the value of limited computed tomography with rectal contrast in the diagnosis of acute appendicitis

The Value of Limited Computed Tomographywith Rectal Contrast in the Diagnosis of Acute

AppendicitisSusan Walker, MD, William Haun, MD, Jeffrey Clark, MD, Kim McMillin, MD, Francine Zeren, MSN,

Terry Gilliland, MD Denver, Colorado

BACKGROUND: Multiple nonrandomized studiesdemonstrate the accuracy of computed tomog-raphy (CT) scan in diagnosing appendicitis. Thisstudy compared CT scan with standard manage-ment in diagnosing appendicitis.

METHODS: This was a prospective randomizedstudy of patients who received general surgeryconsultation for appendicitis. Patients were ran-domized to receive CT scan or standard man-agement.

RESULTS: There were 65 patients in the CT scangroup and 63 patients in the standard manage-ment group. The sensitivity, specificity, and ac-curacy of CT scan were 94%, 100%, and 96%,respectively. CT scan positively altered the man-agement in 26% and made alternative diagnosesin 14%. The sensitivity, specificity, and accuracyof the standard management group were 100%,79%, and 89%, respectively. The standard man-agement group had a negative appendectomyrate of 19%.

CONCLUSIONS: CT scan with rectal contrast is aneffective method for diagnosing appendicitis andshould be performed in all patients suspected ofhaving appendicitis. Am J Surg. 2000;180:450–455. © 2001 by Excerpta Medica, Inc.

Appendicitis has traditionally been diagnosed byintegrating clinical data consisting of history,physical examination, laboratory data, and occa-

sional radiologic imaging. With these methods, at least20% of patients with appendicitis are misdiagnosed.1 Be-cause of the uncertainty inherent in the clinical diagnosisof appendicitis, different modalities for its diagnosis havebeen investigated. Computed tomography (CT) scan of theabdomen and pelvis is a common diagnostic tool used toassist in the evaluation of abdominal pain. There are nowseveral publications in the literature that suggest CT scanis a powerful tool when used in the early diagnosis ofappendicitis.

Although there are multiple studies acknowledging theaccuracy of CT scan, no prospective, randomized trialshave been published comparing CT scan with standardmethods for the diagnosis of acute appendicitis. This pro-spective, randomized study was developed to compare lim-ited CT scan of the appendix with standard methods forthe diagnosis of acute appendicitis.

We hypothesized that CT scan of the appendix would bemore accurate and less cost effective than standard meth-ods for the diagnosis and treatment of acute appendicitis.We postulated that patients who underwent early CT scanwould have a lower negative appendectomy rate and alower missed appendicitis rate.

MATERIALS AND METHODSWe performed a prospective, randomized study of adult

patients receiving general surgery consultation for appen-dicitis at Exempla Saint Joseph Hospital emergency depart-ment in Denver, Colorado, from July 1998 to June 1999.The hospital institutional review board approved the study.

All patients enrolled in the study underwent clinicalevaluation by a general surgeon in the emergency depart-ment. This evaluation consisted of history, physical exam-ination, complete blood count, and any combination of thefollowing: urinalysis, electrolytes, liver function tests, amy-lase, abdominal films, and pelvic ultrasound. All women ofchildbearing age had a beta hCG study included in theirlaboratory data.

Exclusion criteria were patients under the age of 18,pregnant women, patients with any contraindication to theinstillation of contrast material into the colon, and pa-tients who had an appendiceal ultrasound performed priorto general surgical evaluation. We initially considered ex-cluding young men (aged 18 to 40) from the study; how-ever, prior to study commencement, retrospective analysisidentified negative explorations in 3 of 30 young men withright lower quadrant pain. Young men were therefore in-cluded in the study.

