Use of the vertebrae and iliac bone as references for localizing the appendix vermiformis in computed tomography

Table 1 Courses of the appendix in the overall population, acute appendicitis group, and normal appendix group, n (%)

Groups	Ascending	Descending	Total
Acute appendicitis	61 (89.7)	7 (10.3)	68 (15.9)
Normal appendix	325 (90.5)	34 (9.5)	359 (84.1)
Total	386 (90.4)	41 (9.6)	427 (100)

Table 2 Minimum, maximum, and mean ± standard deviation of appendix location in relation to the right iliac bone in the overall population, acute appendicitis group, and normal appendix group, mm

Groups	Ap0 (origin)	ApA (highest point of the appendix)	ApB (lowest point of the appendix)
Acute appendicitis group (n = 68)	(−) 34.1 ± 29.1; (−) 100.8 − (+) 44.2	(−) 17.1 ± 27.8; (−) 84.8 − (+) 48.3	(−) 60.9 ± 27.9; (−) 121.6 − (+) 39.1
Normal appendix group (n = 359)	(−) 42.3 ± 31.5; (−) 126.0 − (+) 40.1	(−) 24.2 ± 34.1; (−) 126.0 − (+) 87.4	(−) 59.8 ± 30.2; (−) 140.5 − (+) 44.1
Total (n = 427)	(−) 41.0 ± 32.7; (−) 126.0 − (+) 44.2	(−) 23.0 ± 30.8; (−) 126.0 − (+) 87.4	(−) 60.0 ± 30.2; (−) 140.5 − (+) 44.1

No statistically significant difference was found between the acute appendicitis and normal appendix groups in ApB location relative to the right iliac bone (P = 0.19). Significant difference was found between the acute appendicitis and normal appendix groups in Ap0 and ApA locations relative to the right iliac bone (P = 0.04 and P = 0.04; respectively).

Table 3 Ap0, ApA, and ApB relative to the highest point of the right iliac bone in male and female patients, mm

Sex	Ap0 (mean ± SD)	ApA (mean ± SD)	ApB (mean ± SD)
Female (n = 206)	(−) 48.1 ± 30.0	(−) 26.2 ± 30.4	(−) 60.4 ± 31.1
Male (n = 221)	(−) 34.3 ± 29.7	(−) 20.0 ± 29.8	(−) 59.6 ± 30.8
Total (n = 427)	(−) 41.0 ± 32.7	(−) 23.0 ± 30.8	(−) 60.0 ± 30.2

No significant statistical difference was found between male and female patients in the measurements of ApA and ApB relative to the right iliac bone (P = 0.08 and P = 0.21; respectively). A significant difference was found between male and female patients in the measurements of Ap0 relative to the right iliac bone (P = 0.03).

Table 4 ApA and ApB localizations relative to the vertebrae in the overall population, n (%)

Vertebral levels	ApA	ApB
L1& L1-L2 intervertebral joint distance	0 (0)	0 (0)
L2& L2-L3 intervertebral joint distance	8 (1.9)	1 (0.2)
L3& L3-L4 intervertebral joint distance	29 (6.8)	2 (0.5)
L4 & L4-L5 intervertebral joint distance	88 (20.6)	20 (4.7)
L5 & L5-S1 intervertebral joint distance	147 (34.4)	81 (19.0)
S1 vertebra	95 (22.2)	96 (22.5)
S2 vertebra	34 (8.0)	81 (19.0)
S3 vertebra	19 (4.4)	66 (15.5)
S4 vertebra	4 (0.9)	56 (13.1)
S5 vertebra & coccygeal vertebrae	3 (0.7)	24 (5.6)

L: Lumbar vertebra; S: Sacral vertebra.

Table 5 Relationship between anthropometric measurements and the locations of ApA and ApB relative to the vertebrae and the right iliac bone

Appendix locations		Age	Height	BMI
Relative to the vertebrae	ApA	P = 0.007/R = −0.13	P = 0.006/R = −0.13	P = 0.044/R = −0.09
	ApB	P = 0.028/R = −0.10	P = 0.007/R = −0.13	P = 0.01/R = −0.12
Relative to the right iliac bone	ApA	P = 0.33/R = −0.12	P = 0.19/R = −0.10	P = 0.12/R = −0.08
	ApB	P = 0.47/R = −0.09	P = 0.53/R = −0.13	P = 0.23/R = −0.14

The relationship between anthropometric measurements and the locations of the appendix relative to the vertebrae and right iliac bone is demonstrated with P and R values. BMI: Body mass index.