Background
Postpartum urinary retention (PPUR) (also known as voiding dysfunction) is a common problem, defined as the inability to completely void after giving birth. If voiding dysfunction is not recognised, bladder overdistension can lead to denervation, detrusor atony and prolonged voiding dysfunction.

Aim
To describe the incidence of PPUR amongst postpartum women undergoing routine bladder scanning and to identify the factors that lead to postpartum voiding dysfunction.

Methods
A retrospective analysis of all postpartum women at Mater Health Services, Brisbane between February and December 2012 was undertaken. Routinely collected postvoid residual bladder volumes (PVRBV) were reported using a bladder scanner at four and six hours and two to three days postbirth or following removal of an indwelling catheter (IDC). The characteristics of women with or without increased PVRBV were analysed.

Results
Postvoid residual bladder volumes at four‐hours postbirth/removal of IDC were available for 5558 women of whom 281 (5.1%) had a residual volume measured >150 mL. Obstetric factors explored included mode of birth, method of analgesia or anaesthesia, duration of labour, degree of perineal trauma, birth weight, gestation, parity, maternal age and body mass index. After controlling for confounders, nulliparity (aOR 1.53; 95% CI 1.05–2.26), birth by caesarean section (aOR 2.21; 95% CI 1.10–4.41) and 3rd/4th degree perineal trauma (aOR 2.01; 95% CI 1.09–3.72) were significant independent predictors of PPUR.

Conclusion
Following the introduction of a protocol of timed voiding and routine measurement of PVRBV after birth/removal of IDC, PPUR is uncommon. Adopting a risk‐factor‐based approach to PVRBV screening is not supported by these data.