Variation in the Definitions of Urinary Retention in Studies of Intravesical Botulinum Toxin for Idiopathic Overactive Bladder: A Narrative Systematic Review.

[PURPOSE] To categorise and quantify definitions of urinary retention reported in studies assessing botulinum toxin (BoNT) injections for idiopathic overactive bladder (iOAB) syndrome.

[MATERIALS AND METHODS] A narrative systematic review was conducted using three databases: EMBASE (via Ovid), PubMed, and SCOPUS. Inclusion criteria comprised studies published as full-text articles in English involving adults receiving BoNT injections (any formulation) for iOAB syndrome, where urinary retention was reported as an outcome.

[RESULTS] From 1986 screened studies, 135 were assessed, and 57 met the eligibility criteria for the narrative systematic review. Reported rates of urinary retention varied widely, ranging from 0% to 42.6%. A definition of urinary retention was provided in 33 studies (57.9%), which were broadly categorised as follows. 1. Post-void residual (PVR) volume threshold: 14 studies (21.5%). 2. Inability to void: 6 studies (9.2%). 3. Initiation of clean intermittent catheterisation (CIC): 6 studies (9.2%). 4. PVR volume threshold and initiation of CIC/indwelling catheterisation (IDC): 6 studies (9.2%). 5. Bladder symptoms and PVR volume threshold and initiation of CIC/IDC: 6 studies (9.2%). 6. Bladder symptoms and PVR volume threshold: 3 studies (4.6%). Notably, 24 studies (42.1%) omitted a definition altogether.

[CONCLUSIONS] Urinary retention rates varied significantly between studies, likely due to the heterogeneous definitions used. The omission of definitions in nearly half of studies further complicates efforts to accurately inform and consent patients regarding the risk of urinary retention and the need for CIC/IDC after intravesical BoNT injection. Standardised definitions are urgently needed to enhance research, improve clinical practice, and support informed patient counselling.