World J. Surg. 14, 271-276, 1990
World Journal of Surgery 9 1990 by ,the Soci~t~ lnternationale de Chirurgie
Acute and Perforated Appendicitis: Current Experience with Ultrasound-Aided Diagnosis Wolf B. Schwerk, M.D., Britta Wichtrup, Joseph Rtischoff, M.D., and Matthias R o t h m u n d , M.D. Departments of Internal Medicine, Surgery, and Pathology, Philipps-University Marburg, Marburg, Federal Republic of Germany The clinical value of high-resolution real-time sonography for the diagnosis of acute and complicated appendicitis was prospectively investigated in 857 patients admitted with suspected appendicitis. The ultrasound findings were correlated with history and physical examination on admission. Sonography was able to make the diagnosis of appendicitis with a sensitivity of 89.7 %, a specificity of 98.2 %, an overall accuracy of 96.3 %, and a positive and negative predictive value of 93.6% and 97 %, respectively. Routine use of ultrasound before making therapeutic decisions has reduced the rate of unnecessary laparotomies from 20.3 % to 11.3 %. In 48 (24.7%) of 194 patients with proven appendicitis, the disease had progressed to perforation at laparotomy. History and clinical findings on admission classified 30 (62.5%) of these patients as "highly suspect;" however, 9 (18.8%) were classified as "equivocal" and 9 (18.8%) as "very unlikely." Only half (48%) of the patients with appendieeal rupture had white blood cell counts higher than 13,000/mm 3 or fever above 38~ (50%). Sonography enabled the visualization of the inflamed appendix and/or appendicular abscess in 44 (91.7%) patients with perforation. In 47 of 48 patients with appendieeal rupture, the ultrasoundaided diagnosis was made on hospital admission. Thus, the incidence of complicated appendicitis (24.7 %) in our study population must be attributed to disease progression before admission and preclinicai diagnostic delay.
The clinical diagnosis of acute appendicitis closely resembles a judgment based on circumstantial evidence, including an unacceptably high rate of misjudgments. Prospective trials have shown that the overall accuracy for the clinical diagnosis of appendicitis is not more than 70--78% [1]. Therefore, laparotomy for suspected appendicitis is incriminated probably with the highest rate of preoperative misdiagnoses in general surgery. Recent reports have suggested that routine use of sonography in experienced hands can improve the diagnosis of acute appendicitis as well as the differential diagnosis of right lower quadrant abdominal pain [2-6]. Furthermore, the application of real-time sonography has substantially reduced the rate of unnecessary laparotomies for appendicitis [2, 5, 6]. This report summarizes the results of a prospective study to determine the clinical value of high-resolution sonography for diagnosis of acute appendicitis. Special attention was focused on whether ultrasound can provide additional useful informaReprint requests: Wolf B. Schwerk, M.D., Department of Internal Medicine, Philipps-University Marburg, D-3550 Marburg, Federal Republic of Germany.
tion in patients with complicated appendicitis and, thus, improve clinical diagnosis and facilitate therapeutic decisions. Material and Methods
Eight hundred and fifty-seven unselected patients admitted to our hospital with suspected acute appendicitis were included in the prospective study. There were 514 (60%) female and 343 (40%) male patients with a mean age of 23 +- 7 years (range, 2-88 years). On admission, all patients were classified by senior surgeons into 3 different categories based on history, symptoms, physical examination, and laboratory data: category I, acute appendicitis, clinically highly-suspect (urgent surgery needed), category H, clinically equivocal cases (in-hospital observation), and category III, appendicitis, clinically very unlikely (discharge or in-hospital observation). Following clinical classification of patients, ultrasound scanning of the entire abdomen and pelvis was performed with detailed examination of the right iliac fossa using real-time equipment and a 5-MHz curved-array transducer (LSC 7000, Picker). Ultrasound visualization of the (inflamed) appendix or appendicular abscess formation were regarded as positive findings of acute appendicitis, nonvisualization as a negative result. Final therapeutic decisions were made after consideration of sonographic findings. All surgically-removed appendices were subjected to careful histological evaluation under the conditions of a clinical trial. These evaluations formed the basis for the definitive diagnoses. Appendiceal perforation was diagnosed in situ on laparotomy. In those patients who did not undergo surgery, the diagnoses were established by evaluating all clinical findings, including follow-up observations. Results
Clinical and Ultrasound Diagnoses The results of clinical and ultrasound examinations regarding the diagnosis of appendicitis in 857 unselected patients admitted with suspected appendicitis are summarized and compared in Tables 1-3.
272
World J. Surg. Vol. 14, No. 2, Mar./Apr. 1990
Table 1. Results of initial physical examination and ultrasound with reference to the diagnosis of acute appendicitis. Clinical category Clinical classification (n = 857) Proven acute appendicitis (n = 194) UltraSonography true-positive (n = 174) Ultrasonography true-negative (n = 651) Ultrasonography false-negative (n = 20) Ultrasonography false-positive (n = 12)
I
II
III
176 118 103 53 15 5
258 49 47 203 2 6
423 27 24 395 3 1
Data indicate number of patients.
