International Journal of Advanced and Integrated Medical Sciences

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Diagnostic Accuracy of Ultrasonography in Cases ofAcute Appendicitis
  IJAIMS
ORIGINAL ARTICLE
Diagnostic Accuracy of Ultrasonography in Cases ofAcute Appendicitis
1Vaibhav Kumar, 2Gaurav Sharma, 3Akhita Singhania, 4Saherish Khan, 5Pooja Singhania, 6Shraddha Singhania
1,2Assistant Professor, 3,4Resident, 5,6Consultant
1Department of Radio-diagnosis, Saraswati Institute of MedicalSciences, Ghaziabad, Uttar Pradesh, India
2-6Department of Radio-diagnosis, Datta Meghe Institute ofMedical Sciences, Wardha, Maharashtra, India
Corresponding Author:
Shraddha Singhania, ConsultantDepartment of Radio-diagnosis, Datta Meghe Institute of MedicalSciences, Wardha, Maharashtra, India,
Phone: +919373373348
e-mail: drshraddhasinghania@hotmail.com
10.5005/jp-journals-10050-10070
 
ABSTRACT
Aims and objectives: To evaluate the accuracy of ultrasonographyin the diagnosis of various pathologies of the appendixand to compare the findings of ultrasonography with surgicaloutcome.
Materials and methods: All the patients suspected of appendicitisclinically were referred for ultrasonography. The accuracyof ultrasonography in the diagnosis of appendicitis wascompared with surgical outcome.
Results: Out of 50 cases who underwent ultrasonography,37 cases were sonographically positive for appendicitis and13 cases were appendicular masses. Right iliac fossa tenderness,rebound tenderness, and Rovsing's sign were the cardinalsigns. The overall specificity and sensitivity were 95% in thediagnosis of acute appendicitis.
Conclusion: Ultrasound is the first-line method in patientsreferred with clinically suspected acute appendicitis and iscost-effective and reduces the cost of treatment of expensiveprocedures like exploratory laparoscopy and computed tomographyabdomen.
Keywords: Accuracy, Acute appendicitis, Diagnosis,Ultrasonography.
How to cite this article: Kumar V, Sharma G, Singhania A,Khan S, Singhania P, Singhania S. Diagnostic Accuracy ofUltrasonography in Cases of Acute Appendicitis. Int J Adv IntegMed Sci 2017;2(1):32-36.
Source of Support: Nil
Conflicts of Interest: None
 
 

INTRODUCTION

Acute appendicitis is the most common cause for acuteabdominal emergency surgery. The vermiform appendix,though a vestigial organ, poses a great diagnostic challengeto both surgeons and radiologists. The decision forsurgical intervention is still primarily based on preciseclinical criteria. Acute appendicitis is a common cause ofabdominal pain for which prompt diagnosis is rewardedby a marked decrease in morbidity and mortality. It isgenerally accepted that in men the negative appendectomyrate should be below 20% and rates of 10 to 15% arecommonly reported.1,2 On the contrary, young womencommonly present with acute gynecological illnessesthat closely mimic acute appendicitis. Reported negativeappendectomy rates in ovulating women thus remaindisturbingly high and range from 34 to 46%.3,4 Accuratediagnosis in a patient with an acute abdomen is essentialfor the following reasons:
  • In total population, there is at least 7% lifetime chanceof suffering from acute appendicitis.5
  • Appendiceal and other rupture incidents account for17 to 40% morbidity, perforation rate being higher inthe elderly and the very young.6
  • Lack of early diagnosis results in perforation andcomplications, such as abdominal abscess, woundinfection, and death.7

 
Despite technological advances, diagnosis of acuteappendicitis is still based primarily on history and clinicalexamination. The routine laboratory examination ofblood and urine is mandatory. Leukocytosis with a "shiftto the left" is useful but nonspecific. Plain abdominalradiographs have an overall accuracy of only 8%. Theradiographic signs are nonspecific. Though the accuracyof barium enema examination is between 50 and84%,8,9 the findings are often negative even when thereis appendiceal perforation or formation of an abscess. It istime consuming, uncomfortable for patients, and entailsionizing radiation.

Helical computed tomography (CT) has reported asensitivity of 90 to 100%, specificity of 91 to 99%, accuracyof 94 to 98%, positive predictive value (PPV) of 92 to98%, and negative predictive value of 95 to 100% for thediagnosis of acute appendicitis. These results are comparablewith those achieved by experienced investigators,who have used thin section conventional and contrastenhancedCT, and is superior to the recently reportedclinical accuracy.10,11 However, the radiation hazard, lackof easy availability, and cost are still major problems inits routine use for investigating appendicular pathology.