If the suspicion for appendicitis, as determined by thesurgeon, warranted either inpatient observation or opera-tion, informed consent was obtained, and the patient wasrandomized to receive either limited CT scan with colo-rectal contrast or standard management. Standard manage-ment varied from observation with serial abdominal exam-inations to right lower quadrant ultrasound, to immediateoperation. Patients in the standard management groupwere allowed to have a CT scan of the abdomen and pelviswith oral or intravenous contrast, or both, if the surgeonfelt it was indicated. Prior to any additional diagnostic tests

From the Department of Surgery Education, Exempla SaintJoseph Hospital, Denver, Colorado.

Requests for reprints should be addressed to Terry Gilliland,MD, 2045 Franklin Street, Denver, Colorado 80205.

Presented at the 52nd Annual Meeting of the SouthwesternSurgical Congress, Colorado Springs, Colorado, April 9–12,2000.

450 © 2001 by Excerpta Medica, Inc. 0002-9610/00/$–see front matterAll rights reserved. PII S0002-9610(00)00540-7

or procedures, patients enrolled in the study were rated ona scale from 1 to 10 for their likelihood of having appen-dicitis. One represented the lowest suspicion for appendi-citis, and 10 represented the highest suspicion for appen-dicitis. Ratings were obtained by third-, forth-, or fifth-yearsurgical residents or the attending surgeon.

Those patients randomized into the CT scan group un-derwent focused, helical, appendiceal CT scan with colo-rectal contrast. As described by Rao et al,2 the protocolrequired the rectal administration of up to 1,500 cc ofdilute Gastrografin, immediately followed by 5-mm helicalcuts through the right lower quadrant of the abdomen. Thethin-collimation helical scanning started 10 to 15 cm su-perior to the iliac crest and continued inferiorly to the levelof the rectum. A staff radiologist read the CT scan and theresult was reported to the surgeon. CT scans were catego-rized as positive, negative, or equivocal for appendicitis.CT scans with appendiceal diameters greater than 6 mmwithout periappendiceal inflammatory changes were con-sidered equivocal. Otherwise, no specific criteria for thediagnosis or exclusion of appendicitis were given to theradiology staff. A single radiologist (KM) performedblinded, retrospective over-reads of all CT scans.

The surgeon initiated appropriate therapy in both studygroups based upon the data collected. The surgeons wereallowed to override the CT scan readings based uponclinical judgement. Patient outcomes were determined atthe time of surgery and by pathology examination of theappendix or by a follow-up telephone call in those patientswho did not have surgery. In addition, a charge comparisonwas performed between the two study groups.

Statistical analysis comparing the two groups’ demo-graphics utilized the chi-square test for patient gender andthe Mann-Whitney test for age. The sensitivity, specificity,and accuracy for each method of management were deter-mined. In addition, a subanalysis calculating the sensitiv-ity, specificity, and accuracy of young men (aged 18 to 40)was performed.

To determine whether CT scan changed the manage-ment of patients, it was assumed that patients with asurgeon’s likelihood score of 7 or greater would have hadsurgery. Those patients with a score from 4 to 6 would haveat least been observed, and those with a score less than 4would have been sent home.

RESULTSA total of 128 patients were randomized: 65 patients in

the CT scan group and 63 patients in the standard man-agement group. There was no significant difference be-tween the two groups’ age and gender (Table 1).

Rectal contrast for the CT scan was well tolerated by themajority of patients. One patient refused more than 200 ccof rectal contrast and other received no contrast at all. Ina third patient, rectal contrast did not provide adequatevisualization of the appendix, requiring a second CT scanafter the administration of oral contrast.

Thirty CT scans were read as positive for appendicitis, 8as equivocal, and 27 as negative for appendicitis. All of thepatients with positive CT scans had appendicitis. Of the 8equivocal CT scan readings, 3 patients had appendicitisand 5 did not. There were 2 false-negative CT scans for

appendicitis. Since equivocal CT scan readings could notbe considered positive or negative, they were excludedfrom sensitivity and specificity calculations. The sensitiv-ity, specificity, and accuracy of rectal contrast CT scan forthe diagnosis of appendicitis were 94%, 100%, and 96%,respectively. CT scan made an alternative diagnosis in 9patients (14%), and positively altered the management in17 patients (26%).

