Table 3.

Subgroup analysis of preoperative and postoperative muscle thickness.

	Nonoperated (mm), mean ± SD	Operated (mm), mean ± SD	Mean Difference ± SD (mm)	95% CI (mm)	P value*
Previous abdominal surgery
Yes (n = 16)
Umbilicus level	8.05 ± 1.19	8.05 ± 1.19	−0.18 ± 1.85	−1.17–0.80	.695
ASIS level	8.22 ± 2.00	7.55 ± 1.61	0.68 ± 1.47	−0.10–1.46	.085
No (n = 15)
Umbilicus level	8.23 ± 1.70	8.09 ± 1.65	0.15 ± 1.60	−0.74–1.03	.728
ASIS level	7.86 ± 1.69	7.95 ± 2.11	−0.08 ± 2.09	−1.24–1.07	.879
Number of perforators
One (n = 25)
Umbilicus level	8.29 ± 1.51	8.55 ± 1.70	−0.26 ± 1.67	−0.95–0.43	.446
ASIS level	8.09 ± 1.93	8.09 ± 1.72	−0.02 ± 1.80	−0.76–0.72	.953
Two (n = 6)
Umbilicus level	7.52 ± 0.89	6.57 ± 1.53	0.96 ± 1.63	−0.75–2.66	.209
ASIS level	7.97 ± 1.53	6.28 ± 1.78	1.68 ± 1.11	0.52–2.85	.014†
Immediate/delayed
Immediate (n = 26)
Umbilicus level	8.15 ± 1.48	8.14 ± 1.97	0.01 ± 1.84	−0.74–0.75	.983
ASIS level	7.83 ± 1.82	7.52 ± 1.80	0.31 ± 1.91	−0.46–1.09	.413
Delayed (n = 5)
Umbilicus level	8.09 ±± 1.35	8.28 ± 0.85	−0.19 ± 0.82	−1.20–0.82	.631
ASIS level	9.19 ± 1.61	8.91 ± 1.85	0.28 ± 1.27	−1.29–1.86	.638

ASIS = anterior superior iliac spine, CI = confidence interval; n, number, SD = standard deviation.

^*Paired t test.

^†Significant values, P < .05.