IMAGING OF ACUTE ABDOMEN

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IMAGING OF ACUTE ABDOMEN

• Dr. Rista D. Soetikno, dr.,Sp.Rad (K),M.Kes

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INTRODUCTION

• Acute abdomen is a term used to encompass a
  spectrum of surgical, medical and gynecological
  conditions (intra-abdominal process), ranging
  from the trivial to the life threatening, which
  require hospital admission, investigation and
  treatment

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• Assesing the patient with an acute abdomen need
  many investigation including laboratory test and
  imaging studies?plain photo, US, CT and contrast
  study .

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Imaging studies

• Plain abdominal films erect chest film, supine,
  and upright (optionalleft lateral decubitus)
• Abdominal US
• Abdominal CT

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Plain abdominal film
Table 1 Plain abdominal film
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Supine abdomen

• Looking for
• Gas pattern
• Calcifications
• Soft tissue masses
• Substitute none

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Erect abdomen

• Looking for
• Free air
• Air-fluid levels
• Substitute left lateral decubitus

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Etiologies

• Hemorrhage
• GI perforation
• Bowel obstruction
• Inflammatory disorder
• Circulatory impairment

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HEMORRHAGE

• Intraperitoneal hemorrhage
• Rupture
• hepatoma
• aortic anuerysm
• ectopic pregnancy
• ovarian bleeding

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• Gastrointestinal hemorrhage
• Upper GI hemorrhage
• Duodenal ulcer
• Gastric ulcer
• Hemorrhagic gastritis
• Esophageal or gastric varices ect.
• Lower GI hemorrhage
• Bleeding of colon cancer
• Ischemic colitis ect.

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Imaging

• US finding
• Free peritoneal fluid accumulation on the
  Morisons pouch, the rectovesical pouch, the
  pouch of Douglas, and the bilateral subphrenic
  space
• Abdominal CT
• CT?gold standars for specific intraabdominal
  pathology

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US
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CT
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Gastrointestinal perforation

• Gastrointestinal perforation are serious disorder
  requiring rapid diagnosis and treatment
• Since they may be severe enough to produce septic
  or hypovolemic shock?rapid decision-making for
  urgent laparotomy is crucially important

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• ? Radiological appearances Plain abdominal
  film - Oval/linear collection of gas ?
  Subhepatic space ? Morisons pouch ?
  Beneath the diaphragm (the cupola sign) ? In
  the centre of the abdomen over a fluid
  collection (the football sign) ? Fissure
  for ligamentum teres

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- Small triangular collections of gas between
loops of bowel.- Visualisation of the outer as
well as the inner wall of a loop of bowel
(Riglers sign).US?not as sensitive as plain
radiography for demonstating pneumoperitoneumCT
Free gas over the liver, anteriorly in the mid
abdomen, in the peritoneal recesses.
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Plain photo
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Pneumoperitoneum
Riglers sign
Fissure for ligamentum teres
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Football sign
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BOWEL OBSTRUCTION

• The first investigation when bowel obstruction is
  suspected is the supine plain abdominal X-ray,
  together with an erect chest film if perforation
  is a possibility
• Occasionally, all the dilated bowel may be fluid
  fill and not visible on a plain X-ray and further
  imaging with contrast studies, CT or US may be
  needed to demonstrate dilated bowel

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• Imaging aims to confirm the presence of bowel
  obstruction, define the level obstruction,
  identify the cause and detect complications such
  as perforation

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Table 2. Cause of bowel obstruction
Extrinsic Bowel wall Intraluminal
Adhesions Neoplasia Intussusception
Hernia Stricturesinflammatory, radiation,chemical Foreign body
Volvulus Intestinal ischaemia Gallstone ileus
Inflammation/abscess
Malignant infiltration (e.g. peritoenal deposits)
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Small-Bowel Obstruction

• Etiology - Adhesions due to previous
  surgery - Strangulated hernias - Volvulus
  - Gallstone ileus - Intussusception
  - Neoplastic, etc.

