Dr Doha Rasheedy

Doha Rasheedy

X ray abdomen

Systematically review:

1. Bowel gas

2. Soft tissues

3. Bones and abnormal calcification

https://www.youtube.com/watch?v=SWd7onzmAPo

1. Bowel gas:

Normal stomach

If the stomach contains air it may be

visible in the left upper quadrant of

the abdomen. The lowest part of

the stomach crosses the midline.

Small bowel (duodenum to terminalileum)

Generally the small bowel lies centrallywithin the abdomen. The valvulaeconniventes (also called plicaecirculares) are thin, circular, folds ofmucosa, some of which arecircumferential and are seen on an X-ray to pass across the full width of thelumen.

Normal <3cm

Dr Doha Rasheedy

Doha Rasheedy

If perforation of the bowel is suspected then an ERECT chest X-ray must be requested. This is the most

sensitive plain radiographic study to detect the presence of free gas in the abdomen.

Normal large bowel

Peripheral position in the

abdomen (the transverse and

sigmoid colon occupy very

variable positions)

Haustra (arrowheads)

Contains faeces

Dr Doha Rasheedy

Doha Rasheedy

air/gas under the diaphragm - erect chest X-ray

This patient has a large volume of free gas under the diaphragm. Dark crescents have formed

separating the thin diaphragm from the liver on the right, and bowel on the left.

This patient had a perforated duodenal ulcer

Rigler's/double wall sign - diagram

Normally only the inner wall of the bowel is visible

If there is pneumoperitoneum both sides of the bowel wall may be visible

Dr Doha Rasheedy

Doha Rasheedy

The double wall sign (Rigler's sign) is visible

Gas separates bowel segments and forms sharp angles and triangles (asterisks)

football sign - example

2 radiographs were required to completely cover the abdomen in this large patient

A large volume of free gas has risen to the front of the peritoneal cavity resulting in a large round black

area - 'football sign'

The double wall sign (Rigler's) is also visible (arrowhead)

Dr Doha Rasheedy

Doha Rasheedy

Perforation:Erect:Free air under diaphragmRigler’s signFootball signSupineFalciform ligament signRigler’s sign

Falciform ligament sign: Silver's sign is a sign seen with a pneumoperitoneum. It is almost never seen in

isolation. If there is enough free air to outline the falciform ligament, there is usually enough air to also

provide at least a Rigler's sign.

Falciform Ligament Sign (Free Air). White

arrows point to falciform ligament, made visible

by a large amount of free air in the peritoneal

cavity. The green arrow demonstrate both sides

of the wall of the bowel wall (Rigler's sign), a

sign of free air. The red arrow points to

increased lucency over the liver from a large

amount of free air.

Falciform Ligament Sign (Free Air). White

arrows point to falciform ligament, made visible

by a large amount of free air in the peritoneal

cavity. The green arrow demonstrate both sides

of the wall of the bowel wall (Rigler's sign), a

sign of free air. The red arrow points to

increased lucency over the liver from a large

amount of free air.

Dr Doha Rasheedy

Doha Rasheedy

Normal stomach bubble - erect chest X-rayRound/ovoid - 'bubble' shape Thick upper wall Fluid level or food contentsIn contrast to this, free intra-abdominal gas forms a crescent under the diaphragm, and is separatedfrom the lungs only by the thin membrane of the diaphragm

Chilaiditi's phenomenon

In patients who have small livers (cirrhosis),

or flattened diaphragms due to lung

hyperexpansion (emphysema), a void is

created within the upper abdomen above the

liver. This space may be filled by bowel. If this

bowel is air filled then it may mimic free gas

Chilaiditi's phenomenon - example

Gas forms a near crescent shape under theright hemidiaphragm

There is however a thick hemidiaphragm(partly consisting of bowel wall)

Gas can be seen to lie within bowel

Importantly, this patient withhyperexpanded lungs, due to emphysema,did not have acute abdominal pain

Dr Doha Rasheedy

Doha Rasheedy

False Rigler's/double wall sign

Gas seen on both sides of the bowel wall is contained within adjacent bowel

There are no black triangles or sharp angles on the outside of the bowel wall

False football sign - example1 - Perirenal fat (retroperitoneal)2 - Peritoneal fat (next to the liver)3 - Abdominal wall fat (separating muscles of the abdominal wall)

Dr Doha Rasheedy

Doha Rasheedy

Small bowel obstruction – features>3cm, multiple air fluid levels>2, some in the same loop at differe thights

Centrally located multiple dilated loops of gas filled bowel (arrowheads)Valvulae conniventes (arrow) are visible - confirming this is small bowelEvidence of previous surgery - note the anastomosis site (red ring) - this suggests adhesions is thelikely cause of obstruction (confirmed at surgery)

Post operative ileusAppearances are similar to those of mechanical obstructionThere are multiple loops of gas filled bowel projected centrally over the abdomenThis patient had prolonged non-colicky abdominal pain following a Caesarian section - recovery wasspontaneous

Dr Doha Rasheedy

Doha Rasheedy

Small bowel obstruction – features>3cm, multiple air fluid levels>2, some in the same loop at different hights

Features of small bowel obstruction include the central position of gas-filled and distended loops of

bowel.

