Transcript
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A b h i s h e k V
# 1 2 8 V i j a y d o c t o r s
c o l o n y k o n a n a k u n t e
B a n g a l o r e 6 2
9 9 8 0 5 7 9 0 8 9
[ T y p e t h e f a x n u m b e r ]
A b h i s h e k V
Abhishek V
Never trust a radiologist.
Abdominal X ray
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Key to not miss any diagnosis is systematic approach
Checklist for systematic viewing of an AXR:
1.Technical assessment - (name, gender, age, date, view, side
labelling; exposure, rotation, field of view)
2. Diaphragms - free air, pleural effusion
3. Liver - size, shape
4. Spleen - size, shape
5. Kidney, Ureter, Bladder - size, shape, calcifications
6. Uterus in females, prostate in males - calcifications
7. Psoas muscle - clear outlining
8. Bowel gas pattern - normal or abnormal
9. Abnormal extraluminal gas - free air, biliary system, portal venous system, bowel wall
10. Bones - osteoarthritis, fractures, metastasis, Paget's disease
11. Extra-abdominal fat and soft tissue - gas or calcifications
12. Calcifications - normal or abnormal
13. Artefacts - iatrogenic, accidental, projectional
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2. Look at the diaphragms
Are they raised or flattened? Are the costophrenic angles clear? Is there any air/gas in the stomach? Is there any free intra-abdominal air? (better to be judged if erect or decubitus)
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Difference of more than 3 cm between two diaphragms significant.
Stomach gas or pneumoperitoneum?
Look at the thickness of left diaphragm normal diaphragm is 1-2mm when stomach wall
included thickness >3mm.
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Above x ray on left u can see pneumoperitoneum with diaphragm and stomach wall separate
thickness
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X ray showing hepatomegaly.
Chiliaditi sign
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Portal vessel gas: in mesentric ischemia and pneumatosis intestinalis.
Air in biliary tree: gall stone ileus. Pneumobilia is commonly seen after biliary instrumentation
but can be seen due to other causes such as Incompetent Sphincter of Oddi, Biliary enteric
surgical anastomosis, Spontaneous biliary enteric fistula (Cholecystoduodenal ~70%),
Infection(emphysematous cholecystitis), Bronchopleuralbiliary fistula (rare) and Congenital
anomalies.
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4. Look at the spleen
Is it enlarged? Is it shrunk? Has it been removed? Are there any calcifications?
The spleen is a soft tissue organ located in the left upper quadrant. The size is usually
comparable to the size of the patient's heart or fist and measures approximately three
vertebrae in length diameter. It may be difficult to delineate this soft tissue organ due to
overlying gas. In fact, mostly the spleen will not be visible at all. If splenic enlargement is
greater than 15 cm displacement of adjacent organs may be caused. Enlargement of the spleen
can be in medial but also in latero-inferior direction.
5. Look at the kidneys, ureter and baldder
Is there position normal? Are they enlarged or shrunk? Are there any calcifications? Is there a normal variant? (e.g. horseshoe kidney)
It may take some effort to detect the outline of the bean-shaped kidneys on a plain abdominal
film. Usually, due to overlying gas, they cannot be delineated in their entirety completely. Inrelation to the thoracic and lumbar spine, they extend from T12 on the left side down to L3 on
the right side. The left kidney is located slightly higher as compared to the right kidney. he left
kidney is also slightly bigger (approx. 1.5 cm longer) than the right kidney. The upper poles of
both kidneys are closer to the spine than their lower poles (approximately 12 degree angle
compared to the spine, supero-medially down to infero-laterally). The kidneys are relatively
mobile. They can move down with inspiration, and drop several centimetres in the erect
position.
If there is a full bladder it usually will be visible as a soft tissues density (water density equals
soft-tissue density radiographically), and will be outlined by the perivesical fat. In particular infemales a full bladder (up to 2 litres volume) may cause upwards displacement of the bowel
loops, and may render the differentiation to a real tumour mass difficult. Therefore, if possible,
the bladder should have been emptied before a plain abdominal film is taken.
