The introduction of the single-port (SP) robotic system has led to new approaches in robot-assisted radical prostatectomy (RARP), such as the transvesical (TV) approach, offering high rates of early urinary continence. While previous studies of SP TV RARP have identified perioperative factors influencing continence outcomes, the impact of anatomical factors remains unexplored. This study aims to assess magnetic resonance imaging (MRI)-based anatomical predictors of urinary continence after SP TV RARP.
A retrospective analysis of consecutive SP TV RARP cases (November 2020 to June 2023) with preoperative prostate MRI was performed. Two urogenital radiologists independently evaluated ten anatomical parameters to distinguish patients achieving urinary continence within 1 wk and 3 mo. Nonparametric methods estimated receiver operating characteristic curves (area under the curve [AUC]) and inter-reader agreement.
In 120 cases, 40% achieved continence within 1 wk, rising to 71.7% by 3 mo. Membranous urethra length (MUL) alone was significantly associated with continence at 3 mo (AUC: 0.67, p = 0.003). At 1 wk, several parameters, including anteroposterior diameter of the prostate, coronal membranous urethra length, prostate volume, and transverse diameter of the prostate, showed promise in predicting continence.
A longer preoperative MUL was significantly associated with better odds of an early return to urinary continence after SP TV RARP. Each 1-mm increase in coronal MUL was associated with a 27% increase in the odds of continence at 3 mo. This information can aid in patient counseling and expectations preoperatively.
I read with interest the recent article by Ramos et al reporting on the role urethral length after single port (SP) robotic radical prostatectomy (RARP) [1]. While I commend the authors for addressing this topic, and I agree on the need of a more accurate preoperative selection to improve not only oncological but also functional outcomes, it is necessary to further emphasise some factors.
First, the presence of a predictive tool for continence status is crucial to help the clinician in counselling patients upfront for the appropriate treatment regardless of the type of surgical technique used. As continence is clearly multifactorial, the development of an accurate and useful predictive model proves to be challenging and requires large real-life datasets.
The increasing attention towards anatomical features related to urinary incontinence (UI), driven by the widespread use of multi-parametric Magnetic Resonance Imaging (mpMRI) during the diagnostic process of prostate cancer, has led to membranous urethral length (MUL) being one of the most studied and important mpMRI variables associated with continence recovery, but is clearly not enough. Urethral length measurement should not be used as a single parameter but should be included into a pre-treatment predictive model where all other significant predictors of incontinence are considered. On top of urethral length, also supporting structures and muscles could be crucial in the mechanism of continence recovery [2]. It is of note that in some previous multivariable models, urethral length was not significantly correlated to continence recovery [3-4]. In this context, probably, also the preservation of urethral integrity is an important denominator. Cho et al. showed that a damaged urethra is significantly more compliant, leading to a disproportionally long urethra when stretched [5]. Predictive factors encompass not only anatomical and surgical aspects, but also the patient’s and disease characteristics. Therefore predictive models should focus on pre-, peri-and early postoperative variables to predict functional outcomes. This may help in a preoperative setting to better counsel patients about their risk of UI. On the other hand, in a postoperative setting, patients could already be informed on the probability of an additional surgery for incontinence. Therefore, in this context a telephone interview or the surgeon's report during the follow up is not sufficient and must be replaced by validated questionnaires that ideally should also be administered in the preoperative setting since we know that preoperative continence status is an important variable to take into account in order to create realistic expectations in the patient after surgery regardless of the technique used [3].
[1] Ramos R, Shankar PR, Soputro NA, Bullen J, Pedraza AM, Chavali JS, Mikesell CD, Ward R, Purysko A, Kaouk J. Preoperative Prostate Magnetic Resonance Imaging-based Anatomical Predictors of Early Urinary Continence Following Single-port Transvesical Robot-assisted Radical Prostatectomy. Eur Urol Focus. 2024 Jun 11:S2405-4569(24)00089-0. doi: 10.1016/j.euf.2024.05.025. Epub ahead of print. PMID: 38866663.
[2] Song C, Doo CK, Hong JH, Choo MS, Kim CS, Ahn H. Relationship Between the Integrity of the Pelvic Floor Muscles and Early Recovery of Continence After Radical Prostatectomy. Journal of Urology 2007;178:208–11. https://doi.org/10.1016/j.juro.2007.03.044.
[3] Tutolo M, Rosiello G, Stabile G, Tasso G, Oreggia D, de Wever L, et al. The key role of levator ani thickness for early urinary continence recovery in patients undergoing robot‐assisted radical prostatectomy: A multi‐institutional study. Neurourol Urodyn 2022;41:1563–72. https://doi.org/10.1002/nau.25001.
[4] Borin JF, Skarecky DW, Narula N, Ahlering TE. Impact of urethral stump length on continence and positive surgical margins in robot-assisted laparoscopic prostatectomy. Urology 2007;70:173–7. https://doi.org/10.1016/J.UROLOGY.2007.03.050.
[5] Cho DS, Choo SH, Kim SJ, Shim KH, Park SG, Kim SI. Postoperative membranous urethral length is the single most important surgical factor predicting recovery of postoperative urinary continence. Urol Oncol. 2020 Dec;38(12):930.e7-930.e12. doi: 10.1016/j.urolonc.2020.07.024. Epub 2020 Sep 6. PMID: 32900623.