Research Article: Significance of the Intraoperative Methylene Blue Test for Postoperative Evaluation of the Vesicourethral Anastomosis

Date Published: August 12, 2012

Publisher: Hindawi Publishing Corporation

Author(s): J. N. Nyarangi-Dix, S. Pahernik, J. L. Bermejo, L. Prado, M. Hohenfellner.

http://doi.org/10.1155/2012/702412

Abstract

We prospectively investigated whether routine evaluation of the vesicourethral anastomosis (VUA) after radical prostatectomy can be waived. Primary integrity of the VUA was analysed by an intraoperative methylene-blue test (IMBT) and postoperatively by conventional cystography. Data on the IMBT, contrast extravasation and prostate volume as well as pad usage were collected prospectively. Significantly more patients with a primary watertight anastomosis demonstrated by the MBT had no leakage in the postoperative cystography (P < 0.001). In a multivariate logistic regression with adjustment for prostate size and surgeon, the positive correlation between IMBT and postoperative cystography remained statistically significant (P = 0.001). The IMBT is easy to perform, inexpensive, and timesaving. With it postoperative evaluation of VUA for integrity can be waived in a significant number of patients. Following our algorithm, the Foley can be removed without further testing of the VUA, whenever the IMBT detected no leakage.

Partial Text

Radical prostatectomy (RP) is one of the major therapeutic options in the management of organ confined prostate cancer [1]. In order to support healing of the vesicourethral anastomosis (VUA) after RP, temporary urinary drainage with a transurethral Foley catheter is routinely performed [1]. This catheterisation is usually continued for the first 4–14 days after the procedure [1–4]. Before removal of the Foley, it is recommended to rule out anastomotic leakage [2]. This makes it often necessary for the patient to revisit his attending physician, for example, for performance of a conventional cystography [2, 3]. This is not only time consuming for all parties involved but also associated with higher costs and patient discomfort [5]. For this reason, we initiated a prospective study aimed at investigating whether cystography studies before Foley removal can be somehow reduced or in certain cases entirely waived. The study was performed according to ethical principles for medical research as noted in the current Declaration of Helsinki and was in accordance with the German Medical Association’s professional code of conduct. All patients gave informed consent for participation in this study.

We prospectively investigated 103 consecutive men undergoing radical retropubic prostatectomy in our institution. All patients were followed up at 0, 3, 6, and 12 months. RP was performed in our institution by 4 skilled surgeons each performing the procedure as described by Walsh et al. [1]. We analysed the primary water tightness of the VUA by filling up the bladder after tying the anastomosis. In order to ease detection of even minimal anastomotic leakage, a sterile solution made of 5 mL methylene blue and 95 mL normal saline was prepared. White sterile dressings were placed around the VUA to further ease identification of methylene blue leakage. A syringe was used to manually instil 100 mL of the prepared methylene blue solution into the bladder via the routinely placed 20 French transurethral Foley. The methylene blue solution remained instilled in the bladder for 15 s, before passive drainage by opening of the Foley was allowed. A primary watertight anastomosis was defined as lack of leakage of the methylene blue solution verified by the unstained white dressings. The methylene blue solution cost us only 1.19 Euros.

The median age of the patients was 66.3 years (range: 45.3–79.2 years). In the investigated collective of 103 men, 71 (68.9%) detected no leakage in the IMBT. Among these patients with a primary watertight VUA, 83.1% (n = 59) had no contrast extravasation in the POD-5-cystography. On the other hand, only 37.5% (n = 12) of patients with leakage in the IMBT detected no contrast extravasation at the same time (Table 1). We found a significantly higher proportion of patients with no leakage in the POD-5-cystography had an intraoperatively watertight anastomosis compared to those with intraoperative methylene blue leakage (83.1 versus 16.9%, P = 0.001). The sensitivity and specificity of the IMBT were 83.1% and 62.5%, respectively (Table 2). 68.9% of all cystography studies demonstrated a watertight VUA. Taking the postoperative POD-5-cystography as a validated technique for evaluating integrity of the VUA, the IMBT reached positive and negative predictive values of 83.1 and 62.5%, respectively. 16.9% of IMBTs were falsely positive, that is, demonstrated leakage when there was no relevant extravasation on POD-5 and 32.5% were falsely negative, that is, showed no intraoperative leakage while there was minimal extravasation on the POD-5-cystography (Table 2). There was significant correlation between results of the IMBT and POD-5-cystography (P < 0.001). In this study, a majority of the patients were accurately classified by the IMBT, that is, 76.7% on POD-5. Interestingly, all men with an intraoperatively watertight VUA ascertained by the IMBT demonstrated no more contrast extravasation at POD-12. In order to increase patient comfort and facilitate recuperation, the duration of Foley catheterisation after RP has successively decreased over the last decades [2–4, 7, 8]. The length of postoperative catheterisation often correlates with the duration of urinary extravasation that on the other hand seems to inversely correlate with anastomotic strictures and continence rates [9, 10]. Even though some authors propose removal of the Foley without prior evaluation of urinary extravasation, this practice has not yet found wide acceptance among urologists [11]. Before Foley removal most institutions routinely investigate anastomotic extravasation, for example, with a cystography, making it often necessary, for the recuperating patient to revisit his attending physician [2–4, 8]. The organisation around and performance of a cystography are not only time consuming for all parties involved but also associated with higher costs and patient discomfort [5, 11]. Depending on institutional practice, the Foley is usually removed when there is minimal anastomotic leakage or none at all [2, 4, 5, 8]. Our institution prefers the latter practice. A number of studies have investigated parameters that predict postoperative anastomotic leakage. So far no validated predictive parameters of postoperative urinary extravasation have been identified that make postoperative proof of anastomotic integrity before Foley removal unnecessary [12]. For this reason, we initiated this prospective study to investigate whether cystography studies for evaluation of the VUA before Foley removal can be minimised or even entirely waived. In conclusion, we find that the IMBT is a promising screening tool that is easy, inexpensive, and timesaving. We suggest routine application as a screening tool to identify patients in whom postoperative evaluation of the VUA can be waived. According to our results the Foley can be safely removed without prior evaluation of the vesicourethral anastomosis when the IMBT demonstrated a watertight anastomosis. Nevertheless, urinary extravasation should still be routinely ruled out in case of intraoperative methylene blue leakage.   Source: http://doi.org/10.1155/2012/702412

 

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