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Small bowel obstruction (SBO)

• Plain film?primary investigation of choice
• Plain film of SBO
• Dilated small bowel loops
• Tend to the central
• Numerous
• 2.5-5.0 cm diameter
• Have a small radius of curvature
• Valvulae conniventes thin, numerous, and extend
  right across the bowel
• Do not contain solid faeces

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• Multiple fluid levels on the erect film
• String of beads sign on the erect film
• Absent or little air in the large bowel

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SBO valvulae conniventes
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SBOstepladder pattern
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Small-Bowel ObstructionString of beads sign
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? Ultrasound - Dilated fluid-filled loops of
small-bowel obstruction. - Assessment
of the peristaltic activity.
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USSBO
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• CT sign of SBO
• Small bowel loops measuringgt2.5 cm in diameter
• Identifiable focal transition zone from
  prestenotic dilated bowel to post-stenotic
  collapsed bowel loops

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CTSBO
Fluid-filled loops
Bowel calibre change
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LARGE-BOWEL OBSTRUCTION

• Etiology
• - Neoplastic (benign malignant)
• - Volvulus (caecal sigmoid), etc.
• Radiological appearances
• Depends on the state of competence
• of the ileocaecal valve

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Large bowel obstruction (LBO)

• Plain-film signs of LBO
• Dilated large bowel loops which
• Tend to be peripheral
• Few in number
• Large above 5.0 cm diameter
• Wide radius of curvature
• Haustra thick and widely separated and may or
  may not extend right across the bowel (compare
  these features with the valvulae conniventes
  found in the small bowel
• Contain solid faeces

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• Caecum maybe dilated
• Small bowel may be dilated
• Contrast enema maybe helpful
• To differentiate pseudo-obstruction and may be
  indistinguishable on plain film from mechanical
  of obstruction
• To localized the point of obstruction
• To diagnose the cause of obstruction e.g. tumour,
  inflamatory mass

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Contrast-enema
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Plain filmSigmoid volvulus
coffee bean sign
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Plain film Caecal Volvulus
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PARALYTIC ILEUS

• Generalised paralytic ileus
• ?Etiology
• - Peritonitis
• - Post-operative
• - Hypokalaemia
• - General debility or infection
• - Drugs morphine
• - Congestive cardiac failure, renal colic,
  etc.
• ?Radiological appearances - Both small
  large-bowel dilatation - Horizontal-ray films
  multiple fluid levels

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PARALYTIC ILEUS
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INFLAMMATORY DISSORDERS

• Acute appendicitis
• Acute pancreatitis
• Acute cholecystitis
• Abdominal absces
• Peritonitis

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Acute appendicitis

• Abdominal x-ray (AXR)
• Non-specific finding
• Approximately 10?a calcified appendicolith
• US
• Generally, the normal cannot be defined with US,
  clear visualization of the appendix is suggestif
  of inflammation
• Swollen, non compressible appendix greater than 7
  mm in diameter with a target or bulls-eye
  configuration is produced by the hypoechoic
  dilated appendiceal lumen
• Assymetrical wall thickening due to phlegmonous
  infiltration, an appendicolith with acoustic
  shadowing

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• US finding
• Echogenic hallo form by omental tissues draped
  over the appendix
• Free fluid in the culdesac
• Atony in the terminal ileum with compression US

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• CT finding
• 90 diagnostic accuracy to detect acute
  appendicitis
• With the good contrast?filling of the terminal
  ileum and the cecum (oral contrast given 1 hour
  before examination)
• Tubular structure 4 mm to 20 mm in diameter with
  a thickened wall that enhance after
  administration IV contrast medium
• Pericecal fluid collection and calcified
  appendicolith

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Plain filmapendicolith
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(No Transcript)
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CT
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Acute pancreatitis

• Severity of acute pancreatitis ranges?mild edema
  with minimal symptoms to a severe necrotizing
  process that culminates in multiple organ failure
• US and CT most precisely define the anatomic
  extent of the lesions and the detect local
  complications

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Imaging

• Plain films?no significant plain film findings in
  up to two-thirds of patients wih acute
  pancreatitis
• Plain-film signs may include
• Paralytic ileus in the left upper quadrant
• Generalized ileus
• Loss of left psoas outline
• Separation of greater curve of stomach from
  tranverse colon

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• CXR signs that may be seen include
• Left pleura effusion
• Atelectasis of left lower lobe
• Elevated left hemidiaphragm

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• US finding
• The acutely inflamed pancreas?enlarged with
  decreased echogenicity and blurred irregular
  margin
• Fluid collection are seen as hypoechoic areas
• US can be used to guide aspiration and the
  drainage procedures, and for follow up

