Clinical Suspicion Of Acute Appendicitis Research Articles

Diagnostic efficacy of ultrasonography in acute appendicitis

Introduction: Acute appendicitis is the most common acute condition of the abdomen requiring surgery in both adults 1,2 and children. 3.5 The overall frequency of appendicitis for symptomatic patients younger than 20 years is 41%; the frequency for those older than 20 years is 59%. Methods: This was a prospective cross sectional study involving 104 patients aged between 8 and 68 years with clinical suspicion of acute appendicitis. Patients with suspected acute appendicitis were evaluated with high frequency linear transducer using graded compression technique. Peroperative findings were noted and histopathological examination were carried out in all the cases for confirmation of acute appendicitis. Sensitivity, specificity, negative predictive value, positive predictive value and accuracy of ultrasonography were calculated by using statistical method. Results: Among 104 patients (61 males and 43 females) with clinical diagnosis of acute appendicitis, ultrasonography was positive for acute appendicitis in 79 patients (75.96%). On histopathological examination, 94 appendices (90.38%) were acutely inflamed. The sensitivity of ultrasonography for the diagnosis of acute appendicitis was 78.72% with specificity of 60%. Positive predictive value, negative predictive value and accuracy of ultrasonography were 94.87%, 23.07% and 76.92% respectively. Conclusion: Ultrasonography is a useful method of diagnosing clinically suspected acute appendicitis especially in doubtful cases. DOI: http://dx.doi.org/10.3126/joim.v34i3.8908 Journal of Institute of Medicine, December, 2012; 34:8-11

Diagnostic efficacy of ultrasonography in acute appendicitis

Introduction: Acute appendicitis is the most common acute condition of the abdomen requiring surgery in both adults 1,2 and children. 3.5 The overall frequency of appendicitis for symptomatic patients younger than 20 years is 41%; the frequency for those older than 20 years is 59%. Methods:  This was a prospective cross sectional study involving 104 patients aged between 8 and 68 years with clinical suspicion of acute appendicitis. Patients with suspected acute appendicitis were evaluated with high frequency linear transducer using graded compression technique. Peroperative findings were noted and histopathological examination were carried out in all the cases for confirmation of acute appendicitis. Sensitivity, specificity, negative predictive value, positive predictive value and accuracy of ultrasonography were calculated by using statistical method. Results: Among 104 patients (61 males and 43 females) with clinical diagnosis of acute appendicitis, ultrasonography was positive for acute appendicitis in 79 patients (75.96%). On histopathological examination, 94 appendices (90.38%) were acutely inflamed. The sensitivity of ultrasonography for the diagnosis of acute appendicitis was 78.72% with specificity of 60%. Positive predictive value, negative predictive value and accuracy of ultrasonography were 94.87%, 23.07% and 76.92% respectively. Conclusion: Ultrasonography is a useful method of diagnosing clinically suspected acute appendicitis especially in doubtful cases. DOI: http://dx.doi.org/10.3126/joim.v34i3.8908   Journal of Institute of Medicine, December, 2012; 34:8-11

Ultrasonography for diagnosis of acute appendicitis

This is the protocol for a review and there is no abstract. The objectives are as follows: Our primary objective is to provide readers with a summary of the diagnostic accuracy of US for appendicitis in patients who present with clinically suspected acute appendicitis. Our secondary objectives are to explore the diagnostic accuracy of US for appendicitis in male and female patients, in the paediatric (under 16 years of age) and pregnant patient subgroups and in patients with intermediate clinical suspicion of acute appendicitis or indeterminate diagnostic scores.

The value of biochemical markers in predicting a perforation in acute appendicitis

