The most useful findings for diagnosing acute appendicitis on contrast-enhanced helical CT

PURPOSE: To evaluate the most useful findings to look for in diagnosing acute appendicitis on contrast-enhanced helical CT. MATERIAL AND METHODS: Appendiceal helical CT scans with intravenous contrast administration (abdomen, 7-mm collimation; abdominopelvic junction, 5-mm collimation) of 71 patients with surgically proven acute appendicitis and 167 patients with alternative diagnoses were reviewed retrospectively. Three radiologists analyzed the following parameters: enlarged appendix (>6 mm in diameter), appendiceal wall thickening, appendiceal wall enhancement, no identification of the appendix, appendicolith(s), appendiceal intraluminal air, intramural air, extraluminal air, periappendiceal fat stranding, extraluminal fluid, phlegmon, abscess, lymphadenopathy, segmental terminal ileal wall thickening, focal cecal apical thickening, focal colonic wall thickening, and segmental colonic wall thickening. The features that best distinguished appendicitis from alternative diagnoses were selected with stepwise logistic regression analysis. RESULTS: Nine CT findings distinguished acute appendicitis from alternative diagnoses (P < 0.05): enlarged appendix (R = 0.739), appendiceal wall thickening (R = 0.525), periappendiceal fat stranding (R = 0.414), appendiceal wall enhancement (R = 0.404), focal cecal apical thickening (R = 0.171), appendicolith(s) (R = 0.157), extraluminal air (R = 0.050), intramural air (R = 0.043), and phlegmon (R = 0.030). Enlarged appendix (sensitivity, 93%; specificity, 92%), appendiceal wall thickening (sensitivity, 66%; specificity, 96%), periappendiceal fat stranding (sensitivity, 87%; specificity, 74%), and appendiceal wall enhancement (sensitivity, 75%; specificity, 85%) showed the statistically most significant association with acute appendicitis. CONCLUSION: On 5-mm-section contrast-enhanced helical CT examinations, enlarged appendix, appendiceal wall thickening, periappendiceal fat stranding, and appendiceal wall enhancement were the most useful findings for diagnosing acute appendicitis.     

Evaluation of perforated and nonperforated appendicitis with CT

Fifty-three patients with 38 cases of perforated appendicitis and 15 cases of appendicitis without perforation were evaluated based on the computed tomography (CT) appearances of appendiceal diameter, phlegmon, abscess, extraluminal air, appendiceal wall enhancement, lateroconal fascial thickening, appendicolith, bowel wall thickening, ascites, ileal wall enhancement, peritoneal enhancement, periappendiceal fluid, omental haziness, retrocecal appendix, intraluminal air, and the combination of intraluminal air and appendicolith. The result of appendiceal diameter was compared using two-sample Student's t test, and the other CT findings were analyzed by Fisher's Exact Test. Our results showed that appendix was larger in caliber in perforated appendix (P<.05). Direct CT signs (i.e., phlegmon, abscess, and extraluminal air) were more specific for perforated appendicitis (P<.05). Indirect signs (bowel wall thickening, ascites, ileal wall enhancement, intraluminal air, and combined intraluminal air and appendicolith) were also found in higher incidence in appendiceal perforation (P<.05). Appendiceal enlargement and ileal wall enhancement were the two predominant findings in one case of perforation. We concluded that direct and indirect CT appearances can differentiate appendicitis with and without perforation. Indirect signs may be helpful in difficult case.     

