Stratified computed tomography findings improve diagnostic accuracy for appendicitis

Table 1 Patient characteristics n (%)

Characteristics	Total population	Negative appendicitis	Pathologically proven appendicitis	P value
	(n = 224)	(n = 47)	(n = 177)
Age (yr)				0.052
< 15	26 (11.6)	10 (21.3)	16 (9.0)
15-64	169 (75.4)	33 (70.2)	136 (76.9)
≥ 65	29 (13.0)	4 (8.5)	25 (14.1)
Gender				0.092
Male	88 (39.3)	13 (27.7)	75 (42.4)
Female	136 (60.7)	34 (72.3)	102 (57.6)
Body mass index (kg/m2)				0.635
< 20	52 (27.1)	12 (31.6)	40 (26.0)
20-25	106 (55.2)	21 (55.2)	85 (55.2)
> 25	34 (17.7)	5 (13.2)	29 (18.8)
Comorbidity				0.350
Charlson index = 0	217 (96.9)	47 (100.0)	170 (96.0)
Charlson index > 0	7 (3.1)	0 (0.0)	7 (4.0)
Symptom duration before presentation				0.740
< 72 h	129 (58.1)	26 (55.3)	103 (58.9)
≥ 72 h	93 (41.9)	21 (44.7)	72 (41.1)
Body temperature (°C)				0.755
< 37.8	119 (88.8)	28 (87.5)	91 (89.2)
≥ 37.8	15 (11.2)	4 (12.5)	11 (10.8)
Presenting symptom				0.507
Abdominal pain	219 (97.8)	47 (100.0)	172 (97.2)
Indigestion	1 (0.4)	0 (0.0)	1 (0.6)
Fever/chill	4 (1.8)	0 (0.0)	4 (2.2)
Pain migration				0.507
No	114 (53.3)	26 (57.8)	88 (52.1)
Yes	100 (46.7)	19 (42.2)	81 (47.9)
Degree of tenderness				0.383
Mild	4 (1.8)	0 (0.0)	4 (2.3)
Moderate	217 (96.9)	47 (100.0)	170 (96.0)
Severe	3 (1.3)	0 (0.0)	3 (1.7)
RLQ localization of pain				0.559
Discrete	205 (91.5)	42 (89.4)	163 (92.1)
Obscure	19 (8.5)	5 (10.6)	14 (7.9)
Lab findings, median (range)
WBC count (× 103/mm3)	9.55 (4.0-29.1)	9.3 (4.6-25.9)	9.6 (4.0-29.1)	0.833
Platelet count (× 103/mm3)	250 (157- 564)	277 (202-564)	241 (157-341)	0.005
Creatinine (mg/dL)	0.64 (0.41- 1.11)	0.56 (0.41-0.69)	0.70 (0.46-1.11)	0.036
Albumin (g/dL)	4.30 (3.3-5.4)	4.40 (3.3-5.2)	4.30 (3.3-5.4)	0.989
Total bilirubin (mg/dL)	0.50 (0.2-1.5)	0.55 (0.2-1.5)	0.77 (0.2-2.2)	0.020
Neutrophil fraction				0.359
< 80%	160 (72.4)	36 (78.3)	124 (70.9)
≥ 80%	61 (27.6)	10 (21.7)	51 (29.1)

Data from patients receiving operations for suspicion of appendicitis with computed tomography findings that were negative or equivocal for appendicitis. RLQ: Right low quadrant of abdomen; WBC: White blood cells.

Table 2 Reevaluations of computed tomography scans preoperatively interpreted as indeterminate for appendicitis n (%)

	Total population	Negative appendicitis	Pathologically proven appendicitis	P value
	(n = 224)	(n = 46)	(n = 178)
Appendiceal visualization				1.000
No	6 (2.7)	1 (2.2)	5 (2.8)
Yes	218 (97.3)	45 (97.8)	173 (97.2)
Appendiceal diameter				< 0.001
< 6.0 mm	89 (39.7)	29 (63.0)	60 (33.7)
≥ 6.0 mm	135 (60.3)	17 (37.0)	118 (66.3)
Thickness of appendiceal wall				0.175
< 2.0 mm	54 (24.1)	15 (32.6)	39 (21.9)
≥ 2.0 mm	170 (75.9)	31 (67.4)	139 (78.1)
Appendiceal wall enhancement				0.059
No	138 (63.3)	34 (75.6)	104 (63.3)
Yes	80 (36.7)	11 (24.4)	69 (39.9)
Presence of intraluminal air				0.024
No	139 (63.8)	22 (48.9)	117 (67.6)
Yes	79 (36.2)	23 (51.1)	56 (32.4)
Presence of appendicolith				1.000
No	206 (94.5)	43 (95.6)	163 (94.2)
Yes	12 (5.5)	2 (4.4)	10 (5.8)
Presence of periappendiceal fat stranding				0.001
No	155 (71.1)	41 (91.1)	114 (65.9)
Yes	63 (28.9)	4 (8.9)	59 (34.1)
Presence of periappendiceal fluid collection				0.669
No	216 (96.4)	44 (95.7)	172 (96.6)
Yes	8 (3.6)	2 (4.3)	6 (3.4)
Presence of periappendiceal lymphadenopathy				1.000
No	200 (89.3)	41 (89.1)	159 (89.3)
Yes	24 (10.7)	5 (10.9)	19 (10.7)
Presence of coexisting lesions				0.084
No	169 (75.4)	30 (65.2)	139 (78.1)
Yes	55 (24.6)	16 (34.8)	39 (21.9)

Table 3 Incidence of coexisting inflammatory lesions

Coexisting lesions	Incidence (n)	% (n = 224)
Ileocolitis	37	17.0
Terminal ileitis	10	4.5
Periappendiceal fluid collection	4	1.0
Pelvic inflammatory disease	2	0.9
Epiploic appendigitis	1	0.4

Data refer to patients who underwent operation with suspicion of appendicitis based on clinical manifestations despite negative or equivocal computed tomography interpretation.

Table 4 Risk estimations n (%)

Groups	Number of risk factors1	Patients with positive appendicitis	OR	95%CI	P value
Low-risk group	0-1	73 (65.8)	1.000
High-risk group	2-3	105 (92.9)	6.832	3.013-15.454	0.001

¹Risk factors include: appendiceal diameter ≥ 6.0 mm, presence of periappendiceal fat stranding, and intraluminal air in the appendix. Data refer to patients who underwent operation for suspicion of appendicitis based on clinical manifestations despite negative or equivocal computed tomography interpretation.