Urinary retention in female OAB after intravesical Botox injection: who is really at risk?

Intravesical onabotulinumtoxinA (Botox) injections are effective for the treatment of idiopathic overactive bladder (OAB) symptoms. The aim of our study was to assess the predisposing factors for urinary retention in women with OAB after intravesical Botox injection.

All participants were women of European descent with idiopathic OAB. OnabotulinumtoxinA (100 U) was administered in 20 intra-detrusor injections. Analysis was performed based on the results of safety assessments made during follow-up (FU) visits on weeks 2, 4 and 12, in 208 women who were treated with Botox injections for refractory OAB and who completed all FU visits.

Women who required clean intermittent self-catheterisation (CISC) and those with post-void residual (PVR) greater than 200 ml were older in comparison with patients with PVR between 50 and 200 ml. Patients who required CISC were also characterised by higher parity and particularly by a higher number of vaginal deliveries. Other factors such as body mass index or comorbidities did not significantly influence PVR and the risk of CISC.

Elderly and/or multiparous women are at increased risk of urinary retention after intravesical 100-U Botox injections. The risk of new onset urine retention in our study has completely disappeared 2 weeks after Botox injections. Based on our results of the way in which the PVRs have changed over time, we can conclude that OAB patients should be optimally assessed during the first 2 weeks after Botox injections.