A subanalysis of young men (aged 18 to 40) yieldedsimilar results. Ten CT scans were read as positive forappendicitis, 1 as equivocal, and 3 as negative for appen-dicitis. The patient with the equivocal CT scan had ap-pendicitis. There was 1 false-negative CT scan. The sen-sitivity, specificity, and accuracy of CT scan for thediagnosis of appendicitis in young men were 91%, 100%,and 96%, respectively. CT scan positively altered the man-agement in 4 of these patients (29%).

Four patients were taken to surgery earlier based uponpositive CT scan interpretations. Three of these patientshad surgeon likelihood scores of 4, 4, and 4.5. One of the4 patients had a surgeon likelihood rating of 3. Since it wasassumed that patients with scores of less than 4 would havebeen sent home, the positive CT scan in this patient mayhave prevented missed appendicitis.

Of the 8 patients with equivocal CT scans, 4 were ex-plored and 3 of the 4 had appendicitis. The other 4 patientswere observed. The most common reason for an equivocalreading was the presence of an enlarged appendix (.6mm) without ancillary signs of appendicitis. This readingoccurred in 6 of the 8 patients; 2 of these patients hadappendicitis. One CT scan was read as a right lower quad-rant inflammatory process, pericecal fluid, and no visual-ization of the appendix. This patient was explored and hadappendicitis. The last equivocal CT scan showed the distalappendix abutting the sigmoid colon with inflammatorychanges. The radiologic interpretation was sigmoid diver-ticulitis versus distal appendicitis. This patient was treatedwith antibiotics and improved. The surgeons’ likelihoodratings for patients with equivocal CT scan interpretationsdid not correlate well with the patients’ management ortheir final diagnoses.

There were 27 CT scans that were interpreted as negativefor appendicitis: 25 true negative and 2 false negatives.Failure to visualize the appendix was common to bothpatients with false-negative CT scans; both were exploredbased upon the surgeon’s judgement (likelihood scores of8.5 and 6), and had appendicitis. Blinded, retrospective

TABLE IPatient Demographics

CT GroupStandard

Group P Value

Number of patients 65 63Age range (years) 18–77 18–80Mean age (years) 36.2 6 13.5 35.3 6 13.5 NSMedian age (years) 34 32 NSGender 22M/43F 22M/41F NS

CT 5 computed tomography; M 5 male; F 5 female; NS 5 not significant(P $0.05).

LIMITED CT WITH RECTAL CONTRAST IN APPENDICITIS/WALKER ET AL

THE AMERICAN JOURNAL OF SURGERY® VOLUME 180 DECEMBER 2000 451

over-read by a single radiologist detected appendicitis in 1of 2 false-negative CT scans.

A true negative CT scan reading changed the manage-ment in 14 patients. Six patients avoided unnecessaryhospital admission, having surgeon likelihood scores rang-ing from 4 to 6.5. Six patients avoided negative explora-tions but were still observed in the hospital, having surgeonlikelihood scores ranging from 7 to 9. One patient avoidedhospital admission and negative exploration; this patienthad a surgeon’s likelihood score of 7. One patient with aCT scan read as cecal diverticulitis, however, was treatedwith antibiotics for 2 days and had a delay in operation fora perforated Meckel’s diverticulum.

Three of the 25 patients with a true negative CT scan forappendicitis were explored. One patient had a negativeexploration, 1 patient had perforated sigmoid diverticulitis,and 1 patient (described above) had a perforated Meckel’sdiverticulum. The surgeons’ likelihood ratings for these 3patients were 7, 10, and 10, respectively.

CT scan made a diagnosis other than appendicitis toexplain the patient’s abdominal pain in 9 cases (14%). CTscan diagnoses included ovarian cyst in 3 patients, diver-ticulitis in 2 patients, mesenteric adenitis in 1 patient, aninflammatory process at the hepatic flexure in 1 patient,terminal ileitis in 1 patient, and PID versus inflammatorybowel disease in 1 patient. One patient with a CT scanread as cecal diverticulitis actually had a perforated Meck-el’s diverticulum (see above). CT scan missed perforatedsigmoid diverticulitis in 1 patient explored in spite of a CTscan negative for appendicitis.

