Long-term catheters (LTCs) are used for intractable urinary incontinence or chronic urinary retention. Prophylactic washouts are hypothesised to reduce LTC associated complications such as catheter blockage and symptomatic catheter associated urinary tract infection (S-CAUTI). This systematic review summarises current evidence on the benefits and harms of regular prophylactic catheter washouts for adults using LTCs.

Literature search was conducted using MEDLINE, EMBASE, CINAHL and CENTRAL (database inception to June 2024) for RCTs and quasi-RCTs comparing prophylactic catheter washouts to standard care, or different catheter washout solutions to each other. The review followed standard methodology as per the Cochrane Handbook. Certainty of evidence was assessed with the GRADE approach. Detailed methods in the PROSPERO protocol (CRD42024553575).

Seven RCTs (340 participants) were included. Pooled analysis in the review found lower S-CAUTI rates in saline washout groups than no washout groups [MD=-0.10 (95%CI -0.50–0.29); low certainty evidence](p=0.61). One recent RCT similarly reported lower S-CAUTI rates in their saline group compared to the no washout group [IRR=0.40(0.20–0.80); p=0.003]. Furthermore, the review found lower S-CAUTI rates in any washout groups compared to no washout groups, though this was statistically insignificant [MD=-0.05 (95%CI -0.42–0.32); low certainty evidence](p=0.79). Pooled analysis in the review found reduced odds of catheter blockage in acidic washout groups than saline washout groups [OR=0.51 (95%CI 0.25–1.03); very low certainty evidence](p=0.06). One RCT also found increased odds of greater encrustation in their no washout group compared to their saline group [OR=0.62(95%CI 0.17–2.25); very low certainty evidence](p=0.46). Pooled analysis in the review found that any washouts had reduced haematuria incidence [RR=0.99(95%CI 0.87–1.12); moderate certainty evidence](p=0.86) compared to no washouts. 

A recent RCT in the review found that washout groups may have improved quality of life (QoL) than no washout groups. Washout groups had higher EQ-5D-5L scores than no washout groups, with the saline group MD=0.056(97.5%CI -0.022–0.134)(p=0.11) and acidic group MD=0.053(97.5%CI -0.024-0.131)(p=0.12) compared to the no washout group. The EQ-5D-5L is a generic quality of life measure where higher scores reflect a better quality of life suggesting possible improvement QoL. The study also used ICIQ-LTCqol (function and concern), a self-report QoL questionnaire for LTC users where higher scores suggest worse QoL. The saline washout group had a lower ICIQ-LTCqol score compared to the control [MD=-1.2(97.5%CI -4.1–1.7)](p=0.34), while the acidic group had a slightly higher score [MD=0.7(97.5%CI -2.2–3.5)](p=0.60) compared to the no washout group.

The review results suggest that prophylactic catheter washouts do not have a statistically significant impact on S-CAUTI, catheter blockage, or catheter removal or replacement rates compared to standard LTC care alone. However, the review did find that catheter washouts may have more benefits and less harms than current urological guidelines suggest. Patients more prone to LTC blockage may benefit from acidic washouts, while those susceptible to S-CAUTI may be more suitable to saline washouts. Existing concerns that washouts could damage bladder urothelium and cause bleeding may be inaccurate, as the review found reduced haematuria incidence and this evidence was of moderate GRADE certainty. In particular, the potential improvement in patient QoL with washout use deserves further investigation with a larger sample size.

Prophylactic catheter washouts may have more benefits and less harms than previously thought. Tailoring the type of prophylactic washout to patients' needs may improve their QoL. However, current evidence is of low certainty. Therefore, international robust RCTs abiding by SPIRIT and CONSORT guidelines are required.