Computed Tomography Diagnosis of Acute Appendicitis—Pictorial Essay

doi:10.4236/ss.2011.23022

Surgical Science, 2011, 2, 109-116

doi:10.4236/ss.2011.23022 Published Online May 2011 (http://www.scirp.org/journal/ss)

109

Computed Tomography Diagnosis of Acute

Appendicitis—Pictorial Essay

Aarthi Govindarajan, Bhawna Dev, Roy Santosham, Santhosh Joseph

Department of Ra di ol o gy a nd Im aging Sciences, Sri Ramachandra Medical College and Research Institute,

Sri Ramachandra University, Chennai, India

E-mail: [email protected]

Received October 11, 2010; revised December 25, 2011; accepted April 11, 2011

Abstract

Acute appendicitis is a common surgical emergency with varied clinical presentations. Early diagnosis is

absolutely necessary to minimize morbidity whereas delayed or missed diagnosis can cause adverse conse-

quences. Computed tomography is a highly accurate imaging technique for diagnosing appendicitis. Hence it

plays a valuable role in selected patients with suspected appendicitis; [1]. In this essay, we review the normal

Computed tomography anatomy of the appendix and the right lower quadrant and illustrate the Computed

tomography signs of appendicitis and important differential diagnostic entities. The Computed tomography

appearance of complications of acute appendicitis is also presented, as are issues concerning clinical presen-

tation and duration of the symptoms. Computed tomography signs can be varied and overlooked as they say

what is easy to see is also easy to miss.

Keywords: Acute Appendicitis, Multislice Computed Tomography

1. Introduction

Acute appendicitis is the commonest cause of acute ab-

domen pain which needs surgical intervention. Atypical

symptoms, varied presentations and multiple differen-

tials of abdomen pain make accurate diagnosis of appen-

dicitis difficult clinically.

Non enhanced & contrast enhanced Computed tomo-

graphy images are helpful in noninvasive evaluation of

appendicitis. The Computed tomography diagnosis of

acute appendicitis has high positiv e and negative predic-

tive values, 96% and 95% [2], respectively. It is also

possible to reconstruct the entire form and position of

appendices from successive Computed Tomography f ind-

ings with high-resolution thin-slice Multidetector com-

puted tomography images [3].

2. Normal Anatomy

Appendix is a narrow worm shaped blind ending tube

arising from the caecum. Appendix is highly mobile and

variable in length by up to 20 cm [4]. It can be retrocae-

cal, subcaecal, pelvic, preileal and post ileal in location.

Most common is the retrocaecal position [5]. Appendix

has a triangular mesentery, the meso appendix. Appen-

dix is supplied by appendicular artery, a branch of ileo-

colic artery and venous drainage is through ileocolic

vein into the superior mesenteric vein.

3. Cases with Detailed Description

(a) (b)

Figure 1. Non enhanced (a) and Enhanced (b) shows nor-

mal blind ending appendix arising from the caecum.

A. GOVINDARAJAN ET AL.

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

3.1. Case I Computed Tomography Appearance

of Normal Appendix

Patient came for evaluation of renal calculi and Computed

tomographic images showed normal appendix as smooth

thin walled tubular organ (arrow) surrounded by mesen-

teric fat (Figures 1(a) and 1(b)). Transverse diameter of

normal appendix should not exceed 6 mm without in-

traluminal material, but some authors considered an upper

limit of 10 mm with intraluminal content [6].

3.2. Case II Acute Appendicitis

Patient presented to Emergency Room with periumblical

pain and vomiting for 2 days and Computed Tomo-

graphic images showed inflammed appendix with peri-

appendicular mesenteric stranding (Figures 2(a), 2(b),

2(c) and 2(d)).

3.3. Case III Retrocaecal Appendicitis with

Lateral Conal Fascia Thickening and

Retroperitoneal Abscess

Patient was referred from Emergency Room to rule out

acute appendicitis and Computed Tomography showed

retrocaecal long inflammed appendix with adjacent re-

troperitoneal abscess (Figures 3(a), 3(b), 3(c), 3(d), 3(e)

and 3(f))

3.4. Case IV Long inflammed Appendix with

Midline Extension

Patient with right iliac fossa pain and fever for 3 days.

Computed Tomographic images showed long appendix

crossing the midline with features of acute appendicitis

(Figures 4(a), 4(b) and 4(c)).

