Appendicitis: selective use of abdominal CT reduces negative appendectomy rate

Routine Computed Tomography Versus Selective Imaging: An Audit of Negative Appendicectomy Rates in Two Hospitals

Introduction There are a variety of conflicting recommendations in the literature for pre-operative imaging in acute appendicitis. There is debate over what the ideal imaging protocol is to lower the negative appendicectomy rate (NAR) without increasing missed appendicitis. The aim of this study is to compare the audited NAR between two groups with different imaging approaches: (i) mandatory pre-operative computed tomography (CT) imaging and (ii) selective imaging with CT, ultrasound (US), or no imaging prior to appendicectomy. Materials and methods A retrospective chart audit was conducted of 400 patients who underwent an appendicectomy at two hospitals with different approaches to pre-operative imaging (hospital A and hospital B). The primary outcome measure was histologically confirmed appendicitis. It was also documented whether there was radiological (CT or US) evidence of appendicitis.  Results At hospital A, all 200 patients underwent CT imaging prior to appendicectomy. The total histologically confirmed NAR for this group was 9.5% (19/200). At hospital B, 97 (48.5%) patients underwent CT, 41 (25.5%) underwent US, 10 (5%) had both US and CT, and 52 (26%) had no imaging. The total NAR was 11.5% (23/200). Conclusion There was no statistically significant difference (p=0.62) in audited NARs when comparing clinician-guided selective imaging versus routine CT imaging for all patients undergoing appendicectomy.

The Impact of Pathological Criteria on Pediatric Negative Appendectomy Rate

INTRODUCTION

Negative appendectomy rate (NAR) is a quality metric used in the surgical management of appendicitis. The rates of negative appendectomy (NA) in children range anywhere from 1% to 40% in the literature. Many reports do not provide clear pathological definitions for either appendicitis or NA on which they base their calculation of NAR. We reviewed our experience with pediatric appendectomy and the pathological spectrum encompassed within our definition of a NA and examined how the pathologic definition impacts our hospital's NAR.

METHODS

A retrospective review from 2012 to 2016 in a single institution identified 1676 children that underwent appendectomy. Average age was 11.4 (2-18 years). Patient demographics, clinical outcomes and pathological findings were collected. At our institution, appendicitis is defined as the presence of transmural acute inflammation in the appendix and those patients without this finding have been considered to have had a negative appendectomy.

RESULTS

1435 patients underwent appendectomy for presumed appendicitis. The rate of pathologically diagnosed appendicitis was 91.1% (1307/1435) and as such, the NAR was 8.9% (128/1435). Review of the pathology of the NA cohort identified 67/128 (52.3%) patients with completely normal pathology. The remaining 61 patients displayed some sort of pathological abnormality including malignancy (n = 2), fecaliths (n = 9), pinworms (n = 3), granuloma (n = 2), fibrous obliteration (n = 4), isolated periappendiceal inflammation (n = 1), and acute inflammation confined to the mucosa (n = 40). Exclusion of these patients with abnormal pathology decreased the NAR to 4.6%. Patients with pathological abnormalities of the appendix other than transmural inflammation had a higher rate of 30-day readmission than patients with acute appendicitis (8.2% versus 4.5% p < 0.01).

CONCLUSION

Pediatric NAR is dependent upon the pathological definition of appendicitis and negative appendectomy. Institutional variation in definition may explain discrepancies in the literature. By example, including only those that show "the absence of inflammation or other appendiceal pathology" would decrease our NAR by 50%. This study calls into question the interpretation of interhospital NAR and the use of NAR as a quality metric in the management of appendicitis. Retrospective comparative study: Level III evidence.

The Diagnostic Utility and Clinical Impact of After-Hours CT Scans of the Abdomen and Pelvis Investigating Abdominal Pain

Introduction

The aim of this study was to evaluate the diagnostic utility and impact on clinical management of after-hours CT scans investigating abdominal pain in surgical patients.

Methods

After-hours CT A/P reports investigating the acute surgical abdomen were compared with clinical outcomes and histopathological findings to assess sensitivity and specificity of CT reporting. Comparisons between CT reports and clinical notes were made. CT scans were categorised as having direct effects on clinical management, ruling out a serious pathology, ruling out a nonserious pathology, or having no effect. Discrepancies between information in case-notes and information provided to radiologists were also analysed.

