Presentation on theme: "Imaging for Acute Appendicitis"— Presentation transcript:
1 Imaging for Acute Appendicitis LT David BrunerLCDR Todd ParkerStaff Emergency PhysiciansApril 2009
2 Objectives Cases Imaging choices Reconsider Cases/Discussion Consider what you would doImaging choicesUSCTNon-contrast vs oral contrast vs rectalMRIReconsider Cases/Discussion
3 Case 1 15 yo male - 1 day worsening abdominal pain Periumbilical migrated to RLQNausea, vomiting, anorexia, hurts to walk, no feverRLQ guarding / rebound / Heel Tap / RovsingLabs:WBC – 8.9 H/H – 12/37UA – 12 WBC, Pos Leuk Est, rare bacteriaWhat imaging, if any?
4 Case 2 8 yo f - >24 hrs of worsening RLQ pain Diarrhea and nausea, subjective feverUrinary frequency / abdominal pain with micturitionT – P – BP – 108/62RLQ TTP at McBurney’s pointGuard/mild reboundUA Negative WBC – Pending
5 Case 3 37 yo man - 30 hours of worsening RLQ pain N/V and Fever to 100.5No urinary symptomsPMHx of kidney stones – but this is differentWife and daughter recently sick with N/V/DRLQ TTP with guarding and reboundUA NegativeDoes he need a CT?If so, what kind
6 Case 4 31 yo female - 2 days worsening pain Epigastric at first, now only RLQNausea, subjective fever, mensesNo urinary symptomsPositive McBurney’s, Rovsing, Heel TapNo CMT or adnexal masses feltHCG negative, UA negativeImaging?
7 Case 4-1 Same as Case 4 except . . . . Imaging? No vaginal bleeding HCG PositiveED US reveals IUP at 10 weeksImaging?
8 Case 573 yo female30 hours lower abdominal pain and nauseaNo vomiting /diarrhea, fever, bloody stool, or dysuriaHx of HTNOtherwise negative PMHx and PSHxBilateral Lower Quad TTP R > L, mild guardingP – T – BP – 135/76
9 Clearly Imaging Reduces NAR Wagner et al., Surgery. 2008; 144(2)Retrospective review of four-year time periods before and after frequent CTNAR decreased 16% to 6%NAR decreased mostly due to adult womenNo change in NAR with kids (8%)Adult male decreased from 9% to 5% (NSS)Adult women decreased 20% to 7%Guss et al., “Impact of Abdominal Helical CT on the Rate of Negative Appendicitis” JEM 2008; 34(1)Retrospective review of before and after frequent CTDecrease in NAR from 15.5% to 7.6%12% CT rate before readily available, 81% afterAcceptable Negative Appendectomy Rate (NAR)?Historically 10-20%Higher % acceptable in women and pedsWith increased imaging5-10% NARSignificantly increased pre-operative CTFrom 32% to 95% - Wegner studyKim, K. et al, “The Impact of Helical CT on Negative Appendectomy Rate: A Multi-Center Comparison; JEM 2008; 34(1)CT Rate and NAR inversely relatedNAR decreased 20% to 6%Limited by no follow up on negative scans
10 Findings on US for appendicitis UltrasoundVery safe! No radiation, no contrast requiredSensitivity and Specificity:Adult - Sensitivity – 74-83%, Specificity – 93-97%Pediatrics – Sensitivity -88%, Specificity – 94%Variables: Body habitus, Location, SkillIf can’t visualize – need to move on to the next stepFindings on US for appendicitisNon-compressible appendixAppendix >6mm diameterSigns of perforationFree fluidAbscess
11 Computed Tomography High overall accuracy, Sens, Spec, NPV, and PPV Available at all hoursRisks:RadiationContrast problemsAllergic reactionsNephrotoxicity
12 Oral Contrast Cons Pros Large volume contrast What if vomiting?If not, probably willRisk of aspirationAren’t they NPO?Increases difficulty of assessing bowel wall2 hour delayDelays surgical decisionRisk of perforation4-8 hrs to advanceSensitivity 94-98% / specificity 95-99%Alternative diagnosesMay see extravasationBetter if little intra- abdominal fatFluid collectionsComfort with reading contrasted vs non- contrasted
