Prevalence and risk factors of overt postpartum urinary retention among primiparous women after vaginal delivery: a case-control study

Postpartum urinary retention (PUR) may lead to bladder neuromuscular damage and subsequently voiding dysfunction. However, the literature regarding the incidence of and risk factors for PUR remains unclear. Moreover, previously reported studies are limited to small sample sizes. Thus, this study aimed to assess the incidence of and risk factors for overt PUR after vaginal delivery.This retrospective case-control study included all primiparas who delivered vaginally between July 1, 2017, and June 30, 2019, at our institution. The case group comprised 677 women diagnosed with overt PUR who required catheterisation after delivery. The control group comprised 677 women without overt PUR randomly selected in a 1:1 ratio matched for date of delivery and who delivered immediately after each woman with overt PUR to minimise the impact of variations over time in obstetric practice. Univariate and multivariate logistic regression analyses were performed to investigate the factors associated with overt PUR.Of the 12,609 women included in our study, 677 were diagnosed with overt PUR (incidence 5.37%). Univariate analysis identified epidural analgesia, episiotomy, perineal tears, instrument-assisted delivery, duration of labour stage, intrauterine operation, and vulvar oedema as risk factors for PUR. Multivariate logistic regression identified epidural analgesia (odds ratio [OR] = 1.41, 95% confidence interval [CI]: 1.11-1.79, P = 0.005), vulvar oedema (OR = 6.92, 95% CI: 4.65-10.31, P < 0.001), forceps delivery (OR = 8.42, 95% CI: 2.22-31.91, P = 0.002), episiotomy (OR = 1.37, 95% CI: 1.02-1.84, P = 0.035), and second-degree perineal tear (OR = 3.42, 95% CI: 2.37-4.94, P < 0.001) as significant independent risk factors for PUR.PUR was highly associated with epidural analgesia, forceps delivery, vulvar oedema, episiotomy, and second-degree perineal tears. More attention should be paid to women at high risk to reduce the incidence of PUR.