穿孔性阑尾炎与非穿孔性阑尾炎的CT鉴别诊断

目的:评价多排螺旋CT对穿孔性与非穿孔性阑尾炎的鉴别诊断价值.方法:搜集手术及病理证实的急性阑尾炎151例,并按照手术及病理结果分为穿孔组(66例)和非穿孔组(85例),总结分析其CT表现,并比较穿孔性与非穿孔性阑尾炎的CT表现.结果:阑尾腔外粪石、阑尾腔外气体、阑尾周围脓肿、阑尾壁局限性强化缺损对诊断阑尾炎穿孔有很高的特异性(P＜0.05),为诊断阑尾炎穿孔的特异性征象;阑尾周围炎、盆腔炎改变在穿孔组发现频率也明显高于非穿孔组(P＜0.05),穿孔组阑尾直径明显大于非穿孔组(P＜0.05),对诊断阑尾炎穿孔有一定价值;阑尾位置、阑尾腔内粪石、阑尾腔内气体、阑尾周围淋巴结肿大在两组中无明显差异(P＞0.05).结论:CT是诊断穿孔性阑尾炎有效、快速的方法,其中阑尾腔外粪石、阑尾腔外气体、阑尾壁局限性强化缺损、阑尾周围脓肿为诊断穿孔性阑尾炎较为特异的CT征象,阑尾周围炎、盆腔炎改变、阑尾直径增大对于诊断阑尾炎穿孔有一定价值.     

Independent predictors of acute appendicitis on CT with pathologic correlation

RATIONALE AND OBJECTIVES: To assess computed tomographic (CT) signs that have been described in published studies for the diagnosis of appendicitis to identify independent findings that predict appendicitis. METHODS AND MATERIALS: A retrospective database search identified 67 patients with a CT scan of the abdomen/pelvis and pathologic evaluation of the appendix, including 41 with appendicitis and 26 with a normal appendix on pathologic examination. Each computed tomogram was re-evaluated by three independent, blinded observers who evaluated appendix diameter, enhancement of the appendix, thickening of the appendix, presence of an appendicolith, infiltration of peri-appendiceal fat, focal cecal thickening, local lymphadenopathy, fluid collections, non-appendiceal bowel thickening, non-periappendiceal infiltration of fat, and comparison of peri-appendiceal fat infiltration to thickening of adjacent bowel loops. RESULTS: Mean diameter of the normal appendix (6.7 +/- 2.2 mm) was significantly lower than that of the inflamed appendix (12.1 +/- 4.3 mm; P < .001). Significant univariate predictors of appendicitis included appendix diameter >8 mm (odds ratio [OR] 34.8), enhancement of the appendix (OR 4.4), thickening of the appendix (OR 4.3), infiltration of peri-appendiceal fat (OR 5.5), focal cecal thickening (OR 5.1), non-appendiceal bowel thickening (OR 0.4), and non-periappendiceal infiltration of fat (OR = 0.3). Of these variables, only appendix diameter and enhancement of the appendix were significant independent predictors of appendicitis on multivariate analysis. An overall diagnostic impression based on all secondary signs was less accurate than a diagnosis based on appendix diameter alone (receiver-operating characteristic analysis: Az = 0.80 vs. Az = 0.91, P = .02). Sensitivity/specificity of appendix diameter was 84%/87% using a cutoff between 8 and 9 mm and 97%/48% using a cutoff between 6 and 7 mm. CONCLUSION: Appendix diameter is the best single diagnostic criterion for appendicitis on CT scan. A cutoff between 8 and 9 mm provided the best balance of sensitivity/specificity in our study population, whereas a cutoff between 6 and 7 mm improved sensitivity at the expense of specificity. The presence of appendiceal enhancement provided additional diagnostic information, but other secondary signs of appendicitis did not improve diagnostic accuracy.     

Primary neoplasms of the appendix manifesting as acute appendicitis: CT findings with pathologic comparison

