(Poster 12) Bladder Scan Use After Foley Catheter Removal in the Postpartum Period

Objectives: Foley catheter placement is often required during vaginal delivery due to regional anesthesia and in all cesarean deliveries. After patients recover from anesthesia, the Foley is removed. Patients that cannot void within 6 hours of Foley removal have post-partum urinary retention (PPUR). At some institutions, patients with PPUR have a bladder scan to measure volume and are then catheterized. This study aims to determine the accuracy of a bladder scan in a postpartum patient.

Methods: In this retrospective cohort study all patients 18 years or older who had a Foley placed and had a vaginal or cesarean delivery at *** Medical Center in 2023 were identified using the electronic medical record. Exclusion criteria included indication for Foley other than delivery, baseline urinary retention, urinary tract infection (UTI) and/or surgery requiring more extensive bladder manipulation. In addition to the volume obtained via bladder scan and catheterized, data collected included demographic information, delivery type, duration of Foley, time to spontaneous void, weight/BMI and presence of UTI up to 6 weeks postpartum. To compare the two methods of measurement paired t-test with a p value of 0.05 and a Bland-Altman plot were used.

Results: A total of 1557 charts were reviewed and 254 were excluded as per protocol. Of the charts analyzed, 280 patients didn’t void spontaneously within 6 hours of Foley removal and thus met criteria for PPUR. Patients with PPUR were more likely to have undergone a cesarean delivery than patients that voided spontaneously (64.3% vs. 5.4%). In comparing the mean volumes measured with the bladder scan (M= 508.76, SD = 288.52) and catheterization (M = 654.3, SD = 394.5) a significant difference was seen with a p-value=.0012. In the Bland-Altman plot (Figure 1) the mean difference between the methods was -145.5 mL with the 95% limits of agreement: -777.2 mL to 486.1 mL. The plot revealed no significant trends or systemic biases at higher or lower volumes and outliers with differences greater than the limits of agreement were identified.

Conclusions: The urine volumes measured with the bladder scan were significantly different from those catheterized. This was demonstrated by both the t-test and the Bland-Altman plot. The significant difference in the means between the two methods indicate that they may not replace each other. The Bland-Altman plot demonstrated a mean difference far from zero and a wide limit of agreement indicating variability in the differences and suggesting a weak agreement. This data should be taken into consideration when determining how to evaluate for PPUR. If 150 mL difference is perceived as clinically acceptable, then the two methods may be used interchangeably.