There have been numerous publications on the useof ultrasound (US) as a diagnostic tool. These studiesdemonstrate a sensitivity of 75 to 94% and specificity of 87to 96%.8,9 Several prospective studies have been conductedwhere the results of ultrasonography (USG) were usedas an aid for surgeons in making an operative decision.Ultrasound is the most important bedside tool for investigatingappendicular pathologies because of its easy availability,relatively low cost, and no radiation hazard. It isvery important to exclude the nonappendicular pathologyand give an accurate diagnosis since it helps in managementdecision and planning the surgery when needed.

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Diagnostic Accuracy of Ultrasonography in Cases of Acute Appendicitis

AIMS and OBJECTIVES

This study was conducted to evaluate the diagnosticaccuracy of US in pathologies of the appendix. The studywas based on the presumption that an accurate diagnosishelps to reduce high negative appendectomy rates,unnecessary delay in the surgery and hence, the chancesof complications, and thereby benefit affected patients.

MATERIALS AND METHODS

The study was conducted on 50 patients, referred fromsurgical services for suspected appendicular pathology.Ultrasonography was performed with high-frequencylinear array transducer and low-frequency curvilineartransducer, wherever needed. The examination wascommenced from right upper quadrant in the region ofthe hepatic flexure followed by the ascending colon andended in the right lower quadrant in the region of thececum. Graded compression was applied until the iliacvessels and psoas muscles were clearly visible.

Scanning at the point of maximum tenderness wasfound to be more useful in localizing appendix and hasbeen reported to decrease the average time of examinationby one third. When the patient can localize one pointof maximum tenderness, US has been reported to yield acorrect diagnosis in 94% of the cases, whether the diagnosisis that of appendicitis or not. This also applies tocases where the portion of the appendix adjacent to thececum is normal and only the tip or the distal portion ofthe appendix is inflamed. Ultrasonography has also beenfound to be useful in elucidating alternative diagnoses.

In patients with significant abdominal guarding orextreme discomfort, gradual application and release oftransducer pressure was useful in ensuring the adequacyof examination. Asking the patient to flex their lowerextremities at hips and knees facilitated the examinationby decreasing the abdominal tension. Analgesics werefound to be useful in accomplishing a successful and apainless examination by Larson et al.12

Since appendix has a variable position, it may notalways be visible from an anterior approach; lateral orposterolateral scanning is thus useful and recommendedin all examinations. This technique demonstrates anotherwise nonvisible retrocecal appendix. Scanning bothwith full and empty urinary bladder may allow easiervisualization of an otherwise hidden appendix.

 
Apart from right iliac fossa, the entire abdomen is examinedto exclude disease of the gallbladder, pancreas, kidney,aorta, stomach, small and large bowel, uterus, and ovaries.

The presence of free air is excluded by turning thepatient in the left decubitus position, which allows air toaccumulate between the liver and lateral abdominal wall.

In women, a full bladder allows a better survey ofthe uterus and ovaries. Transvaginal US is helpful indiagnosing gynecological disease.

Interpretation

Our prospective real-time US assessment of the appendixand of inflammatory changes in the right lower abdominalquadrant was based on a set of criteria derived from reportsin the literature:13,14 Enlarged appendix, lack of compressibilityof the appendix, inflammatory changes in perientericfat in the right lower quadrant, cecal wall thickening,right lower quadrant lymph nodes, and peritoneal fluid.The appendix was considered enlarged when its outeranteroposterior diameter under compression, measuredin the transverse plane, was 6 mm or larger. Inflammatorychanges were defined as the presence of an area of regionallyincreased echogenicity (hyperechoic halo) adjacent toor surrounding the distal ileum wall, cecum, or appendixthat possibly contained ill-defined hypoechoic zones. Alymph node in the right lower quadrant was consideredclinically important when it measured 5 mm or larger atits smallest diameter.15 Cecal wall thickness from the outerwall to luminal surface was measured on transverse sectionsunder compression,16 and thickening were definedas when the cecal wall measured 5 mm or larger.

If the appendix is not visualized or if a nonappendicularpathology is discovered, the scan was consideredas normal, for diagnosis of appendicular pathology forthis study.