Results

79 clinical notes were located. After-hours CT demonstrated 91% sensitivity and 82% reporting specificity using clinical outcomes as the standard. In the 26 patients with histopathological findings, CT reports demonstrated 91% sensitivity. In 79.7% of cases, CT scanning had an impact on management. In 35.4% of cases, an indication for scanning was not documented with variation in clinical information in 8.9% of cases.

Discussion

This study demonstrates after-hours CT A/P reports result in significant impacts on clinical management of surgical patients with acute abdominal pain. Improvements in providing information when requesting scans are however needed to facilitate accurate reporting.

Improvement in the diagnosis of appendicitis

Our attempts to systematically improve accuracy in the evaluation of patients with suspected appendicitis are, in some ways, hindered by the fact that the condition is so frequently straightforward to diagnose. Careful history-taking and physical examination are reliable in most patients. However, establishing the diagnosis with these skills alone remains vulnerable to conditions that masquerade as acute appendicitis. A substantial body of clinical research over the last quarter-century has shown that improved accuracy is possible. Strategies for improvement include the use of diagnostic scoring systems, laboratory makers such as CRP, diagnostic laparoscopy, and advanced imaging modalities such as CT, MRI, and US. How clinicians use these strategies depends on many factors related to practice setting, the population served, and clinical goals. In children, for instance, the desire to limit exposure to ionizing radiation competes with the greater anatomic detail that a CT scan can provide; at the same time, many hospitals that treat children do not have the resources to maintain the sort of full-time, highly sophisticated abdominal US programs that achieve the highest rates of diagnostic accuracy in clinical studies. Trade-offs have to be made, but improvement is possible in almost all groups of patients: the clinical community should no longer settle for a 15% NA rate when 5% is clearly possible without adverse consequences. Many clinicians will be faced with the task of evaluating patients suspected of having acute appendicitis. A deliberate, proactive, and, ideally, benchmarked strategy for improving diagnosis should be the standard to which we hold ourselves and the promise we deliver to our patients.

Use of white blood cell count and negative appendectomy rate

BACKGROUND

Despite increased utilization of laboratory, radiologic imaging, and scoring systems, negative appendectomy (NA) rates in children remain above 3% nationwide. We reviewed the clinical data of patients undergoing appendectomy to further reduce our NA rate.

METHODS

A retrospective review was conducted of all appendectomies performed for suspected appendicitis at a tertiary children's hospital during a 42-month period. Preoperative clinical, laboratory, and radiographic data were collected. Variables absent or normal in more than half of NAs were further analyzed. Receiver operating characteristic curves were constructed for continuous variables by using appropriate cutoff points to determine sensitivity and false-positive rates. The results were validated by analyzing the 12 months immediately after the establishment of these rules.

RESULTS

Of 847 appendectomies performed, 22 (2.6%) had a pathologically normal appendix. The only variables found to be normal in more than half of NAs were white blood cell (WBC) count (89%) and neutrophil count (79%). A receiver operating characteristic curve indicates that using WBC cutoffs of 9000 and 8000 per µL yielded sensitivities of 92% and 95%, respectively, and reduction in NA rates by 77% and 36%, respectively. Results observed in the subsequent 12 months confirmed these expected sensitivities and specificities.

CONCLUSIONS

Absence of an elevated WBC count is a risk factor for NA. Withholding appendectomy for WBC counts <9000 and 8000 per µL reduces the NA rate to 0.6% and 1.2%, respectively. Missed true appendicitis in patients with normal WBC counts can be mitigated by a trial of observation in those presenting with early symptom onset.

Characteristics of perforated appendicitis: effect of delay is confounded by age and gender

INTRODUCTION

The effect of age and gender on time to perforation in acute appendicitis has not been well characterized. This study examined the relationship between duration of disease and appendiceal perforation in different subgroups of age and gender.

METHODS

This study is a retrospective analysis of 380 patients who underwent an appendectomy from January 2000 to June 2005 at a rural teaching hospital.