The white lines passing across the full width of the bowel are 'valvulae conniventes' - these are only

found in the small bowel.

Dr Doha Rasheedy

Doha Rasheedy

Air–fluid levels on erect AXR—

associated with obstruction, ileus, ischaemia and gastroenteritis.

erect supine

Dr Doha Rasheedy

Doha Rasheedy

sentinel loopIntra-abdominal inflammation, such as with pancreatitis, can lead to a localized ileus. This may appear as asingle loop of dilated bowel known as a 'sentinel loop

Large bowel obstruction: Dilatation of the caecum >9cm, and >6cm for the rest of the colon is consideredabnormal.Large bowel obstruction

Here the colon is dilated down to the level of the distal descending colon. There is the impression of

soft tissue density at the level of obstruction (X). No gas is seen within the sigmoid colon.

Obstruction is not absolute in this patient as a small volume of gas has reached the rectum (arrow).

An obstructing colon carcinoma was confirmed on CT and at surgery.

Dr Doha Rasheedy

Doha Rasheedy

Volvulus is a specific cause of obstruction with characteristic X-ray appearances

The two commonest types of bowel twisting are sigmoid volvulus and caecal volvulus.Sigmoid volvulus - 'coffee bean' sign

The sigmoid colon is very dilated because it is twisted at the root of its mesentery in the left iliacfossa (LIF). The proximal large bowel is also dilated (asterisks).

The twisted loop of sigmoid colon is said to resemble a coffee bean. As in this case the loop ofdilated sigmoid colon - or 'coffee bean' - usually points upwards towards the diaphragm.

This patient is at high risk of perforation and/or bowel ischaemia

Caecal volvulus: The massively dilated caecum no longer lies in the right iliac fossa (RIF). Rather this is occupied by small bowel (red

outline). The small bowel is identified by the valvulae conniventes - mucosal folds that cross the full width of the bowel

(arrowheads). Caecal volvulus was confirmed at laparotomy

Dr Doha Rasheedy

Doha Rasheedy

Sigmoid volvulus: Coffee bean sign in RLQ

Dr Doha Rasheedy

Doha Rasheedy

Bowel wall inflammation

Abdominal X-rays sometimes demonstrate signs of bowel inflammation such as mucosal thickening'thumb-printing' or a featureless colon 'lead pipe' colon.

Dr Doha Rasheedy

Doha Rasheedy

Toxic megacolon

The colon is very dilated in this patient with acute abdominal pain, sepsis, and a known history of ulcerative

colitis. The clinical features and X-ray appearances are consistent with toxic megacolon.

There is evidence of bowel wall oedema with 'thumbprinting', and pseudopolyps or 'mucosal islands' (red-

patches).

Dr Doha Rasheedy

Doha Rasheedy

The transverse colon is dilated and shows evidence of thumbprinting (black arrow)

The descending colon has a thickened featureless wall and possible pockets of intra-mural gas (white arrow). It is not

clear whether this appearance is due to intra-mural gas, or properitoneal fat interposed between the descending colon

and abdominal wall.

Patient has known Crohn's disease

Appearances are consistent with toxic megacolon

Intra-mural gas refers to abnormal gas in the wall of hollow abdominal viscus. Intra-mural gas is one of the most

serious findings on abdominal plain film requiring timely surgical intervention in adults. Linear streaks of intra-mural

gas indicate infarction of the bowel wall

Dr Doha Rasheedy

Doha Rasheedy

Other aberrant air:

Pneumobilia: Pneumobilia is typically seen as linear branching gas within the liver most prominent in

central large calibre ducts as the flow of bile pushes gas toward the hilum. This is in contrast to portal

venous gas where peripheral small calibre branching gas is usually seen due to the hepatopetal flow of

blood away from the hilum.

