A Clinical Study of Acute Appendicitis and Role of Ultrasonography in Its Diagnosis

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108 A Clinical Study of Acute Appendicitis and role of Ultrasonography in its Diagnosis Nisar Ahmad Shah, MS; Mumtaz-ud-Din Wani, MS; Shahnawaz Ahangar, MS; Umar Kirmani, MD; Yasmeen Jan, MBBS; Abdul Munnon Durrani, MBBS; Mohammad Idrees Bashir, MBBS and Nusrat Jehan, DGO ABSTRACT Acute appendicitis is the commonest cause of acute abdomen and subsequent surgery. The diagnosis is essentially on clinical grounds and as a result misdiagnosis is a common and crucial problem in general surgery. Gra
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  108 Shah NA et al. Clinical study and USG in Appendicitiswww.physicians-academy.comPhysicians Academy October 2010 vol 4 no 10   A Clinical Study of Acute Appendicitis and role of Ultrasonography in its Diagnosis Nisar Ahmad Shah, MS; Mumtaz-ud-Din Wani, MS; Shahnawaz Ahangar, MS; Umar Kirmani, MD;Yasmeen Jan, MBBS; Abdul Munnon Durrani, MBBS; Mohammad Idrees Bashir, MBBS and NusratJehan, DGO ABSTRACT Acute appendicitis is the commonest cause of acute abdomen and subsequent surgery. The diagnosisis essentially on clinical grounds and as a result misdiagnosis is a common and crucial problem ingeneral surgery. Graded compression ultrasonography is one of the diagnostic techniques that arereported to decrease the negative surgical interventions, especially in females. The aim of the presentstudy was to assess the sensitivity and specificity of high resolution of ultrasonography in thediagnosis of acute appendicitis. We prospectively studied two hundred successive patients admitted inour emergency department with the clinical suspicion of acute appendicitis. All 200 patients of suspected acute appendicitis were subjected to high resolution graded compression ultrasonography.Out of these 200 patients, ultrasonography accurately diagnosed 107 (53.8%) patients with acuteappendicitis which were later confirmed on laparotomy and subsequent histopathological examination,12 patients were falsely interpreted as negative and 4 were falsely interpreted as positive. In 74(37%) patients alternative diagnosis was provided. Thus the sensitivity of the diagnostic tool was90%, specificity 94.87%. The predictive value of positive results was 96.40%. Predictive value of negative results was 86.05% and over all accuracy was 91.88%. Hence we reach to the conclusionthat the transcutaneous abdominal ultrasonography in a patient with a clinical diagnosis or suspicionof acute appendicitis has 90% sensitivity and 94.8% specificity. INTRODUCTIONVermiform appendix though described–anatomically to be vestigial, is one of the mostimportant surgically concerned organs in the human body. There are many pathologicalconditions involving appendix and acute appendicitis is the commonest one. It can presentat all ages, although it occurs more frequently during the 2nd and 3rd decades of life. Theoverall lifetime risk of developing appendicitis is estimated to be of 7%. It is easy todiagnose typical cases of this disease, but atypical cases prove to be a very great diagnosticchallenge for a clinician. This resulted in negative appendicectomy rate of 20 to 30% andhas been considered acceptable; but even removal of a normal appendix carries a definitemorbidity. High resolution; graded compression ultrasound has been reported to be usefulfor the diagnosis of appendicitis. The ultrasound in the diagnosis of acute appendicitis wasfirst popularized by Puylaert in1986. In graded compression technique, uniform pressure isapplied in right iliac fossa by a hand held ultrasound transducer. Whenever needed endovaginal probe was used. Normal and gas filled loops of intestine are either displaced fromthe field of vision or compressed between anterior and posterior abdominal walls. Inflamedappendix being incompressible is thus optimally seen as a blind-ended tubular structurewith laminated wall arising from the base of cecum. It is aperistaltic, noncompressible andits diameter should be more than 6mm. Appendicoliths appear as bright echogenic foci withdistal acoustic shadowing, and their visualization is another contributory finding. Similarlythere may be increased echogenicity of the periappendiceal fat. In this study weinvestigated the role of high resolution ultrasonography (USG) in the diagnosis of acuteappendicitis