3.5. Case V Appendicolith without Inflammation

Patient presented with right iliac fossa pain for 2 days

and Computed Tomographic showed appendicolith with

no evidence of appendix enlargement/periappendicular

stranding (Figures 5(a) and 5(b))

3.6. Case VI Appendicolith with Inflammation

Patient complained of lower abdomen pain with vomit-

ing. Computed Tomography showed enlarged thickened

appendix with minimal periappendicular mesenteric

stranding seen. (Figures 6(a) and 6(b)).

3.7. Case VII Base Appendicitis

Patient presented with lower abdomen pain and Com-

puted Tomography showed acute inflammation at the

take off of appendix from caecum with minimal strand-

ing (Figures 7(a) and 7(b)).

3.8. Case VIII Terminal Appendicitis with

Perforation and Pneumoperitoneum

Patient presented with dull aching right iliac fossa pain

and Computed Tomographic images showed thickened

tip of appendix with mesenteric stranding (Figures 8(a),

8(b) and 8(c)).

(a) (b) (c) (d)

Figure 2. (a) Non-enhance d axial section of computed tomography shows diffuse thickening of distal cae cum with surround-

ing inflammatory mesenteric stranding (arrow); (b) Non enhanced Computed Tomography shows enlarged and thickened

appendix (arrow) with luminal diameter 11 mm in its cross section. (c) Non enhanced axial Computed Tomography shows

appendicolith (arrow) measuring 9 mm within the lumen. (d) Coronal section of Non Contrast Enhanced Computed Tomo-

graphy abdomen shows pericolic mesenteric fat stranding with thickening of distal ileal loops and caecum (arrow head) and

appendicolith within the lumen (arrow).

A. GOVINDARAJAN ET AL. 111



Figure 3. (a) Non enhanced axial Computed Tomography shows periappendicular stranding (arrow) at the level of take off of

appendix from caecum. (b) Non enhanc ed axial Computed Tomography shows thickened appendix with transverse diameter

of 1.3 cms (arrow). (c) & (d) Non enhanced (c)and enhanced (d) axial Computed Tomography shows small loculated abscess

(c, arrow) in retro peritoneum adjacent to thickened appendix showing enhancement after contrast administration (d, arrow).

(e) Thickened retrocaec al appendix (small arrow) leading to thickened right lateral conal fascia (arrow) with multiple mesen-

teric lymph nodes (arrow head). (f) Contrast Enhanced Computed Tomography oblique images shows long retrocaecal thick-

ened appendix (arrow) (1.3 cm) extending up to posterior renal fascia.

3.9. Case IX Appendicular Mass

Right Iliac Fossa pain for 2 weeks and Computed Tomo-

graphic images showed heterog eneous mass in right iliac

fossa with thickening of ascending colon and distal il-

eum (Figures 9(a), 9(b) and 9(c)).

3.10. Case X Appendicular Abscess

Lower abdomen pain for 2 weeks and Computed Tomo

A. GOVINDARAJAN ET AL.

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

Figure 4. (a) Nonenhanced Computed Tomography shows 10 cm long edematous appendix (arrows) crossing the midline with

luminal diameter 1.2 cm, w ith surrounding fat stranding. Line ar appendicolith (Small arrow) is seen within the lumen. Small

pericolic fluid collection (arrowhead) is seen anterior to caecum. (b) Enhanced axial Computed Tomography shows Large

fluid collection (Arrow) anterior to rectum with attenuation similar to bladder. (c) Enhanced coronal Computed Tomogra-

phy shows long inflammed appendix (arr ows) with periappendicular str anding. Fluid collection (arrow head) seen in pelvis.

(a) (b)

Figure 5. (a) Non enhanced axial Computed tomography

shows appendicolith (arrow) noted within appendix lumen.

(b) Coronal oblique images of Computed Tomography ab-

domen shows noninflammed appendix (arrow) with faeco-

lith.

(a) (b)

Figure 6. (a) Non enhanced axial Computed Tomography

shows fluid filled thickened appendix with appendicolith

(arrow) at the neck of appendix. (b) Saggital oblique nonen-

hanced images shows fluid filled appendix with appendico-

lith.

graphy showed irregular thick walled abscess with ap-

pendix not separately visualized (Figures 10(a) and

10(b)).

