ObjectiveTo establish a rat model of postpartum stress urinary incontinence (PPUI) through vaginal placement of urinary catheter balloon causing pelvic organ injury.MethodsAfter the vaginal catheter balloon dilation for 8 hours on 40 Sprague-Dawley female rats, 25 were randomly selected as experimental group and 5 normal rats of the same age as control group. Sneeze test was used on the day of the procedure and on weeks 1,2, 4 and 8. The animal models were evaluated through urodynamics as measured by leak point pressure (LPP), maximum bladder volume, pelvic floor muscle acetylcholine receptor content, comparison of serum lactate dehydrogenase (LDH) and creatine kinase (CK) according to the JSCC standards, pelvic floor muscle strength and RT-PCR assessment of caspase-3 expression. ResultsAfter 8 hours of vaginal balloon dilation, a rat model of PPUI was established with a success rate of 72.5% (29/40). In the model animals, LDH and CK were initially increased, peaked on day 7, and finally decreased toward normal values. The pelvic floor muscle contraction strength and pelvic pubococcygeus acetylcholine receptors were declined. There were significant differences in the values between experimental and control groups (P<0.05). Pubococcygeal muscle caspase-3 gene expression peaked on the day of the procedure (P<0.05) and decreased thereafter. ConclusionsRats subjected to vaginal balloon dilation for 8 hours display biochemical alterations in sera, activation of caspase-3, and decreased pelvic floor muscle contraction strength, similar to those observed in human PPUI patients. 