-7
-
8/2/2019 Acute Abdomen Poto
5/17
mm is generally used.
Normal appendix: CT shows an air-containing non-distended
appendix (arrowheads), with homogeneous low-density
periappendiceal fat.
A normal appendix has a
maximum diameter of 6 mm,is surrounded by
homogeneous non-inflamed
fat, is compressible and oftencontains intraluminal gas.
Inflamed appendix at sonography. Longitudinal (A) and transverse
(B) cross-section show a distended noncompressible appendix,
surrounded bij hyperechoic inflamed fat (arrowheads).
Inflamed AppendixAn inflamed appendix has a
diameter larger than 6 mm,
and is usually surrounded byinflamed fat. The presence of
a fecolith or hypervascularity
on power Doppler stronglysupports inflammation.
Inflamed appendix at CT. The appendix (arrows) is fluid-filled and
distended with periappendiceal fat-stranding.
CT depicts an inflamed
appendix as a fluid-filled
blind-ending tubular structuresurrounded by fat-stranding.
In the case on the left a hyper-
attenuating wall is seen on theenhanced CT.
In patients who lack intra-
abdominal fat the use of iv.contrast can be helpfull in
depicting the inflamedappendix.
-
8/2/2019 Acute Abdomen Poto
6/17
Sigmoid diverticulitis at sonography. A hypoechoic thickeneddiverticulum is surrounded by hyperechoic inflamed fat (arrows).
LLQ : Diverticulitis
If the pain is located in theLLQ your main concern is
sigmoid diverticulitis.
In diverticulitis sonography
and CT show diverticulosiswith segmental colonic wall
thickening and inflammatory
changes in the fat surroundinga diverticulum.
Uncomplicated sigmoid diverticulitis. Fat stranding and focalthickening of the colonic wall in an area with diverticula. No
abscess formation.
Complications of diverticulitis
such as abscess formation orperforation, can best be
excluded with CT.
-
8/2/2019 Acute Abdomen Poto
7/17
LEFT: Sigmoid diverticulitis. Diverticulum (arrow) is surroundedby hyperattenuating fat. The sigmoid wall is thickened.
RIGHT: Sigmoid carcinoma with limited fat stranding.
An important pitfall is colon
cancer, which may present
with similar imaging features,especially when the colon
cancer is surrounded by fat
stranding due to invasivegroth, desmoplastic reaction or
inflammation.
Frequently it is not possible toreliably distinguish
diverticulitis from colon
cancer and therefore we
routinely include colon cancerin the differential diagnosis of
sigmoid diverticulitis.RUQ : Cholecystitis
Cholecystitis occurs when acalculus obstructs the cystic
duct. The trapped bile causesinflammation of the
gallbladder wall.
As gallstones are often occulton CT, sonography is the
preferred imaging method for
the evaluation of cholecystitis,also allowing assesment of the
compressiblity of the
gallbladder.The diagnosis of a hydropicgalbladder is solely made on
the non-compressability of the
galbladder. Do not rely onmeasurements. Some
galbladders happen to be small
and others are large.The imaging appearance of
cholecystis consists of an
enlarged hydropic (meaning
non-compressible) gallbladderwith a thickened wall in the
region of maximum tenderness
(the so-called 'Murphy sign')
-
8/2/2019 Acute Abdomen Poto
8/17
Longitudinal and transverse US show thickened gallbladder wall.
The gallbladder is noncompressible ('hydropic') and causes an
impression in the anterior abdominal wall (arrowheads).
Cholecystitis at CT. The gallbladder is enlarged with edematous
thickening of its wall (arrowhead), and some regional fat-strandingcan be found.
The inflamed gallbladder
usually contains stones orsludge, whereas the
obstructing calculus itself mayor may not be identified
because it is located deep
within the galbladder neck orcystic duct.
The gallbladder may be
surrounded by inflamed fat,but on sonography this
frequently is not seen, while
CT sometimes does show fat-stranding.
Potential pitfalls are
pancreatitis, hepatitis or right-
sided heart failure, which allmay lead to thickening of the
gallbladder wall without
cholecystitis.Therefore be certain that
hydropic obstruction of the
gallbladder is present before
assigning the diagnosis ofcholecystitis.
Pain in LUQ
An acute abdomen with LUQpain is rare.
Its most common cause is
gastric pathology in whichradiological imaging plays a
minor role.Screen for general signs of
pathology
After excluding these frequentdisorders, search for signs of
any other pathology, by
systematically screening thewhole abdomen.
Look for inflamed fat, bowel
wall thickening, ileus, ascites
and free air.
-
8/2/2019 Acute Abdomen Poto
9/17
Inflamed fat at sonography. Extended-view of the ventral abdomen
depicting an area of hyperechoic noncompressible inflamed fat inthe omentum (red arrows). Compare this to the echogenicity of
normal abdominal or subcutaneous fat (green arrows). This patient
had an omental infarction.
Inflamed fat
Inflamed fat is hyperechoic,space occupying and
noncompressible at
sonography.
