Deep pelvis and low visceral fat mass as risk factors for neurogenic bladder after rectal cancer surgery.

Background: Postoperative neurogenic bladder (PONB) frequently occurs as a complication after rectal cancer surgery. This study aimed to analyze risk factors for developing PONB after rectal cancer surgery, particularly the association between pelvic anatomy and visceral fat mass.

Methods: We included 138 patients who underwent rectal resection for lower rectal cancer in our department between 2017 and 2021. PONB was defined as the need for urethral catheter reinsertion or oral medication administration for urinary retention after catheter removal with severe NB that required treatment for ≥ 60 days. We obtained visceral fat area (VFA) at the umbilical level based on a CT scan and measured five pelvic dimensions.

Results: Of the 138 patients, 19 developed PONB, with 16 being severe cases. PONB more frequently occurs in patients with a height of < 158 cm, age ≥ 70 years, surgery lasting ≥ 8 h, intraoperative bleeding volume ≥ 150 mL, lateral lymph node dissection, and narrower pelvis. It was more prevalent in cases with low VFA. Conversely, gender, body mass index (BMI), and medical history showed no significant correlations. Multivariate analysis revealed older age, prolonged surgery, and low VFA as independent risk factors for PONB. Independent risk factors for severe PONB included low VFA, older age, prolonged surgery, and deep pelvis.

Conclusion: Lower VFA, older age, and prolonged surgery are independent risk factors for developing PONB. Additionally, a deep pelvis is an independent risk factor for severe PONB. Delicate surgical techniques should consider the risk of nerve injury in cases with low VFA and deep pelvis.