Purpose: Surgery for renal cell carcinoma (RCC) with an inferior vena cava (IVC) tumor thrombus can be done via a robotic approach. While this approach is thought to minimize blood loss, it may still result in significant losses ( 1 ) and current publications indicate that it can require upwards of 3-day hospital stays ( 1 , 2 ). However, innovative surgical techniques, such as the split and roll, may curtail this. The purpose of this video is to present the case and surgical technique of robotic assisted radical nephrectomy with IVC thrombectomy. Materials and Methods: The patient was a 77-year-old male found to have a right upper pole renal mass on CT urogram. On MRI ( Figure 1 ), a renal mass and level II thrombus was seen. For this case, the Da Vinci Xi Intuitive robotic system was used, with four robotic 8-millimeter (mm) metallic trocars, two 5 mm assistant trocars, and one 12 mm air seal port. The split and roll technique were utilized to access the IVC and lumbar veins. This surgical method uses the adventitia of the IVC as a plane of dissection and safely identifies all branches/tributaries of the IVC to minimize the chance of vascular injury ( 3 ). Results: Robotic console time was 150 minutes. The patient had an excellent outcome, with all tumor thrombus removed, less than 50cc of blood loss, and was discharged within 24 hours of the operation. The tumor pathology came back as papillary, high grade, and was stage pT3bN1. Conclusions: The robotic approach with split and roll technique is a great surgical option for urologists to consider in patients with RCC and a level I or II thrombus, which can minimize blood loss and expedite discharge.

308 Background: Prostate biopsy is one of the most frequently performed procedures in urology. Recently, there has been a nationwide shift towards offering transperineal (TP) biopsies due to a reduced rate of infectious complications compared to the transrectal (TR) route. While infection may be reduced, TP biopsy is not without complication, most notably, acute urinary retention (AUR). Estimates vary as to the true rate of AUR following TP biopsy. Further, some studies have reported higher rates of AUR following TP biopsy than TR. Here we report the rate of AUR following TP biopsy at a single academic institute and relate it to risk factors for developing AUR. Methods: Retrospective case-control study. All biopsies performed with TR ultrasound (TRUS) guidance using TP technique under general anesthesia in dorsal lithotomy with a grid template. TRUS volumes were recorded during the procedure, and MRI volumes were calculated by a trained radiologist pre-biopsy. Charts of men undergoing TP biopsy from 2012 to present were reviewed. AUR was defined as patients who reported inability to urinate within 72 hours post-biopsy and underwent thorough evaluation including PVR and relevant H&P and required catheter placement. Independent samples t-test was run to relate AUR to risk factors pre/post-biopsy. Results: A total of 767 TP biopsies were completed in the study window, but not all had TRUS/MRI data. Total rate of AUR was 5.48% (N=42/767). Risk factors for AUR were increased TRUS (p=0.009, [6.49, 42.30]) and MRI prostate volumes (p=0.027, [2.90, 43.13]). Age, number of cores taken, and number of previous biopsies were not associated with AUR. Conclusions: While data is scant, the rate of AUR at our institution is consistent with current estimates in the literature. There is a growing body of evidence that the rate of AUR post-TP biopsy is higher than TR, but more investigation is needed. There is also a gap in the literature on risk factors predicting AUR after TP biopsy, however our findings are relatively consistent with the few studies currently published. Urologists must recognize patients presenting for TP biopsy with large volume prostates and consider altering management to prevent AUR. [Table: see text]

314 Background: Determining the correct size (volume) of the prostate is imperative for patients with prostate cancer. Prostate size can affect many parameters in patient care such as cores in a biopsy taken and available treatment options. Traditionally, most patients underwent transrectal ultrasound (TRUS) during prostate biopsy to estimate prostatic volume. While TRUS is still used to estimate prostate volume, more recently prostate Magnetic Resonance Imaging (MRI) has also come into favor. Current literature indicates MRI is more accurate than TRUS for prostate size, but few studies exist, and whether differences in the two are clinically significant remains uncertain. The purpose of this study was to compare prostate volumes from TRUS and MRI to gross specimens after prostatectomy. Methods: Patients who underwent radical prostatectomy for prostate cancer between 2017–2022 were identified. TRUS and MRI measurements closest to the date of surgery were obtained. These were compared to gross prostate specimens after surgery, which was considered the gold standard. All TRUS volumes were recorded by a urologist during prostate biopsy using the ellipsoid formula (L*W*H*(π/6)). MRI measurements were done by a radiologist also using the ellipsoid formula. The weight and dimensions of gross specimens were measured by a pathologist. Ellipsoid formula was then used to calculate final volume measurements in gross specimens. Paired samples t-test was used to compare averages of TRUS and MRI to the gross specimen. Results: 83 patients were included in the study with an average age at prostatectomy of 65.47 years. TRUS volume significantly differed from gross specimen volume by an average of –4.56 mL (p=0.017) and gross specimen weight by -14.31 g (p <0.001). MRI volume was not significantly different from gross specimen volume, by an average of –0.56 mL (p=0.771) and was significantly different from prostate weight by –10.32 g (p <0.001). When compared to one another, TRUS and MRI significantly differed on average by –4 mL (p=0.033). Conclusions: MRI is more accurate than TRUS to estimate prostate volume. Both MRI and TRUS underestimate prostate weight. Urologists should be aware of potential inaccuracies when assessing preoperative prostate volume with TRUS, and recognize MRI is the best predictor of size. While imperfect, TRUS is still relatively accurate measuring prostate volume, and given its ease of availability and cost, we feel it is a useful modality to determine prostate size. [Table: see text]