West African Journal of Ultrasound Vol 17 Number 2 (2016) Evaluation of the of the sensitivity, accuracy and positive predictive value of ultrasonography in the diagnosis of Appendicitis. 1 2 3 Oguntola A. S, Bello T. O, Alakabani J 1 Departments of Surgery, Al-Hawra General Hospital Tabuk Region Kingdom of Saudi-Arabia 2 2 Department of Radiology Ladoke Akintola University College of Health Sciences Ogbomosho Oyo State- Nigeria. 3 Department of Radiology,Al-Hawra General Hospital Tabuk Region Kingdom of Saudi-Arabia Abstract Diagnosis of appendicitis is mainly clinical but usually supported with laboratory and r a d i o l o g i c a l d i a g n o s i s e s p e c i a l l y ultrasonography. There is conflicting report on the role of ultrasound in the management of appendicitis. Our objective is to assess the sensitivity of ultrasound in the diagnosis of appendicitis. Graded compression pelvic ultrasound was performed on 431 patients with suspected appendicitis over a 20-month period. Criteria considered for the ultrasound diagnosis included non-compressible appendix and measured maximal outer diameter (MOD) greater than 6 mm, edema of the appendix, presence of faecolith, peri-appendiceal fluid collection and mesenteric lymphadenopathy. Only 43 out of the 431 suspected cases had open appendectomy, ultrasonography and histology diagnosis. The intraoperative findings were compared with histology and ultrasound assessment. The accuracy and sensitivity of ultrasound in the diagnosis of appendicitis was estimated, and the findings on appendectomy were used as the gold standard.aage, sex, clinical diagnosis, intra-operative findings, ultrasound results, histological results were collected and analysis performed using SPSS version 15 ( Illinois, Chicago, USA). P-values less than 0.05 were accepted as significant. Corresponding author: Dr Bello Temitope O Department of Radiology Ladoke Akintola University, Ogbomosho. A total of 43 patients qualified for inclusion in this study, the mean age was 21.9 ±9.51yrs. Ultrasound correctly diagnosed edema of the appendix in all 24 patients, presence of faecolith or periappendiceal fluid in 6 and 8 patients respectively and one patient demonstrated appendiceal mass. The MOD of the appendix ranges from 6 to 17 mm (mean 9.91mm ±3.21) and 37% of appendix with MOD above 10mm had appendicitis. Ultrasound diagnosed 24 true positive, and 18 false negative, given a sensitivity of 57 %. Ultrasound is a good adjunct in the clinical diagnosis of equivocal appendicitis. Keywords appendicitis, graded compression ultrasound Introduction Acute appendicitis is the commonest acute surgical condition in the developed world and 1,2 has an overall mortality of about 1%. It is also the most common surgical condition in the third world, and the cost of investigation and prompt therapy may be out of reach of the 3 patients resulting in higher mortality. It has also been established that acute abdominal pain is a common presentation of children seeking medical care. Suspected acute appendicitis is the most common condition requiring abdominal surgery in the paediatric population and must be differentiated from other similar 4 conditions. Occasionally, clinical presentations may be confusing, especially in children and older patients. A history of abdominal pain, classically beginning in the periumbilical region and traveling to 12
McBurney's point, combined with leucocytosis and other associated symptoms such as 5 anorexia remains the best diagnostic clue. Diagnosis of appendicitis is mainly clinical but usually supported with laboratory and radiological diagnosis. There is a need to reduce the frequency of unnecessary appendectomy which has been estimated to be between 10 and 3 0 %. T h i s i m p l i e s m o r e d e t a i l e d investigations to identify the cause of abdominal pain, such as abdominal ultrasound, and Computerised tomographic scan. However, ultrasonography offers the advantages of affordability, ionizing radiation free, and portability. It is often the first imaging test in the evaluating patients with suspected 6 appendicitis. This reports summarized the sensitivity, and positive predictive values of ultrasonography in the diagnosis of acute appendicitis in various age groups. Methodology This a prospective cross sectional study of patients with suspected acute appendicitis carried out at the Al-Hawra General Hospital, in the Tabuk Region of the kingdom of Saudi- Arabia over a 20-month period spanning from August 2009 to March 2011. Patients with suspected appendicitis were evaluated by the consultant general surgeon and cases