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Renal calculi
6. Look for the uterus in female patients, and the prostate in male patients
Rarely, the uterus may be visible on a plain AXR. But there may be an intrauterine contraceptive
device (IUCD) or a calcified fibroid visible. If the uterus is visible it may be seen on top of the
bladder, possibly identing the bladder.
The prostate is deeply located in the pelvis. Usually the prostate becomes visible on a plain AXR
when calcified.
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Prostatic calculi
7. Look for the psoas muscle
Are the lateral borders of the iliopsas muscles sharply demarcated or are theyobscured?
The psoas muscle originates from the lumbar spine and extends downwards and inferolaterally
before finally inserting on the lesser trochanters of the femora.
Obscuration of the psoas muscle may allude to a pathological retroperitoneal process, e.g.
retroperitoneal fluids/ascites, retroperitoneal haemorrhage/haematoma, retroperitoneal
abscess, retroperitoneal tumour.
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NORMAL PSOAS SHADOW
Obliterated psoas shadow in retro peritoneal hematoma
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8. Look for the bowel gas pattern
Where are the bowel loops located (central vs. peripheral)? Is there too much intraluminal gas? What is the distribution of the gas in the abdomen? What is the intraluminal calibre of the small and large bowel? Are there any dilatations of the small and/or large bowel? Can you identify any air-fluid levels? Are there any areas of faecal loadingLook systematically at the whole gastrointestinal tact, starting with the stomach, via small
bowel, caecum, ascendingcolon, hepatic flexure, transverse colon, splenic flexure,
descending colon and sigmoid colon down to the rectum, provided that those are visble.
Note that any gas on a normal AXR will belong to a part of the gastrointestinal
tract. Remember that the transverse colon frequently drops down to the pelvis.
Remember the normal intraluminal gas pattern
Stomach - small amount of gas Small bowel - very little amount of gas Large bowel - usually some gas, very variable, from almost none to large amount of gas
9. Look for abnormal extraluminal gas
Free intra-abdominal air Under the diaphragm
- If extraluminal, consistent with free air on an erect or lateral decubitus view
- If intraluminal, consider Chilaiditi's syndrome, i.e. the interposition of the colon
between the right hemidiaphragm and the liver.
In the biliary tree- Normal after sphincterotomy or biliary surgery
- Otherwise pathological, e.g. due to fistula between the biliary tree and the intestine
In the portal venous system- Always pathological
Within the bowel wallRemember:
Gas in biliary tree is located more centrally projected on the liver as opposed to the more
peripheral location of the portal venous gas.
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10. Look at the bones
Check bones for general bone density, cortical outline, trabecular pattern, joint and discspace, osteolysis, fracture, sclerosis, epiphyseal lines.
Check for fractures, metastases (osteolytic, osteoplastic, absent pedicles)or degenerative changes in the lower rib cage, lumbar spine, sacrum, pelvis, ilio-sacral
joints, hip joints.
Check for Paget's disease Screen from superior to inferior.
The shape of the pelvis may allude to the patient's gender.
Loss of bone density may indicate osteopenia due to osteoporosis, osteomalacia and Rickets
(vitamin D deficiency) or hyperparathyroidism.
11. Look at the extra-abdominal fat and soft tissues/muscles
Is there any gas or calcification indicating e.g. subcutaneous emphysema, abscess,calcified injection sites, in particular in the area of the buttocks.
12. Check for calcifications in the following areas:
Cartilage of ribs Gallbladder Pancreas Kidneys , ureter and bladder Intra-abdominal arteries, predominantly the aortoiliac , mesenteric and renal arteries Pelvis (most commonly phleboliths ).
Normal calcifications
Costal cartilage Mesenteric lymph nodes:
- Usually they are oval shaped, granular opacities in the mesentery.