3.11. Case XI Acute Appendicitis with Contained

Perforation

Patient complained of acute abdomen pain for 2 days

A. GOVINDARAJAN ET AL. 113



(a) (b)

Figure 7. Axial nonenhanced (a) and Saggital oblique images shows thickening at its origin (10 mm). Body and tip of ap-

pendix (arrow head) is normal. Minimal ascites noted in right iliac fossa. (a, small arrow)

Figure 8. (a) Nonenhanced coronal Compute d Tomography shows thickened tip (arrow head) with appendicolith within and

adjacent fat stranding. Base of appendix (arrow) is nor mal. (b) Non enhanced axial Computed Tomography shows appe ndi-

colith (arrowhead) noted at the tip with surrounding mesenteric stranding. (c) Axial non enhanced Computed Tomography

shows small pneumoperi tone um (ar row) in right sub diaphragmatic space.

A. GOVINDARAJAN ET AL.

114



Figure 9. Axial nonenhanced (a) and enhanced (b) axial Computed Tomography shows complex heterogeneous mass in the

right iliac fossa (arrow) .Wall enhancement noted on contrast administration (b arrow). Large 14 mm appendicolith (arrow

head) within the mass. (c) Right iliac fossa shows heterogeneous mass (arrow) fluid filled appendix (arrow) with appendico-

th (arrowhead) within the lumen. li

(a) (b)

Figure 10. Nonenhanced (a) and enhanced (b) axial Com-

puted Tomography shows ill-defined heterogeneous mass (a,

arrow) in right iliac fossa. On contrast injection, wall en-

hancement (b, arrow) seen with necrotic areas within.

and Computed Tomography taken showed perforated ap-

pendix with adjacent air pockets(Figures 11(a) and 11(b)).

3.12. Case XII Mucocele of Appendix

Patient presented with mild lower abdominal pain for 1

(a) (b)

Figure 11. Axial nonenhanced (a) and enhanc ed cor onal (b)

Computed Tomography show s thickened appendix (arrow)

at its take off from caecum with surrounding inflammed

mesentery. Small Faecolith noted at the base. Focal gas

pockets (arrowhead) noted adjacent to the appendix.

week and Computed Tomographic images showed

distended edematous fluid filled appendix with appen-

dicolith and air pockets within (Figures 12(a) and

12(b)).

A. GOVINDARAJAN ET AL. 115



(a) (b)

Figure 12. Nonenhanced (a) and enhanced (b) axial Com-

puted tomography shows enlarged, edematous (10 mm)

fluid filled appendix(arrow) with appendicolith (small

arrow) in the base and few air pockets (a, arrowhead) seen

within. Enhancement of appendicular wall (b, arrow) in

Contrast Enhanced Computer Tomogr aphy.

4. Pathophysiology

The pathophysiology of appendicitis is the constellation

of processes that leads to the development of acute ap-

pendicitis from a normal appendix. Appendicitis results

due to obstruction of the appendiceal lumen. The main

source of obstruction include lymphoid hyperplasia due

to infection in the gastrointestinal tract and occasionally

by inflammatory bowel disease (Crohn’s disease and

ulcerative colitis), feces, parasites, or growths that clog

the appendiceal lumen and trauma to the abdomen

Understanding the pathophysiology helps to explain all

the signs and symptoms and the complications seen in

appendicitis. In all the cases, independent of etiology, the

main thrust of events is increase in the pressu re within the

lumen followed by continuous secretion of fluids and mu-

cus and the stag nation of this mater ial leading to co mpro-

mised blood supply and becoming very vulnerable to in-

vasion by bacteria found in t he gut norm all y.

The pathophysiology [7] involved in inflammation of

appendix is as follows:

Luminal Obstruction

↓

Continuous Secretion of Mucus

↓

Raised Intraluminal Presume with Distended Lumen

↓

Reduced Venous Supply

↓

Arterial Compromise with Ischemia

↓

Micro Perforation & Bacterial Colonization

5. Discussion



Appendicitis is an acute inflammation of the vermiform

appendix, typically resulting in abdominal pain, anor exia,

and abdominal tenderness

Computed Tomography Criteria for Diagnosing

Acute Appendicitis: Computed Tomography is a highly

accurate and effective cross-sectional imaging technique

for diagnosing and staging acute appendicitis. Abdomi-

nal and pelvic Computed Tomography scanning with or

without oral & intravenous contrast can be done, de-

pending upon radiologist preference. However targeted

Computed Tomography technique for evaluation of ap-

pendix is done in all the cases strongly suspicious of

appendicular pathology. Computed Tomography scan-

ning has the advantage of direct visualization of the ap-

pendix, periappendiceal region and other intra-abdominal

structures.