Causes

recent biliary instrumentation

o ERCP

o percutaneous or intraoperative cholangiography (small amount of gas only)

incompetent sphincter of Oddi

o sphincterotomy (~50% pneumobilia at 1 year)

o following passage of a gallstone

o scarring e.g. chronic pancreatitis

o drugs e.g. atropine

o congenital

biliary-enteric surgical anastomosis

o cholecystoenterostomy

o choledochoduodenostomy (with or without bile sump syndrome 2)

o Whipple procedure

spontaneous biliary-enteric fistula (cholecystoduodenal accounts for ~70% 3)

o gallstone ileus

o peptic ulcer disease

o traumatic

o neoplasm, eg. cholangiocarcinoma, ampullary cancer

infection (rare)

o cholangitis

Dr Doha Rasheedy

Doha Rasheedy

o emphysematous cholecystitis (usually gallbladder gas only, ~20% will have gas in the

biliary tree also)

o liver abscess (if contains gas and communicates with the biliary tree)

biliary-bronchopleural fistula (rare)

Supine radiographs often

demonstrate a sword-shaped

lucency in the right paraspinal

region representing gas from the

common duct and the left hepatic

duct. This has been termed the

sabre sign and is present in ~50% of

patients with pneumobilia

Dr Doha Rasheedy

Doha Rasheedy

Portal venous gas: is the accumulation of gas in the portal vein and its branches. It needs to be

distinguished from pneumobilia, although this is usually not too problematic, when associated findings

are taken into account along with the pattern of gas (i.e. peripheral in portal venous gas, central in

pneumobilia).

Causes:

alterations of bowel wall

o ischaemic bowel (usually mural gas as well as mesenteric gas: mortality of 75-90%, but

gas is not an independent predictor)

o necrotic/ulcerated colorectal carcinoma (CRC)

o inflammatory bowel disease (IBD)

o perforated peptic ulcer

bowel luminal distention

o iatrogenic gastric and bowel dilatation (e.g. upper and lower endoscopic procedures,

enemas)

o paralytic ileus / mechanical bowel obstruction

o acute gastric dilatation

o barotrauma

intra-abdominal sepsis

o diverticulitis

o pelvic abscess

o cholecystitis/cholangitis

o appendicitis

unknown mechanism

o pneumatosis intestinalis

o chronic obstructive pulmonary disease (COPD)

o corticosteroid usage

Dr Doha Rasheedy

Doha Rasheedy

Gas forming infection in soft tissue

Air filled urinary bladder Wall: emphysematous cystitis!

An abdominal x-ray revealed gas surrounding the urine

bladder, shows curvilinear or mottled areas of increased

radiolucency in the region of the urinary bladder, separate

from more posterior rectal gas. Intraluminal gas will be seen as

an air-fluid level that changes with patient position, and, when

adjacent to the nondependent mucosal surface, may have a

cobblestone or “beaded necklace” appearance. This is thought

to reflect the irregular thickening produced by submucosal

blebs as seen at direct cystoscopy.

Dr Doha Rasheedy

Doha Rasheedy

Some times gas take nonspecific pattern and location:

Dr Doha Rasheedy

Doha Rasheedy

Soft tissues:

Abdominal X-rays provide a limited means of assessment of soft tissue structures,

Soft tissue organs visible on abdominal X-rays include the liver, spleen, kidneys, psoas muscles,

bladder (within pelvis), and lung bases (within thorax)

Liver on abdominal X-ray

The liver lies in the right upper quadrant

(RUQ) and is seen as a bland area of grey on

an abdominal X-ray.

The superior edge of the liver forms the right

hemi-diaphragm contour (arrowhead).

In this patient the breast shadow (red line)

overlies the liver, and markings of the right

lung are visible behind the liver.

The gallbladder is only rarely visible on an

abdominal X-ray. Its position is very variable.

This patient has had a cholecystectomy. The

clips mark the previous location of the

gallbladder.

Lung bases on abdominal X-ray

The lung bases, which pass behind the liver

and diaphragm in the posterior sulcus of

the thorax, may be visible on some

abdominal X-rays.

It is worth checking the lung bases as some

patients with lung pathology present with

abdominal symptoms.

If there is consolidation suspected from the

abdominal X-ray then a review of the

patient's respiratory system is necessary.

Dr Doha Rasheedy

Doha Rasheedy

Psoas edges on abdominal X-ray

The psoas muscles (red) arise from the transverse processes of the lumbar vertebrae (arrowheads) and

combine with the iliacus muscles. Together these powerful muscles form the iliopsoas tendon, which

attaches to the lesser trochanter of the femur (asterisk). The iliopsoas muscles are the flexors of the hip.