Acute appendicitis is the most common surgical diagnosis of abdominal pain. Perforated appendicitis can result in increased morbidity and mortality. Identifying a perforation early can reduce the impact on the patient. Bilirubin, C-reactive protein (CRP) and white cell count (WCC) have been shown to indicate perforation in appendicitis. This study aimed to identify whether these biochemical markers can be used to identify if patients are suitable for either a conservative or surgical approach. A retrospective post hoc analysis of all appendicectomies over a 6-year period investigating the association between preoperative bilirubin, CRP, WCC, and neutrophil count and the histological findings of either the presence or lack of a perforation. One thousand two hundred seventy-one patients had appendicitis, 154 (12.12%) of which were perforated upon histological examination. All biochemical markers were significantly higher in perforation (P < 0.001). The greatest sum of sensitivity and specificity of CRP was at 34.6 mg/L (sensitivity 78.57%, specificity 63.01%), and for bilirubin was at 21.5 μmol/L (sensitivity 62.96%, specificity 88.31%). Combining CRP and bilirubin improved sensitivity and specificity, but this was reduced by further incorporating WCC and neutrophils. Logistic regression analysis identified CRP as the most sensitive marker of perforation (odds ratio (OR) = 1.064 (1.043-1.085) ) (P < 0.001), with bilirubin (OR = 1.005 (1.003-1.008) ) also significant (P < 0.001) for a 1-unit increase. Bilirubin and CRP are markers of perforation in appendicitis, but are not accurate enough to be diagnostic. In a patient with high clinical suspicion of acute appendicitis, a raised CRP and bilirubin suggests that a patient is not suitable for conservative treatment.

Whether Intravenous Contrast is Necessary for CT Diagnosis of Acute Appendicitis in Adult ED Patients?

To assess the necessity of intravenous contrast medium for abdominopelvic computed tomography (CT) diagnosis of acute appendicitis (APP) among adult patients with right lower quadrant (RLQ) abdominal pain at emergency department (ED). ED patients with clinical suspicion of APP from RLQ pain for a period of 8 months were enrolled retrospectively. Both pre- and postintravenous contrast-enhanced CT scans were performed for these patients. The visibility of vermiform appendix and specific CT findings of APP were recorded separately for noncontrast CT (NCT) and contrast-enhanced CT (CCT) images without knowledge of the patient's identity and final diagnosis. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of CT diagnosis for APP were compared between the two groups. The ease of identifying appendix was also compared. Forty-two (42.0%) of the 100 patients (55 males, 45 females; age range, 16-90 years; mean age, 49.3 years) were APP. There was no significant difference for the visibility of appendix (94% vs. 91%; P = .589) and radiological characters between the CCT and NCT groups. There were significant differences between the two groups for sensitivity (100% vs. 90.5%; P = .036), specificity (94.8% vs. 100%; P = .038), PPV (93.3% vs. 100%; P = .021), NPV (100% vs. 93.5%; P = .021), but no significant difference for accuracy (97% vs. 96%; P = 1). The appendix was easier to detect on CCT than NCT images (P = .013). The diagnostic sensitivity of CCT was significantly better than that of NCT. Intravenous contrast administration could also make doctors easier in indentifying appendixes.

Clinical suspicion of acute appendicitis – is the time ripe for more conservative treatment?

Traditionally, the diagnosis of acute appendicitis has been based mainly on a history compatible with acute appendicitis and pain at McBurney's point, and the treatment of choice in patients with right iliac fossa pain referring to acute appendicitis has been (laparoscopic) appendicectomy. In too many centers where these traditional rules are followed the accuracy of diagnosis of acute appendicitis still remains at the level of 80 to 85%. It is time to re-evaluate these general guidelines. Here, I face the issue from a few points of view the clinical value of which has not been extensively discussed in the literature but that in my opinion markedly improve the diagnostic accuracy and treatment of patients with right iliac fossa pain. Although there is a clinical suspicion of acute appendicitis, it can be excluded in adult patient, if both leucocyte count and C-reactive protein value are normal on admission to hospital and remain normal in the follow-up. In expert centers, up to 100% sensitivity and specificity have been reported for contrast-enhanced multidetector computed tomography in the diagnosis of acute appendicitis. Antibiotic treatment can be considered a safe first-line therapy in selected patients with acute appendicitis.

Abdominal Computed Tomography During Pregnancy for Suspected Appendicitis: A 5-Year Experience at a Maternity Hospital