PURPOSE: To evaluate the computed tomographic (CT) findings in patients with acute appendicitis related to an underlying appendiceal neoplasm. MATERIALS AND METHODS: Clinical and pathologic data obtained over a 10-year period in 65 patients with primary appendiceal neoplasms were reviewed. Preoperative CT studies in patients who presented clinically with symptoms of acute appendicitis were analyzed retrospectively and in consensus by three radiologists. The appendix was evaluated on CT scans for morphology, location, presence of calcification, maximal diameter, and wall thickness. RESULTS: Twenty-six (40%) of the 65 patients with appendiceal neoplasms had presented with symptoms of acute appendicitis. Preoperative CT studies available in 22 patients showed increased appendiceal diameter, wall thickening, and periappendiceal fat stranding in 22 (100%), 22 (100%), and 21 (95%) patients, respectively. The appendiceal diameter was greater than 15 mm (mean diameter, 2.9 cm) in 19 patients (86%). Morphologic changes of concern for neoplasm were present in 19 patients (86%) and included cystic dilatation in nine patients and presence of a soft-tissue mass without dilatation in 10 patients. An appendiceal diameter greater than 15 mm and/or a morphologic abnormality were present in 21 of 22 cases (95%). CONCLUSION: CT findings strongly suggest the presence of underlying neoplasm in the majority of patients with secondary appendicitis.     

CT predictors of failed laparoscopic appendectomy

PURPOSE: To identify computed tomographic (CT) signs that may help predict possible failure of laparoscopic appendectomy and subsequent conversion to open appendectomy. MATERIALS AND METHODS: Of 234 consecutive patients who underwent preoperative CT and in whom laparoscopic appendectomy was attempted, 26 required conversion to open appendectomy. Conversion was correlated with the following CT findings: appendix location, appendicolith, cecal wall thickening involving the base of the appendix, lymphadenopathy, and appendiceal diameter. The extent of inflammation was graded by using a six-point scale: 0 meant normal appendix; 1, possibly abnormal appendix (6-mm diameter without other abnormality); 2, abnormal appendix (diameter > or = 6 mm with wall enhancement) without adjacent fat stranding; 3, abnormal appendix surrounded by fat stranding; 4, abnormal appendix surrounded by fat stranding and fluid; and 5, inflammatory mass or abscess. Student t and chi2 tests were used for statistical analysis of interval and nominal values, respectively. RESULTS: Although there was a significant difference in appendiceal diameter between the patients in whom laparoscopic appendectomy was successfully completed (11.3 mm +/- 3.5 [SD]) and those who required conversion (12.9 mm +/- 3.9), no distinct cutoff point was identified. Of the five CT findings evaluated, none was a significant predictor of conversion to open appendectomy. Eleven (7%) of 164 patients with a CT inflammation grade of 0-3 required conversion, whereas 15 (21%) of 70 patients with a grade of 4 or 5 required conversion (P <.04). CONCLUSION: The majority of patients with appendicitis can be treated with laparoscopic appendectomy. Nevertheless, patients who require conversion to open appendectomy tend to have high CT inflammation grades of 4 or 5, which indicate the presence of periappendiceal fluid or an inflammatory mass or abscess.     

Non-Hodgkin's lymphoma of the appendix: clinical and CT findings with pathologic correlation

OBJECTIVE: The purpose of this report is to describe the clinical, CT, and pathologic features of non-Hodgkin's lymphoma of the vermiform appendix. CONCLUSION: Non-Hodgkin's lymphoma of the appendix typically manifests with acute symptoms in patients who have no prior history of lymphoma. Most patients with the disease present clinically with signs and symptoms suggestive of acute appendicitis. On CT, lymphomatous infiltration of the appendix produces markedly diffuse mural soft-tissue thickening (range of diameters, 2.5-4.0 cm; mean diameter, 3.2 cm). The vermiform morphology of the appendix is usually maintained, and aneurysmal dilatation of the lumen is sometimes seen. Stranding of the periappendiceal fat seen on CT may represent superimposed inflammation or even direct lymphomatous extension. Coexisting abdominal lymphadenopathy is not seen in all patients. Although appendiceal lymphoma is rare, the characteristic CT appearance could lead to a preoperative diagnosis.     