Twenty-nine patients in the standard management grouphad appendicitis and 34 did not. Seven patients had anegative exploration, resulting in a negative appendectomyrate of 19%. There were no cases of missed appendicitis inthe standard management group. The sensitivity, specific-ity, and accuracy for the diagnosis of appendicitis in thestandard management group were 100%, 79%, and 89%,respectively. The surgeons’ likelihood score for standardmanagement patients who went to surgery ranged from 1 to10, with a mean score of 7.5 and a median score of 8. Thesurgeons’ likelihood score for standard management pa-tients who did not go to surgery ranged from 1 to 9, with amean score of 5.3 and a median score of 5.

Thirteen patients in the standard management groupwere young men. Seven of these patients had appendicitisand 6 did not. Two patients had a negative exploration,yielding a negative appendectomy rate of 15%. The sensi-tivity, specificity, and accuracy of standard management inthis subset of patients were 100%, 67%, and 85%, respec-tively.

The blinded, retrospective CT scan over-reads by a singleradiologist did not improve on the sensitivity, specificity, oraccuracy of the original CT scan interpretations performedby other staff radiologists.

The mean charge per patient in the CT scan group was$7,879, with a median charge of $7,161. The mean chargeper patient for the standard group was $7,973, with amedian charge of $7,404. There was no significant differ-ence in charges between these two groups (P 5 0.69).

COMMENTSThe efficacy of CT scan in the diagnosis of appendicitis

has been the subject of multiple publications. Table IIdetails the results of some recent studies in the literature,which yield an overall sensitivity, specificity, and accuracyof 96%, 95%, and 96%, respectively, for the use of CT scanin the diagnosis of appendicitis. In contrast to these re-ports, our study was designed in a prospective, randomizedfashion to see if this previously reported data could bereproduced in a community-based teaching hospital, and tosee if CT scan would prove to be more accurate thanstandard methods for the diagnosis of appendicitis.

We found limited CT scan with rectal contrast to be lesssensitive (94% versus 100%), more specific (100% versus79%), and more accurate (96% versus 89%) than standardmethods for the diagnosis of acute appendicitis. Thesefindings held true for our young male (aged 18 to 40)population, despite popular belief that this group of pa-tients is easier to diagnose and should not require addi-tional diagnostic tests to establish the diagnosis of appen-dicitis. CT scan in young men was found to be less sensitive(91% versus 100%), more specific (100% versus 67%), andmore accurate (92% versus 85%), than standard methodsfor the diagnosis of appendicitis.

The 100% sensitivity achieved by the standard manage-ment group, however, was at the expense of a 19% negative

TABLE IISummary of Recent Publications on Computed Tomography Scan in the Diagnosis of Appendicitis

AuthorType ofStudy

Number ofPatients

Type ofContrast

Sensitivity(%)

Specificity(%)

Accuracy(%)

Balthazar2 Prospective 100 PO/IV 98 88 93Malone3 Prospective 211 None 87 97 93Rao4 Prospective 100 PO/rectal 100 95 98Lane5 Prospective 109 None 90 97 94Rao6 Prospective 100 Rectal 98 98 98Rao1 Prospective 97 Rectal 98 98 98Schuler7 Retrospective 97 PO/IV 98 91 96Funaki8 Prospective 100 PO/rectal 97 94 95Total 96 95 96

PO 5 oral; IV 5 intravenous.