An abdominal X-ray often demonstrates the lateral edge of the psoas muscles as a near straight line. The

iliacus muscles are not visible, as they lie over the iliac bones of the pelvis.

Kidneys on abdominal X-ray

Natural contrast between the kidneys and the low density retroperitoneal fat that surrounds them means they are often visible on an X-

ray of the abdomen.They lie at the level of T12-L3 and lateral to the psoas muscles. The right kidney is usually slightly lower than the left

due to the position of the liver.

Dr Doha Rasheedy

Doha Rasheedy

Abnormal soft tissues

Spleen on abdominal X-ray: The spleen lies in the left upper quadrant immediately superior to the left

kidney

Bladder abdominal X-ray

The bladder has variable appearance

depending on how full it is. It has the

same density as other soft tissue

structures, due to its water content.

Dr Doha Rasheedy

Doha Rasheedy

HepatomegalyThere is diffuse soft tissue density shadowing in the right upper quadrant due to hepatomegaly (liverenlargement)The enlarged liver has displaced the normal bowel downwards and to the left (arrows)The spleen is also mildly enlarged

Massive splenomegalyThis patient with a myeloproliferative disorder has both hepatomegaly and massive splenomegalyThere is generalised increase in soft tissue density but the bowel appears pushed away by the edge ofthe spleen

Dr Doha Rasheedy

Doha Rasheedy

Enlarged kidneysBoth kidneys are very enlargedThe bowel is not displaced because the kidneys are retroperitoneal structuresThis patient had a family history of polycystic kidneysThis diagnosis was confirmed with ultrasound

AscitesFree fluid and solid organs have similar densitiesIn the presence of ascites gas within bowel is located centrally

Dr Doha Rasheedy

Doha Rasheedy

Pelvic masses can displace bowel upwards

Dr Doha Rasheedy

Doha Rasheedy

Bones:

1.

2.

3.

4.

The lower ribs, lumbar vertebrae and sacrum are highlighted.

Bones can be used as landmarks for invisible soft tissue structures. Note the transverse

processes of the lumbar vertebrae act as landmarks for the course of the ureters (arrowheads).

The vesico-ureteric junctions (asterisks) are located at the level of the ischial spines (arrows)

.

The sacrum, coccyx, pelvic bones and proximal femora are highlighted. The sacro-iliac joint is

formed by the overlapping of the sacrum and iliac bones of the pelvis.

Dr Doha Rasheedy

Doha Rasheedy

4. Calcification and artifact

Ideally all jewellery that overlies anatomically important structures should be removed prior to acquiring

an X-ray

Vascular calcification and ring pessary

If seen, vascular (aorto-iliac) calcification implies a more generalised atherosclerosis.

Note the ring pessary in this elderly patient.

Dr Doha Rasheedy

Doha Rasheedy

Calcified structures

There are multiple incidental and asymptomatic calcified structures seen on this X-ray. The

patient is recovering from an appendicectomy (note surgical clips).

Gallstones are seen only if calcified (20% are calcified). Although they may cause symptoms they

are usually asymptomatic. If gallstone disease is suspected ultrasound examination is a more

appropriate investigation.

Costochondral calcification, calcified mesenteric lymph nodes, and phleboliths (calcified pelvic

veins) are rarely clinically significant. Occasionally additional investigations are required to

differentiate them from pathological calcium. For example phleboliths may be mistaken for

ureteric calculi. Other investigations such as intravenous urogram (IVU) or CT-KUB (CT Kidneys-

Ureters_bladder) should only be performed if there are typical clinical features of ureteric

calculi.

Dr Doha Rasheedy

Doha Rasheedy

Residual contrast

The large areas of very high density seen in the descending colon and rectum are caused by

residual contrast material in this patient who had a Barium enema 10 days previously.

Also note costochondral calcification, and phleboliths.

Do not mistake the tips of the transverse processes for ureteric calculi.

Dr Doha Rasheedy

Doha Rasheedy

Pelvic fracture and osteoarthritis

This elderly patient presented with abdominal pain with no clear history of traumaTenderness in the suprapubic regions was thought to be due to intra-abdominal pathologyThe pubic ramus fractures was the cause of symptomsNote the osteoarthritic appearances of the hips and lumbar spine

