One-stage closure of the small non-growing bladder plate: new insight into the anatomy of exstrophy - Trapezoid interpubic ligament (TIPL).

Purpose: The purpose of this study is to examine whether retrovesical fibromuscular structures-specifically the trapezoid interpubic ligament (TIPL)-mechanically restrict the inversion of small, non-growing bladder plates (SNGBP) in bladder exstrophy, and to evaluate bladder growth after one-stage closure with TIPL dissection, including the effect of anticholinergic therapy.

Materials and methods: Between 2004 and 2023, 15 patients with SNGBP underwent one-stage bladder closure using a modified surgical approach with TIPL dissection. The TIPL, identified as a fibromuscular structure impeding bladder plate (BP) inversion, was targeted. Postoperative bladder capacity was evaluated based on age at surgery and the use of anticholinergic therapy.

Results: The TIPL was identified as the primary mechanical impediment to BP inversion. Its dissection restored tissue compliance, facilitating successful one-stage closure in all patients. In children under three years of age at the time of surgery, the mean annual bladder capacity increased by 17.76 mL. Anticholinergic therapy further enhanced bladder growth.

Conclusion: TIPL dissection enables one-stage closure in SNGBP patients who were previously considered unsuitable for this method. Early intervention supports bladder development and favorable functional outcomes. These findings provide novel anatomical insights, warranting further morphological and embryological research to validate the universality of this structure and technique.