CT对不典型阑尾炎的诊断价值

目的探讨CT对症状不典型急性阑尾炎的诊断价值。方法收集临床首诊未考虑阑尾炎,而经手术和病理证实的阑尾炎病例23例,对其CT表现进行观察分析。结果有11例表现为阑尾增粗,肠壁增厚;2例表现为右下腹脓肿;2例盲肠周围可见少量游离气体影;3例女性患者表现为盆腔脓肿;4例表现为盲肠及回肠肠壁增厚,周围渗液;1例伴有小肠梗阻。其中6例阑尾内可见结石。结论 CT能清楚显示阑尾的位置、形态以及周围组织的关系,对不典型阑尾炎的临床诊断,具有较高价值。     

Ultrasonographic findings identifying the faecal-impacted appendix: differential findings with acute appendicitis

The aim of this study was to identify ultrasonographic findings that show the normal faecal-impacted appendix, in order to avoid unnecessary surgery via a misdiagnosis of acute appendicitis. Of 160 patients who underwent ultrasonography between January 2004 and July 2005 for right lower quadrant pain, 22 cases (including 7 cases confirmed pathologically and 15 confirmed clinically and on follow-up ultrasonography) were diagnosed as a normal faecal-impacted appendix. The criteria that we used to distinguish a faecal-impacted appendix from acute appendicitis include preservation of the normal wall layering of the appendix, maximum mural thickness, presence of peri-appendiceal fat infiltration and increased blood flow in the appendiceal wall. The maximum measured outer diameter of a normal faecal-impacted appendix was 0.54-1.03 cm, with a mean diameter of 0.68 cm. The maximum mural thickness ranged from 0.08 cm to 0.26 cm, with a mean thickness of 0.15 cm. The normal wall layers of the appendix were preserved and no evidence was seen of peri-appendiceal fat infiltration in any case. No demonstrably increased blood flow in the appendiceal wall was observed. In conclusion, faecal impaction increases the outer transverse diameter of the normal appendix, frequently leading to a misdiagnosis of acute appendicitis. Recognition of preservation of the normal layering of the appendiceal wall, smaller maximal outer diameter, thinner maximal mural thickness, the absence of peri-appendiceal mesenteric infiltration and no demonstrably increased blood flow in the appendiceal wall should help to prevent unnecessary surgery.     

腹膜假性黏液瘤CT诊断(附21例报告)

目的:探讨腹膜假性黏液瘤的CT表现,提高对本病的认识.方法:搜集经手术、病理证实的腹膜假性黏液瘤21例,回顾性分析其CT表现.结果:21例中原发瘤恶性8例,其中卵巢黏液囊腺癌3例,阑尾黏液囊腺癌4例,结肠黏液腺癌1例;良性13例,其中阑尾黏液囊腺瘤4例,阑尾黏液囊肿2例,卵巢黏液囊腺瘤6例,胰腺黏液囊腺瘤1例.CT平扫见肝脾等实质脏器边缘扇贝样或结节状压迹,腹腔不规则囊实性肿块,CT值19.9～25.8 HU;脏器周围、网膜间隙、腹腔、盆腔见大量黏液性腹水,CT值10～15 HU;腹膜增厚,厚度1.0～2.0 cm;增强扫描显示囊实性病变仅见囊壁、网膜、腹膜轻度强化,囊内病灶无明显强化.结论:腹膜假性黏液瘤CT表现具有一定的特征,是诊断腹膜假性黏液瘤的重要方法.     

Abdominopelvic actinomycosis involving the gastrointestinal tract: CT features.

PURPOSE: To assess the computed tomographic (CT) features of abdominopelvic actinomycosis involving the gastrointestinal tract. MATERIALS AND METHODS: CT scans were analyzed in 18 patients with pathologically proved abdominopelvic actinomycosis involving the gastrointestinal tract. Eight patients had a history of using intrauterine contraceptive devices. Bowel site, wall thickness, length, bowel involvement patterns, inflammatory infiltration, and features of peritoneal or pelvic mass, if present, were evaluated at CT. RESULTS: Of the gastrointestinal tract, the sigmoid colon was most commonly involved (50%). All patients showed concentric (n = 15) or eccentric (n = 3) bowel wall thickening, with a mean thickness of 1.2 cm and a mean length of 8.3 cm. The thickened bowel enhanced homogeneously in nine patients and heterogeneously in the other nine. Inflammatory infiltration was mostly diffuse and severe. In 17 patients, a peritoneal or pelvic mass (mean maximum diameter, 3.2 cm) was seen adjacent to the involved bowel and appeared to be heterogeneously enhanced in most cases; infiltration into the abdominal wall was seen in four patients. CONCLUSION: Actinomycosis should be included in the differential diagnosis when CT scans show bowel wall thickening and regional pelvic or peritoneal mass with extensive infiltration, especially in patients with abdominal pain, fever, leukocytosis, or long-term use of intrauterine contraceptive devices.     