- They appear to be quite mobile and change position if you acquire several AXRs at
several points of time.
- Sometimes they may be confused with and need to be differentiated from renal or
ureteral calculi.
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Pelvic phleboliths ('Lithos' is Greek and means stone):- They usually appear as small round opacifications in the pelvis some of which can also
be more transparent centrally.
- They represent calcified pelvic veins.
- There can be one or several of those venous stones in the pelvis.
- There is no known clinical significane to them. However, they may be confused withureteric or bladder calcifications necessitating an intravenous urogram (IVU), also
referred to as KUB (Kidneys, Ureters and Bladder), or a computed tomography (CT) or
Magnetic Resonance (MR) urogram may be necessary to rule out ureteric or bladder
calculi.
Prostate gland:- Calcifications can occur in the prostate, in particular in the elderly.
- The calcifications are usually benign but may also accompany malignant processes in
the prostate.
Abnormal calcifications
Gallbladder:- Radiographically gallstones are visible in 10-20% of cases only. Ultrasound would be
superior to an AXR to rule out gallstones.
- A porcelain gallbladder may result from several episodes of cholecystitis that, in turn,
may become malignant (11%).
Pancreas:- Calcifications indicate chronic pancreatitis.
- The pancreas lies across the midline at the level of the vertebrae T9 to T12.
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Renal parenchymal tissue:- Calcifications indicate diseases such as medullary sponge kidney, renal tubular acidosis
and hyperparathyroidism.
Renal pelvic and ureteral system:- Single and multiple calcifications may be visible as well as staghorn calculi ; filling the
calices and renal pelvis and obstructing the ureter.- The most frequent locations for ureteral calculi are the pelvi-ureteric junction, brim of
the pelvis, and vesico-ureteric junctions.
Bladder:- Usually bladder calculi are quite large and multiple.
- Rarely, a bladder tumour may show calcifications too.
Blood vessels and vascular aneurysms (aortoiliac arteries (Fig. 10)):- Over the age of forty, usually some calcifications in the aorto-iliac arteries can be
seen. Premature calcifications can allude to underlying diseases such as diabetes or
chronic renal failure.
- Look over the lumbar spine for speckles of linear opacifications, sometimes running inparallel, resembling railway tracks.
- Aorta can be elongated and tortouous, bending to the right or to the left of the spine
(without evidence of an aneurysm).
Splenic artery :- Calcifications of the splenic artery may resemble a 'Chinese dragon' due to
the tortuous course of the splenic artery to the splenic hilum.
Mesenteric arteries Tumours:
- Uterine fibroid
- Ovarian teratoma
Vascular calcifications may allude to atherosclerotic lesions, frequently associated with the
metabolic syndrome (high blood pressure, diabetes, obesity, elevated serum triglycerids,
dyslipoproteinaemia), and overall morbidity.
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Pancreatic calcification
Staghorn calculi
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Aortoiliac calcification
13. Look for artefacts
Artefacts e.g. surgical clips, interuterine contraceptive device, renal or biliarystents, endoluminal aortic stent, or inferior vena cava filter.
Projectional , i.e. objects are projected into the abdomen but, in fact, lie in front of orbehind the abdomen, e.g. pyjama buttons, coins in pockets, body piercings.
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Now lets come to the main part surgeon stuff
The small bowel has a wall pattern
that is known as valvulae conniventes
(white arrow). The muscular bands
encircling the small bowel are usually
seen to traverse the bowel wall at
right angles to the long axis of thebowel
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The large bowel wall features pouches or
sacculation that protrude into the lumen
that are known as haustra(black arrow .In
between the haustra are spaces known
as plicae semilunaris- white arrow
(semilunaris refers to their semi-lunar
shape).
The abdominal cavity has a lining
of fat of variable thickness known
as the properitoneal fat. This isoften seen as a fat density stripe
along the lateral wall of the
abdomen on an AP abdominal
plain film(white arrow).