452 THE AMERICAN JOURNAL OF SURGERY® VOLUME 180 DECEMBER 2000

appendectomy rate. There were 2 patients (5%) in the CTscan group who had negative explorations. One of thesepatients had an equivocal CT scan reading with a 7-mmappendix without ancillary findings for appendicitis and asurgeon’s likelihood rating of 7. The other patient had aCT scan negative for appendicitis, but was operated onbecause of the surgeon’s clinical judgement. This patienthad a surgeon’s likelihood rating of 7. Trusting the CT scanreading would have prevented a negative exploration.Even with these negative explorations, the CT scan groupstill had a lower negative exploration rate (5%) than thestandard management group. Similar findings were pub-lished by Schuler et al3 who found their CT scan group tohave a negative appendectomy rate of 5.8% compared witha 14% rate for the preceding 3 years using standard meth-ods of diagnosis.

The lower sensitivity of the CT scan group comparedwith the standard management group was due to 2 false-negative CT scans. The appendix was not visualized on CTscan in both of these patients; our study suggests an im-portant criterion for a negative CT scan should be a clearlyvisualized appendix. CT scan criteria for ruling out appen-dicitis varies in the literature. Rao et al4 interpreted a CTscan as negative for appendicitis only if a normal appendixwas visualized. CT scan findings of a normal appendixinclude a contrast or air-filled appendix, an appendicealwall 2 mm or less regardless of appendiceal maximumdiameter, or a nonfilling appendiceal lumen with an ap-pendix less than 6 mm in maximum diameter.4 In threemore recent studies, however, CT scan of the appendix wasconsidered negative if the appendix was 6 mm or smaller,or if the appendix was not conclusively seen, and ancillarysigns of appendicitis were not present.2,5,6 If we had im-posed Rao’s more stringent criteria requiring visualizationof a normal appendix for the exclusion of appendicitis, nofalse-negative interpretations would have occurred, andthe sensitivity of CT scan in diagnosing appendicitis wouldhave been 100%.

Our CT scan interpretations were left to the discretion ofthe radiologists reviewing the films in an effort to reflectcommon practice in a community hospital. This is incontrast to other studies where specific criteria were out-lined for diagnosing and ruling out appendicitis. The cri-teria for diagnosis are fairly uniform and are described inseveral sources.7–9 Demonstration of an enlarged appendix(.6 mm in maximum diameter) in conjunction with peri-appendiceal inflammatory changes (fat stranding, phleg-mon, fluid collection, or extraluminal gas) are the mostconsistently cited findings diagnostic for appendicitis.3–10

Leaving CT scan interpretation to the discretion of theradiologist allowed for an unexpected subset of patients toemerge with equivocal CT scan readings. Our initial pro-tocol assumed that all CT scans would be read as eitherpositive or negative for appendicitis. In fact, CT scans wereread as equivocal 12% of the time. Although this rate ishigher than reported in some studies, we believe it accu-rately reflects the fact that patients with appendicitis willnot always exhibit strictly defined CT scan criteria forappendicitis. Various studies have specific criteria that jus-tify an equivocal reading. Funaki et al7 interpreted a CTscan as equivocal if ancillary signs of appendicitis were

present, but the appendix was not identified. Lane et al5

recognized the presence of an appendicolith and periap-pendiceal changes as secondary findings for appendicitisbut did not diagnose appendicitis by CT scan unless anenlarged appendix was definitely identified in associationwith the secondary findings. The management of patientswith equivocal CT scans must be individualized, takinginto account the reason for the equivocal reading and thesurgeon’s suspicion for appendicitis.

CT scan provides the additional benefit of positivelyaltering management in 26% of patients and establishingan alternative diagnosis in 14%. Schuler et al,3 Lane et al,5

and Funaki et al,6 found CT scan to establish an alterna-tive diagnosis in 22% to 54% of patients. CT scan identi-fies patients with appendicitis who would have otherwisebeen observed and provides the clinician with informationallowing accurate diagnosis and treatment of other acuteabdominal processes even when appendicitis is not identi-fied. Although difficult to quantify monetarily, this benefitfrom using CT scan undoubtedly reduces cost by establish-ing a timely and correct diagnosis in patients with rightlower quadrant abdominal pain.

