Evaluation of the acute abdomen evidenced based testing strategies
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Evaluation of the Acute Abdomen Evidenced-based Testing Strategies. Thomas W. Lukens MD PhD FACEP MetroHealth Medical Center Cleveland, OH Associate Professor of Emergency Medicine Case Western Reserve University School of Medicine. Greetings from Cleveland, OH. The Acute Abdomen.

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Evaluation of the Acute Abdomen Evidenced-based Testing Strategies

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Evaluation of the acute abdomen evidenced based testing strategies

Evaluation of the Acute AbdomenEvidenced-based Testing Strategies

Thomas W. Lukens MD PhD FACEP

MetroHealth Medical Center

Cleveland, OH

Associate Professor of Emergency Medicine

Case Western Reserve University School of Medicine


Evaluation of the acute abdomen

Greetings from Cleveland, OH


The acute abdomen

The Acute Abdomen

  • Pain less than one week

  • Sudden onset

  • Surgery needed

  • Peritonitis

  • Severe pain

    Any condition that needs rapid

    decision making and/or operative intervention


Evaluation of the acute abdomen

ABDOMINAL PAIN

Emergency Department:

  • Undifferentiated patients

    • A collection of symptoms and signs are gathered to predict the conditional probability of a diagnosis

    • Traditional teaching is the reverse

  • Few evidenced based studies in undifferentiated conditions


Abdominal pain emergency department series

ABDOMINAL PAINEmergency Department Series

DischargeDiagnosis1972 19771993 Undifferentiated (UDAP) 41% 39% 25% GI causes 13% 19% 18% Gastroenteritis 7% 12% 5% Surgical GI 10% 18% 8% UTI 11% -- 11% Pelvic Disorder 12% -- 12% Admission rate 27% 42% 18%

Ref:Brewer, Am J Surg, 1976; Jazon, AC Scand, 1982; Powers, AJEM, 1995


Acute abdomen testing

Acute AbdomenTesting

  • History and Physical Examination

    • Serial examinations

  • Laboratory

    • WBC

    • Urinalysis/pregnancy test

  • Plain Radiography

  • CT

  • Ultrasound

    • Color flow Doppler

  • Nuclear Medicine

  • MRI


  • Acute abdomen history physical examination

    Acute AbdomenHistory & Physical Examination

    • Intraabdominal

      • 3 G’s-- GI, GU, GYN

      • Vascular

    • Extraabdominal

      • Cardiovascular

      • Metabolic

      • Abdominal wall

      • Neurogenic


    Acute abdomen history physical examination1

    Acute AbdomenHistory & Physical Examination

    • Accuracy is lacking at times

      • Atypical presentations

      • Missed findings

    • Appendicitis

      • 50-87% sensitive

        • false positive = negative laporatomy

        • false negative = perforation

    • Acute Abdominal Aneurysm (AAA)

      • < 50% sensitive

    • Diverticulitis - 34% sensitivity

      • LR+ = 2-3, LR- = 0.4

    Bergeron, Am J Surg, 1999;177:460, Chervu Surg 1995;117:454,

    Korner, World J Surg 1997;21:313


    Likelihood ratios

    Likelihood ratios

    A way to measure performance

    • LR of positive test: sensitivity of test/1-specificity

    • LR of negative test: 1-sensitivity/specificity

  • LR+ - the likelihood of the test being positive in a patient with the disorder, compared to the likelihood of a positive test in someone without the disorder

  • LR-the likelihood of a negative test in someone with the disorder compared to a negative test in one without the disorder


  • Likelihood ratios calculating probabilities

    Likelihood ratiosCalculating probabilities

    • LR times the (estimated) pretest probability = post test odds of the disease

      • Appendicitis- all ED abdominal pain patients

        • Estimated pretest probability ~ 4%

        • LR+ of the “test” ~4, LR- is 0.3

          If all received the test for appendicitis (4 X 1:25) = ~16%

          chance that a positive test is actually detecting appendicitis in

          the patient. If negative test (0.3 x 1:25), there is still a 1.2%

          probability of patient having appendicitis (lowered pre-test

          probability by about a third)