There are primary as well as secondary signs for diag-

nosing appendicular pathologies on cross sectional imag-

ing.

Primary signs

Enlarged Unopacified Appendix

Abnormal Thickened Appendix

Abnormal Enhancement on CECT

Periappendicular Fat Stranding [8]

Secondary signs

Mesenteric Adenopathy

Appendicolith

Caecal Bar Sign—Focal Caecal Wall Thickening [9-11].

Arrow Head Sign—Arrowhead Shaped Collection of

Contrast in Upper Part of Caecum near the Orifice of

Appendix [9-11].

Para Colic Gutter Fluid

Diffuse Caecal Wall Thickening

Abscess/Extra Luminal Air

The inflamed appendix usually measures 7 - 15 mm in

diameter. Circumferential and symmetric wall thicken-

ing is always present and is best demonstrated on images

obtained with intravenous contrast material enhancement.

Homogenous enhancement of thickened wall is seen.

Other important findings include focal cecal apical

thickening and the arrowhead sign (cecal contrast mate-

rial funnels symmetrically at the cecal apex to the point

of appendiceal occlusion). This secondary finding may

A. GOVINDARAJAN ET AL.



116

help to establish the diagnosis in equivocal cases.

Enlargement of the appendix with associated fluid and

loculated air within the lumen is seen in Gangrenous

appendicitis.

Perforated appendicitis is usually accompanied by pe-

ricecal phlegmon or abscess formation. Other findings

include extraluminal air, marked ileocecal thickening,

localized lymphadenopathy, peritonitis, and small-bowel

obstruction.

6. Conclusions

Computed Tomography can show a normal appendix as

well as various other ways appendicitis can appear [12].

It is the accurate modality for the diagnosis of acute ap-

pendicitis, especially in patien ts with equivocal presenta-

tion. Radiologist must be aware of various clinical and

radiological features of these presentations which aid in

faster diagnosis and optimize treatment of these patients.

7. References

[1] D. Choi, H. Park, Y. R. Lee, S. H. Kook, S. K. Kim, H. J.

Kwag, et al., “The Most Useful Findings for Diagnosing

Acute Appendicitis on Contrastenhancedhelical CT,” Acta

Radiologica, Vol. 44, No. 6, 2003, pp. 547-582.

[2] A. N. Chalazonitis, I. Tzovara, E. Sammouti, N. Ptohis, E.

Sotiropoulou, E. Protoppapa, et al., “CT in Appendicitis,”

Diagnostic and Interventional Radiology, Vol. 14, No. 1,

2008, pp. 19-25.

[3] T. Miki, S. Ogata and M. Uto, “Enhanced Multidetector-

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Acute Appendicitis and Its Severity,” Radiation Medicine,

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[4] A. J. Malone, “Unenhanced CT in the Evaluation of the

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[5] A. A. Ghiatas, S. Chopra and K. N. Chintapalli, “Com-

puted Tomography of the Normal Appendix and Acute

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[6] K. R. Curtin, S. W. Fitzgerald, A. A. Nemcek, F. L.

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905-909.

[7] J. M. Pereira, et al., “Disproportionate Fat Stranding: A

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doi:10.1148/rg.243035084

[8] K. E. Applegate, C. J. Sivit, M. T. Myers and B.

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505.

[9] E. J. Balthazar, B. A. Birnbaum, J. Yee, A. J. Megibow, J.

Roshkow and C. Gray, “Acute Appendicitis: CT and US

Correlation in 100 Patients,” Radiology, Vol. 190, 1994,

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[10] P. M. Rao, J. T. Rhea and R. A. Novelline, “Sensitivity

and Specificity of the Individual CT Signs of Appendicitis:

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doi:10.1097/00004728-199709000-00002

[11] P. M. Rao, J. T. Rhea, R. A. Novelline, et al., “Helical CT

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[12] A. A. Ghiatas, S. Chopra and K. N. Chintapalli, “Com-

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