J Korean Soc Radiol.  2014 Apr;70(4):283-289. 10.3348/jksr.2014.70.4.283.

In Vivo Location of the Vermiform Appendix in Multidetector CT

• Lee SL
• Ku YM
• Choi BG
• Byun JY

• KMID: 2041939
• DOI: http://doi.org/10.3348/jksr.2014.70.4.283

Abstract

PURPOSE
To provide a more detailed classification system regarding the position of the vermiform appendix within the right lower quadrant, as seen on multidetector computed tomography (MDCT) and to investigate the relative differences in frequency of appendiceal position according to patient gender and the pathologic state of appendix.
MATERIALS AND METHODS
Between January 2008 and December 2010, 1157 patients were included in our final analysis: 542 patients with preoperative MDCT and subsequent appendectomy and 615 patients with visible appendix seen on MDCT performed as part of a health checkup. We classified the appendix according to its position relative to the cecum, the terminal ileum, and the external iliac vessels: type 1: antececal; type 2: preileal; type 3: postileal; type 4: subileal; type 5: subcecal; type 6: deep pelvic; type 7: retrocecal; and type 8: paracecal.
RESULTS
The relative incidence of various positions of the appendix found in all of our study patients was: type 1: 3.5%; type 2: 1.7%; type 3: 9.0%; type 4: 12.9%; type 5: 42.3%; type 6: 16.2%; type 7: 10.9%; and type 8: 3.0%. According to patient gender, type 1 (male: 3.7% vs. female: 3.3%), type 3 (8.6% vs. 9.8%), type 4 (14.3% vs. 9.8%), type 5 (47.5% vs. 32.7%), type 7 (9.2% vs. 14.4%), and type 8 (3.4% vs. 2.2%) positions showed a statistically significant male predominance. In terms of the inflamed state, type 2 preileal (normal: 0.8% vs. inflamed: 2.8%), type 3 (10.2% vs. 7.6%), type 4 (14.0% vs. 11.6%), and type 5 (14.1% vs. 18.5%) positions showed a statistically significant difference.
CONCLUSION
Contrary to the common assumption that the retrocecal appendix is the most common position, the in vivo appendix is seen more often on MDCT in the subcecal and deep pelvic positions. The relative frequency of various positions of the appendix can also differ according to patient gender and the pathologic state.

MeSH Terms

Appendectomy
Appendicitis
Appendix*
Cecum
Classification
Female
Humans
Ileum
Incidence
Male
Multidetector Computed Tomography

Figure

• 

  Fig. 1 Illustration of the appendiceal positions classified according to their relative location to the iliac crest (IC), terminal ileum (TI), cecum (Ce), and the iliac vessels (IV). 1, type 1 antececal; 2, type 2 preileal; 3, type 3 postileal; 4, type 4 subileal; 5, type 5 subcecal; 6, type 6 deep pelvic; 7, type 7 retrocecal; and 8, type 8 paracecal.

• 

  Fig. 2 Eight types of appendiceal positions seen on contrast-enhanced multidetector CT scans. A. Axial image shows an inflamed appendix (arrow) located in front of the cecum (type 1). B. Axial image reveals an inflamed appendix (arrow) directed upward and anterior to the terminal ileum (arrowhead) (type 2). C. Axial image demonstrates an inflamed appendix (arrow) directed upward and posterior to the terminal ileum (arrowhead) (type 3). D. Coronal reformatted image shows an inflamed appendix (arrows) directed toward the sacral promontory in the peritoneal cavity (type 4). E. Coronal reformatted image reveals an inflamed appendix (long arrows) located beneath the cecum (short arrow) and in the iliac fossa and lateral umbilical fossa, although not beyond the external iliac vessels (thick arrow) (type 5). F. Coronal reformatted image demonstrates an inflamed appendix (arrows) located in the true pelvic peritoneal cavity and with the tip located below the right external iliac vessels (thick arrow) (type 6). G. Axial image demonstrates an inflamed appendix (long arrow) with the tip posterior to the cecum (short arrow) (type 7). H. Coronal reformatted image shows an inflamed appendix (long arrows) with the tip posterolateral or lateral to the cecum (short arrow) (type 8).

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