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Acute Abdominal Pain: Diagnostic Imaging Strategies
Nordic Forum - Trauma & Emergency Radiology
Borut MarincekInstitute of Diagnostic Radiology
University Hospital Zurich, Switzerland
U Acute Abdominal Pain: Diagnostic Imaging Strategies
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• To become familiar with the most frequent causesof an acute abdomen
• To select the appropriate imaging techniques in the diagnostic work-up of acute abdominal pain
• To appreciate the growing role of MDCT for the evaluation of an acute abdomen
Lecture Objectives U Outline
• Acute abdomen
Definition, causes
• Differential diagnosis acute abdominal pain
Localized RUQ, RLQ, LUQ, LLQ
Diffuse
Flank or epigastric
• Diagnostic imaging strategies and changing role of
Abdominal plain film (APF)
US
CT
U Acute Abdomen: Definition
Acute abdomen = syndrome with clinical symptoms
linked to
(1) visceral distension or ischemia
(2) peritonitis
U
Appendicitis 28%
Cholecystitis 10%
Small bowel obstruction 4%
Gynecologic 4%
Pancreatitis 3%
Renal colic 3%
Peptic ulcer 2%
Cancer 2%
Diverticulitis 2%
No clinical diagnosis 34%
(de Dombal, Scand J Gastroenterol 1988)
Acute Abdomen: Causes in 10´320 Patients
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Abdominal plain film (APF)• initial diagnostic examination
US• localized pain in an abdominal quadrant
or flank pain
CT• unclear findings on APF or US• obesity
Acute Abdomen: Traditional Approach to Imaging U Diagnostic Value APF vs CT
Sensitivity (%)
CT(N=188)
APF(N=871)
7549Bowel obstruction
689Urolithiasis
600Pancreatitis
90Intraabdominal foreign body
250Diverticulitis
400Pyelonephritis
500Appendicitis
(Ahn, Radiology 2002)
U Diagnostic Value APF vs Non-enhanced CT
No. of Correct DiagnosesFinal Diagnosis (Total No.)
Non-enhanced Helical CT
Three-View Abdominal Series
10 (100.0)2 (20.0)Acute appendicitis (10)
6 (100.0)2 (33.3)Acute diverticulitis (6)
6 (100.0)2 (33.3)Urolithiasis (6)
3 (100.0)0Ovarian cyst (3)
3 (100.0)3 (100.0)SBO (3)
4 (100.0)2 (50.0)Metastatic disease (4)
5 (100.0)1 (20.0)Acute pancreatitis (5)
(MacKersie, Radiology 2005)
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APF • detection of intraabdominal foreign body• urolithiasis often missed• presence of bowel obstruction, otherwise insensitive
US • “used by many, understood by few”
MDCT increases diagnostic confidence because of• multiplanar viewing• scrolling sequential images• arterial & venous phase of contrast enhancement used instead of APF more credible than US
Acute Abdomen: Modern Approach to Imaging
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0
500
1000
1500
2000
2500
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
APF Utilization Emergency Radiology USZ U CT Utilization Relative to ED Patient Volume
(Broder, Emerg Radiol 2006)
Duke University Medical Center
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U The Acute Abdomen and the Clock U Acute Abdomen: Systematic Diagnostic Approach
Localized pain in an abdominal quadrant• Right lower & left lower (R. Novelline)
Right upper, left upper
Diffuse pain • Gastroenterocolitis• Bowel obstruction (B.Marincek)• Bowel ischemia (R. Novelline)• GI tract perforation
Flank or epigastric pain• Acute obstruction by ureteral stones,
pancreatitis, …
U RUQ Pain
⅔ Acute cholecystitis
95% calculous
5% acalculous (total parenteral nutrition bile
viscosity functional obstruction)
⅓ Differential diagnoses
• Choledocholithiasis / cholangitis
• Pancreatitis
• Peptic ulcer
• Acute hepatitis
• Liver abscess
• Spontaneous rupture hepatic neoplasm
U Acute Uncomplicated Cholecystitis
US as preferred initial imaging technique - findings:• Cholelithiasis (stone within GB neck or cystic duct may
or may not be visualized) • GB wall thickening >3-5 mm• Pericholecystic fluid• Positive Murphy sign (maximum pain over GB)• GB distension (less specific)
U Acute Complicated Cholecystitis
Gangrenous cholecystitis - CT findings (Bennett, AJR 2002):
• Foci of gas in GB wall • Lack of GB wall enhancement• Intraluminal membranes
(= sloughed mucosa)• Pericholecystic fluid
Complication of gangrenous cholecystitis =
perforation wall defect
U Acute Complicated Cholecystitis
Emphysematous cholecystitis:• Elederly men, often diabetes mellitus • Gas-forming bacteria (Clostridium, E. coli, …) proliferate
within GB wall or lumen
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U Acute Complicated Cholecystitis
Subcutaneous abscess, drainage
Suppurative cholecystitis (GB empyema)
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8th week of pregnancy:
acute calculouscholecystitis
Acute RUQ Pain and Pregnancy
9th week of pregnancy: choledocho-
lithioasis
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• Splenic infarction
• Splenic abscess
• Gastritis
• Gastric or duodenal ulcer
Left Upper Quadrant Pain U
Common causes of splenic infarction: • Embolic (atrial fibrillation, bacterial endocarditis)• Hematologic (sickle hemoglobinopathies, any cause of