Our study did not show a significant cost advantage forusing CT scan in diagnosing appendicitis. Uniform use ofCT scan in the diagnosis of appendicitis clearly adds addi-tional cost but is more than offset by reducing negativeexplorations, a fact that held true even for young men. OurCT scan group charges would have been lower if all pa-tients with negative CT scans (where a normal appendixwas visualized) had been observed as outpatients. Sixteenof 25 patients with true negative CT scans for appendicitiswere observed in the hospital; 1 of these underwent anegative exploration. We believe a significant cost advan-tage from CT scan for appendicitis would be recognized ifall patients with negative scans were monitored as outpa-tients and if a monetary value could be assigned to thepatients whose management was positively altered in atimely fashion based on the results of the CT scan.

Currently there is no gold standard for the diagnosis ofacute appendicitis short of operation. As available operat-ing room time and staff continue to contract, the histori-cally accepted negative appendectomy rate of 20% cannotbe sustained when there is a more accurate method ofdiagnosis available without additional cost. Although CTscan may not be helpful in 12% of patients due to anequivocal CT scan, in the remaining 88% CT scan pro-vides an accurate assessment of the appendix as long as theappendix is visualized. In addition, CT scan will positivelyalter the management in 26% of patients and make analternative diagnosis in 14%. We conclude that CT scanfor appendicitis is more accurate than standard manage-ment, positively alters patient management, provides alter-native diagnoses when appendicitis is not present, andshould therefore be routinely performed for every patientwhom the surgeon suspects of having appendicitis.

REFERENCES1. Rao PM, Rhea JT, Novelline RA, et al. Effect of computedtomography of the appendix on treatment of patients and use ofhospital resources. NEJM 1998;338:141–146.2. Rao PM, Rhea JT, Novelline RA, et al. Helical CT combinedwith contrast material administered only through the colon for



imaging of suspected appendicitis. AJR Am J Roentgenol. 1997;169:1275–1280.3. Schuler JG, Shortsleeve MJ, Goldenson RS, et al. Is there a rolefor abdominal computed tomographic scans in appendicitis? ArchSurg. 1998;133:373–377.4. Rao PM, Rhea JT, Novelline RA, et al. Helical CT techniquefor the diagnosis of appendicitis: prospective evaluation of a focusedappendix CT examination. Radiology. 1997;202:139–144.5. Lane MJ, Katz DS, Ross BA, et al. Unenhanced helical CT forsuspected acute appendicitis. AJR Am J Roentgenol. 1997;168:405–409.6. Funaki B, Grosskreutz SR, Funaki CN. Using unenhanced he-lical CT with enteric contrast material for suspected appendicitis in

patients treated at a community hospital. AJR Am J Roentgenol.1998;171:997–1001.7. Curtin KR, Fitzgerald SW, Nemcek AA Jr, et al. CT diagnosisof acute appendicitis: imaging findings. AJR Am J Roentgenol.1995;164:905–909.8. Birnbaum BA, Jeffrey RB Jr. CT and sonographic evaluation ofacute right lower quadrant abdominal pain. AJR Am J Roentgenol.1998;170:361–371.9. Rao PM. Technical and interpretative pitfalls of appendicealCT imaging. AJR Am J Roentgenol. 1998;171:419–425.10. Malone AJ Jr, Wolf CR, Malmed AS, Melliere BF. Diagnosis ofacute appendicitis: value of unenhanced CT. AJR Am J Roentgenol.1993;160:763–766.

DISCUSSIONDr. Kenric Murayama (Chicago, IL): Increasingly, the

task of diagnosing appendicitis has been usurped from thesurgeon and surgical house staff by the use of emergencydepartment CT scans. We are led to believe the “accept-able negative appendectomy rate” is no longer “accept-able”. Several retrospective studies have supported the useof CT scans to improve the accuracy with which a diag-nosis of appendicitis is made. Although most studies sup-port this practice, none are randomized or perspective. Theauthors have performed a prospective randomized study todetermine the accuracy of CT in the evaluation of acuteappendicitis. This is a single institution study, which madeit feasible to also address the issue of cost. A total of 128patients were randomly assigned to either a CT evaluationgroup or standard treatment group after evaluation bymembers of the surgical team.