RESULTS

Factors associated with perforated appendicitis included age, symptom duration, CT scan, and distance from the hospital. Factors associated with increased patient time included age, temperature >101.5 F, and referral from an outside institution. Factors associated with shorter system time included right lower quadrant tenderness, classic or severe presentation, and leading diagnosis of acute appendicitis. Preoperative CT scan increased system time by approximately 3 h. Analyzing symptom duration and time to perforation, males have a higher prevalence of perforated appendicitis compared to females with similar duration of symptoms. In patients older than 55 years of age, 29% had perforated appendicitis at 36 h of symptoms and 67% at 36 to 48 h of symptoms. In a multivariate regression analysis, age greater than 55 years (odds ratio (OR) 3.0, P value 0.007), fever (OR 4.3, P 0.007), and symptom duration more than 24 h (OR 4.1, P 0.001) were significant predictors of perforated appendicitis.

CONCLUSIONS

There is an early risk of perforated appendicitis even within the first 36 h of symptoms. This risk appears to be higher in males and patients older than 55 years, a quarter of whom are perforated within the first 36 h of symptom duration. Additionally, perforation in acute appendicitis may be more of a continuous phenomena worsening exponentially with duration of symptoms rather than a threshold phenomenon.

Impact of computed tomography of the abdomen on clinical outcomes in patients with acute right lower quadrant pain: a meta-analysis

BACKGROUND

Clinical evaluation alone is still considered adequate by many clinicians who treat patients with appendicitis. The impact of computed tomography (CT) on clinical outcomes remains unclear, and there is no consensus regarding the appropriate use of CT in these patients. We sought to evaluate the impact of abdominal CT on the clinical outcomes of patients presenting with suspected appendicitis.

METHODS

We conducted a systematic review of the literature to identify studies that examined clinical outcomes related to the use of abdominal CT in the diagnosis of acute appendicitis. Inclusion criteria were studies of adult patients with suspected appendicitis that evaluated the impact of abdominal CT on negative appendectomy rates, perforation rates or time to surgery. Two independent investigators reviewed all titles and abstracts and extracted data from 28 full-text articles. Statistical analysis was conducted using Review Manager 5.0.10 software.

RESULTS

The negative appendectomy rate was 8.7% when using CT compared with 16.7% when using clinical evaluation alone (p < 0.001). There was also a significantly lower negative appendectomy rate during the CT era compared with the pre-CT era (10.0% v. 21.5%, p < 0.001). Time to surgery was evaluated in 10 of the 28 studies, 5 of which demonstrated a significant increase in the time to surgery with the use of CT. Appendiceal perforation rates were unchanged by the use of CT (23.4% in the CT group v. 16.7% in the clinical evaluation group, p = 0.15). Similarly, the perforation rate during the CT era was not significantly different than that during the pre-CT era (20.0% v. 19.6%, p = 0.74).

CONCLUSION

This meta-analysis supports the hypothesis that the use of preoperative abdominal CT is associated with lower negative appendectomy rates. The use of CT in the absence of an expedited imaging protocol may delay surgery, but this delay is not associated with increased appendiceal perforation rates. Routine CT in all patients presenting with suspected appendicitis could reduce the rate of unnecessary surgery without increasing morbidity.

CT scans and acute appendicitis: a five-year analysis from a rural teaching hospital

INTRODUCTION

Studies examining the relationship between computed tomography (CT) scans and appendiceal perforation have largely been conducted in urban centers. The present study sought to evaluate this relationship in a rural hospital.

METHODS AND PROCEDURES

This is a retrospective analysis of 445 patients who underwent appendectomies from January 2000 to June 2005 at a rural teaching hospital.

RESULTS

Four hundred forty-five patients were analyzed in two groups; those who underwent CT scans (N = 245) and those who did not (N = 200). Patients undergoing CT scans were significantly older (median age 38 vs. 22 years, P < 0.0001), were more likely to have perforated appendicitis (P 0.001), were less likely to undergo a negative appendectomy (P = 0.003), and had a significantly longer length of stay than those who did not (P 0.009). Analysis by gender showed that perforation rates continued to be significantly higher in males undergoing CT scans (P 0.004). To examine the possibility that sicker patients were more likely to receive CT scans and also be found to have perforated appendicitis, a sensitivity analysis was performed. Patients showing perforated appendicitis on initial CT scans were excluded and the analysis was repeated. The difference in perforation rates continued to remain significant (P 0.037).

CONCLUSION

Males undergoing CT scans are significantly more likely to have perforated appendicitis. A protocol-driven rational approach to CT evaluation of suspected appendicitis may lower perforation rates, especially in males.