OBSERVATION AND RESULTS

The maximum incidence of appendicular pathologieswas noted in the age group of 21 to 30 years. Theyoungest patients was 7 years and the eldest was85 years. Addis et al10 reported similar findings. The mostcommon appendicular pathology detected was acuteappendicitis. Complications of acute appendicitis likeperforation, appendicular mass, or abscess were notedin 13 (26%) patients (Table 1). The most common positionof the appendix was found to be retrocecal, followedby pelvic. The minimum diameter noted was 5.5 mmand maximum was 17 mm, the average being 11.5 mm.Jeffrey et al17 and Rao et al18 reported similar findings andconcluded that diameter of appendix >6 mm is the mostimportant criteria in diagnosing acute appendicitis. Thelayered architecture of the appendix was preserved in allcases of acute nonperforated appendicitis (Figs 1 and 2).However, in cases of perforated appendicitis and appendicularabscess, focal loss of the layered architecture wasnoted in 11.90% patients. Similar findings were noted byBorushok et al.19 In cases of nonperforated acute appendicitis,the appendix was found to be noncompressible inall cases. This has been postulated as an important criteriain diagnosing acute appendicitis by Rioux.20 In cases ofreactive inflammation of appendix, compressibility wasseen in 50% patients. Fecoliths were noted in 25.92% casesof acute nonperforated appendicitis and in 28.57% cases ofappendicular perforation. Similar findings were reportedby Horrow and White.21 They reported that appendicolithoccurred in 36% patients, more often in perforated appendicitis(49%) than in nonperforated appendicitis (27%). Theinflammation of cecum and/or terminal ileum was seenmore in cases of complicated acute appendicitis (61.53%)than in nonperforated acute appendicitis (14.81%). Horrowand White21 reported cecal thickening in 41% of perforatedappendicitis and 24% of nonperforated appendicitis.

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Vaibhav Kumar et al

Table 1: Pathologies found on USG
Diagnostic Accuracy of Ultrasonography in Cases of Acute Appendicitis

Diagnostic Accuracy of Ultrasonography in Cases of Acute Appendicitis
Fig. 1: Ultrasonography revealed inflamed appendix withblind-ended loop

Diagnostic Accuracy of Ultrasonography in Cases of Acute Appendicitis
Fig. 2: Ultrasonography revealed appendix giving target sign

 
Mesenteric inflammation was noted in 37.03% of casesof acute nonperforated appendicitis and in 84.61% ofcases of complicated appendicitis. Broushok et al19 alsoconcluded that inflammatory changes in periappendicealfat tend to be more severe in the perforated group.

In the nonperforated acute appendicitis, small fluidcollections were noted in 37.03% cases (Fig. 3). In cases ofappendicular perforation and abscess, free fluid was seenin all the cases and larger in amount. In appendicularlump, free fluid was noted in 50% cases. Borushok et al19have also noted similar findings.

Enlarged regional lymph nodes were noted in 14.81%of cases, slightly more in complicated appendicitis thanin nonperforated appendicitis.

DISCUSSION

A set of 50 patients with clinically suspected appendicularpathology were studied with abdominal USG.Sonographic findings were correlated with the intraoperativefindings.

Diagnostic Accuracy of Ultrasonography in Cases of Acute Appendicitis
Fig. 3: Ultrasonography revealed inflamed appendix withperiappendix collection

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Diagnostic Accuracy of Ultrasonography in Cases of Acute Appendicitis

Out of the 50 patients, age of the young patient was 7years and age of the oldest patient was 85 years. Maximumnumber of patients suffering from some pathology of theappendix belonged to 21 to 30 years age group. Out of 50patients, 30 were male and 20 patients were female, maleto female ratio being 1.5:1. The most common pathologydetected was acute nonperforated appendicitis (27 cases),followed by appendicular perforation (7 cases), recurrentappendicitis (8 cases), appendicular abscess (4 cases),appendicular lump (2 cases), and reactive inflammationof appendix (2 cases). Out of 50 patients who have oneof the appendicular pathologies, USG was detected correctlyin 42 patients (sensitivity 86.86%, PPV 98.85%).These findings are almost similar to the results from thestudy done by Puylaert et al22 Abu Yousef et al.8 Out of30 surgically proven cases of acute appendicitis (withoutcomplications), USG diagnosed it correctly in 27 patients(sensitivity 95%, PPV 100%). The diagnosis was missed inthree cases. Out of seven cases of appendicular perforation,US gave a correct diagnosis in six cases (sensitivityand PPV 92.85%). The USG missed the perforation inone case. Out of four cases of appendicular abscess, USGdiagnosed correctly in all four cases (sensitivity and PPV100%). Out of two cases of appendicular lump, USG gavea correct diagnosis in both cases. Reactive inflammationof appendix was correctly diagnosed by USG in one case.Out of 42 cases of appendicitis, complications like perforation,abscess, or lump were detected in 15 cases. Theoverall incidence of complicated appendicitis was thus35.71%. Of these 15 cases, USG gave a correct diagnosisin 13 (PPV 96.15%). Korner et al23 reported perforationrate of 19 to 35% in cases of acute appendicitis. In all theeight cases of recurrent appendicitis, patients underwentUS examination in the relatively symptom-free period,and USG could not give the diagnosis in any case. Thediagnosis was confirmed on interval appendicectomy.The most important factor for diagnosing appendicularpathology was found to be the direct visualization of theappendix. The appendix was visualized in 42 patients.The two most accurate appendiceal findings for acuteappendicitis were a diameter of 6 mm or larger and a lackof compressibility. These two criteria show 100% sensitivityand 100% PPV for acute nonperforated appendicitis.Jeffrey et al17 and Rao et al18 reported similar findingsand concluded that diameter of appendix >6 mm is themost important criteria in diagnosing acute appendicitis.Noncompressibility has been postulated as an importantcriteria in diagnosing acute appendicitis by Rioux20and Jeffrey et al.17 However, for acute appendicitis withcomplications, the diameter criteria revealed sensitivityvarying from 57.14 to 93.75% and PPV varying from66.6 to 100%. Noncompressibility showed sensitivity from50 to 81.25% in complicated appendicitis.