Same patient as above. Unenhanced CT depicts an area of fatty
tissue with slightly increased density (arrowheads), in the right-upper quadrant. Compare this to normal low-density subcutaneous
fat. Diagnosis: omental infarction.
Inflamed fat is shown as fat-
stranding at CT. Inflamed fat
usefully points out where and
what the problem is.As a rule, the organ or
structure in the centre or
nearest to the inflamed fat isthe cause of the inflammation.
-
8/2/2019 Acute Abdomen Poto
10/17
Diffuse thickening of bowel wall in a patient with colitis.
Bowel wall thickening
Thickening of bowel wallindicates inflammation or
tumor, and has an extensive
differential diagnosis.
Thickening of small bowelloops usually indicates
regional inflammation, as
small bowel tumors(carcinoid, lymphoma, GIST)
are relatively infrequent.
In patients with local colonicwall thickening a carcinoma is
a prime concern.
Obstructive ileus. CT depicts distended small bowel loops, but partof the small bowel and the whole colon is nondistended. Therefore
this must be an obstructive small bowel ileus, and in this case its
cause can easily be identified: intussusception (arrowhead).
Ileus
Pathologic distention of bowelloops 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 nondistended
bowel loops, which, if present,
strongly suggest an obstructive
cause for the ileus.
View more images: 3/4
Small bowel obstruction
(SBO) accounts for
approximately 4% of all
patients presenting with anacute abdomen.
The diagnosis of SBO is made
when you see dilated small
bowel and collapsed smallbowel loops.
If obstruction is present, try toidentify its cause and location
(adhesion, tumor, volvulus,
intussusception, inguinal
hernia).Adhesions account for 60-80%
http://www.radiologyassistant.nl/en/42d54f75d111dhttp://www.radiologyassistant.nl/en/42d54f75d111d -
8/2/2019 Acute Abdomen Poto
11/17
Scroll through the images
Small Bowel Feces Sign: Feces in the dilated small bowel just
proximal to the site of obstruction.Obstruction was due to adhesions
of all cases and are the likely
cause when a smooth
transition from dilated tocollapsed small-bowel loops is
noted.
The 'Small Bowel Feces Sign'
(SBFS) is a very useful sign asit is seen at the zone of
transition thus facilitating
identification of the cause ofthe obstruction.
The SBFS has been defined as
gas and particulate materialwithin a dilated small-bowel
loop that simulates the
appearance of feces.Scroll through the images on
the left to see the small bowel
feces sign indicating the site of
obstruction.Alternatively, an ileus without
any normal bowel loops
strongly suggests a paralyticcause.
This is usually a response to
general peritonitis, wich may
have many possible causes ofthe inflammation.
-
8/2/2019 Acute Abdomen Poto
12/17
Clinically appendicitis. US only showed a little bit of ascites. A
diagnostic puncture (arrow marks needletip) revealed blood. In awoman this finding is very suspicious of an EUG.
Ascites
Asymptomatic volunteers donot have a detectable amount
of free intraperitoneal fluid,
with the exception of an
incidental drop of fluid inDouglas in fertile women.
The presence of ascites is a
nonspecific sign of abdominalpathology, indicating that
'something is wrong'.
You may want to perform aUS-guided diagnostic
puncture of the ascites, in
order to investigate whether itis sterile reactive fluid, pus,
blood, urine, or bile.
Intraperitoneal air in a patient suspected of having appendicitis. Airbetter seen on images with lungsetting on the right.
Free air
The presence of free
intraperitoneal air is proof ofbowel perforation, and
indicates a surgicalemergency.
A pneumoperitoneum has only
two frequent causes:
- Perforation of a gastric ulcer
- Perforation of colonic
diverticulitis
Free air is usually not seen inperforated appendicitis).
Always examine the images in
lungsetting for better detection
of free intraabdominal air(figure).
Differential diagnosis
-
8/2/2019 Acute Abdomen Poto
13/17
A complete list of all possible
causes of an acute abdomen is
of little use in daily practice,therefore we just provide some
imaging examples of several
frequent causes of acuteabdominal pain
US shows enlarged mesenteric lymph nodes in the right lower
quadrant, with no other abnormalities
Mesenteric lymphadenitis.
Mesenteric lymphadenitis is acommon mimicker of
appendicitis.
It is the second most commoncause of right lower quadrant
pain after appendicitis.
It is defined as a benign self-limiting inflammation of right-
sided mesenteric lymph nodeswithout an identifiable
underlying inflammatoryprocess, occurring more often
in children than in adults..
This diagnosis can only bemade confidently when a
normal appendix is found,
because adenopathy alsofrequently occurs with
appendicitis.
Key finding:Lymphadenopathy with anormal appendix and normal
mesenteric fat.
On the left a CT of mesentericlymphadenitis in a child
suspected of appendicitis.
-
8/2/2019 Acute Abdomen Poto
14/17
Normal appendix (green arrow) and enlarged mesenteric
lymphnodes (yellow arrows).