and record its sensitivity and specificity.PATIENTS AND METHODSThe study cohort consisted of successive two hundred patients admitted with the clinicalsuspicion of acute appendicitis. Subsequent to hospital admission all patients underwentthorough physical examination and routine lab exams. Pre ultrasound clinical diagnosis wasmade based on medical history, physical examination as well as laboratory findings. Realtime, high resolution (5 MHz, 7.5 MHz) graded compression ultrasound examination wasperformed by a senior radiologist after a clinical diagnosis was made. The definite decisionregarding therapy was made after ultrasound examination. A primary criterion for thediagnosis of appendicitis was demonstration of a non-compressible appendix with anteroposterior > 6mm. Other criteria were peri-appendiceal fluid collection, presence of fecolith,compressibility and target sign. Sonographic films were taken and findings were recorded.  109 Shah NA et al. Clinical study and USG in Appendicitiswww.physicians-academy.comPhysicians Academy October 2010 vol 4 no 10   Surgical outcome of all patients was recorded separately. Definitive diagnosis was based onhistopathological examination. The following were the indications of surgery in patients withsuspected acute appendicitis. ã   Definite clinical signs of appendicitis with positive USG for acute appendicitis. ã   Equivocal clinical signs and symptoms with positive ultrasound scans. ã   Definite clinical and laboratory evidence with negative ultrasound scans.RESULTSAge: 56.07% cases were recorded in the age group of (20-40), followed by 29.91% cases in(0–20) years while as only 13.08% and 0.94% cases were in the age group of (40–60) andabove 60 years respectively.Sex distribution: Majority of our patients were males as against females (60.75% vs39.25%).Presenting symptoms: Pain in the right lower quadrant of abdomen was the most commonpresenting symptom. Final clinical diagnoses following ultrasound performance in the 200 patientsincluded in the study (Table 1)Diagnosis Number (%) Acute appendicitis 107 (53.5)Abdominal pain of unknown srcin 37 (18.5)Right Nephrolithiasis 10 (05)Pelvic Inflammatory Disease 4 (02)Right Ovarian Cyst 6 (03)Mesenteric adenitis 3 (1.5)Worms in gut lumen 4 (2)Acute cholecystitis 3 (1.5)Acute Pyelonephritis 2 (01)Right Ureteric Calculus 1 (0.5)Right Hydronephrosis 1 (0.5)Thickened Bladder Wall with acute cystitis 1 (0.5)Live Intrauterine Foetus with Right Ovarian Cyst 1 (0.5)Appendicular Lump 1 (0.5)Non diagnostic 19 (9.5) Total 200 (100) Table 1: Showing final clinical diagnoses following ultrasound evaluation Distribution of Anterior Posterior Diameter of appendix on USG (Table 2)Antero posterior (mm)   Appendicitis  < 6 mm 39 (19.50%)6 – 10 mm 118 (59.00%)> 10 mm 43 (21.50%)Table 2: Showing distribution of Anterior Posterior Diameter of appendix on USG  110 Shah NA et al. Clinical study and USG in Appendicitiswww.physicians-academy.comPhysicians Academy October 2010 vol 4 no 10   Other Features of Appendicitis on USG (Table 3) Finding No. of PatientsCompressibility 70Target Sign 8Faecoliths 7Peri appendicular fluid 10Free Fluid in Pelvis & Peritoneal Cavity 22Table 3: Ultrasound findings other than AP diameter Final Diagnosis on Exploration and subsequent Histopathological examination(Table 4)Diagnosis No. of Cases Catarrhal Appendicitis 93Perforated Appendicitis 22Gangrenous Appendicitis 04DU Perforation 01Mesenteric Adenitis with normal appendix 02Spontaneous Bacterial Peritonitis 01Table 4: Showing final diagnosis on exploration and HPE examination Reliability of Diagnostic tool. (Table 5)Sensitivity, Specificity, Predicative value of positive results, predicative value of negative results and overall accuracy of USG.Measurement   Percentage  Sensitivity 90.00%Specificity 94.87%Positive Predictive value 96.40Negative Predictive value 86.05%Accuracy 91.88%Table 5: Sensitivity and specificity of USG Prediction of perforation preoperatively by ultrasound (Table 6)Free Fluid on USGAppendicitis withPerforationAppendicitis withoutperforation 19 0 903 17 0Table 6: USG as a predictor of appendicular perforationDISCUSSIONDespite being one of the most frequent diagnoses among surgical emergencies, acuteappendicitis continues to pose significant diagnostic problems. The diagnosis of acuteappendicitis in most cases is based on clinical history and physical exploration. 