Acute appendicitis in young children: cost-effectiveness of US versus CT in diagnosis--a Markov decision analytic model

PURPOSE

To compare the cost-effectiveness of different imaging strategies in the diagnosis of pediatric appendicitis by using a decision analytic model.

MATERIALS AND METHODS

Approval for this retrospective study based on literature review was not required by the institutional Research Ethics Board. A Markov decision model was constructed by using costs, utilities, and probabilities from the literature. The risk of radiation-induced cancer was modeled by using the Biological Effects of Ionizing Radiation VII report, which is based primarily on data from atomic bomb survivors. The three imaging strategies were ultrasonography (US), computed tomography (CT), and US followed by CT if the initial US study was negative. The model simulated the short-term and long-term outcomes of the patients, calculating the average quality-adjusted life span and health care costs.

RESULTS

For a single abdominal CT study in a 5-year-old child, the lifetime risk of radiation-induced cancer would be 26.1 per 100,000 in female and 20.4 per 100,000 in male patients. In the base-case analysis, US followed by CT was the most costly and most effective strategy, CT was the second-most costly and second-most effective strategy, and US was the least costly and least effective strategy. The incremental cost-effectiveness ratios (ICERs) of CT to US and of US followed by CT to US were both well below the societal willingness-to-pay threshold of $50,000 (in U.S. dollars). The ICER of US followed by CT to CT was less than $10,000 in both male and female patients.

CONCLUSION

In a Markov-based decision model of pediatric appendicitis, the most cost-effective method of imaging pediatric appendicitis was to start with a US study and follow each negative US study with a CT examination.

Defining the current negative appendectomy rate: for whom is preoperative computed tomography making an impact?

BACKGROUND

Historically, the negative appendectomy rate (NAR) for patients operated on for acute appendicitis (AA) has exceeded 20%. We sought to define the current NAR with increased use of computed tomography (CT) and laparoscopy.

METHODS

Records of 1425 consecutive patients undergoing appendectomy for suspicion of AA during the past 7 years at a single institution were reviewed. The NAR was calculated and compared with earlier data from this institution (1995-1999). Statistical methods included the Fisher exact test and the Student t test; differences of P < .05 were considered statistically significant.

RESULTS

The overall NAR was 7.65% compared to 16.3% over the period 1995-1999 (P = .0001), without a change in the perforation rate. Concurrently, the rate of preoperative CT increased from 32% to 95%. CT was associated with a lesser NAR only among adult females (7.6% vs 20.8%, P = .005) but not among adult males or children. No difference in NAR was noted in comparing laparoscopic and open appendectomy. Patients without AA had a greater mean duration of symptoms and lower white blood cell count at presentation than those with AA. Most patients undergoing negative appendectomy had a CT, and more than 50% had CT interpretations that were positive for, or could not exclude, AA.

CONCLUSIONS

The NAR in our hospital has decreased progressively to approximately 5%. Although preoperative CT is used in almost all patients, it is only associated with a lesser NAR among adult females. False-positive CTs may contribute to the residual NAR, and further data are needed to determine whether subgroups of male or pediatric patients benefit from preoperative CT.

[Right iliac fossa pain and Alvarado Score]

INTRODUCTION

Unsuspected or undiagnosed acute appendicitis could progress to a perforation or could lead to the removal of a normal appendix.

OBJECTIVES

using a clinical score system as a diagnostic tool for this pathology and can decrease negative appendectomies.

MATERIAL AND METHOD

Prospective and protocolized study.

SETTING

National Clinicas Hospital. Córdoba. Argentina. Between May 2007 and June 2007 224 patients were studied of which 117 were male and 107 were female with a mean age of 26.65 years. An Alvarado score was performed on all patients on admission. Based on the clinical evidence and a second assessment with the Alvarado Score, surgical exploration was decided in 207 patients. The remaining 17 were excluded due to other pathology. The diagnosis of acute appendicitis was confirmed by surgical finding and histopathological studies.

RESULTS

In the surgical findings it was shown that 189 (91%) patients had acute appendicitis. There was no surgical mortality. As regards morbidity, 3.86% had medical and 27% had surgical complications. The histopathology reports showed a normal caecal appendix in 18. Whereas the incidence of negative appendicectomy was about 8.69%.