Table 5, Age distribution of patients with perforated appendicitis (n = 48). Age (yr)
%
60 Mean
12.5 73.0 14,5 34.5 yr
Table 6. White blood cell counts on admission to hospital in 48 patients with perforated appendicitis. White blood cells(/mm 3)
Table 2. Diagnostic accuracy of ultrasonography with reference to the diagnosis of acute appendicitis in 857 patients with suspected appendicitis. Sensitivity Specificity PV positive PV negative Overall accuracy
89.7% 98.2% 93.6% 97.0% 96.3%
Table 3. Comparison of initial physical examination and ultrasound regarding the diagnosis of appendicitis in 857 patients admitted with suspected acute appendicitis.
Diagnosis
Initial physical examination (%)
Ultrasound (%)
True-positive True-negative False-positive False-negative Equivocal (category II)
i3.8 57.9 6.8 3.2 30.0
20.3 76.0 1.4 2.3 -
Table 4. Incidence of acute appendicitis and perforated appendicitis
rate in 857 patients admitted with suspected acute appendicitis. Patients n (%)
Acute appendicitis n (%)
Perforated appendicitis n (%)
514 (60) 343 (40) 857
91 (47) 103 (53) 194 (23)
16 (33) 32 (67) 48 (25)
In 48 (24.7%) o f 194 patients with histologically proven acute appendicitis (prevalence 23%), the disease had progressed to perforation based on intraoperative findings (Table 4). Age distribution, white blood cell counts, and body temperature of these patients at the time of hospital admission are listed in Tables 5-7. Only 48% of cases in this subgroup presented with a distinct leukocytosis which exceeded 13,000/mm 3. Fever above 38~ was recorded in 50%; 44% showed a difference between rectal and axillary temperature greater than 0.5~ The clinical categories and ultrasound evaluation of 48 patients with perforated appendicitis are listed separately in Table 8. After physical examination on admission, only 62% of these patients were allocated into the urgent category I. In 19%, however, appendicitis was classified as being "equivocal"
8,000--13,000 40%
> 13,000 48%
Table 7. Rectal temperature on admission to hospital in patients with perforated appendicitis. Body temperature (~ --
World Journal of Surgery 9 1990 by ,the Soci~t~ lnternationale de Chirurgie
Acute and Perforated Appendicitis: Current Experience with Ultrasound-Aided Diagnosis Wolf B. Schwerk, M.D., Britta Wichtrup, Joseph Rtischoff, M.D., and Matthias R o t h m u n d , M.D. Departments of Internal Medicine, Surgery, and Pathology, Philipps-University Marburg, Marburg, Federal Republic of Germany The clinical value of high-resolution real-time sonography for the diagnosis of acute and complicated appendicitis was prospectively investigated in 857 patients admitted with suspected appendicitis. The ultrasound findings were correlated with history and physical examination on admission. Sonography was able to make the diagnosis of appendicitis with a sensitivity of 89.7 %, a specificity of 98.2 %, an overall accuracy of 96.3 %, and a positive and negative predictive value of 93.6% and 97 %, respectively. Routine use of ultrasound before making therapeutic decisions has reduced the rate of unnecessary laparotomies from 20.3 % to 11.3 %. In 48 (24.7%) of 194 patients with proven appendicitis, the disease had progressed to perforation at laparotomy. History and clinical findings on admission classified 30 (62.5%) of these patients as "highly suspect;" however, 9 (18.8%) were classified as "equivocal" and 9 (18.8%) as "very unlikely." Only half (48%) of the patients with appendieeal rupture had white blood cell counts higher than 13,000/mm 3 or fever above 38~ (50%). Sonography enabled the visualization of the inflamed appendix and/or appendicular abscess in 44 (91.7%) patients with perforation. In 47 of 48 patients with appendieeal rupture, the ultrasoundaided diagnosis was made on hospital admission. Thus, the incidence of complicated appendicitis (24.7 %) in our study population must be attributed to disease progression before admission and preclinicai diagnostic delay.
