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Yr 3 - Skills & Extras > AXR Interpretation > Flashcards

AXR Interpretation Flashcards

1
Q

Give an overall structure of interpreting a CXR

A
  1. Confirm patient details
  2. Confirm date and time film was taken
  3. Request previous imaging for comparison (if necessary)
  4. Assess projection
  5. Assess exposure
  6. Bowel and other organs
  7. Bones
  8. Calcifications and artefact
  9. Presentation
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2
Q

Label the structures

A

Top left → liver edge

Bottom left → kidney

Top right → spleen

Middle right → stomach

Bottom right → psoas

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3
Q

Label the structures

A

Top → large bowel

Middle → small bowel

Bottom → bladder

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4
Q

What is the typical projection of an abdominal XR?

A
  • Anterior posterior (AP) supine → most common
  • Anterior posterior (AP) erect
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5
Q

Why do AXRs not provide a good view of posterior abdominal structures?

A

due to overlying bowel and gas

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6
Q

If bowel perforation is considered, which imaging would be useful?

A

An erect CXRT is more useful to see free gas under the diaphragm (patient needs to have sat upright for at least 15-20 minutes prior to XR to allow time for air to rise).

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7
Q

Where does the small bowel lie in relation to the large bowel on an AXR?

A

Small bowel usually lies more centrally, with the large bowel framing it

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8
Q

What are the mucosal folds of the small bowel called?

A

Valvulae conniventes

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9
Q

What are valvulae conniventes also known as?

A

Plicae circulares

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10
Q

Do the valvulae conniventes of the small bowel appear to cross the full width of the lumen on an AXR?

A

Yes

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11
Q

Which parts of the large bowel are retroperioneal?

A

Ascending colon, descending colon, and rectum

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12
Q

If visible, which is the widest segment of the colon?

A

Caecum → 9cm

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13
Q

The longitudinal muscles (taenia coli) and circular muscles of the colon form sacculations/pouches called what?

A

Haustra

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14
Q

What are found in between the haustra?

A

Plicae semilunaris

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15
Q

Are haustra thicker or thinner than the valvulae conniventes of the small bowel?

A

Thicker

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16
Q

Do the haustra completely traverse the large bowel

A

No

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17
Q

Are faeces typically seen in the small or large bowel?

A

Large bowel

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18
Q

Give the appearance of faeces on an AXR

A

Faeces have a mottled appearance due to trapped gas in colon.

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19
Q

What are the upper limits for the normal diameter of different bowel segments on an AXR?

A

3/6/9 rule

  • Small bowel → 3cm
  • Colon → 6cm
  • Caecum → 9cm
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20
Q

What would a small bowel dilatation (>3cm diameter) indicate?

A

Small bowel obstruction

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21
Q

Give some AXR features of a SBO

A
  • Dilation of small bowel (>3cm diameter)
  • Much more prominent valvulae conniventes – create a ‘coiled-spring’appearance
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22
Q

What is the most common cause of SBO in the developed world?

A

Adhesions (75%)

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23
Q

Give some other causes of SBO

A
  • Adhesions (75%)
  • Abdominal hernias (10%)
  • Intrinsic or extrinsic compression by neoplastic masses
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24
Q

When interpreting an AXR, which region should you always inspect if considering a hernia as a cause of SBO?

A

Inguinal region

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25
Q

Give 2 major causes of large bowel obstruction (LBO)

A
  • Colorectal carcinoma
  • Diverticular strictures
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26
Q

Give 2 minor causes of LBO

A
  1. Hernias
  2. Volvulus
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27
Q

What is volvulus?

A

Twisting of the bowel on its mesentery → Results in partial or complete obstruction

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28
Q

Where does volvulus usually occur in the colon?

A

Sigmoid colon or the caecum

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29
Q

What are potential complications of volvulus of the colon?

A

Patients at high risk of bowel perforation (? sepsis) and/or bowel ischaemia 2ary to vascular compromise

30
Q

What is ileus?

A

Ileus is a temporary lack of the normal muscle contractions of the intestines e.g. certain drugs.

This can lead to a build-up and potential blockage of food material.

31
Q

What is the characteristic feature of sigmoid volvulus?

A

Coffee bean appearance

32
Q

SBO vs paralytic ileus

A
33
Q

Is sigmoid or caecal volvulus more common?

A

Sigmoid - accounts for up to 80% of all intestinal obstructions

34
Q

Who is volvulus more common in?

A

Most common in elderly persons (often neurologically impaired)

35
Q

What is typically seen in the PMH of a patient with sigmoid volvulus?

A

Chronic constipation

36
Q

Treatment of sigmoid volvulus?

A
  • Decompression with rectal flatus tube or sigmoidoscope if no signs of bowel ischaemia or perforation
  • Laparoscopic derotation or laparotomy +/- bowel resection
  • Caecopexy suture fixation of bowel to peritoneum may prevent recurrence
37
Q

Sigmoid volvulus XR:

A
38
Q

Caecal volvulus XR:

A
39
Q

is extra-luminal gas ever normal?