CONCLUSIONS

The use of the Alvarado Score together with the surgical and histopathology findings confirmed it was sensitive from 6 points for the diagnosis of acute appendicitis.

Dramatic decline of acute appendicitis in Greece over 30 years: index of improvement of socioeconomic conditions or diagnostic aids?

BACKGROUND AND AIMS

There are several reports showing a continuing fall in the incidence of acute appendicitis in the western countries. Our aim was to study the trend of the incidence of acute appendicitis in the Greek population over 30 years.

METHODS

We analyzed the data referring to the years 1970-1999 on the incidence and mortality of acute appendicitis for the entire Greek population. Data were retrieved from the Annual Bulletin for the Social Welfare and Health Statistics of the National Statistics Service of Greece. In this database, acute appendicitis was a hospital discharge diagnosis.

RESULTS

Over the study period, there was a 75% decrease of the age-standardized incidence of acute appendicitis from 652/100,000 to 164/100,000. The median female-to-male ratio of hospitalized patients for appendicitis of the study period (1970-1999) fell progressively from 1.27 in the year 1970 to 0.93 in the year 1999. The case fatality rates remained constant, ranging below 0.09 deaths per 100 appendicitis cases.

CONCLUSION

There is a significant decline of the incidence of acute appendicitis in the Greek population over the years 1970-1999. This time trend is probably related to the improvement of the socioeconomic conditions over the same period and not to the introduction of new diagnostic aids.

Focused helical CT using rectal contrast material only as the preferred technique for the diagnosis of suspected acute appendicitis: a prospective, randomized, controlled study comparing three different techniques

PURPOSE

Focused helical CT using rectal contrast material only has emerged recently as an accurate diagnostic tool for the evaluation of suspected acute appendicitis. This study was designed to prospectively compare the efficacy of rectal contrast CT to other commonly used contrast-enhanced and nonenhanced CT techniques for the detection of acute appendicitis.

METHODS

A total of 232 patients with clinically suspected appendicitis were randomly assigned to one of three focused helical CT techniques: noncontrast enhanced CT, CT using rectal contrast material only, and dual-contrast CT using both oral and intravenous material. All scans were interpreted by the on-call residents and reported immediately to the surgeon. The sensitivity, specificity, predictive values, and overall accuracy rates were compared between the protocols.

RESULTS

One hundred eleven patients (48 percent) had acute appendicitis. The sensitivity and specificity rates of rectal contrast CT were 93 and 95 percent, respectively, with overall accuracy of 94 percent. The sensitivity and specificity rates of dual-contrast CT were 100 and 89 percent, respectively, with overall accuracy of 94 percent. The sensitivity and specificity of noncontrast enhanced CT were 90 and 86 percent, respectively, but the overall accuracy was significantly lower (70 percent) compared with the other studies.

CONCLUSIONS

Rectal contrast CT is as accurate, although less sensitive, compared with dual-contrast CT and significantly superior to noncontrast-enhanced CT for the diagnosis of acute appendicitis. Rectal contrast CT may be performed rapidly, saves resources, and may avoid the diagnostic delay and potential allergic reactions associated with oral and intravenous-enhanced studies, and, therefore, may be the preferred initial technique in the diagnostic workup of suspected acute appendicitis.

Routine versus selective abdominal computed tomography scan in the evaluation of right lower quadrant pain: a randomized controlled trial

OBJECTIVES

To determine the role of abdominal computed tomography (CT) imaging in patients with right lower quadrant (RLQ) pain. The authors hypothesized that selective use of abdominal CT would reduce imaging without increasing the rates of negative appendectomy and perforated appendicitis.

METHODS

A prospective randomized clinical trial was conducted in a community teaching emergency department. Adult patients with acute RLQ abdominal pain with suspected acute appendicitis were included. Patients were randomized to mandatory (all patients) or selective (based on clinical evaluation) abdominal CT imaging. The primary outcome was the negative appendectomy rate.