The objective of this article is to evaluate the role of computed tomography (CT) in a pregnant patient with right lower quadrant pain in whom there was a clinical suspicion of acute appendicitis. During a 5-year period the clinical records of all pregnant women who underwent imaging examination for clinically suspected appendicitis were reviewed. The imaging findings were correlated with patient management and final outcome. Thirty-nine pregnant patients were referred for imaging, of which 35 underwent initial evaluation with sonography, 23 of these women underwent a computed tomographic examination, and an additional 4 patients were directly imaged with CT without earlier sonographic assessment. Surgery confirmed appendicitis in all 5 patients who were operated on on the basis of findings of appendicitis on a CT scan. Two patients underwent surgery based on an alternate diagnosis suggested preoperatively (tubal torsion = 1, ovarian torsion = 1). All patients with negative findings at CT had an uneventful clinical course. In those patients who were evaluated only with ultrasound, a diagnosis of appendicitis was missed in 5 patients. The sensitivity of CT in the diagnosis of appendicitis in our study group was 100%, compared with a sensitivity of 46.1% for ultrasound. CT provides an accurate diagnosis in patients suspected to have acute appendicitis and is of value in avoiding false negative exploratory laparatomy with its consequent risk of maternal and fetal mortality and morbidity. Although sonography is the preferred initial imaging modality as its lack of ionizing radiation, CT is more accurate in providing a timely diagnosis and its use is justified to reduce maternal mortality and mortality in patients with appendicitis.

Peritoneal seeding from appendiceal carcinoma: A case report and review of the literature

Non-carcinoid appendiceal malignancies are rare entities, representing less than 0.5% of all gastrointestinal malignancies. Because of their rarity and particular biological behavior, a substantial number of patients affected by these neoplasms do not receive appropriate surgical resection. In this report, we describe a rare case of primary signet-ring cell carcinoma of the appendix with peritoneal seeding which occurred in a 40-year old man admitted at the Emergency Surgery Department with the clinical suspicion of acute appendicitis. After a surgical debulking and right hemicolectomy, the patient had systemic chemotherapy according to FOLFOX protocol. After completion of the latter, the patient underwent cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy. This report offers a brief review of the literature and suggests an algorithm for the management of non-carcinoid appendiceal tumors with peritoneal dissemination.

Receiver operating characteristic analysis of leukocyte counts in operations for suspected appendicitis

Study Objective There has been no clear-cut value of the white blood cell (WBC) count in differential diagnosis of acute appendicitis in emergency medicine. Therefore, the aim of this study was to assess the preoperative WBC counts in 3 groups of patients operated on for a clinical suspicion of acute appendicitis with different findings at appendectomy: uninflamed appendix, uncomplicated acute appendicitis, or complicated acute appendicitis. Methods The medical records of 540 patients who underwent appendectomy for suspected acute appendicitis during a 17-month period were retrospectively reviewed. Data for 3 groups of patients were analyzed to calculate the sensitivity and specificity of the WBC count in the diagnosis of acute appendicitis, and we calculated likelihood ratios for 2 cut-points with either high sensitivity or high specificity. Receiver operating characteristic curves were used to evaluate the WBC count in relation to the true diagnosis and severity of acute appendicitis. Results We were able to identify patients with appendicitis on a statistically significant level using receiver operating characteristic curves of WBC counts (area under the curve = 0.756, P < .001), but the WBC count had no diagnostic value in differentiating between uncomplicated and complicated groups (area under the curve =0.55, P = .086). Likelihood ratio ranged from 1.79 (95% confidence interval, 1.17-2.3) for WBC count of more than 10 500 cells/mm 3 to 3.20 (95% confidence interval, 2.72-3.24) for WBC count of more than 14 300 cells/mm 3. Conclusion White blood cell count is helpful in the diagnosis and exclusion of appendicitis. However, there is no value to differentiate advanced appendicitis.

Sonographic Accuracy in Determining Acute Appendicitis in the Children in a Tertiary Care Hospital

Material and Methods: 220 paediatric patients (range 3-14 years, mean age 11.3 years) attending the Emergency Department Of Lahore General Hospital Lahore with clinical suspicion of acute appendicitis were evaluated by the author. Children with vague abdominal pain or without suspicion of acute appendicitis were not in included in the study. Four criteria i.e. enlarged appendix (diameter more than 6 mm), lack of compressibility, a blind ending loop without peristalsis and localized fluid collection were taken into consideration before declaring a patient to be having acute appendicitis.