13 Rectal Contrast CT Gravity drip – little risk of perforation Few minutes to perform scanAs little as 15 minutesAccuracy equal to oral contrastNo reported increased discomfort
14 Rectal contrast study 96/283 kids had rectal contrast 95% Sens and PPV Berg ER, et al, Acad Emerg Med Oct; 13(10)Compared oral and rectal contrast CT in a randomized trialShowed decreased length of stay in the ED by one hourNo increased patient discomfort between oral or rectal contrastEqual diagnostic accuracy.Stephen AE, et al., J Ped Surg. Mar 2003; 38(3)96/283 kids had rectal contrast95% Sens and PPVMissed cases still went to OR because of clinical scenario
15 Non-Contrast CT For diagnosis of appendicitis No need to drink contrast – no delayNo change in diagnostic accuracy with IV ContrastSensitivity 94-98% Specificity – 95-99%Significant supporting evidence for non- contrast CT in suspected appendicitis
16 Lane MJ, et al, Radiology. 1999; 213 300 consecutive patientsNon-contrast CT for appendicitisCompared with surgical pathology results96% sensitive99% specific97% accuracy“Stacked the Deck”
17 Hoecker CC, et al, JEM. May 2005 Retrospective study 112 children Atypical presentation (13% of total abd pain pts)CT’d without PO contrast (helical CT)40% positive appendicitis rateCompared to those given PO contrast (prev studies)Equal sensitivity and specificity in both groupsOverall 91% diagnostic accuracy
18 Lowe LH, et al., Am J Roent. Jan 2001 Retrospective cohort of 72 children with non-contrast CT (atypical PE)97% sensitive (95% CI, %)100% specific (95% CI, %)Only took 5 minutes to perform the study
19 Lowe, L. H., et al, Radiology 2001; 221 75 consecutive patients - non-contrast CTAtypical/Equivocal PE findingsCompared residents’ and attendings’ readsResults:91% agreement in reading studies96% specificity and 88% accuracy in residents98% specificity and 97% accuracy in attendingsAttendings more confident of reads
20 Ege G, et al., Br J Radiology. 2002; 75 296 adults non-con CT for suspected appendicitisEquivocal Exams Only45% positive for appendicitisCompared with surgical pathology or follow up96% sens and 98% spec/ 97% PPV and 98% NPVRecommends non-con CT for diagnosis of appendicitis in adultsNegative study requires observation or follow up
21 Anderson BA, et al, Am J Surg. Sep 2005 Study type# of studiesSensSpecAccuracyRectal597Oral2839592Oral + Rectal96Oral + IV793NonCon898Oral vs None92 vs 9495 vs 9792 vs 96Systematic review of 23 studies (19 prospective, 4 retrospective)Over 3700 patients over 16 years old
22 IV Contrast Basak S, et al., J Clin Imag. 2002; 26. Performed study without contrast then with contrastNo difference in making the diagnosis with IV or no contrastSome even thought IV obscured the intra-abdominal structuresKeyzer, C., et al, Am J Roent. August 2008Equal agreement between resident and attending readsEqual ability to visualize the appendix
23 Alternative Diagnoses? Likely the most compelling argumentWhat are the data?No good head to head studiesPlenty of data showing that both enhanced and unenhanced find alternative diagnosesWhich is best?
24 Alternative Diagnoses in Non-Contrasted Studies Malone, A. et al, Am J Roentgen 199335% alternative diagnosisDiverticulitis, Ovarian Cysts or masses, PID, IBDLane MJ, et al, Radiology. 199921% alternative diagnosisUreteral Calculi, Diverticulitis, Chron’s, Mesenteric Adenitis, NeoplasmsAlternative diagnoses advocated by IV and Oral/Rectal contrastEpiploic appendagitis, diverticulitis, Meckel’s Torsion, gynecologic disorders, obstructive uropathy, RLL PNAHow much advantage does contrasted vs non-contrasted study provide?