1,2 Amongyoung male patients the negative appendicectomy rate is relatively low while for women of childbearing age the figure may be as high as 30-50% 3-5 . The difficulty of diagnosing acuteappendicitis in old age is reflected by the high incidence of perforation, 60-90% in manyreports rather than by a high rate of negative appendicectomy 2,6 . Diagnosis is also difficult  111 Shah NA et al. Clinical study and USG in Appendicitiswww.physicians-academy.comPhysicians Academy October 2010 vol 4 no 10   during pregnancy and may result in both maternal and fetal mortality. Appendicitis is agreat leveler in surgery, an antidote to diagnostic complacency. The problem arises becausepatients presenting with acute right iliac fossa pain may have acute appendicitis, whichrequires surgery, or some other cause of pain, which may not. The surgeon resolves thedilemma in one of two ways: by observation until the signs and symptoms make thediagnosis more obvious or by immediate operation. As the incidence of perforation is usuallyproportional to the duration of the disease process, traditional teaching has encouragedsurgeons to operate even when the diagnosis is probable rather than wait until it is certain.This teaching has been challenged by some who have shown that intensive observation inhospital can decrease the incidence of negative appendicectomy without increasing the rateof perforation. Prolonged observation is, however, not an ideal solution as it is expensive tothe health services. Furthermore, no one can be sure how many of these patients in facthave appendicitis which resolves spontaneously under observation only to recur at a laterdate.The morbidity and mortality rates associated with appendicitis are greatly increased whenperforation ensues wound infection rates may treble, intra abdominal abscess formationincreases 15-fold and mortality may be 50 times greater. Appendiceal perforation can alsocause tubal infertility 8 . It is therefore obvious that the aim of the surgeon must be toprevent perforation at any price. The price is the high rate of removal of a histologicallynormal appendix, which is not inexpensive as it carries with it a complication rate not muchlower than that after removal of a pathological appendix. The operation of negativeappendicectomy is accompanied by the usual spectrum of immediate postoperativecomplications in up to 15% of patients. Some patients may even die after negativeappendicectomy because of associated comorbid conditions. Additional patients may sufferlate complications such as intestinal obstruction, incisional hernias and sterility due tofimbrial adhesions 9,10,11,12 . It appears, therefore, that surgeons have chosen for themselvesa surgical security zone which allows them to accept a 15-30% negative laparotomy ratewith impunity.All 200 patients of suspected acute appendicitis were subjected to high resolution gradedcompression USG. Out of these USG accurately diagnosed 107 (53.8%) patients with acuteappendicitis which were later confirmed on laparotomy and subsequent histopathologicalexamination, 12 patients were falsely interpreted as negative and 4 were falsely interpretedas positive. In 74 (37%) patients alternative diagnosis was provided. TotalPatientsProvenAcuteAppendicitisS O N O G R A P H YTrue(+)True(-)False(+)False(-)NonDiagnostic 200 119 107 74 4 12 3Table 7: Results of USG in suspected appendicitisThe variables on USG for diagnosis of acute appendicitis were anteroposterior diameter of appendix, position of appendix, compressibility of appendix, fecoliths, target sign, free fluidaround appendix and in peritoneal cavity. Anterior Posterior Diameter of appendix: Anteroposterior is the only USG sign that is specific for appendicitis on USG (P Vasavada,2004). Sonographic diagnosis of appendicitis can be established with confidence if appendixis visualized with antero posterior diameter measurements consistently 6 mm or greater. If multiple measurements are greater than 5mm but less than 6 mm, the results of theexamination are inconclusive and conservative management with close clinical observationis warranted except in presence of fecoliths and compelling clinical signs.In present study 118 (59.0%) patients AP diameter of appendix using electronic caliperswas 6-10 mm. In 39 (19.5%) patients it was >10mm and in remaining 43 (21.5%) patients
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