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Abdomen is gasless or featureless
A gasless abdominal plain film refers to an absence or minimum of gas in the gastrointestinal
tract.
A featureless abdominal plain film is one in which there is little or no visualisation of the normal
abdominal viscera.
The Gasless Abdominal Plain Film
Gas in the gastrointestinal tract can commonly accumulate from two sources. Firstly, gas in the
stomach and small bowel can be ingested with food. Some patients habitually air swallow or
may air-swallow when in pain. Gas in the large bowel can be endogenous, resulting from
fermentation processes of faecal material.
An absence of gastrointestinal gas on abdominal plain film is not specifically abnormal (but is
suspect). However, consideration should be given to the possibility of a gasless obstruction.
Equally, a check of the patient history may reveal relevant information such as total colectomy.
Causes
A gasless abdomen could indicate
Patient is not an air-swallower
Mesenteric ischaemia
Obstruction of the stomach or oesophagusPersistent vomiting from conditions such as pancreatitis or gastroenteritis
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This patient has a gasless rather than
featureless abdomen. Note that the rena
liver, psoas muscles and urinary bladder
outlines are visualized
This appearance is a gasless small
bowel obstruction and the opaque
looking small bowel loops (white
arrow) are filled with normal succus
entericus, and/or ingested fluid
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The normal abdominal viscera are not
demonstrated. Apart from the
prominent bowel, the abdomen is
featureless. The cause of this
appearance is a large quantity ofascites. Note that the liver, spleen,
kidneys, psoas and urinary bladder
outlines are not seen. The reason
that the bowel is somewhat centrally
located is that it isfloating in the
ascites.
This is more likely to be tumour than
blood or ascites
Bowel loops look more like they are
pushed down by tumour(s) rather
than floating in fluid
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Normal bowel characteristics
Characteristic Stomach Small Bowel Large Bowel
Position Left Upper QuadrantFundus directly under left
hemidiaphragm
obliquely orientated
attached to transverse
colon via gastro-colic
ligament (variable in
length)
Central abdomen circumferential- thelarge bowel tends
toframe the small
bowel
Contents fluid and air fluid-like succus
entericus and air
faeces of variable
consistency from liquid
to hard formedMucosal/Wall
Pattern
Rugal folds (can be
effaced if distended)
Can have a random
faceted/tessellated
appearance when air-
filled (but not dilated).
Encircling valvulae
Haustral folds
interspaced with Plicae
semilunaris
Wall pattern can be
effaced if distended
The supine abdominal plain film
demonstrates a featureless pattern.
There are no clearly defined psoas,
kidneys or spleen. A CT abdominal scan
revealed extensive laceration of his left
kidney and spleen.
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conniventes visible
depending on degree of
air filling/distention.
Valvulae conniventes
more widely spaced in
ileum
Wall pattern can be
effaced if distended
Size Variable Up to 30mm Up to 50-60mm
Up to 90mm for the
caecum
The stomach can be equally
characteristic in its appearance on an
erect abdominal plain film. The often
smoothly radiused contour of the air-
filled gastric fundus under the left
hemidiaphragm and the characteristic
air-fluid level make for easy
identification.
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The Small Bowel
Normal Gasless Small Bowel
Normal Air-filled Small Bowel
The appearance of the small bowel
visualised in the left iliac fossa is a result
of normal air swallowing (white arrow).
The bowel diameter has been measured
at 30mm which is the upper limit of
normal. This patient is likely to be in pain
and is therefore more likely to air-swallow
resulting in this appearance.
The appearance has been likened to crazy
paving or the pattern on a giraffe. It
appears as an interlocking, random,tessellated pattern.
