imaging of acute abdomen Flashcards by Amy Hollis

what imaging is used for bowel obstruction?

supine AXR

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what imagine is used for assessing a hollow viscus perforation?

erect CXR

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pros of xray

-widely available
-quick
-well tolerated
-inexpensive

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cons of xray

-overall sensitivity low
-rarely changes management
-ionising radiation

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USS pros

-easy
-safe (no ionisation)
-clear visualization of solid organs, free fluid, aorta, female pelvic organs
-correlate imaging with tenderness

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USS cons

-operator and patient dependant
-challenging in obese and/or immobile patients

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pros of a CT

-quick
-relatively widely available and tolerated
-accurate (sensitivity CT vs USS= 89% vs 70%)
-allows imaging of multiple structures at the same time
-allows better planing for surgical approach or any other intervention

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cons of CT

-radiation exposure (risk of complications increases as dose increases)
-contrast induced nephropathy (more likely in peeople with pre existing renal impairement)
-contrast allergy

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pros mri

no radiation and good soft tissue delineation

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cons MRI

long examination times
not 14/7 in most regions
contraindications/ claustrophobia

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what is MRI used second line for?

hepato biliary
small bowel
pelvis

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RIF- possible diagnosis?

-appendicitis
-renal colic
-tubo ovarian pathology

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imaging used for appendicitis?

1st= USS
CT if USS is inconclusive

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USS findings- acute appendicits

-Aperistaltic, non compressible, dilated appendix (>6mm outer diameter)
-appears round when compression is applied
-periappendiceal fluid collection
-target appearance (axial section)
-periappendicreal reactive nodal prominence/ enlargement
-wall thickening (3mm or above)

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CT findings- acute appendicitis

-appendiceal dilatation (>6 mm diameter)
-wall thickening (>3 mm) and enhancement
-thickening of the caecal apex
-periappendiceal inflammation
(fat stranding, thickening of the fascia or mesoappendix, extraluminal fluid, phlegmon , abscess)
-focal wall nonenhancement representing necrosis
-perforation

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presentation of right ureteric calculus?

loing to groin pain

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test or right ureteric calculus (loin to groin pain)

non contrast CT KUB= gold standard

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LIF pain- differentials

Diverticulitis
Colitis
Colorectal cancer
Tubo-ovarian pathology
Renal colic

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who is most at risk of acute diverticulitis?

-elderly patients

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presentation of acute diverticulitis?

-left iliac fossa pain
-unremitting pain with associated tenderness
-possibly, an ill-defined mass
-as the disease progresses, symptoms become more generalised

investigations for acute diverticulitis?

CT with IV contrast

epigastric and RUQ pain- differentials

Biliary colic
Cholecystitis
Pancreatitis
Perforation

what is acute cholecystitis secondary to?

always secondary to gallstones

what is acute cholecystitis diagnosis based on?

-sign of inflammation (RUQ pain etc)
-sign of inflammation (fever ,WCC, CRP)
-Confirmatory imaging

first line investigation for acute cholecystitis?

USS first line to assess gall bladder and biliary tree CT can be for false calculi MRI if biliary tree dilatation

US findings- acute cholecystitis?

gallbladder wall thickening (>3mm) pericholecystic fluid also assess biliary tree

CT findings- acute cholecystitis

cholelithiasis: gallstones isodense to bile will be missed on CT gallbladder distension gallbladder wall thickening mural or mucosal hyperenhancement pericholecystic fluid and inflammatory fat stranding enhancement of the adjacent liver parenchyma due to reactive hyperaemia

pancreatitis presentation

acute onset of severe central epigastric pain (over 30-60 min) poorly localised tenderness and pain exacerbated by supine positioning radiates through to the back in 50% of patients Elevation of serum amylase 90-95% specific for the diagnosis

role of imaging in pancreatitis?

to clarify the diagnosis when the clinical picture is confusing to assess severity and determine prognosis to detect complications to determine possible causes

pancreatitis on CT presentation

focal or diffuse parenchymal enlargement indistinct pancreatic margins owing to inflammation surrounding retroperitoneal fat stranding liquefactive necrosis of pancreatic parenchyma infected necrosis/abscess formation Vascular complications

causes of perforation?

Common: Perf. Ulcer (decrease incidence) Diverticular (1-2% generalized, most localised) Less common Secondary to cancer Secondary to ischaemia

first line imaging- perforation?

if there is a lot of gas- is it more likely to be upper or lower bowel problem

high volume of gas- more likely to be lower bowel as theres more gas in large bowel wall

abdominal pain + distention differentials

Bowel obstruction (small or large) Masses Ascites

symptoms/ signs of small bowel obstruction

Symptoms: vomiting, pain and distension Signs: Increased bowel sounds, tenderness, palpable loops

common causes of small bowel obstuction?

adhesions, cancer, herniae and gallstone ileus

1st line imaging for small bowel obstruction

XRAY

what can be seen on Xray of small bowel obstruction?

valvulae conniventes are visible Loops are central Dilatation > 2.5 - 3 cm Paucity of gas distally

what can be seen on CT of small bowel obstruction?

dilated small bowel loops >2.5 cm up from outer wall to outer wall normal calibre or collapsed loops distally small bowel faeces sign may identify a mass

causes of large bowel obstruction?

Colorectal cancer 60% Volvulus 15% Diverticulitis 10%

large bowel obstruction presentation on xray?

peripheral >5cm haustra -colonic distension -collapsed distal colon -small bowel dilatation, which depends on duration of obstruction and incompetence of the ileocaecal valve -rectum has little or no air -Caecum can reach upto 10cm

what imaging is used for large bowel obstruction

Xray and CT

sudden abdominal pain and shock- differentials

Bowel ischaemia Perforation Pancreatitis Leaking AAA Ruptured ectopic pregnancy

causes of bowel ischaemia?

Arterial occlusion – 60-70% Venous occlusion – 5-10% Non-occlusive hypoperfusion – 20-30%

presentation of bowel ischaemia on CT?

Lack of enhancement of the lumen of the affected vessel mucosal/serosal enhancement reduced or increased Altered wall thickness ileus / dilated loops of bowel >3 cm in diameter Pneumatosis intestinalis other changes: mesenteric oedema free fluid intrahepatic portal venous gas: due to pneumatosis intestinalis free intra-abdominal gas

imaging of bowel ischaemia?

imaging for AAA

what is seen on CT of AAA?

Retroperitoneal haemorrhage adjacent to the aneurysm is the most common finding large aorta