A

no

40
Q

In healthy individuals, which wall of the bowel should be visible on a AXR?

A

Inner wall only

41
Q

What is Rigler’s sign? What does it indicate?

A

The presence of free air within the abdomen (pneumoperitoneum) can result in both sides of the bowel wall becoming visible (this is known as Rigler’s sign) → gas outlines bowel.

42
Q

Give 2 major causes of a pnuemoperitoneum

A
  1. Perforated abdominal viscus
  2. Recent abdominal surgery
43
Q

What can cause a perforation of an abdominal viscus?

A
  • Diverticular disease with rupture of diverticulum
  • Perforated gastric or duodenal ulcer
  • Trauma
  • Obstruction
  • IBD with ruptured bowel
44
Q

What does the ‘football’ sign indicate?

A

The football sign is seen in cases of massive pneumoperitoneum, where the abdominal cavity is outlined by gas from a perforated viscus.

The abdomen appears as a large oval radiolucency reminiscent of an American football

45
Q

What is Chilaiditi’s Sign?

A

Interposition of the bowel, usually colon, between the inferior surface of the right diaphragm and the superior surface of the liver

46
Q

What is Chilaiditi’s sign often misdiagnosed as?

A

Often misdiagnosed as a true pneumoperitoneum resulting in unnecessary investigations/treatment

47
Q

What is Chilaiditi’s syndrome?

A

Chilaiditi syndrome is a rare condition when pain occurs due to transposition of a loop of large intestine (usually transverse colon) in between the diaphragm and the liver, visible on an AXR. Normally this causes no symptoms, and this is called Chilaiditi’s sign.

48
Q

Give 3 potential AXR features seen in IBD

A
  1. Thumbprinting
  2. Leadpipe colon
  3. Toxic megacolon
49
Q

What is ‘thumbprinting’?

A

Mucosal thickening of the haustra due to inflammation and oedema causing them to appear like thumbprints projecting into the lumen

50
Q

What is a ‘leadpipe colon’?

A

loss of normal haustral markings 2ary to chronic colitis

51
Q

What is toxic megacolon?

A

It is defined as a non-obstructive dilation of the colon, which can be total or segmental and is usually associated with systemic toxicity.

52
Q

What is the main cause of toxic megacolon?

A

IBD

53
Q

Complications of toxic megacolon?

A

Perforation, sepsis, death

54
Q

Give some examples of soft tissue structures visible on an AXR

A
  • Lung bases
  • Liver
  • Gallbladder
  • Stomach
  • Psoas muscles
  • Kidneys
  • Spleen
  • Bladder
55
Q

Why should you ensure to inspect the lung bases in an AXR?

A

as abdominal pain can sometimes be caused by basal pneumonia → check for consolidation

56
Q

Where is the liver seen in an AXR?

A

RUQ

57
Q

Is the gallbladder normally visible on an AXR?

A

rarely visible on AXR but quickly inspect for calcified gallstones and cholecystectomy clips

58
Q

Where is the stomach usually visible on an AXR?

A

Between the LUQ and midline

59
Q

Where are the psoas muscles typically visible?

A

lateral edge is marked by a relatively straight line either side of the lumbar vertebrae and sacrum

60
Q

Which kidney is lower on an AXR?

A

Right due to presence of liver

61
Q

Where is the spleen located?

A

located in LUQ, superior to left kidney

62
Q

Which bones are visible on an AXR?

A
  • Ribs
  • Lumbar vertebrae
  • Sacrum
  • Coccyx
  • Pelvis
  • Proximal femurs
63
Q

What structure can be used to locate the vesicoureteric junction on an AXR?

A

ischial spines (asterisks & arrows at bottom)

64
Q

What are the 2 causes of added densities on an AXR?

A
  1. Calcified soft tissue
  2. Artefacts e.g. medical device
65
Q

Give some examples of structures that can calcify in an AXR

A
  • Calcified gallstones in RUQ
  • Renal stones/staghorn calculi
  • Pancreatic calcification
  • Vascular calcification
  • Costochondral calcification
66
Q

What % of renal calculi are idiopathic?

A

90%

67
Q

give some other causes of renal calculi

A
  • Hyperparathyroidism
  • Vitamin D excess
  • Primary hyperoxaluria
68
Q

What are staghorn calculi?

A

complex renal stones that occupy the majority of the renal collecting system

69
Q

Complications of staghorn calculi?

A
  • High morbidity
  • Can lead to recurrent UTIs, urosepsis, renal deterioration and death if left untreated
70
Q

What % of gallstones are visible on an AXR?

A

Only 10% of gallstones contain enough calcium to be visible on AXR

71
Q

Gold standard imaging for gallstones?

A

US

72
Q

What is the calcification of arteries seen on xrays a sign of?

A

more generalised atherosclerosis:

  • Diabetes
  • Chronic renal failure

Yr 3 - Skills & Extras (7 decks)

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