that were diagnosed to be acute or subacute appendicitis, or complicated or equivocal appendicitis were sent for ultrasonography. Out of the 431 patients with suspected appendicitis, only 43 qualified for this study. The 43 patients had open appendectomy, graded compression ultrasonography and specimen histology. The Radiologist performed a graded compression ultrasonography with a LOGIC 400 OK (GE,Phillips, USA) ultrasound machine using a 8-14 MHZ linear probe. Criteria considered for the diagnosis of appendicitis included non-compressible appendix and measured maximal outer 13 diameter of greater than 6 mm, edema of the appendix, presence of faecolith, periappendiceal fluid collection and mesenteric lymphadenopathy. The ultrasound results were classified as diagnostic and non-diagnostic. Open appendicectomy under general anesthesia were done for the patients. The intraoperative findings of the appearance and thickness of the appendix, presence of periappendicial fluid and pus were documented. Histopathological assessments were done at the histopathological department at the King Khalid Hospital Tabuk. The age and sex of patients were obtained from the case notes, and analysis of data was performed using SPSS for Windows (version 15 0). P-values less than 0.05 were accepted as significant. Results The study comprise of 43 patients, 33 males and 9 females, the ages ranged from 5 to 44years (mean age 21.9 ±9.51). The mean for the males is 23.7 years and 20.09 yrs for females. Figure 1: Ultrasound demonstrated marked thickening of the appendix (small white arrow) and peri-appendiceal fluid collection (big white arrow) Ultrasonography (US) correctly diagnosed appendicitis in 24 patients, but not in 19 patients (Table 1). The US findings included oedema of the appendix in 24, presence of
faecolith or periappendiceal fluid in 6 and 8 patients respectively and a finding of an appendiceal mass. (Table 2 and figure 1) Table 1: Test of Accuracy of ultrasonography compared with Histology appendicitis cases diagnosed as reactive lymphoid hyperplasia on histology; however all cases of perforated ruptured appendix were diagnosed correctly (Table 3). Also there was no significant difference in diagnostic accuracy of US in both sexes ( P value 0.652, ) Table 3: Ultrasound dignosis and histological diagnosis The maximal outer diameter of the appendix ranges from 6 to 17 mm ( mean 9.91mm ±3.21) Fifteen percent of patients with diameter of the appendix below 10mm had appendicitis, as compared to 37% of patients with appendix diameter greater than 10mm. (Table 2) Table 2: Ultrasound features of inflammed appendix The reference standard for the diagnosis of appendicitis was histology. Forty two (42) out of the 43 patients were diagnosed as appendicitis on histology, out of which ultrasound correctly diagnosed 24 true positive, 0 false positive, 18 False negative, and 1 true negative. Therefore, this study showed that ultrasound specificity and sensitivity for the diagnosis of acute appendicitis is 100% and 57 % respectively. The accuracy of ultrasound is 58%. US was not diagnostic in any of the Discussion Ultrasonography features of acute appendicitis are visualization of non compressible blind ended loop without peristaltic movement, thickened wall more than 6mm,increased echogenicity of the peri-appendiceal fat, presence of appendicoliths and appendiceal 7 mass. There are many disease states that can mimick acute appendicitis such as Urolithiasis, salpingitis, torsion of ovarian cyst etc. Due to its many modes of presentations there is need for diagnostic aids to assist the surgeons in making accurate diagnoses. The most widely used modalities are CT scan, Ultrasonography and Laparoscopy. Ultrasonography is usually the first imaging modality of choice because of its simplicity, availability, and absence of ionizing radiation. It is also non-invasive, portable, and the cost is modest and within reach of the average income earner; however, it is of limited use in obese and it is highly user- 6,8 dependent.. The presence of gas in the abdomen and unusual location of appendix 9 limits its sensitivity and specificity. However cost analysis had suggested that pelvic ultrasound for suspected appendicitis is 8,10 justified in most cases. Diagnosis of acute appendicitis is not always 14
Comparison between surgeon's clinical jugdement and Diagnostic aids. Emr Surg 1997;163:433-43. 18. Preeyacha Pachan, Jm Ying, Lean E, Linan M D, S. A. Sonography in the evaluation of Acute appendicitis.. J Ultrasound Med 2010;29:1749-55. 15
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