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• CT?imaging investigation of choice for acute
  pancreatitis, and is particularly useful for the
  following
• Confirmation of the diagnosis
• Identification of necrotic gland tissue
• Diagnosis of complication
• Guidance of interventional procedures
• CT signs of acute pancreatitis include
• Diffuse or focal pancreatic enlargement with
  decreased density and indistinct gland margins
• Thickening of surrounding fascial planes e.g.
  left paranephric fascia

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• Acute fluid collections, most commonly related to
  pancreas though also in the lesser sac and in the
  left pararenal space
• Phlegmon appears as an irregular mass spreading
  along fascial planes and can be quite extensive
• Abscess
• Pseudocyst

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US
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CT
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Acute cholecystitis

• Approximately 85-90 of cases with acute
  cholecystitis (AC) develop as a complication of
  cholelithiasis
• Conversely, approximately 10-20 of patients
  with gallstone will require surgery for
  complication, usually cholecystitis, within 15
  years after their stone disease is diagnosed
• Acalculous cholecystitis account for 5-15 of
  cases of acute cholecystitis (immunocompromize,
  critically ill,iatrogenic, congenital etc)

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Imaging

• Plain films?insensitive for acute cholecystitis
• Plain films sign?nonspesific and include
• Gallstone (only seen in 10)
• Soft tissue mass in the right upper quadrant due
  to distended gallbladeer
• Paralytic ileus in the right upper quadrant

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Imaging

• US?investigation of choice for suspected acute
  cholecystitis
• US signs of acute cholecystitis include
• Gallstoneshyperechoic lesions with acoustic
  shadowing which are mobile
• Thickening of gallbladder wall to greater than 4
  mm
• Hypoechoic gallblader wall due to oedema
• Surrounding fluid or localized fluid collection
• Distended gallbladder
• Localized tenderness to direct probe pressure

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• CT?scanning contribute little to diagnosis of
  cholecystitis
• CT?investigation of complicatios?biliary or
  pericholecystic abscess

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USAcute cholecystitis
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USAcute cholecystitis
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USAcute cholecystitis
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Peritonitis

• Peritonitis?an inflammatory or suppurative
  reaction of the peritoneum to direct irritation
• Cause
• Inflammatory
• Infectious
• Ischemic

Exudation, Hematogenous, Contiguous
extension, Iatrogenic manipulation
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Imaging

• Plain abdominal radiograph cannot provide
  specific
• Air-fluid Levels
• Stones
• Ascites
• Eggshell calcification
• Air in Biliary tree.
• Obliteration of psoas-shadow in retro- peritoneal
  disease
• Right lower quadrant sentinel loops in acute
  appendicitis

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• US?nonspecific
• Abdominal CT
• CT signs ?
• Ascites (free or encapsulated)
• Infiltration of the omentum and/or mesentery
• Thickening of the parietal peritoneum
• Angiography for ischaemia, hemorrhage

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ACUTE COLITIS

• Acute inflammatory colitis
• Toxic megacolon
• Pseudomembranous colitis
• Ischaemic colitis

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Acute inflammatory colitis

• Plain film can assess
• ? the extent of the colitis
• ? the state of mucosa
• It can be assessed from
• - the faecal residue
• In left-sided disease, the
  proximal limit of
• faecal residue will indicate the
  extent of
• active mucosal lesion.
• - the width of the bowel lumen
• - the mucosal edge
• - the haustral pattern

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Toxic megacolon

• A fulminating form of colitis with transmural
  inflammation, extensive deep ulceration
  neuromuscular degeneration.
• Involve the transverse colon
• Ro. Findings
• Mucosal islands (pseudopolyps) dilatation
  (8 cm)
• Common complication
• Perforation in the sigmoid peritonitis

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Toxic megacolon
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Ischaemic colitis

• Etiology
• Vascular insufficiency bleeding into the
  wall
• of the colon.
• Sudden onset of severe abd.pain in the early
  hours of the morning, followed by bloody
  diarrhoea.
• In middle-aged elderly patients.
• The wall of splenic flexure descending colon is
  greatly thickened? thumb printing (plain films).
• The right side of colon is frequently distended.

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Pathophysiology of mesenteric ischaemia
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Ischaemic colitis
thumb printing
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