US typically shows submucosal wall thickening (arrowheads) of the
terminal ileum and cecum without inflammation of the surroundingfat.
Bacterial ileocecitis
Infectious enterocolitis may
cause mild symptoms
resembling a common viralgastroenteritis, but it may also
clinically present with features
indistinguishable fromappendicitis especially in
bacterial ileocecitis, caused by
Yersinia, Campylobacter, or
Salmonella.
Key finding: ileocecal wall
thickening without inflamedfat, adenopathy, normal
appendix
CT shows an inflamed cecal diverticulum (arrowhead) withregional colonic wall thickening.
Right-sided diverticulitis
Right-sided colonic
diverticulitis may clinicallymimic appendicitis or
cholecystitis, though thepatient's history is generally
more protracted.
In contrast to sigmoiddiverticula, right-sided colonic
diverticula are usually true
diverticula, that is,outpouchings of the colonic
wall containing all layers of
the wall.This may possibly explain the
essentially benign self-
limiting character of right-
sided diverticulitis.
-
8/2/2019 Acute Abdomen Poto
15/17
Enlarged adnex due to salpingitis
Salphingitis
Salphingitis is a commonmimicker of both of
appendicitis and diverticulitis.
Transvaginal sonography
depicts an inhomogeneousenlarged inflamed ovary.
CT characteristic of epiploic appendagitis with a right-sided fatty
mass surrounded by a hyperattenuating ring.
Epiploic appendagitis.
Epiploic appendages are small
adipose protrusions from the
serosal surface of the colon.
An epiploic appendage mayundergo torsion and secondary
inflammation causing focal
abdominal pain that simulatesappendicitis when located in
the right lower quadrant or
diverticulitis when located in
the left lower quadrant.The characteristic ring-sign
corresponds to inflamedvisceral peritoneal lining
surrounding an infarcted fatty
epiploic appendage.
Epiploic appendagitis has beenreported in approximately 1%
of patients clinically suspected
of having appendicitis.It is very important to make a
positive diagnosis of thischaracteristic entity sinceepiploic appendagitis is a self-
limiting disease.
Both US and CT will depict an
inflamed fatty mass adjacentto the colon.
-
8/2/2019 Acute Abdomen Poto
16/17
Left sided epiploic appendagitis in patient clinically suspected of
having a diverticulitis.
Characteristic hyperattenuating ring sign.
Key finding: inflamed fatty
mass adjacent to the colon
with characteristic ring sign.
Small stone in right ureter (arrow) causing right flank pain.
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 ureteral
inflammation from an adjacent
inflamed appendix.
Left retroperitoneal fluid collection due to ruptured aneurysm.
Ruptured Aneurysm
Most abdominal aortic
aneurysms rupture into the left
retroperitoneum (4).Clinically this may simulate
sigmoid diverticulitis or renal
colic due to impingement ofthe hematoma on adjacent
structures.
However most patient willpresent 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 ismuch less sensitive and
specific for the diagnosis ofaneurysmal rupture than CT.
The absence of sonographic
evidence of rupture does notrule out this entity if clinical
suspicion is high.
-
8/2/2019 Acute Abdomen Poto
17/17
Pancreas surrounded by fat stranding due to exsudative pancreatitis.
Pancreatitis
CT depicts fat-stranding(arrowheads) surrounding the
primary focus of the
inflammation: the pancreas.
Conclusion
In patients with an acuteabdomen 'the stakes are high'.
A misdiagnosis may have
serious consequences. Weadvocate a systematic
approach:
1. First focus on the most
common diseases and make afirm diagnosis or exclude
them.
2. Always screen the wholeabdomen for general signs of
pathology.
References
1. A prospective study of ultrasonography in the diagnosis of appendicitisJB Puylaert et al; NEJM Volume 317:666-669
2. Signs in Imaging, The Hyperattenuating Ring Sign
Adriaan C. van Breda Vriesman et al ; Radiology 2003;226:556-557
3. Frequency and Relevance of the 'Small-Bowel Feces' Sign on CT in Patients with Small-
Bowel Obstruction
Dawn E. Lazarus et al, AJR 2004; 183:1361-1366
4. Abdominal Aortic Aneurysm, Rupture in eMedicine
by Walter A Tan, MD, MS and Michel S Makaroun, MD
http://content.nejm.org/cgi/content/abstract/317/11/666http://radiology.rsnajnls.org/cgi/content/full/226/2/556http://www.ajronline.org/cgi/content/full/183/5/1361http://www.ajronline.org/cgi/content/full/183/5/1361http://www.emedicine.com/radio/topic2.htmhttp://content.nejm.org/cgi/content/abstract/317/11/666http://radiology.rsnajnls.org/cgi/content/full/226/2/556http://www.ajronline.org/cgi/content/full/183/5/1361http://www.ajronline.org/cgi/content/full/183/5/1361http://www.emedicine.com/radio/topic2.htm