Appendix in children with cystic fibrosis: US features

PURPOSE: To evaluate the ultrasonographic (US) appearance of the appendix in children with cystic fibrosis but who were asymptomatic for appendicitis. MATERIALS AND METHODS: Between March 2001 and March 2002, 31 children (14 boys, 17 girls; mean age, 9.5 years; range, 2-16 years) with cystic fibrosis underwent graded-compression US of the appendix. The recordings were analyzed in consensus by two radiologists specialized in US. The overall appendiceal diameter and change in diameter during graded compression, wall dimensions, contents of material in the lumen, and periappendicular fat were evaluated. The exclusion criterion was abdominal pain at the time of investigation. RESULTS: In all but one patient, the appendix was visualized with US. The diameter of the appendix ranged from 4.0 to 14.5 mm (mean, 8.3 mm). In 25 patients (83.3%), the appendix measured more than 6.0 mm. In six patients, the diameter of the appendix changed when graded compression was applied. Mucoid material was found in the lumen in 27 of 30 patients. No wall thickening occurred, and concentric layer structures of the wall were intact. No involvement of the neighboring mesenteric or omental fat was encountered. CONCLUSION: The appendiceal diameter was enlarged in the majority of children examined. The lumen contained mucoid contents. Therefore, the diameter of the appendix alone may not be a parameter for diagnosing appendicitis in patients with cystic fibrosis.     

Enhanced CT in the diagnosis of acute appendicitis to evaluate the severity of disease: comparison of CT findings and histological diagnosis

PURPOSE: To assess the potential of CT in evaluating the histological severity of acute appendicitis in comparison with surgical and pathological findings. METHOD: The CT images of 75 patients with surgically proven appendicitis, including 10 cases of catarrhal, 34 of phlegmonous, and 31 of gangrenous appendicitis, were retrospectively analyzed for the following five CT findings: (1) hazy periappendiceal densities, (2) enlarged appendix, (3) increased enhancement of the appendiceal wall, (4) increased enhancement of the periappendiceal intestinal wall, and (5) deficiency of the appendiceal wall. By comparing all the CT findings and the pathological severity of appendicitis (catarrhal, phlegmonous, and gangrenous), the prevalence of the five CT findings was calculated for each pathological category. RESULTS: Abnormal CT findings were noted in only one case of catarrhal appendicitis. Increased enhancement of the appendiceal wall was observed in all 29 cases of phlegmonous appendicitis (100%), but in only 66.7% (18 cases) of gangrenous appendicitis. Deficiency of the appendiceal wall was more frequently observed in gangrenous (19/27, 70.4%) than phlegmonous appendicitis (4/29, 13.8%). CONCLUSION: Findings of enhanced CT provide useful information in evaluating the pathological severity of acute appendicitis.     

Computed tomography of the gastrointestinal manifestation of hereditary angioedema

We report a case of gastrointestinal manifestation of hereditary angioedema. Computed tomography (CT) revealed wall thickening of the gastric antrum, duodenum, and jejunum. Dilatation of the third part of the duodenum, thickening of the small bowel mesentery and omentum, and retroperitoneal edema were present. The importance of considering this condition in patients presenting such CT findings correlated with the appropriate history is discussed.     