Comparison of Graded Compression Ultrasonography and Unenhanced Spiral Computed Tomography in the Diagnosis of Acute Appendicitis

To compare the accuracy of graded compression ultrasonography (US) and unenhanced spiral computed tomography (CT) in the diagnosis of acute appendicitis.This prospective study comprised 58 consecutive patients with high clinical suspicion of acute appendicitis. After careful clinical assessment and laboratory investigations, all the patients were independently evaluated by graded compression US followed by unenhanced spiral CT, in order to establish the diagnosis. CT was performed from the level of the third lumbar vertebral body to the pubic symphysis, and no patient was given oral, rectal or intravenous contrast agents. The results were compared with operative findings and clinical follow-up.Out of the 58 patients evaluated, surgical confirmation was obtained in 52 patients and the remaining six patients were managed conservatively. Statistical analysis was based on the 52 patients who were surgically confirmed. 48 of the operated patients had evidence of appendicitis and four patients had negative findings. In our study, 90 percent of patients were adults and the following results were more applicable to the adult age group. Analysis of the data for US and CT, respectively, revealed a sensitivity of 67.3 percent versus 95.8 percent, specificity of 100 percent versus 75 percent, accuracy of 71.2 percent versus 90.3 percent, positive predictive value of 100 percent versus 97.8 percent, and negative predictive value of 15.8 percent versus 60 percent. Out of the operated patients, four patients did not have acute appendicitis and alternative diagnosis was suggested by US and CT in one patient. Of the six patients managed conservatively, an alternative diagnosis was reached both by US and CT in two patients.We conclude that unenhanced spiral CT is more sensitive than US in detecting appendicitis, especially in adult patients.

Alternative diagnoses of acute appendicitis on helical CT with intravenous and rectal contrast

At our institution, helical CT of the abdomen and pelvis with intravenous and rectal contrast (CTRC) has become the modality of choice for investigation of patients with right lower quadrant pain and clinical suspicion of acute appendicitis. CTRC has proven useful for the diagnosis of acute appendicitis (AA) and at the same time identifies alternative diagnoses mimicking AA. This pictorial assay illustrates the imaging findings of AA and its mimickers including primary epiploic appendagitis, right-sided diverticulitis, torsion of Meckel's diverticulum, gynecologic disorders, obstructive uropathy, right lower lobe pneumonia, and other conditions.

Pathology of the appendix in children: an institutional experience and review of the literature

The appendix can be affected by a variety of congenital and acquired diseases, but acute appendicitis is the most common pathology found in the pediatric population. This is a retrospective review of all appendectomies performed during a 2-year period at a major children's hospital with a review of the literature regarding the most common pathologic findings. The pathology database was reviewed for appendectomy specimens, and patient medical records were evaluated to determine the age, gender, race and operative diagnosis. All slides were reviewed and the histologic findings were recorded. A total of 392 appendectomies were performed, including 68 incidental appendectomies and 324 performed for clinical suspicion of acute appendicitis. In 247 of the latter, acute appendicitis was confirmed histologically, and of the remainder 14 were interval appendectomies, 2 had findings suspicious for Crohn disease, 1 confirmed diverticulitis and 60 were histologically negative for appendicitis. Acute appendicitis is the most common pathologic cause of appendectomy, but various other pathologic entities are found in children. Examination of the appendix is warranted even when it appears normal on exploration.

Ultrasound and white blood cell counts in suspected acute appendicitis

The use of radiological studies as diagnostic tools in patients with suspected acute appendicitis has increased recently. In this setting, abdominal ultrasonography is viewed as a possible means of avoiding unnecessary surgery. This retrospective study of patients who underwent laparotomy for suspected acute appendicitis was undertaken to determine the sensitivity and specificity of ultrasound in diagnosing acute appendicitis and the frequency of leucocytosis in patients in whom the diagnosis was confirmed by histology. The ultrasound and surgery registers were reviewed to identify 254 referrals for abdominal ultrasound between January 2001 and December 2002 because of a clinical suspicion of acute appendicitis. Of these cases, 223 did not proceed to surgery. The study sample comprised 31 patients who had appendectomies after abdominal ultrasonography. The ultrasound reports, pathological diagnoses and white blood cell counts of these patients were obtained and formed the basis for the analysis. A histological diagnosis was available for 30 cases, in 17 of whom appendicitis was confirmed In these patients, positive ultrasound and leucocytosis were present in five (29%) and nine (53%) respectively. Ultrasound showed 92% specificity and 29% sensitivity for the pre-operative diagnosis of appendicitis. The positive predictive value of ultrasonography (83%) was higher than that of leucocytosis (69%). The sensitivity and specificity of ultrasound and leucocytosis in this study indicate limited utility as preoperative diagnostic tools.