The clinical diagnosis of acute appendicitis closely resembles a judgment based on circumstantial evidence, including an unacceptably high rate of misjudgments. Prospective trials have shown that the overall accuracy for the clinical diagnosis of appendicitis is not more than 70--78% [1]. Therefore, laparotomy for suspected appendicitis is incriminated probably with the highest rate of preoperative misdiagnoses in general surgery. Recent reports have suggested that routine use of sonography in experienced hands can improve the diagnosis of acute appendicitis as well as the differential diagnosis of right lower quadrant abdominal pain [2-6]. Furthermore, the application of real-time sonography has substantially reduced the rate of unnecessary laparotomies for appendicitis [2, 5, 6]. This report summarizes the results of a prospective study to determine the clinical value of high-resolution sonography for diagnosis of acute appendicitis. Special attention was focused on whether ultrasound can provide additional useful informaReprint requests: Wolf B. Schwerk, M.D., Department of Internal Medicine, Philipps-University Marburg, D-3550 Marburg, Federal Republic of Germany.
tion in patients with complicated appendicitis and, thus, improve clinical diagnosis and facilitate therapeutic decisions. Material and Methods
Eight hundred and fifty-seven unselected patients admitted to our hospital with suspected acute appendicitis were included in the prospective study. There were 514 (60%) female and 343 (40%) male patients with a mean age of 23 +- 7 years (range, 2-88 years). On admission, all patients were classified by senior surgeons into 3 different categories based on history, symptoms, physical examination, and laboratory data: category I, acute appendicitis, clinically highly-suspect (urgent surgery needed), category H, clinically equivocal cases (in-hospital observation), and category III, appendicitis, clinically very unlikely (discharge or in-hospital observation). Following clinical classification of patients, ultrasound scanning of the entire abdomen and pelvis was performed with detailed examination of the right iliac fossa using real-time equipment and a 5-MHz curved-array transducer (LSC 7000, Picker). Ultrasound visualization of the (inflamed) appendix or appendicular abscess formation were regarded as positive findings of acute appendicitis, nonvisualization as a negative result. Final therapeutic decisions were made after consideration of sonographic findings. All surgically-removed appendices were subjected to careful histological evaluation under the conditions of a clinical trial. These evaluations formed the basis for the definitive diagnoses. Appendiceal perforation was diagnosed in situ on laparotomy. In those patients who did not undergo surgery, the diagnoses were established by evaluating all clinical findings, including follow-up observations. Results
Clinical and Ultrasound Diagnoses The results of clinical and ultrasound examinations regarding the diagnosis of appendicitis in 857 unselected patients admitted with suspected appendicitis are summarized and compared in Tables 1-3.
272
World J. Surg. Vol. 14, No. 2, Mar./Apr. 1990
Table 1. Results of initial physical examination and ultrasound with reference to the diagnosis of acute appendicitis. Clinical category Clinical classification (n = 857) Proven acute appendicitis (n = 194) UltraSonography true-positive (n = 174) Ultrasonography true-negative (n = 651) Ultrasonography false-negative (n = 20) Ultrasonography false-positive (n = 12)
I
II
III
176 118 103 53 15 5
258 49 47 203 2 6
423 27 24 395 3 1
Data indicate number of patients.
Table 5, Age distribution of patients with perforated appendicitis (n = 48). Age (yr)
%
60 Mean
12.5 73.0 14,5 34.5 yr
Table 6. White blood cell counts on admission to hospital in 48 patients with perforated appendicitis. White blood cells(/mm 3)
Table 2. Diagnostic accuracy of ultrasonography with reference to the diagnosis of acute appendicitis in 857 patients with suspected appendicitis. Sensitivity Specificity PV positive PV negative Overall accuracy
89.7% 98.2% 93.6% 97.0% 96.3%
Table 3. Comparison of initial physical examination and ultrasound regarding the diagnosis of appendicitis in 857 patients admitted with suspected acute appendicitis.
Diagnosis
Initial physical examination (%)
Ultrasound (%)
True-positive True-negative False-positive False-negative Equivocal (category II)
i3.8 57.9 6.8 3.2 30.0
20.3 76.0 1.4 2.3 -
Table 4. Incidence of acute appendicitis and perforated appendicitis
rate in 857 patients admitted with suspected acute appendicitis. Patients n (%)
Acute appendicitis n (%)
Perforated appendicitis n (%)
514 (60) 343 (40) 857
91 (47) 103 (53) 194 (23)
16 (33) 32 (67) 48 (25)
In 48 (24.7%) o f 194 patients with histologically proven acute appendicitis (prevalence 23%), the disease had progressed to perforation based on intraoperative findings (Table 4). Age distribution, white blood cell counts, and body temperature of these patients at the time of hospital admission are listed in Tables 5-7. Only 48% of cases in this subgroup presented with a distinct leukocytosis which exceeded 13,000/mm 3. Fever above 38~ was recorded in 50%; 44% showed a difference between rectal and axillary temperature greater than 0.5~ The clinical categories and ultrasound evaluation of 48 patients with perforated appendicitis are listed separately in Table 8. After physical examination on admission, only 62% of these patients were allocated into the urgent category I. In 19%, however, appendicitis was classified as being "equivocal"
8,000--13,000 40%
> 13,000 48%
Table 7. Rectal temperature on admission to hospital in patients with perforated appendicitis. Body temperature (~ --