          Not a particularly accurate test in undifferentiated

          patients


    Acute abdomen laboratory testing

    Acute AbdomenLaboratory testing

    • WBC - limited utility

      • WBC > 11,000 LR+ = ~ 2

        < 11,000 LR- = ~ 0.5

        • WBC alone doesn’t distinguish patients with surgical disease from non-specific abdominal pain

    • Urinalysis

      • AAA - misleading

        • Hematuria in up to 30% with AAA

        • Most common misdiagnosis in AAA- kidney stone

      • Renal colic - hematuria

        • LR+ ~ 2 , LR- = 0.3


    Acute abdomen laboratory testing1

    Acute AbdomenLaboratory testing

    • Liver function tests

      • Normal in up to 40% with acute cholecystitis

      • Not specific for any disease entity

    • Amylase/Lipase

      • Often normal in active pancreatitis

        • Sensitivity ~60%


    Acute abdomen imaging

    Acute AbdomenImaging

    • Plain films- provide little in addition to H & P

      • Few specific findings

        • Sensitive for free air 90-95%

        • Bowel obstruction- 70% sensitive (LR+ ~3, LR- 0.6)

      • Appendicitis

        • LR+ = 1

        • LR- = 0.4

      • Cholecystitis

        • LR+ = 2

        • LR- = 0.5

    Frager, AJR, 1994,162:37, Gruber, Ann Emerg Med, 1996,28:273,

    Izbicki, Eur J Surg,1992,158:227,


    Acute abdomen imaging ct

    Acute AbdomenImaging-CT

    CT- test of choice in most abdominal conditions

    LR+LR-

    • Appendicitis

      Unenhanced focused 29 0.1

      Contrast focused 49 0.02

      Abdomen/pelvis (contrast) 18 0.1

    • Small bowel obstruction 22 0.1

      low grade 3 0.5

    • Diverticulitis 98 0.02


    Acute abdomen imaging ct1

    Acute AbdomenImaging-CT

    LR+LR-

    • AAA 19 0.03

    • Renal colic (Unenhanced) 32 0.02

    • Mesenteric ischemia

      • CT angiography 5 0.3

        • MRA enhanced gadolinium 8 0.2

  • Biliary tract (stones) 28 0.2

    • Common duct 8 0.3

      • MR cholangiography 320.05


  • Acute abdomen imaging ultrasound

    Acute AbdomenImaging-Ultrasound

    LR+LR-

    Biliary tract (stones)300.1

    • Cholecystitis29 0.1

    • Common duct obst11 0.1

    • Common duct stone 8 0.2

      • HIDA scan 10-200.05

  • AAA (nonleaking) 9 0.1

  • Diverticulitis18 0.2

  • Appendicitis11 0.5

  • Ectopic TVS (BHGC>1500)80 0.2


  • Appendicitis ct

    Appendicitis - CT

    Liberal use of CT has lowered negative

    appendectomy rate to 5.4%

    Peck, Am J Surg 2000;180:133

    CT for appendicitis has lowered hospital stay

    by 1/2Raptopoulos, Radiology 2003;226:521

    Appendicitis - most common operation but

    accuracy hasn’t changed significantly in

    past decade(data through 1999) Flum, JAMA 2001;286:1748


    Appendicitis ct1

    Appendicitis - CT

    Use in equivocal cases- not high or low

    probability patients- not routinely

    Ujiki, J Surg Research 2002;105:119

    Call for a surgeon not a CT- more cost

    effective and accurate to have the surgeon

    see the patient first Morris. Am J Surg, 2002;183:547


    Acute abdominal pain imaging

    Acute Abdominal Pain -Imaging

    • History & examination and simple lab tests have about a 50-60 % accuracy (initial to final diagnosis)

    • Technological advances in imaging are responsible for our increased accuracy in diagnosing patients with acute abdominal pain

      Helical CT

      Ultrasound by EM physicians 24/7

      MRI


    Good judgment comes from experience and a lot of that comes from bad judgment will rodgers

    Good judgment comes from experience, and a lot of that comes from bad judgment.Will Rodgers


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