Modified posterior sagittal anorectoplasty (mPSARP) versus transfistula anorectoplasty (TFARP) for anorectal malformation with rectovestibular fistula (RVF): a retrospective study of surgical outcomes and the impact of preoperative pelvic muscle development

Background This study aimed to compare the clinical characteristics, postoperative outcomes, complications, and reoperation rates of two surgical techniques: modified posterior sagittal anorectoplasty (mPSARP) and transfistula anorectoplasty (TFARP), and to assess the correlation between preoperative magnetic resonance imaging (MRI)-based evaluation of pelvic muscle development and postoperative functional outcomes. Methods A retrospective review of 38 female patients with RVF who underwent surgery at Shanghai Children's Hospital between January 2014 and December 2022 was conducted. Patients were divided into two groups: mPSARP (n = 31) and TFARP (n = 7). Baseline characteristics, sacral ratio (SR), and preoperative MRI-based evaluation of pelvic muscle development were collected before surgery, postoperative hospital stay,and postoperative outcomes were evaluated using the Kelly score and Krickenbeck classification. Results Postoperative hospital stay was significantly longer in the mPSARP group than in the TFARP group (10.71 ± 3.76 days vs. 8.00 ± 1.53 days, p < 0.05). There were no significant differences between the two groups in terms of postoperative complications, functional outcomes, and reoperation rates (p>0.05). However, the mPSARP group demonstrated lower rates of soiling grade II, constipation grade III, and reoperation (0.0% vs. 16.7%; 3.7% vs. 33.3%; 3.6% vs. 16.7%, p > 0.05). The Kelly scores were similar between the two groups (5.00 [4.00–5.00] vs. 5.50 [3.00–6.00], p>0.05). Bivariate Kendall’s tau analysis demonstrated a moderate positive correlation between preoperative MRI-based evaluation of pelvic muscle development and Kelly score (Tau = 0.584, p = 0.001). Birth weight showed a weak positive correlation with the Kelly score (Tau = 0.296, p = 0.029). Preoperative MRI grade also correlated strongly and negatively with Krickenbeck soiling grade (Tau=-0.702, p = 0.001). Patients with spinal anomalies had significantly lower Kelly scores than those without (4.00 [3.50–4.50] vs. 5.00 [4.00–5.50], p = 0.040). Conclusion Both mPSARP and TFARP demonstrated similar functional outcomes, but mPSARP may have advantages in reducing moderate-to-severe voluntary bowel dysfunction and reoperation rates. The preoperative development of pelvic muscle is essential for the restoration of anorectal function following surgery.