The Role of Serum Inflammatory Markers in Acute Appendicitis and Their Success in Preventing Negative Laparotomy

Improving the diagnosis of acute appendicitis in order to prevent unnecessary surgery is crucial. This study was intended to identify the role of serum inflammatory markers in patients with preliminary diagnosis of acute appendicitis with a retrospective design. Eighty-five patients with the preliminary diagnosis of acute appendicitis were recruited in this study within the period of November–December 2003. The avarage age was 31.8 years (ranged from 15 to 85). There were 62 males (72.9%) and 23 females (27.1%). In addition to performing routine tests, preoperative serum samples were obtained from the patients to measure C-reactive protein, interleukin-6, and interleukin-10. All the patients were operated on for a clinical suspicion of acute appendicitis. Depending on the macroscopic evidence during the operation and the histopathological examination of the specimen, the patients were separated into two groups: the ones who did not have acute appendicitis as the cause for acute abdomen (group I; n = 14) and the ones who had acute appendicitis (group II; n = 71). The ones who had acute appendicitis (group II) were further grouped as noncomplicated appendicitis (group IIA; n = 44) and complicated appendicitis (group IIB; n = 27). Being a male with elevated levels of leukocytes (white blood cells, WBC); C-reactive protein (CRP), interleukin-6 (IL-6); and interleukin-10 increased the probability of having acute appendicitis in patients with evidences of acute abdomen. The risk of complication of acute appendicitis significantly increased when patients had increased levels of C-reactive protein, increased erythrocyte sedimentation rate, and increased interleukin-6 levels, had symptoms for more than 24 h, and were female. Interleukin-10 levels within normal range might be helpful in eliminating the possibility of acute appendicitis. Thus, elevated levels of WBC, IL-6 and CRP might be helpful in confirming a potential diagnosis of acute appendicitis. In addition, normal levels of IL-10 might be of additional help to possibly rule out the diagnosis of acute appendicitis.

US Features of the Normal Appendix and Surrounding Area in Children

To evaluate prospectively the frequency of depiction with ultrasonography (US) of the appendix in children without clinical suspicion of acute appendicitis and to evaluate the US appearance of the normal appendix. Between March 2003 and July 2003, 146 consecutive patients (62 boys and 84 girls; mean age, 7 years; age range, 2-15 years) without clinical suspicion of acute appendicitis were examined with US. Patients with cystic fibrosis and those with acute abdominal pain were excluded from the study. Outer diameters, mural thickness, and color Doppler flow were measured. Appendiceal lumen and surroundings of the appendix were determined. The overall diameter and mural thickness of the appendix were examined for relationship to age, weight, or height of the patient. For statistical analysis, the Mann-Whitney test, Student t test, and linear regression analysis were applied. In 120 (82%) children, the appendix was depicted with US; in 26 (18%) children, this was not possible. In 114 (95%) of the depicted appendices, the position was classical; we observed six (5%) retrocecal appendices. All appendices were compressible. Mean diameter of the appendix was 0.39 cm (range, 0.21-0.64 cm), and the mean mural thickness was 0.18 cm (range, 0.11-0.27 cm). The appendiceal lumen was empty in 74 (62%) children. The others were filled with fecal material, gas, or both. In 75 (51%) of the 146 children, lymph nodes were present in the right lower quadrant of the abdomen. We found no relation between the age, weight, or height of the examined child and the overall diameter or wall of the appendix. The results of this study show that a normal appendix can be depicted with US in 82% of asymptomatic children.

Assessment of the value of pelvic ultrasonography (PU) in pre-menopausal women with right iliac fossa pain

The aim of this study was to determine whether ultrasound examination performed in the acute setting can avoid the need for diagnostic laparoscopy in pre-menopausal women presenting with right iliac fossa pain in whom the diagnosis of acute appendicitis is suspected. All female patients aged fifty or under, who presented to the Emergency Department with right iliac fossa pain over an eighteen-month period, and who went on to have a diagnostic laparoscopy performed, were included in the study. Ultrasound and operative findings were recorded. 147 patients fulfilling the study criteria were identified. 38 (26%) had pre-operative ultrasound performed. 15 of these had normal findings, 10 had gynaecological pathology identified, 8 had non-specific findings. Of the 38 patients who had pelvic ultrasound pre-operatively, 26 (68%) had acute appendicitis at laparoscopy, only 5 of whom had a sonographic diagnosis of acute appendicitis made pre-operatively. We conclude that while positive ultrasound findings in cases of acute appendicitis are helpful, negative studies do not exclude the diagnosis. Patients in whom there is a strong clinical suspicion of acute appendicitis should proceed directly to laparoscopy while patients in whom the diagnosis is less certain, should be admitted for a period of observation facilitating repeated clinical evaluation. In this subgroup of patients, further imaging studies such as computed tomography may be indicated.

