Indian Journal of Urology
: 2013  |  Volume : 29  |  Issue : 4  |  Page : 363--364

Anti-biofilm mechanism for indwelling wireless capsule endoscopy in bladder cancer surveillance: A study in sheep model

Kuldeep Sharma 

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How to cite this article:
Sharma K. Anti-biofilm mechanism for indwelling wireless capsule endoscopy in bladder cancer surveillance: A study in sheep model.Indian J Urol 2013;29:363-364

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Sharma K. Anti-biofilm mechanism for indwelling wireless capsule endoscopy in bladder cancer surveillance: A study in sheep model. Indian J Urol [serial online] 2013 [cited 2019 Aug 25 ];29:363-364
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Though cystoscopy is the 'gold standard' for bladder cancer surveillance, it is an invasive and expensive procedure and follow-up is often arduous for patients. [1] Wireless capsule endoscopy (WCE) is a novel technology used successfully in the gastrointestinal tract mainly to diagnose small bowel pathology. Similar technology can be used in the urinary tract but long-term dwelling in urine would probably result in surface encrustation and biofilm formation, leading to obscured image transmission and increased risk of urinary tract symptoms or infection. The authors developed a unique anti-biofilm technology. [2]

The device (WCE) is housed within a silicone balloon, which is filled with mineral oil (rather than isotonic or hypertonic clear fluids). The size of the capsule is adapted to fit the lumen of a standard resectoscope sheath (26 F), in its deflated state its diameter is 7 mm and its length is 25 mm. On inflation, the balloon diameter increases to 32 mm. An image can be transmitted from the bladder to a side console on demand. The surface of the balloon has semi-permeable, unidirectional properties, which allow continuous diffusion of oil at a mean rate of 3 × 10−4 ml/h while preventing urine from diffusing in. Thus, the total volume lost after 2 years should not exceed 6 ml, which encompasses ~20% of the initial volume, allowing the device to float. The continuous permeation of oil minimizes accumulation of surface proteins, potentially preventing adherence of bacteria and surface encrustation along with regeneration of the portion of oily film removed during friction with the bladder wall. The transparency of the surface was assessed by evaluating a resolution target (consisting of a metal sheath engraved with fine linear notches, placed inside the balloon) at serial intervals using cystoscopy at 3, 12 and 20 weeks under general anesthesia. Animal behavior (interaction with each other, with other living beings and with the environment), voiding patterns with urine for hematuria and cultures were monitored throughout the study. The device was retained in the bladder a total of 5 months.

No notable adverse effects or behavioral changes were noted during the entire follow-up period. Blood evaluation was unremarkable and all urine cultures were negative. At study termination, the capsule was extracted and assessed using scanning electron microscopy. The capsule maintained a clear surface after 20 weeks as confirmed by cystoscopy and upon retrieval. This was also confirmed using a scanning electron microscope as opposed to rapid encrustation on a standard Foley catheter immersed in urine for 3 days. Notably, the volume of oil in the balloon did not change substantially and the device could still float when placed in sterile saline.


Although various methods exist for monitoring the bladder, adopting the concept of WCE in patients who require lifelong bladder cancer surveillance seems appealing. However, lengthy dwelling of foreign bodies in urine will ultimately result in surface encrustation, limiting the ability to obtain serial images. In the present study, the authors demonstrated the efficacy of a novel anti-biofilm mechanism allowing the capsule to reside in a sheep bladder for 5 months without biofilm encrustation, urinary tract infection or associated adverse side- effects. Svatek et al. concluded that a large number of patients with suspicious cystoscopic findings might undergo unnecessary biopsies. [3] Thus, a WCE device with an automated sequence for imaging the entire bladder and digital image processing to improve the accuracy of detecting mucosal abnormalities would theoretically decrease the false-negative rate of white light cystoscopy and at the same time prevent unnecessary invasive intervention with its attendant morbidity. [4] Whether this would translate into improved oncological outcomes remains to be studied.

Theoretically, if bladder imaging can be acquired by technicians or through home-based retrieval devices, WCE can potentially shift the labor associated with bladder cancer monitoring from the practicing urologist to ancillary health team providers; this approach can lead to a reduction in costs for health-care systems.

The study has some limitations. - Bladder images were obtained through cystoscopy rather than transmitted to an outside console using the wireless technology. An efficient navigation system to manipulate the capsule in the bladder was not used. Animal discomfort or voiding trends cannot be translated to human subjects. The present study was terminated after 5 months while bladder monitoring is generally required for substantially longer periods.

In conclusion, the authors have demonstrated the effectiveness of a novel technology to prevent biofilm accumulation on the outer surface of a designated capsule sustained in a urine environment, which will ultimately be implemented in WCE of the bladder in patients requiring cystoscopic surveillance.


1Schrag D, Hsieh LJ, Rabbani F, Bach PB, Herr H, Begg CB. Adherence to surveillance among patients with superficial bladder cancer. J Natl Cancer Inst 2003;95:588-97.
2Neheman A, Schulman C, Yossepowitch O. Novel anti-biofilm mechanism for wireless capsule endoscopy in the urinary tract: Preliminary study in a sheep model. BJU Int 2013;111:1156-60.
3Svatek RS, Lee D, Lotan Y. Correlation of office-based cystoscopy and cytology with histologic diagnosis: How good is the reference standard? Urology 2005;66:65-8.
4Clark KR, Higgs MJ. Urinary infection following out-patient flexible cystoscopy. Br J Urol 1990;66:503-5.