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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

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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