THE ACCURACY OF ABDOMINAL ULTRASONOGRAPHY IN THE DIAGNOSIS OF ACUTE APPENDICITIS

Acute appendicitis is the most common causes of abdominal emergencies that necessitate surgical intervention. This study aimed to evaluate the accuracy of abdominal ultrasonography in the diagnosis of acute appendicitis. This prospective study was performed in Alsadr Teaching Hospital from November 2015 to January 2017 involving 131 patients. The results showed that 84.7% of the patients who presented with positive features of acute appendicitis were confirmed by ultrasonographic study, while 15.2% of the patients showed negative ultrasound examination confirmation. In conclusion, ultrasound study is effective in the assessment of patients presented with clinical features of acute appendicitis.


Introduction
cute appendicitis is one of the most common causes of emergencies which require surgical intervention. Early diagnosis of acute appendicitis is very important for successful outcome 1 . The vermiform appendix is a tubular structure arising from the cecum, it is about 10 cm long 2 . Acute appendicitis is an inflammation of the appendix which is either caused by obstructive or non-obstructive factors 2 and is mainly diagnosed by the clinical picture in which there is anorexia, migratory pain to the right iliac fossa (RIF) and vomiting. On examination, there may be RIF tenderness, rebound tenderness especially at McBurney's point and elevation in body temperature 3 . Many diagnostic tools are used to assist the diagnosis of acute appendicitis such as the Alvarado score system, plain abdominal film, Barium enema, abdominal ultrasonography and CT scan of the abdomine 4 .
Ultrasound test is a technique that depends on high frequency (7-7.5MHZ) 5 .
The possible criteria of acute appendicitis in ultrasonography are: non compressible, a peristaltic blind tubular structure, An outer diameter of 6mm or more, presence of fecolith, Peri-appendicular fluid or collection, and hyper-vascularization of the appendix on color doppler 6 . This study aimed to assess the accuracy and effectiveness of abdominal ultrasonography in patients suspected to have acute appendicitis to help in the diagnosis that aid to improve the outcome and decrease the complications. After reaching diagnosis of acute appendicitis, the patients were admitted to the surgical ward, and then were subjected to appendectomy. The specimens of the appendices were send for histopathological examinations. Data about ultrasound, operative and histopathological results were analyzed for sensitivity, specificity, positive predictive value, negative predictive value and accuracy.

Results
One hundred and thirty one patients were included in this study. They were 69

Discussion
Acute appendicitis is one of the most common surgical emergencies that need early management and intervention. In spite of it is common, it should be carefully diagnosed because it has wide range of differential diagnosis such as renal, gynecological, and gastrointestinal pathologies 1 . In this study, 131 patients were included, number of males was 69 (53%) which is higher than females 62 (47%), and it is a similar frequency as in other studies 7,8 . Acute appendicitis occurs most frequently at the age of 20-29 years in this study, which correlate with other studies 7,9 . Regarding symptoms and signs of acute appendicitis: anorexia was the most common symptom, right iliac fossa pain is the next symptom in frequency, vomiting was the least common one as found in another study 10 .
There was an increase in WBC counts in 57 patients representing 43.5% of all patients in this study, while it is within normal range in 74 patients (56.4%).
Normal WBC counts may occur in elderly, immunocompromised patients, patient with malignancy and others. So WBC counts may not reflect the severity of the disease 11 . In comparing ultrasound, and histopathological results, it was found that 111 patients (84.7%) showed positive findings in ultrasound study, and 109 patients (83.2%) were found to be positive by histopathological examination, this represents the true positive results. Two patients (1.5%) out of 111 were found positive by ultrasound study and they had negative results by histopathology, this represents the false positive results. The presence of the appendix in some positions like retrocecal appendix, or when the inflammation confined to the tip of the appendix, the presence of large amount of gas within the bowel loops, or in case of perforated appendix, all these may lead to difficulty in identifying the appendix and thus will give false negative results 12 . There are other abdominal conditions like inflamed Mickle's diverticulum, Crohn's disease, inflamed fallopian tube or tubo-ovarian abscess, these may be falsely identified as inflamed appendix and lead to false positive results 12 . In this study the sensitivity was 86.5%, specificity was 60%, positive predictive value was 98.1%, negative predictive value was 15%, and the accuracy was 85.4%.
In conclusion, the clinical picture in addition to ultrasound findings suggests the diagnosis of acute appendicitis, this combination have significantly high sensitivity and accuracy values in the diagnosis of acute appendicitis especially in cases with atypical presentations.