Diagnostic Value Of Ultrasonography On Negative Appendectomy And Perforation In Children

We prospectively evaluated the impact of ultrasound (US) in the outcome of appendectomy findings in children. We analyzed the clinical data of 96 consecutive patients who had appendectomy following clinical suspicion of acute appendicitis. Pre-op US was performed in 60 patients while 36 patients had surgery without pre-op US. The total rate of negative appendectomy for all patients that had pre-op US was 16.7 % (mis-diagnosis and other pathologies not appendicitis; n = 10/60), for misdiagnosis only is 3.3 % and for perforation was 20 %. The rate for negative appendectomy in patients without pre-op US was 33.3 % and perforation rate was 13.9 %. Statistical analysis revealed a significant association between the use of pre-op US and positive appendectomy (P = 0.001). No statistically significant difference in the rates of perforation (P = 0.630) or rates of negative appendectomy (P =0.105) between the two groups. In conclusion, pre-op US is essential for the reduction of negative appendectomy rate especially when performed by highly trained and experienced sonologists with a close rapport between the surgeons and sonologists. Unnecessary delay in surgery should be prevented by prompt preparation and performance of pre-op US so as to further reduce the perforation rate.

Validação do escore de Alvarado no diagnóstico de apendicite aguda em crianças e adolescentes no Instituto Materno Infantil de Pernambuco, IMIP

OBJETIVOS: determinar a acurácia do escore de Alvarado para o diagnóstico de apendicite aguda em crianças e adolescentes admitidos na emergência do Instituto Materno Infantil de Pernambuco (IMIP). MÉTODOS: foi realizado um estudo de validação de método diagnóstico (escore clínico-laboratorial para diagnóstico de apendicite aguda) tendo o exame histopatológico como padrão ouro. A amostra estudada consistiu de 81 crianças e adolescentes, admitidas na emergência pediátrica do IMIP com dor abdominal suspeita de apendicite aguda, no período de março a outubro de 2002. Os pacientes foram atendidos na emergência pediátrica e avaliados quanto ao escore de Alvarado. Entretanto a decisão cirúrgica foi tomada pelo cirurgião responsável. RESULTADOS: tomando como ponto de corte o valor &gt;5 pontos, encontramos uma sensibilidade de 92,6%, especificidade 63,6%, valor preditivo positivo de 86,2% e valor preditivo negativo de 77,8%. CONCLUSÕES: o escore de Alvarado é um procedimento pouco invasivo, simples, rápido, reprodutível, que utilizando o ponto de corte &gt;5 pontos apresenta-se como instrumento de alto valor na triagem de crianças e adolescentes com suspeita diagnóstica de apendicite aguda.

Ovoid shape of the vermiform appendix: a criterion to exclude acute appendicitis--evaluation with US.

To investigate whether the shape of the appendix in transverse section may be considered an ultrasonographic (US) criterion to exclude or confirm acute appendicitis. The shapes of appendices of 100 control subjects, of 174 patients with clinical suspicion of acute appendicitis but without acute appendicitis, and of 108 patients with acute appendicitis were prospectively evaluated with US. Definite diagnoses in patients with clinical suspicion of acute appendicitis were established and confirmed either with surgery and histologic examination in 161 patients or with clinical follow-up in 121 patients. Statistical measures such as sensitivity, specificity, positive and negative predictive values, and accuracy were assessed for the appendiceal shape as a diagnostic US criterion for acute appendicitis. An at least partly round appendix indicated acute appendicitis with a sensitivity of 100%; specificity of 37%; positive and negative predictive values of 50% and 100%, respectively; and accuracy of 61%. In 67 of 174 patients with clinical suspicion of acute appendicitis but without acute appendicitis, the partly ovoid appendiceal shape aided in the exclusion of acute appendicitis, since it indicated a normal appendix with a probability of 86%. In 65 of 174 patients with clinical suspicion of acute appendicitis but without acute appendicitis, the ovoid shape over the entire appendiceal length excluded acute appendicitis with confidence. The shape of the appendix in transverse section is a useful US criterion, since an ovoid shape over the entire appendiceal length reliably rules out acute appendicitis.