CT appearance of the normal appendix in adults

The aims of this study were to identify (1) the normal range of the appendix on computed tomography (CT), (2) the correlation of patient age and sex with the visibility and appearance of the appendix on CT, and (3) the normal variations in wall thickness, intraluminal content, and location of the appendix. Three hundred seventy-two outpatients underwent abdominopelvic CT. The scans were reviewed on the picture archiving and communication system and appendiceal outer-to-outer wall diameter, wall thickness, location, content and its correlation with appendix diameter were analyzed. The appendix was visualized in 305/372 patients. Its location relative to the cecum was highly variable. The diameter range was 3–10 mm; in 42% of cases the diameter was greater than 6 mm. When the intraluminal content (185/305) was visualized, the diameter was slightly superior to the mean (p=0.0156). In 329 CT scans in which oral contrast material was given, the appendix was filled by contrast material in 74/329 patients. The appendix wall thickness was measurable in 22/305 patients (average 0.15 cm). There is significant overlap between the normal and abnormal CT appearance of the appendix. Consequently the diagnosis of acute appendicitis should be based not only on the appearance of the appendix but also on the presence of secondary signs.     

Diagnostic accuracy of focused appendiceal CT in clinically equivocal cases of acute appendicitis.

PURPOSE: To determine the diagnostic accuracy of modified focused appendiceal computed tomography (CT) to exclude or confirm appendicitis in patients who presented with equivocal symptoms and signs of appendicitis. MATERIALS AND METHODS: One hundred patients (age range, 14-81 years; mean age, 30.6 years) with equivocal symptoms and signs of acute appendicitis were included in this prospective study. Patients were given 30 mL of diatrizoate meglumine and diatrizoate sodium and 60 mL of sorbitol mixed in 1 L of water orally over 1 hour. CT was performed 1.5 hours after the commencement of oral contrast material administration. The criteria used for the diagnosis of appendicitis were (a) appendix greater than 6 mm in maximum diameter, (b) no contrast material in the appendiceal lumen, and (c) inflammatory changes in the periappendiceal fat. CT results were compared with histopathologic findings at appendectomy. Patients with negative CT findings were followed up by telephone or clinically. RESULTS: Of 100 cases, 30 were positive at CT and 70 were negative. There were 28 true-positive cases; two false-positive cases, one cecal diverticulitis and one pelvic peritonitis with periappendicitis; and two false-negative cases, one perforated appendix and one mucosal and submucosal inflammation of the appendix but no transmural inflammation. Sensitivity was 93%, specificity was 97%, and accuracy was 96%. CONCLUSION: Focused appendiceal CT in which oral contrast material is used alone yields high levels of accuracy in clinically equivocal cases of acute appendicitis.     

The prevalence and patterns of intraluminal air in acute appendicitis at CT

The purpose of this study is to investigate if the presence and distribution of intraluminal air in the appendix contributes to the computed tomography (CT) diagnosis of appendicitis. We identified 100 consecutive patients (57 men and 43 women; mean age, 38) with CT prior to appendectomy for acute appendicitis over a 5-year period and a control group of 100 consecutive patients (29 men and 71 women; mean age, 39) who underwent CT for acute abdominal pain without appendicitis. Patients were scanned using multidetector row CT scanners at 1.25 or 5-mm slice thickness, peak tube voltage of 120 kVp, and milliamperse automatically adjusted to attain a noise index of 12. Ninety-two of 100 study patients and 95 of 100 controls received 150 mL intravenous contrast. Two independent readers noted the presence and distribution pattern of intraluminal air in the appendix, appendiceal diameter, wall hyperemia, wall thickening (>3 mm), and wall stratification and presence of any secondary signs of appendicitis including fat stranding and free fluid. Data were compared between groups using Fisher’s exact test and Student’s t test. Intraluminal air in the appendix was more common in control patients versus patients with appendicitis (66 of 100 versus 27 of 100, p?<?0.001). No significant differences in the patterns of intraluminal air were found between cases and controls. Among appendicitis cases, there was no significant difference in mean appendiceal diameter (12.8 versus 12.0, p?=?0.20) or number of CT signs of appendicitis (1.93 versus 1.86, p?=?0.78) in cases with intraluminal air versus without. No case of appendicitis demonstrated intraluminal air without secondary signs of appendicitis. Although intraluminal air is sometimes assumed to exclude a diagnosis of appendicitis, it is actually a common finding seen in up to 27 % of cases at CT. The pattern of intraluminal air was not helpful in differentiating a normal appendix from appendicitis.     