25 Why Scan at All? Kalliakmans V, et al., Scan J Surg. 2005; 94(3) 717 adults evaluated for appendicitis by 6 surgeonsNormal practice patterns - recorded decisions11% Negative appendectomy rate based on history, physical, and labsCT did not change diagnostic accuracy except in cases of atypical history and physicalRecommends only using CT in equivocal cases
26 CT in Pediatrics Increased lifetime cancer risk Less intra-abdominal fatIs a negative CT enough?Garcia K, et al, Radiology. Feb 20091139 pediatric cases over 4 yearsCT results compared to surgical pathology or follow upAll except 8 had CT with IV contrast onlyNPV (non-visualized appendix) – 98.7%NPV (Visualized) – 99.8%NPV (Partially visualized) – 100%
27 What About MRI? Pros: No radiation and can do reconstructions Cons: Cost, Time, not always available 24/7Highly accurate, operator dependentSensitivity 93-99% Specificity %Less robust evidence, but most studies show reliable and reproducible diagnostic accuracyCaution with gadolinium if pregnant
28 Pregnancy and Appendicitis Pedrosa, I et al, Radiology. Mar 200651 consecutive pregnant pts suspicion for appendicitisUnderwent MRI if US inconclusive4 had appendicitis – MRI correctly dx all3 inconclusive – clinically resolved spontaneouslySens – 100% / Spec – 93.6% / Accuracy – 94%Pedrosa, I et al, Radiology. Mar 2009148 consecutive pregnant pts suspicion for appendicitisUnderwent MRI, 140/148 had ultrasound first14 had appendicitis – MRI correctly dx all, U/S 5/149 False-PositivesSens – 100% / Spec – 93% / PPV – 61% / NPV – 100%Same incidence as non-pregnantQuestionable evidence of appendix moving out of RLQRisk of surgery/anesthesia is less than risk of mortality to mother and fetus if appendicitis is missed or perforation occursWant to avoid radiation risks to fetus – right?US may miss appendix in a different locationMRI has good sensitivity and specificity in appendicitis
30 Case 1 – 15 yo male with 1 day of pain, migration, and peritonitis No imaging – take to the ORKalliakmans V, et al., Scan J Surg. 2005; 94(3Guss DA, et al., JEM. 2008; 34(1)Wagner PL, et al., Surgery Aug; 144(2)All showed no improved negative appy rate for males with pre-operative CT scanning.“The routine use of CT for adult male and pediatric patients with a clinical picture suggestive of acute appendicitis should therefore be discouraged.”
31 Case 2 – 8 yo girl, 1 day of pain, peritoneal signs, fever Actual caseUS done firstThen an MRI was performedThen went to the ORRecommendation in this caseUS or straight to the ORCT vs MRI if still unsure
32 Another case 13 year old girl Ultrasound Positive Appy Straight to the OR
33 Case 3 – 37 yo male, 36 hours of pain, RLQ ttp, fever, hx of stones Non-contrast CTWhat if his WBC count was 19.5 with a left shift?No imaging To the OR?
34 Case 4 – 31 yo female, good exam, negative urine Do you want to avoid radiation?Could start with USCould go directly to CTLittle reason for MRI
35 Case 4-1 - Pregnant US first MRI vs CT Serial exams Dose of radiation thought to be teratogenic and increase risk of cancer in fetuses is 50 mGyACOG gives CT a level 2 recommendation- Must weigh risks and benefitsPatel SJ, Reede DL, Katz DS, et al., RadioGraphics. 2007;McCollough CH, Schuler BA, Atwell TD, et al., Radiographics. 2007; 27:Ratnaplalan S, Bona N, Chandra K, American Journal of Roentgenography May; 182:American College of Radiology. ACoR bylaws. Reston, VA: American College of Radiology, 2005.ACOG Committee on Obstetric Practice. Guidelines for Diagnostic Imaging during Pregnancy. ACOG Committee Opinion no 299, September Obstetrics and Gynecology 2004; 104:
36 Case 5 – 73 yo woman Non-contrast CT What if her Creatinine is 2.2? Does she need IV Contrast
37 Take home points Classic presentations do not require imaging Reserve imaging for equivocal casesAbdominal CT estimated increase cancer risk 1 in 2000CT not shown to decrease NAR in men and childrenMultiple studies suggest oral contrast provides no added value – no need to make them drinkConsider US first for kids, women, and pregnantMRI is a reasonable alternative if availableCan CT pregnant women safely – inform of risksConsider Informed Consent in certain cases