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Moderately Dilated Air-filled Small Bowel
Severely Dilated Air-filled Small Bowel (Coiled Spring Sign)
The small bowel demonstrated in
this image is moderately dilated
(36mm). There is evidence of loss
of the normal random tessellatedpattern associated with undilated
air-filled small bowel. Instead,
the bowel is showing signs of a
pattern which is more organised
rather than random. There are,
for example, multiple loops of
small bowel which have become
aligned or parallel.
This appearance is typical of an
early small bowel obstruction ora partial small bowel obstruction.
The coiled spring appearance
only occurs in dilatedair-filled
small bowel. It also is most
noticeable in the jejunum wherethe valvulae conniventes are
tightly spaced.
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String-of-Pearls Sign
A similar appearance is sometimes seen in the large bowel but can usually be differentiated by
the fact that the gas bubbles are larger and have flat under-surfaces.
The curvi-linear arrangement of
air bubbles visualised on thisimage is known as the string of
pearls sign. The appearance is
considered to be diagnostic of
obstruction (as opposed to ileus)
and is caused by small bubbles
of air trapped in the valvulae of
the small bowel
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The Large Bowel
Haustral Pattern
The air-filled large bowel commonly features a haustral pattern as shown. The haustral folds
are thicker than the valvulae conniventes of the small bowel. They also commonly do not
appear to completely traverse the bowel. This distinction is unfortunately unreliable- air dilated
large bowel can have a haustral pattern that does traverse the bowel. Furthermore, in some
cases, the haustral pattern can be lost completely.
The large bowel will normally contain air. This is air produces partly from fermentation
processes within the large bowel. The transverse colon and sigmoid colon are the least
dependent segments of the large bowel in the supine position and will tend to fill with air.
Feces in large bowel..
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The Large Bowel String of Pearls Sign
The large bowel has its own version of the small bowel string of pearls sign. Because the plicae
semilunaris of the large bowel are larger than the valvulae of the small bowel, the pockets of air
tend to be larger. Also, because they are larger in the large bowel, surface tension is unable to
render them completely round- instead they tend to have a flat underside. They look more like
a string of air-fluid levels.
One of the functions of the large bowel is to absorb water from the faecal content. The faeces
should not be able to form an air/fluid level by the time it gets to the splenic flexure. An
extensive arrangement of these small air/fluid levels in the large bowel may simply indicate that
the patient has diarrhoea.
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The large bowel (white arrows) can
be seen to frame the abdomen.
The prominent air-filled ileum
(black arrow) occupies a more
central location within the
peritoneal cavity. These
distribution features can be helpful
in differentiating large bowel from
small bowel.
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Normal Variation of Large Bowel Distribution
Dilated Sigmoid Colon
This patient's transverse colon
(white arrow) dips low into the
pelvis. Note the characteristic
haustral pattern of the large bowel.
The dilated sigmoid colon isoften difficult to positively
identify. This patient has
dilated colon which is sited mid
to low abdomen. The
maximum diameter is 88mm.
Small bowel rarely dilates to
more than 50mm. The position,
size and ambiguous wall
pattern suggest that this is
dilated sigmoid colon.
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The Gastrocolic Ligament
The gastrocolic ligament is the
major apron-like part of the
greater omentum which
attaches the stomach to the
transverse colon. Unfortunately,
this ligament can vary in length
up to 15cm. Despite this
variable length, if you can
identify the greater curve of the
stomach, you can hazard a
reasonable approximation of
where the transverse colon
should be.
This patient has a dilated
stomach which has been treated
with a naso-gastric tube. The
transverse colon can be seen to
be following the greater curve
of the stomach.
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Generalised Adynamic Ileus
The appearance of generalised
adynamic ileus on plain film is
quite characteristic . The large and
small bowel are extensively
airfilled but not dilated. With air in
rectum.
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Reflex Ileus
Localised Ileus (Sentinel Sign)
Reflex ileus refers to a
secondary ileus in response to
some type of insult. The causes
of reflex ileus are numerous
including abdominal
inflammations and infections,
chemical and pharmacological
causes, trauma and abscess.