MRI features associated with acute appendicitis

Objectives

To identify MRI features associated with appendicitis.

Methods

Features expected to be associated with appendicitis were recorded in consensus by two expert radiologists on 223 abdominal MRIs in patients with suspected appendicitis. Nine MRI features were studied: appendix diameter >7 mm, appendicolith, peri-appendiceal fat infiltration, peri-appendiceal fluid, absence of gas in the appendix, appendiceal wall destruction, restricted diffusion of the appendiceal wall, lumen or focal fluid collections. Appendicitis was assigned as the final diagnosis in 117/223 patients. Associations between imaging features and appendicitis were evaluated with logistic regression analysis.

Results

All investigated features were significantly associated with appendicitis in univariate analysis. Combinations of two and three features were associated with a probability of appendicitis of 88 % and 92 %, respectively. In patients without any of the nine features, appendicitis was present in 2 % of cases. After multivariate analysis, only an appendix diameter >7 mm, peri-appendiceal fat infiltration and restricted diffusion of the appendiceal wall were significantly associated with appendicitis. The probability of appendicitis was 96 % in their presence and 2 % in their absence.

Conclusions

An appendix diameter >7 mm, peri-appendiceal fat infiltration and restricted diffusion of the appendiceal wall have the strongest association with appendicitis on MRI.

Key points

? An enlarged appendix, fat infiltration and restricted diffusion are associated with appendicitis. ? One such feature on MRI gives an 88 % probability of appendicitis. ? Two features in combination give a probability of appendicitis of 94 %. ? Combinations of three features give a probability of appendicitis of 96 %. ? The absence of these features almost rules out appendicitis (2 %).     

Ascending retrocecal appendicitis: clinical and computed tomographic findings

OBJECTIVE: To describe the clinical presentation and computed tomographic (CT) features of ascending retrocecal appendicitis. METHODS: During the past 8 years, 1670 patients with surgically proven appendicitis were identified by a retrospective investigation. Thirty-three patients who underwent contrast-enhanced abdominal CT before surgery and had ascending retrocecal appendicitis at surgery were included in the patient cohort. The clinical and CT findings of these 33 patients were analyzed. RESULTS: Patients presented with right lower abdominal pain (49%, 16/33), right flank pain (24%, 8/33), right upper abdominal pain (18%, 6/33), and periumbilical pain (15%, 5/33). Inflamed ascending retrocecal appendices were visualized completely in 70% (23/33), partially in 21% (7 of 33), and not detected in the remaining 9% (3/33). Periappendiceal inflammatory changes were most commonly observed in the retrocolic space in 88% (29/33), followed by paracolic gutter (30%, 10/33), pararenal space (27%, 9/33), mesentery (24%, 8/33), perirenal space (18%, 6/33), and subhepatic space (3%, 1/33). Inflammatory thickening of Gerota fascia (70%, 23/33) and the lateroconal fascia (64%, 21/33) was observed as well. Perforation of the appendix with the formation of an abscess was present in 49% (16/33). The abscesses were most commonly located in the retrocolic space (88%, 14/16). Diffuse wall thickenings of the cecum (67%, 22/33) and the ascending colon (64%, 21/33) were often observed also. Appendicoliths were found in 33% (11/33). CONCLUSIONS: More than half of patients with ascending retrocecal appendicitis presented with atypical clinical presentation. At CT, ascending retrocecal appendicitis was associated with a high incidence of retroperitoneal inflammatory changes and appendiceal perforation.