Bone metastases

There are numerous sclerotic

densities (white) of the vertebrae,

sacrum, pelvis and proximal

femora

This patient had a known history of

breast cancer

Dr Doha Rasheedy

Doha Rasheedy

Paget's disease

This patient has Paget's disease

which affects his lumbar spine

and right hemipelvis

This was an incidental finding

when looking for a cause of

abdominal pain

The typical features of Paget's are

bone expansion and coarsening of

the trabecular pattern involving

the whole of the bone(s) affected

Dr Doha Rasheedy

Doha Rasheedy

Ureteric stone/calculus

Look carefully for ureteric stoneswhich can be very subtle

Don't mistake a transverseprocess for a stone

Bladder stones

Multiple well defined calcific densities are

seen within the bladder

Gallstones and mesenteric lymph node

Gallstones have a variable positiondepending on the position of thegallbladder and may be mistaken for renalstones

Unlike renal stones they are often roundedand cluster together

This X-ray also shows an incidentalcalcified mesenteric node which may alsomimic renal stones

Dr Doha Rasheedy

Doha Rasheedy

Abdominal aortic aneurysm -

AAA

There is calcification of

the dilated aortic wall

Frequently only one

side of the aneurysm

is visible - as in this

image - the other

being projected over

the spine

Vascular

calcification

There is striking

calcification of the

aorta and iliac

vessels

This is a sign of

generalised

atherosclerosis

elsewhere in the

body

Appendicoliths are highly predictive of

appendicitis in patients presenting with

right iliac fossa pain

Dr Doha Rasheedy

Doha Rasheedy

Retroperitoneal calcification (pancreatic- adrenal):

Dr Doha Rasheedy

Doha Rasheedy

Naso-jejunal tubePlaced for the purpose of enteral feedingThe tube passes through the stomach and forms a C-shape as it navigates the 4 parts of theduodenum (D1-4)The tube tip lies beyond the duodenojejunal flexure which lies on the left

Pig-tail (JJ) stentA ureteric stent has been placed to relieve ureteric obstructionThe catheter has loops (pig-tails) at both ends which hold it in place

Dr Doha Rasheedy

Doha Rasheedy

Colonic stentLarge bowel obstruction can be treated with placement of a metallic colonic stentThis is often used as a temporary measure allowing a patient to recover from the effects ofobstruction prior to definitive colonic resection

Inferior vena cava (IVC) filterAn IVC filter may be used to reduce the risk of large pulmonary emboliMost commonly used in patients who have had pulmonary embolism but for whom anticoagulation is contraindicatedIVC filters are self-expanding wire structures shaped like an umbrellaSmall clots may pass between the wires of the filter but large clots are prevented from reaching the pulmonary arteries

Dr Doha Rasheedy

Doha Rasheedy

Foreign body - ingested

This psychiatric patient has ingested numerous radio-opaque objectsThe navel jewellery is external!

Dr Doha Rasheedy

Doha Rasheedy

Air under Diaphragm

Plain film of the chest X-ray (A) and simple abdomen (B). After colon perforation, free air under the both

diaphragm were noted.

Dr Doha Rasheedy

Doha Rasheedy

free air under the patient’s diaphragm (pneumoperitoneum

Dr Doha Rasheedy

Doha Rasheedy

Thumb printing (bowel wall inflammation)

Findings: Mild to moderate bowel edematous walls of the tranverse colon.

Diagnosis: Crohn's Disease

Discussion:

Thumbprinting of Bowel DDx:

Inflammatory Bowel Disease - most common. i.e. Crohn's and Ulcerative Colitis

Diverticulosis or Diverticulitis

Ischemic Colitis with hemorrhage into bowel wall

Other Uncommon causes include:

Amyloidosis

Carcinoid

Angineurotic Edema

CMV colitis in AIDS

Endometriosis

HUS

Lymphoma

Parasitic Infections esp Amebiasis, Strongyloides, Schistosomiasis

Pseudomembranous Colitis

Toxic Megacolon

Typhlitis

Urticaria "colon hives"

Dr Doha Rasheedy

Doha Rasheedy

Dr Doha Rasheedy

Doha Rasheedy

Thumbprinting

(red arrows) of

ascending and

transverse colon

and featureless

bowel wall

(yellow arrow) at

the left transverse

colon extending

into splenic

flexure, consistent

with wall

thickening.

Dr Doha Rasheedy

Doha Rasheedy

The normal diameter of the intestines on an AXR do not usually exceed:

3 cm for small bowel

6 cm for colon (large bowel)

9 cm for caecum

Arrows: bowel

wall thickening

Arrow heads:

thumb printing

Dr Doha Rasheedy

Doha Rasheedy

Small bowel obstruction

Small bowel obstruction can be visualised

on an AXR as dilatation of the small

bowel (>3cm). The valvulae conniventes

are much more visible and have what is

referred to as a “coiled spring

appearance”.

Dr Doha Rasheedy

Doha Rasheedy