X ray shows reflex ileus secondary
to renal calculi
This patient has a segment ofinflamed transverse colon (white
arrow). The cause of the inflammation
is unknown but would be typical of
ulcerative colitis or Crohn's disease.
This appearance is known as
"thumbprinting".
Just inferior to the diseased segment
of colon are a few prominent air-filled
loops of jejunum. It is possible thatthis is localised ileus of the jejunum
associated with the diseased colon.
This is known as "sentinel sign".
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Plain Film Signs of PneumoperitoneumThe plain film signs of pneumoperitoneum are well established in the literature as follows
1 Anterior Subhepatic Space Air
2 Doges Cap Sign (free Air in Morrison's Pouch)3 Air Anterior to Ventral Surface of Liver
4 Riglers sign on supine AXR (also known as double-wallor bas-reliefsign)
5 Falciform Ligament Sign
6 The football sign
7 The cupola. Air accumulation beneath the central tendon of the diaphragm
8 Continuous diaphragm sign
9 The triangle- air trapped between three loops of bowel
10 Air under diaphragm on erect cxr
11 Air outlined against liver/flank on decub AXR
12 Other-
diaphragmatic muscle slips, ligamentum teres air, Double Gastric Fundus sign, The
Inverted-V sign, Scrotal air
13 Abscess Gas
14 Pneumoretroperitoneum
RUQ/liver signs on supine AXR
There are 3 separate signs of free air around the liver as follows.
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Pneumoperitoneum: Importance of Right Upper Quadrant Features
1. Anterior Subhepatic Space Free Air (RUQ sign 1)
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Pneumoperitoneum: Importance of Right Upper QuadrantFeatures
Anterior subhepatic space free air
tends to be vaguely linear in
shape (arrowed). A visible medial
border of the liver is often seen
outlined by fat. A careful
examination of this image (left)
shows the arrowed density to be
air density rather than fat
density.
The differentiation between fatand air density becomes easier
with experience. This image of
normal fat surrounding the liver
shows a consistent density
continuous with the
properitoneal fat stripe.
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2. Doges Cap Sign (RUQ sign 2)
Pneumoperitoneum: Importance of Right
Upper Quadrant Features
Doges Cap sign refers to free air in Morrison's
pouch. Morrison's pouch is normally a potential
space between the right kidney and the liver.
This is a particularly difficult sign of
pneumoperitoneum for several reasons. Firstly, it
may be the only sign of pneumoperitoneum and
may be very subtle. Secondly, it can be easily
misinterpreted as gas in the duodenum.
Gas in Morrison's pouch may have the following
features
Triangular in shape
concave medial border
positioned inferior to the right 11th rib
positioned superior to the right kidney
This sign is known asDoges Cap sign. The
Italian Doges wore this
distinctively shaped
cap. Gas in Morrison's
pouch is only loosely
shaped like a Doges cap
and should not be
taken too literally. Bear
in mind that the
"triangle Sign" was
already taken!
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Morrisons pouch free gas
demonstrated on supine
Radiographs typically show the
following Characteristics
1.Typically triangular shaped
2.The lower lateral corner is
commonly sharp
3.The lateral border is typically
concave and outlines the medial
border of the liver
4.It is positioned inferior to the
11thrib
5.It is positioned superior to the
right kidney
3. Air Anterior to Ventral Surface of Liver(RUQ sign 3)
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Air sitting against the
ventral surface of the liver
can be any shape and, as
in this case, is frequently
"geographical" in shape.
The liver is a homogenous
organ and should be
homogenous in density on
plain film. If the liver is
seen to demonstrate an
uneven density,
pneumoperitoneum
should be considered.
Note also Rigler's sign
4. Decubitus Abdomen Sign
This patient is inthe left lateral
decubitus position.
It is conventional
in radiography to
mark the side the
side that is up.