The authors determined that CT scan is more accuratethan surgeon clinical judgement and does not significantlyadd to cost. Additionally, CT made an alternative diagno-sis in nearly 15 percent of patients and altered the man-agement in 30 percent.

I have a few questions. First, no criteria were identified forjudging the clinical likelihood of appendicitis; yet, signifi-cant attention is devoted to the physician’s clinical suspi-cion. Since there seems to be little correlation betweenclinical impression and the equivocal CT scan, can theauthors comment on the clinical presentation of these 8patients with equivocal CTs? Also, since this group ofpatients seems to be where the most improvement can bemade, did the authors note any specific trends in theclinical presentation or CT findings that might help toplace these patients in either the appendicitis or no appen-dicitis groups? The accuracy of CT is 96 percent if theequivocal CT group is excluded. However, if these CTscans are assumed to be positive, the accuracy of CT goesdown to 89 percent, which is the same as the accuracy inthe standard management group. Since 5 of 8 patients withequivocal CTs did not have appendicitis, it would seemmore appropriate to arbitrarily assign these patients to thenegative group. How would the accuracy of CT be im-pacted if the CT scans in the equivocal group were assumedto be negative?

At my institution, CT scans are read after hours, whenmost of these patients present, by radiology house staff, andit is not unusual to find a final report by an attendingradiologist that is different from the resident’s initial re-

port. I believe the quoted series from the MassachusettsGeneral Hospital involve CT interpretations of attendingradiologists. Were all of these CTs read by attending radi-ologists in your institution? I suspect the incidence offalse/positive readings in my own institution is muchhigher since house staff tend to over read CT scans, to besure they’re not missing anything.

Finally, a logistic question: In this era of cost contain-ment, who paid for these CT scans?

Dr. William W. Turner, Jr. (Jackson, MS): I’m trying tounderstand whether this paper proves the benefit of CTscan or proves the benefit of surgery. A couple of questions:

What percentage of your patients were excluded fromundergoing CT scan so that we may have some idea of howoften this would be applicable?

Some details of the morbidity of the contrast study in thepatient with the perforated sigmoid diverticulum may behelpful. What was the complication rate in the patientswho underwent negative appendectomies?

What sort of complications occurred? You indicated thatcost data between the two groups were similar. Presumably,these are charge data, and we recognize charges as a surro-gate for cost of variable accuracy. So I’m not sure that youcan say that costs were similar between the two groups.

Finally, still looking for that measure of benefit of CTversus exploration, and its attendant negative appendec-tomy rate, do you have any measures of patient satisfactionin the CT group compared to the group who underwentnegative appendectomy?

Dr. Ronald M. Stewart (San Antonio, TX): I’d like toask a few simple questions. First, I would assume there’s nodifference in perforation rates between the groups. Manypeople who do not believe the CT data point out correctly,that it does add some time.

I quibble with the overall conclusion that everyoneshould have a CT. It seems to me that the patient whodoesn’t need a CT is the patient with the classic historyand physical presentation. Do those patients really needCT scan, or does your data support the CT scan in thatgroup?

Finally, in otherwise healthy patients without renal fail-ure, could you make a case for routine use of IV contrast, asopposed to not using IV contrast?

Dr. Maria D. Allo (San Jose, CA): In order to do a costanalysis, one needs to identify those people in the standardtreatment group who had CT scans, ultrasounds, or somecombinations of the above. Such studies significantly raise


454 THE AMERICAN JOURNAL OF SURGERY® VOLUME 180 DECEMBER 2000

the cost of care, and I think it really confounds differenti-ating between your two groups.

