Atrophic change of the abdominal rectus muscle significantly influences the onset of parastomal hernias beyond existing risk factors after end colostomy

Purpose: To investigate optimal risk factors, including atrophy of the abdominal rectus muscle (ARM) for postoperative parastomal hernia (PH) in patients who underwent end colostomy at left lower quadrant. Methods: This single-institution retrospective study included 91 patients who underwent end colostomy between April 2004 and December 2015. The surgical and long-term outcomes among patients with or without PH were collected and compared. Results: Altogether, 22 (24.2%) patients had a PH including 15 (68.2%) patients with a simultaneous incisional hernia. Univariate analysis showed that older patients (71 ± 11.9 vs. 64 ± 12.2 years, p = 0.03) and those with higher body mass index (BMI) (23.8 ± 3.8 vs. 20.9 ± 3.3 kg/m², p < 0.001) had a statistically significant relation with having PHs. Relative atrophy of left abdominal rectus muscle was more frequently found in patients with PH (ratio of left side/right side; caudal level and medial side: 0.66 vs. 0.92, p < 0.01, caudal level and lateral side: 0.95 vs. 1.03, p = 0.04). Multivariate analysis revealed that BMI > 25 kg/m² [odds ratio (OR) 9.05, 95% confidence interval (CI) 2.06–39.76, p = 0.003] and atrophy of the left lower medial portion of the abdominal rectus muscle (OR 12.85, 95% CI 2.49–66.39, p = 0.002) were independent risk factors for PHs. Neither the laparoscopic approach nor the extraperitoneal route of the colostomy was proven to correlate with a lower rate of PHs. Conclusions: High BMI and atrophic change of ARM were significantly associated with PH development. Surgical techniques for prevention of atrophic change of ARM are expected to reduce the incidence of PHs.