The objective of this prospective study was to evaluate the accuracy of conventional 2D ultrasound (CUS) versus doppler planimetry (DP) in the assessment of postpartum urinary bladder volume compared to a true estimate using urethral catheterisation. Fifty-two women were assessed within 24 hours of delivery. Evaluation of bladder volume was performed using CUS (1-estimate) and DP (6-estimates). CUS had a higher correlation (r=0.796) with the true volume and lower % error than DP in the postpartum group. DP readings were highly reproducible (ICC 0.81) but tended to overestimate the true value especially with smaller volumes. DP was suboptimal for the assessment of the postpartum PVR. Postpartum evaluation using CUS is more accurate in calculating the true urinary volume.