I would also underscore the last comment, with respect tothose patients who have classic unequivocal appendicitis.As a public hospital physician, it would be very hard tojustify spending 800 dollars on a CT scan in a 20-year-oldmale with pain over McBurney’s point who I know doesn’thave Mittleschmertz or an ovarian cyst.

Dr. John D. Middleton (Billings, MT): What role did theemergency physicians or house staff play? Did they providean initial screen, or are the house staff seeing all theabdominal pain patients?

CLOSINGDr. S. Walker: Dr. Murayama, it is understandable why

many surgeons feel CT scan performed by emergency roomphysicians usurps the clinical judgment of the surgeon. Weview CT scan more as an adjunct to improve the surgeon’saccuracy in treating appendicitis, and therefore designedour study so that surgeons made the determination whethera patient warranted a CT scan, so that we continue toparticipate in the diagnosis of appendicitis and to preventrunaway costs associated with indiscriminate scanningprior to surgical consultation. When a diagnostic imagingstudy is available that improves the accuracy of the surgeonin treating appendicitis, we believe a negative appendec-tomy rate of 20% is in fact no longer acceptable. How canwe with a clear conscience recommend an operation thepatient does not need 20% of the time when an availablecharge-neutral imaging study lowers that rate to less than5%?

Patients with equivocal CT scans should probably beconsidered separately, since it is in this circumstance wherethe experience of the surgeon allows for proper treatmentof the patient. An equivocal CT scan thus becomes an-other piece of information the surgeon assimilates in thediagnosis and treatment of appendicitis. Half of these eightpatients were explored and 75% of these had appendicitis,roughly approximating the standard negative appendec-tomy rate.

There are no radiology residents in our institution, so astaff radiologist reads our CT scans 24 hours a day. We canunderstand how off-hour resident interpretation in someinstitutions may limit usefulness of CT scan for appendi-citis. CT scans were paid for by the insurer, and when thepatient was uninsured, by the hospital.

Dr. Turner, our only exclusion criteria were pregnant

women and those aged less than 18, so CT scan is appli-cable to most patients suspected of having appendicitis.There was no morbidity associated with administration ofrectal contrast in the patient with perforated sigmoid di-verticulitis, and the complication rate was low in thepatients who underwent negative appendectomies. Com-paring costs rather than charges is everyone’s ideal, but notfeasible, so we are left with comparing charges. We did notmeasure patient satisfaction in the CT group compared tothe group with negative explorations. In general, our ob-servation is that patients would rather have a rectal con-trast CT than have a 20% chance of having an operationthey do not need.

Dr. Stewart, the perforation rate was actually higher inthe standard management group, clearly an artifact sincewe would agree with you that the CT scan does take sometime. We pushed to keep the time for CT scan less than 2hours. We did not always succeed, but we know of noinstances where a patient perforated while in the CTscanner. Some advocate the routine use of IV contrast inpatients without renal disease since it may help enhancethe appendiceal wall; ample studies show this does notincrease the accuracy of CT scan and adds the risk ofcontrast reactions.

Dr. Allo, in the standard management group five patientshad CT scans and thirty four had ultrasounds, which meansless than half were operated on without imaging studies.We believe the charges of imaging studies should not besegregated in the standard management group since theyare simply part of diagnosing and treating appendicitis.Ultrasound adds about $250 and CT scan $500, or 2% ofthe charges associated with managing possible appendicitisin the standard management group. These charges aretrivial relative to the expense of negative explorations. Forthe young man with unequivocal appendicitis, use of CTscan for appendicitis is charge-neutral due to the benefit ofnot having 8–10% who have an operation they did notneed. If one is willing to disregard the patients with neg-ative explorations, deciding whether to use CT scan todiagnose appendicitis in young men at any hospital, publicor otherwise, would seem to depend on which resourcecommands the highest premium—the CT scanner or theoperating room.

Dr. Middleton, emergency physicians performed the ini-tial screen of patients with abdominal pain followed bysurgical house staff or attending surgeon evaluation.



the value of limited computed tomography with rectal contrast in the diagnosis of acute appendicitis

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