Effect of the duration of labor on postpartum postvoid residual bladder volume.

In order to investigate the possibility of protracted labor as a risk factor for postpartum urinary retention and to study the relation between duration of labor and postpartum day 1 postvoid residual bladder volume, the postpartum postvoid residual bladder volume (PVRBV) of a group of patients was studied using ultrasonography. Out of 707 patients investigated during a 2-month study period, a homogeneous group of 164 patients, with possible risk factors for postpartum urinary retention being controlled, was studied. The homogeneous group's postpartum day 1 postvoid residual bladder volumes were assessed by ultrasonography and analyzed with respect to the duration of labor. The incidence of postpartum urinary retention ( > or = 150 ml) was 11% in this homogeneous group. Labor duration longer than or equal to 800 min was associated with a higher incidence of postpartum urinary retention (chi2 test; p < 0.05). Moreover, there is a direct relationship between the duration of labor and PVRBV which is described by a quadratic regression curve. Protracted labor longer than or equal to 800 min is a risk factor for postpartum urinary retention. The PVRBV is directly related to the duration of labor.