hypersplenism)
Splenic, Renal & Hepatic Infarcts (Acute Leukemia)
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Subcapsular pyogenicsplenic abscess(Spherocytosis)
Splenic and hepatic abscesses
(Tuberculosepsis)
Splenic Abscess U Diffuse Abdominal Pain - Causes
• Gastroenterocolitis• Bowel obstruction (B. Marincek)• Bowel ischemia (R. Novelline)• GI tract perforation
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“Accordion sign” severe colonic edema
Pseudomembranous Necrotizing Colitis
On antibiotics for suspected meningitis
U Pseudomembranous Necrotizing Colitis
Post kidney-/pancreas-TPL
U GI Tract Perforation
• Stomach/duodenumpeptic ulceriatrogenic (endoscopy)
• Small boweluncommon (except trauma)
• Large bowel appendicitis (usually walled-off)diverticulitis (usually walled-off) neoplasmsvolvulusischemic / ulcerative colitis iatrogenic (endoscopy, polypectomy)
Free perforation: free extraluminal gas Walled-off perforation: abscess
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• Upright chest radiography• Abdominal plain film
supine / upright / left lateral decubitus
• Sensitivity (Maniatis, Abdom Imaging 2000):
Abdominal plain film 51% CT 85%
CT for small pneumo(retro)peritoneum
Free GI Tract Perforation: Extraluminal Gas
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Direct findings1. Extraluminal gas
- mottled gas bubbles adjacent to bowel wall- free floating gas in abdomen
2. Ruptured wall = bowel wall discontinuity
Indirect findings1. Segmental bowel wall thickening with enhancement2. Perivisceral fat stranding3. Extraluminal fluid collection or abscess
Free GI Tract Perforation: CT Findings U Intraperitoneal Perforation: Prepyloric Ulcer
Extraluminalgas & fluid,segmental thickening
anteriorgastric wall
Ulcersecondary to
NSAID
GI tract perforation: MDCT predictive of perforation site in 86% (Hainaux, AJR 2006)
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U Intraperitoneal Perforation: Postpyloric Ulcer
Extraluminal gas & fluid, segmental thickeninganterior duodenal wall
U Intraperitoneal Perforation: Sigmoid Diverticulitis
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Sepsis & epigastric pain as initial manifestation of perforated diverticulum with fecal thrombosis
in IMV & PV
“Intravenous” Perforation: Sigmoid Diverticulitis U Intramesenterial Perforation: SB Diverticulosis
Herniation of mucosa through sites of weakening on mesenteric border of bowel wall, complicating
inflammation & perforation of a solitary diverticulum
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Mesenteric inflammatory mass after walled-off perforation
Walled-off Perforation: Meckel Diverticulum U
Retroperitoneal & mediastinal gas, pneumothorax
Retroperitoneal Perforation: ERCP
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U Walled-off Perforation: Endoscopic Biopsy
Cecum: intramural hematoma & gas several (delay 6 hours)
U Walled-off Perforation: Endoscopic Polypectomy
Polypectomyproximal ascendingcolon 2 days ago
U Intraperitoneal Perforation: Foreign Body (4 cm) U Incorporated Foreign Bodies - Perforation?
Borderlinepersonalitydisorder: 8 metallic needles
U Incorporated Foreign Body - Perforation?
Non-metallic, syntheticmaterial (dildo) in rectum
U Flank or Epigastric Pain - Causes
• Urinary tract pathologyacute obstruction by ureteral stonespyelonephritisrenal artery or vein thrombosisrenal neoplasm
• Acute appendicitis • Sigmoid diverticulitis• Gallstones• Acute pancreatitis• Acute gynecologic conditions• SBO hernia
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Non-enhanced CT established as best method
Advantages:• 94-96% sensitivity (IVU: 75-87%) for detecting ureteral
stones: radiopacity calcium stones 400-600 HU, uric acid & cystine stones 100-300 HU
• Identification of extraureteral pathologies• None of risks associated with iv contrast medium
Disadvantage:• Radiation dose: 4.7-6.5 mSv (IVU: 1.5-3.3 mSv) low dose CT as alternative; if in doubt standard dose CT with oral and iv contrast
(Mulkens, AJR 2007; Kennish, Clin Radiol 2008)
Ureteral Stones - Imaging U
Secondary CT findings in acute obstruction by ureteralstones:- hydroureter / hydronephrosis- periureteral / perinephric stranding (engorged draining
lymphatics)
Obstructing Ureteral Stone
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Bilateral urolithiasis: not visible on APF
Obstructing Left Ureteral Stone U Ureteral Stones: APF vs Low Dose CT
Low dose CT: Obstructing stone left ureter,
additional stones left & right ureter
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• RLQ pain US / CT:first exclude appendicitis, than consider alternative diagnosis
• LLQ pain CT:diverticulitis most frequent
• Diffuse pain (APF) / CT:bowel obstruction most frequent
• Flank or epigastric pain non-enhanced CT:first exclude obstruction by ureteral stones,than consider alternative diagnosis
Imaging Strategies Acute Abdomen: Summary