RESULTS

A total of 152 patients were randomized to selective (n = 80) and mandatory (n = 72) intervention groups. The mean (+/-SD) age was 34.1 (+/-3.5) years, and 48% were female. CT imaging was performed in 54 of 80 patients (68%; 95% confidence interval [CI] = 56% to 78%) in the selective group and in 70 of 72 patients (97%; 95% CI = 90% to 100%) in the mandatory group. There was a trend to a decreased rate of negative appendectomy in the mandatory group (1/39 [2.6%]; 95% CI = 0.5% to 13.2%) as compared with the selective group (6/43 [13.9%]; 95% CI = 6.6% to 27.3%), with a difference in prevalence rates of 11.3% (95% CI = -3.5% to 26.3%). There was also a trend to a decreased perforated appendix rate in the mandatory group (4/39 [10.3%]) as compared with the selective group (7/38 [18.4%]), with a difference in prevalence rates of 8.2% (95% CI = -8.0% to 24.4%).

CONCLUSIONS

In this small sample of adult patients with RLQ abdominal pain and suspected acute appendicitis, CT imaging was performed less frequently in the selective group and there was a trend with mandatory CT imaging to reduced rates of negative appendectomy and perforated appendices.

Impact of helical computed tomography on the rate of negative appendicitis

OBJECTIVE

To assess the impact of helical computed tomography (HCT) on the rate of negative appendicitis (NA).

METHODS

A before-and-after comparison study comparing data from a prospective consecutive case series to data from a retrospective chart review. The prospective series included all patients presenting to the ED during a 19-month period, during which patients with suspected appendicitis were managed in accordance with a guideline that stipulated HCT in selected cases. The retrospective group included patients taken to the operating room (OR) with a preoperative diagnosis of appendicitis over a 4-year time frame before the use of HCT. The primary outcome variable was the rate of NA.

RESULTS

During the HCT era, 104 of 310 patients, 71 (68%; 95% confidence interval [CI], 59-76) men and 33 (32%; 95% CI, 24-41) women, were taken to the OR with a diagnosis of appendicitis. Fourteen (13.5%; 95% CI, 8-21) were NA. During the pre-HCT period, 445 patients, 280 (62.9%; 95% CI, 58-67) men and 165 (37.1%; 95% CI, 33-42) women were taken to the OR with the preoperative diagnosis of appendicitis, and 66 (14.8%; 95% CI, 12-19) were NA.

CONCLUSION

At the study institution, the selective use of HCT did not result in a significant decline in the rate of NA.

Negative Appendectomy Rate: Influence of CT Scans

Negative appendectomy rate varies significantly depending on patient age and sex. However, the impact of computed tomography (CT) scans on the diagnosis of appendicitis is unknown. The goal of this study was to examine the negative appendectomy rate using a statewide database and analyze the association of receipt of CT scan. Using the California Inpatient File, all patients undergoing appendectomy in 1999–2000 were identified (n = 75,452). Demographic and clinical data were analyzed, including procedure approach (open vs laparoscopic) and appendicitis type (negative, simple, abscess, peritonitis). Patients with CT scans performed were identified to compare the negative appendectomy rate. For the entire cohort, appendicitis type was 59 per cent simple, 10 per cent with abscess, 18.7 per cent with peritonitis, and 9.3 per cent negative. Males had a lower rate of negative appendicitis than females (6.0% vs 13.4%, P < 0.0001). The use of CT scans was associated with an overall lower negative appendectomy rate for females, especially in the <5 years and >45 years age categories. Use of CT scans in males does not appear to be efficacious, as the negative appendectomy rates were similar across all age categories. In conclusion, use of CT was associated with lower rate of negative appendectomy, depending on patient age and sex.

CT method for visualization of the appendix using a fixed oral dosage of diatrizoate--clinical experience in 525 cases

PURPOSE

The purpose of this study is to determine if focused CT examinations of the pelvis, utilizing fixed oral dosage of diatrizoate contrast media, improve overall reader confidence in visualization of the appendix.

MATERIALS AND METHODS

Five hundred and twenty-five patients referred for, rule out appendicitis, evaluations underwent focused CT examinations of the pelvis following fixed oral dosage of diatrizoate contrast media. A five-point scale was used to assess the effect of contrast enhancement of the distal small bowel, cecum, and appendix on overall reader confidence, and subsequent visualization of the appendix.

