Right Lower Quadrant Pain: Value of the Nonvisualized Appendix in Patients at Multidetector CT Suvranu Ganguli, MD, Vassilios Raptopoulos, MD, Fabio Komlos, MD, Bettina Siewert, MD and Jonathan B. Kruskal, MD, PhD Radiology 2006;241: 175-180 MED96 蘇熙淵

Introduction The most common cause of acute abdominal emergency requiring surgical intervention is acute appendicitis Other causes of abdominal pain, however, can mimic appendicitis, such as colitis, diverticulitis, pelvic inflammatory disease, and renal calculi. CT has become increasingly used in the work-up of right lower quadrant pain.

CT scans obtained for RLQ pain, the appendix is not visualized CT scans obtained for RLQ pain, the appendix is not visualized. two recent reports, 13% &14 % Nonvisualization of the appendix on transverse CT scans may safely be used to exclude acute appendicitis if no secondary CT findings of appendicitis are present. -- Nikolaidis et al advances in multidetector CT , enhance the visualization of the appendix strengthen the confidence of negative

Purpose To retrospectively determine the value of the nonvisualized appendix at multidetector computed tomography (CT) in patients with acute right lower quadrant pain in whom appendicitis was a consideration.

Materials & Methods

Patient Selection and Study Design Retrospective review of all consecutive abdominal CT scans April 29 to October 31, 2003. ER record "right lower quadrant pain" CT reports classified four categories positive for appendicitis, negative for appendicitis (normal appendix and normal results), alternative acute diagnosis other than appendicitis, appendix not visualized.

Imaging Technique Protocol eight–detector row CT scanner (Lightspeed Ultra; GE Medical Systems, Milwaukee, Wis). oral contrast agent (600–900 mL of barium sulfate ) 60–90 minutes before scanning IV contrast (100–150 mL of ioversol ; rate 2.5 mL/sec), 60 seconds before scanning.

A single scan lung base to the symphysis pubis 1.25-mm collimation Total in 10–15 seconds routine 5-mm-thick continuous transverse sections & continuous coronal sections Additional thin sections /interactive multiplanar images were not obtained

Image Analysis an abdominal imaging attending physician and a radiology resident Normal appendix : <6 mm ;lacked a thickened enhancing wall ;no intraluminal calcifications, no periappendical stranding. appendicitis :thickened enhancing wall ;>8 mm. 6 ~8 mm with periappendiceal stranding

Clinical Follow-up appendix was not visualized  retrospective chart review To those loss f/u after MBD, authors asked institutional review board–approved questions to determine whether they had appendicitis at the time of CT examination.

Statistical Analysis Descriptive statistics of the age and sex of the patients in the four groups x2 test for sex and t test for age , P<.05 statistical software (SPSS )

Results

400 examinations, 132 (33.0%) male ;268 (67.0%) ages : 16 ~ 88 yrs All oral contrast ; IV contrast 27 (6.8%) normal appendix /CT without for abdominal pain: 182 (45.5%) 79 patients (19.8%) with other causes 7.pyelonephritis or renal infarction ( 3) 8 small-bowel obstruction ( 3) 9volvulus ( 2) 10 ruptured ovarian cyst or dermoid ( 2) 11tubo-ovarian abscess ( 2) 12.bladder outlet obstruction (1) 13pelvic arteriovenous malformation (1). 1.inflammatory bowel disease or colitis ( 26), 2.diverticulitis ( 15) 3 obstructing nephrolithiasis (11), 4. acute cholecystitis ( 5) 5 typhilitis / mesenteric adenitis(4) 6.cancer (4)

80 (20.0 %) with Dx of acute appendicitis by CT 59 patients (14.8% ) :appendix was not visualized 9/59 not f/u , MBD in good condition & not return ER 3/59 (exploration /appendectomy) without finding in CT. Pathology: no evidence There was no statistically significant difference between groups regarding mean age or sex

50 could be f/u in 59 patients whose appendix was not visualized: 46 note; 4 questionnaire 49 without related S/S 49(98%) patients with a nonvisualized appendix who were negative for appendicitis 1 return 15 wks later, acute appendicitis ; initially 11 days after C/S, Dx: postoperative infection of unclear etiology ; 24hr IV A/B

80 with Dx of acute appendicitis in CT 6 :Tx with A/B without op, improved 74 appendectomy: 70 confirm appendicitis; 1 no finding 3 appendix Ca, endometriosis, ruptured ovarian cyst 95% (70 / 74) patients with multidetector CT findings that were positive for appendicitis

Discussion

acute appendicitis (inflamed appendix): use of CT for RLQ pain  increased availability ;fast, accurate, & operator independent. an appendix that is visualized at CT and that has a normal appearance can be used to exclude appendicitis acute appendicitis (inflamed appendix): distended with fluid. >8 mm without surrounding inflammation, >6 mm with surrounding changes. wall is usually thickened & increased mural enhancement with IV contrast . Appendicoliths & periappendiceal inflammation

This study: positive: 95% CT in Dx RLQ pain: sensitivity98%, specificity99%, positive predictive value97%, negative predictive98% This study: positive: 95%

Nonvisualization appendix :15% of the scans in this study Uncomfortable for discharging : leads to increased obs time & admission This study, high percentage (98%) of negative allow to exclude appendicitis when the appendix is not visualized at CT.

Similarities: retrospective; multidetectorCT. Differences: The absence of a distinctly visualized appendix in the right lower quadrant and the absence of secondary findings can be used to exclude appendicitis. — Nikolaidis Similarities: retrospective; multidetectorCT. Differences: No of nonvisualized with f/u ; Dr for image Dx, No of loss f/u (hospital records & interviews) group

Improve identify appendix: contrast, focused scan Protocol in this study is optimal for D/D Imaging protocol use in susp appendicitis: contrast agents are routinely given with 79%IV, 82% oral, and 32%rectal in practice ,most common CT oral & IV contrast

P’t with nonvisualized appendix had surgery according :history, PE, lab CT scans nonvisualized appendix highly correspond to negative for appendicitis Clinicians should be more comfortable with conservative care in this group of patients.

Limitation the retrospective nature of follow-up 15% of patients were lost to follow-up

Conclusion Patients with right lower quadrant pain that is unexplained at multidetector CT, a nonvisualized appendix is a reliable predictor of the absence of acute appendicitis.

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