There is evidence
of free air between
the abdominal wall
and the liver
(white arrow).
There is also
evidence of free
fluid in the
peritoneum (black
arrow).
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5. Riglers Sign on supine AXR
Rigler's sign is named after Leo
G. Rigler. The sign refers to the
appearance of the bowel wall
on plain film when it is outlined
by intraluminal and
extraluminal air (arrowed). The
extraluminal air is free
peritoneal gas.
6. Falciform Ligament Sign
The falciform ligamentconnects the anterior
abdominal wall to the
liver. The ligament
continues to extend
inferiorly beyond the
liver where it becomes
the round ligament
(white arrow). Given
that the falciform
ligament is situated
against the anterior
abdominal wall, it is not
surprising that it
becomes outlined with
air in a supine patient
with free abdominal gas.
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7. The football sign
The football sign likens the massively air-
filled peritoneum to an American
football. To extend the simile a little
further, the falciform ligament has been
likened to the seam in the football, and
the rarely seen medial and lateral
umbilical ligaments are likened to the
football laces.
This neonatal patient has massive
pneumoperitoneum and could
reasonably be said to display footballsign. There is also falciform ligament
sign, Rigler's sign and air in the scrotum.
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8. Continuous Diaphragm Sign
Another
manifestation of
massive
pneumoperitoneum is
the continuous
diaphragm sign.
Where there is
sufficient air beneath
the diaphragm, the
continuous nature of
the diaphragm is
demonstrated. Note
that the left and right
hemidiaphragmscontrasted by the free
gas appear as a
continuous structure.
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9. Double Bubble Sign
The double bubble sign is an
appearance of
subdiaphragmatic gas under
the left hemidiaphragm inwhich there are two
collections of overlapping
gas- one of these collections
is subdiaphragmatic free gas
and the other is normal gas
within the fundus of the
stomach. Note that the
diaphragm (black arrow) is a
thinner walled structure than
the stomach wall (white
arrow). This distinction issometimes useful in
distinguishing between the
two structures.
Note also free
subdiaphragmatic gas under
the right hemidiaphragm
10. The Cupola Sign.The Cupola Sign refers to an air
accumulation beneath the
central tendon of the
diaphragm (white arrows)
The term cupola comes from a
dome such as this famous
dome of the Duomo in
Florence.
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11. Lesser Sac Gas
This image offree gas has
a cupola
sign (white
arrows) and a
lesser sac gas
sign (black
arrows). The
lesser sac is
positioned
posterior to thestomach and is
usually a
potential space.
There is free
connection
between the
lesser sac and the
greater sac
through
theforamen of
Winslow.
12. The Triangle Sign
The triangle sign refers to
small triangles of free gas
that can typically be
positioned between the
large bowel and the
flank(black arrow)
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12. The Others
Sign Notes
Leaping DolphinsSign
Air under hemidiaphragm and diaphragmatic muscle slips visible
Urachus Sign Air contrasted urachus. Appears as vertical line between bladder and
umbilicus. Outline of medial umbilical ligament
The Inverted V
Sign
" in infants the inverted V is undoubtedly caused by the large umbilical
arteries, in adults I believe it is the inferior epigastric vessels that produce
the inverted V sign.
Air in the Fissure
for the
LigamentumTeres
Air in the Fissure for the Ligamentum Teres. May appear in isolation.
Appears as a lucent vertical stripe over liver
Coronary
Ligament
Outlined by Air
The coronary ligament is sited anterior to the liver.
Pneumo-gall
bladder
Air in the gall bladder fossa outlining the gall bladder
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14. Pneumoretroperitoneum
This patient has free air in the
retroperitoneal space. The air
is seen surrounding the lateral
border of the right kidney
(white arrow). There is other
evidence of free gas including
Rigler's sign.
If you are not confident that
the appearance is
pneumoretroperitoneum, you
can try an erect and decubitus
view to see if the gas moves. If
the gas is seen to move, it'snot in the retroperitoneum.