 
The round shape of the inflamed appendix withlayered structure constitutes the so-called target sign.It showed 100% sensitivity and PPV. In cases of appendicularperforation, focal loss of this layered structureis an important sign with a high PPV (100%); however,it is not very sensitive (43.75% in appendicular abscess).Similar findings were noted by Borushok et al.19 Presenceof appendicolith is an important criterion; however, it isnot very sensitive. Fecoliths were noted in 25.92% cases ofacute nonperforated appendicitis and in 28.57% cases ofappendicular perforation. Similar findings were reportedby Horrow and White.21 They reported that appendicolithoccurred in 36% patients, more often in perforated appendicitis(49% than in nonperforated appendicitis [27%]).Periappendiceal fat inflammation has high PPV of 84.61%;however, the sensitivity was low (37.31%) in acute nonperforatedappendicitis. In complicated appendicitis, thesensitivity was higher (87.5 to 100%). Borushok et al19 alsoconcluded that inflammatory changes in periappendicealfat tended to be more severe in the perforated group.Inflammatory thickening of the cecum and/or terminalileum also revealed similar results. It has low sensitivityfor acute nonperforated appendicitis (14.81%) and highersensitivity (61.53%) noted for complicated appendicitis.Horrow and White21 reported cecal thickening in 41%of perforated appendicitis and 24% of nonperforatedappendicitis. The presence of free/loculated intraperitonealfluid revealed very high sensitivity for appendicularperforation and abscess (100%). Sensitivity was 50% forappendicular lump and 37.03% for acute nonperforatedappendicitis. Puylaert et al22 and Borushok et al19 havealso noted similar findings. The presence of enlargedmesenteric lymph nodes showed low sensitivity (14.81%)for acute nonperforated appendicitis. Variable sensitivity(43.75 to 100%) was noted for complicated appendicitis.Kessler et al24 have reported lymphadenopathy in 32%cases of appendicitis.

In reactive inflammation of the appendix, all thesecriteria are neither sensitive nor specific. When present,they do help in diagnosis. Usually, the primary pathologyis obvious and the visualized appendix does not fulfillthe criteria for acute appendicitis. Appendicolith was notvisualized in all of these cases.

CONCLUSION

Ultrasonography has high sensitivity and specificityin the detection of various appendicular pathologies.The overall accuracy of US in diagnosing appendicularpathology was found to be 95%. Direct visualization ofthe appendix is the most important criteria in diagnosingany appendicular pathology. In acute nonperforatedappendicitis, a diameter of 6 mm or larger and lack ofcompressibility were the most sensitive and accuratecriteria. However, the periappendiceal findings like mesentericand cecal inflammation, the presence of free intraperitonealfluid, and regional lymphadenopathy havelow sensitivity. When present, these findings increasethe confidence in diagnosis.

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Vaibhav Kumar et al

In appendicular perforation, focal loss of the layeredstructure of the appendix is very specific, but it is notvery sensitive. Instead, the presence of free fluid has bothhigh sensitivity and PPV. The periappendiceal findingslike mesenteric and cecal inflammation and regionallymphadenopathy were also seen more commonly incomplicated appendicitis.

In recurrent appendicitis USG is highly sensitive inthe acute phase; however, in the symptom-free period,it loses sensitivity.

In conclusion, this study showed that USG has a highdegree of accuracy in diagnosing various pathologies ofthe appendix. It is thus recommended that US should beconsidered as an important modality in patient evaluationin all clinically diagnosed cases of acute appendicitisand in doubtful cases for a better management decisionand patient care.

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