Vaginal delivery effects on 3D morphology of the bladder, urethra, and vagina: a pilot study comparing women with different numbers of deliveries.

Abstract

To explore 3D morphological changes of the bladder, urethra, and vagina following different numbers of vaginal deliveries. Sampled patients had undergone magnetic resonance imaging for gynecological diseases in Nanfang Hospital. A total of 167 patients who met the study inclusion and exclusion criteria were enrolled and divided into four groups. Mimics and UG software packages were used for reconstructions and measurements, and data were compared with one-way analyses of variance. A total of 167 3D models were constructed, and eight parameters related to the bladder and urethra were measured (5 angles, 2 lengths, and 1 thickness). No statistically significant differences were found between subgroups, although mean plot figures of urethra pubic and α angles showed trends to increase with more deliveries, and the opposite trend was seen for the urethra tilt angle. There were no obvious trends between other parameters and delivery number. There were seven vaginal parameters (6 lengths and 1 shape). Mid-urethral and vaginal gap measurements tended to become wider as delivery number increased, and the opposite was seen for the distal gap. Mid-vaginal 2D cross-sectional shape and the proportion of shallow concave types also tended to significantly increase with more deliveries, especially after the third birth. As the number of deliveries through the vagina increases, the lateral support function of this organ and the urethra become relatively weaker. These fine anatomical changes are related to delivery numbers and become most obvious after the third birth.