It is useful to be able to distinguish between the appearance of air under the right hemi-
diaphragm, colonic interposition and pneumothorax.
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Leaping dolphin sign. Air under hemidiaphragm and diaphragmatic muscle slips visible
This paient has a pneumothorax. The right hemidiaphragm contrasted with air in the pleural
space resembles the liver contrasted with free air in the peritoneum
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This appearance of colonic interposition does bear some similarity to the appearance of
pneumoperitoneum.The white arrowed structure is probably a haustral marking and the black
arrowed structure is diaphragmatic
Always get a left lateral when in doubt
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The 3,6,9 Rule
The maximum diameter of the bowel is shown below
Maximum Normal Diameter
small bowel 30mm
large bowel 50-60mm
caecum 90mm
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Geometric Magnification Issues
Geometric Magnification of Small Bowel (exaggerated) The 3,6,9 rule isfor uncorrected measureme
nts. The error associatedwith an uncorrected
measurement is usually not
a problem. Where it can be
a problem is in morbidly
obese patients where the
small bowel is situated close
to the LBD/focal spot.
If you perform erect
abdominal images PA rather
than AP you may identifyingsmall bowel affected by
geometric enlargement
demonstrated on the
supine image
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Bowel obstruction
High-grade SBO. Plain abdominal radiograph shows multiple air-fluid levels (arrows), some witha width of more than 2.5 cm. In addition, there is a differential vertical height of more than 2
cm between corresponding air-fluid levels in the same bowel loop (circled area). There is also
distention of the small bowel diameter to more than 2.5 cm and a small bowelcolon diameter
ratio of greater than 0.5
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Slit/Stretch Sign
This patient has a small bowel obstruction. Apart from the solitary air-filled dilated central loop
of small bowel, there is also evidence of slit sign or stretch sign (white arrows).
Slit sign is a result of small amounts of air caught in the valvulae of fluid-filled bowel. The subtle
fluid filled loops of small bowel and the slit sign are highly suggestive of small bowel
obstruction. This appearance is deserving of an erect abdominal projection. This patient had
one of the best string of pearl signs you will ever see!
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Even a single dilated bowel loop > 10 cm is obstruction.
Dilated bowel with parallel patterning in obstruction
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Large bowel obstruction.
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Caecal and Sigmoid Volvulus
Caecal Volvulus Sigmoid Volvulus
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Caecal Volvulus
Uncommon
caecum is characteristically relocated to the
mid-abdomen or left upper quadrantaccompanying SBO is rare
characteristically, the walls are smooth and the
haustra are preserved
Persistent dilated distal colon is rarely seen
Sigmoid Volvulus
extends into the right upper abdomen to T10
or higher
The colon proximal to the twist distendsThe rectum usually empties
Gas distended sigmoid usually shows Coffee
bean sign in common with other closed loop
obstructions
At the point of the twist a barium enema
demonstrates a characteristic beak-like
termination
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Cecal volvulus
Sigmoid volvulus
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Plain Film Signs of Appendicitis
Sign Comment
Appendicolith Also known as coproliths, fecaliths and stercoliths
Appendicoliths are common
Can appear in various locations with variation in location of the appendix
Not all appendix stones are calcified
Gas in Appendix This is not necessarily a sign of appendicitis- can be seen in the normal
appendix
Abscess
RIF mass
There can be a general increase in opacity in the right lower quadrant
associated with an appendiceal abscess
Can also be seen as bubbles of gas in the abscessCaecal Ileus Seen as dilated caecum
Flank Sign Separation of the bowel from the right flank stripe by the lateral accumulation
of pus and ascites
SBO Reflex ileus
Scoliosis Scoliosis of lumbar spine
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Appendicolith
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Dilated caecum in appendicitis
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Localised small bowel ileus in appendicitis.
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