RESULTS

Bowel preparation was ideal in 504 of 525 (96%) patients. Enhanced supine CT images following oral administration of fixed dosage of diatrizoate had consistently good scores for reader confidence for bowel opacification (4.8+/-0.1, P<0.005) and visualization of the appendix (3.7+/-0.1, P<0.005), at 50 min following oral contrast administration. This method improved visualization of the normal appendix in 446 of 504 (88%) patients, with a specificity of 99%. In a patients meeting CT criteria for appendicitis, 21 of 21 (100%) patients were proven at surgery.

CONCLUSION

The use of fixed oral dosage of diatrizoate contrast media resulted in good overall reader confidence to visualize the appendix and peri-appendiceal area, in addition to high specificity and rapid transit time.

Acute appendicitis: added diagnostic value of coronal reformations from isotropic voxels at multi-detector row CT

PURPOSE

To assess retrospectively the added value of coronal reformations from isotropic voxels obtained with 16-section multi-detector row computed tomography (CT) of the abdomen and pelvis in patients with suspected acute appendicitis.

MATERIALS AND METHODS

This study was approved by the institutional review board, and informed consent was waived. One hundred consecutive patients (21 men, 79 women; mean age, 38 years) with suspected appendicitis underwent 16-section multi-detector row CT (section thickness, 0.625 mm; pitch, 1.75; table speed, 35 mm/sec [17.5 mm per rotation, two rotations]; and gantry speed, 0.5 second per rotation), with coronal reformations. Twenty-four patients had appendicitis; 76 did not. Protocol included 150 mL oral iopamidol administered at 3 mL/sec. Transverse scans were reconstructed with 5-mm-thick sections at 5-mm intervals and 0.625-mm-thick sections at 0.625-mm intervals. The second data set was reformatted coronally, with 3-mm-thick sections at 5-mm intervals. Three independent blinded readers interpreted transverse scans alone and then coronal scans; confidence in visualization of any portion of appendix, entire appendix, wall thickening, distention, inflammation, fluid, and appendicitis was scored with 1-5 scale. Sensitivity and specificity were determined for each reader and compared by means of signed rank test. Agreement between readers was determined with kappa statistic. Differences in mean confidence ratings for each finding were determined with Wilcoxon signed rank test.

RESULTS

Mean sensitivity and specificity for all three readers together were 96% and 95% for transverse reformations alone and 95% and 94% for combined transverse and coronal reformations (not significant), respectively. Visualization rates for portion or all of appendix were higher for combined transverse and coronal reformations than for transverse reformations alone (higher mean confidence scores: 0.23 higher [P < .009] and 0.51 higher [P < .001], respectively). In patients without appendicitis, transverse and coronal reformations together enhanced confidence in exclusion of wall thickening, distention, and fluid (lower confidence scores: 0.21 lower [P < .001], 0.17 lower [P < .01], 1.00 lower [P < .001], respectively). Combined transverse and coronal reformations enhanced confidence in identification of appendix in mean of 57 patients. Combined transverse and coronal scans helped exclude appendicitis in mean of 38 patients and aided diagnosis of it in 15.

CONCLUSION

Sixteen-section multi-detector row CT transverse and coronal reformations are equally sensitive and specific for diagnosis of appendicitis. Coronal reformations improve confidence in visualization of appendix (whether diseased or normal) and in diagnosis or exclusion of appendicitis.

The Influence of Age and Gender on the Utility of Computed Tomography to Diagnose Acute Appendicitis

Few studies have examined the effects of age and gender on the utility of diagnostic computed tomography (CT) for appendicitis. We retrospectively studied all adult patients undergoing appendectomy from January 2000 through December 2002 (633 patients). Patients 15–30 years old (“younger”) were compared to patients >30 (“older”) and further subdivided by gender. CT accuracy and the influence of CT on negative appendectomy (NA) rates for each group were evaluated. CT was associated with a lower NA rate in older patients (23% vs 8%, P = 0.004) but had no effect on NA rate in younger patients (26% vs 20%, P = 0.2). Appendiceal CT had greater sensitivity, negative predictive value, and accuracy in older than in younger patients. When subdivided by gender, CT was associated with lower NA rates for all female patients but had no effect in either age group of men. Although CT may be more accurate in patients older than 30 years, it has the greatest benefit in female patients, where it is associated with lower NA rates in all adult patients. CT should be strongly considered for all female patients before operation for suspected appendicitis. Further study is needed to determine which, if any, male patients benefit from preoperative CT.