Advice

Technology overview

Technology overview

This briefing describes the regulated use of the technology for the indication specified in the setting described and with any other specific equipment referred to. It is the responsibility of health care professionals to check the regulatory status of any intended use of the technology in other indications and settings.

About the technology

CE marking

The multiple components of the SpyGlass system (described in the next section) are individually CE marked as Classes 1 to 2b. All components of the SpyGlass system are distributed by Boston Scientific Corporation.

Description

The SpyGlass is a single-operator cholangioscopy system designed to overcome the limitations of the standard 'mother‑baby' cholangioscopy procedure. As well as needing only a single operator, the SpyGlass has 4‑way tip deflection and a single‑use baby endoscope for access and delivery. The system allows users to visually examine the biliary ducts, take biopsy samples and treat large biliary stones by either electrohydraulic or laser lithotripsy. The current system produces fibre‑optic images which are generally considered to be inferior to digital images taken with standard video endoscopes (Chen 2007, Alameel et al. 2013, Nguyen et al. 2013).

The system consists of non‑disposable and disposable components. The disposable components are listed below:

  • The SpyScope access and delivery catheter (single use), a flexible catheter measuring 3.3 mm in diameter and 2300 mm in length, with single‑operator controls. The SpyScope can be inserted through any duodenoscope with a 4.2 mm working channel. It has 3 dedicated ports:

    • 1 for water flushing and aspiration to clear the field of view

    • 1 for the fibre‑optic SpyProbe

    • 1 for taking biopsies or applying electrohydraulic lithotripsy fibres (1.2 mm).

  • The SpyBite biopsy forceps (single use), allowing biopsy specimens to be taken under direct visualisation.

  • The SpyProbe direct visualisation probe (re‑useable for up to 20 cases), which is a fibre‑optic probe that contains a 6000‑pixel image bundle, surrounded by approximately 225 light transmission fibres. There is a lens connected to the image bundle at the distal tip to capture images across a 70‑degree field of view. The tip of the probe has 4‑way deflection. When loaded into the dedicated optic port, it is designed for complete circumferential visualisation.

The non‑disposable components are listed below:

  • Light source and cable: the light source uses 300 W Xenon light technology. The light cable is composed of a flexible fibre‑optic bundle that transmits the light to the SpyProbe (see below).

  • High‑resolution LCD monitor (1280 x 1024 pixel) that can attach to a cart.

  • Camera system, which includes a camera controller, a camera head, ocular (a mechanical and optical coupler) and video cables for connection to the monitor. The camera uses a sensor that captures light and converts it to digital data which provide 3 types of video outputs (RGB, standard (S)‑video or composite). The ocular aids focus and transmission of the image from the SpyProbe.

  • Flexible 3‑joint arm to hold the camera in place and out of the way.

  • Water irrigation pump with footswitch. The irrigation pump and tubing provide water flow to the SpyScope catheter (see below) in order to clear the duct of debris and maintain clear visualisation. The footswitch controls the variable flow rate.

  • The cart, which provides space for the equipment along with 3 storage drawers to fit the system's storage trays.

  • Large and small storage trays designed to protect the reusable SpyProbe.

  • Power cable pack (5 cables of varying lengths to connect the non‑disposable units to the isolation transformer).

  • Isolation transformer, to manage all electrical demands of the equipment on the cart.

Optional components which are not part of the system and will need to be purchased separately are as follows:

  • Electrohydraulic lithotripsy generator to create oscillating shock waves in short pulses that generate sufficient pressure to fragment the stone.

  • Holmium laser.

The reported complications associated with the use of the SpyProbe are inflammation of the biliary system, duct trauma resulting in bleeding or perforation, infection, peritonitis and breakage of the SpyProbe with fragments remaining in the body (Boston Scientific 2007).

Intended use

The SpyGlass system is intended as a first‑ or second‑line alternative to standard ERCP to provide direct visualisation of the biliary system during endoscopic procedures.

Setting and intended user

The SpyGlass system is intended for use in endoscopic units which have both the equipment and expert staff to carry out ERCP. The intended user is a clinician trained in ERCP endoscopy who performs a large number of ERCPs annually. In the UK this will most commonly be a gastroenterologist, an upper gastrointestinal surgeon or an interventional radiologist (Green et al. 2007).

Current NHS options

NICE guidance on gallstone disease states that people with bile duct stones should have ERCP before or at the time of laparoscopic cholecystectomy to remove the stones. If the stones cannot be cleared with ERCP, the guideline suggests biliary stenting for temporary biliary drainage until endoscopic or surgical clearance is achieved.

The British Society of Gastroenterology guidelines for the management of difficult to remove stones recommend that endoscopists performing ERCP should be able to supplement standard stone extraction techniques with mechanical lithotripsy when needed (Williams et al. 2008). If mechanical lithotripsy fails, electrohydraulic or laser lithotripsy should be used.

In the case of cholangiocarcinoma, symptoms from biliary obstruction in irresectable disease may be relieved by biliary stent placement. Stent placement resulting in adequate biliary drainage improves survival (Khan et al. 2012).

NICE is aware of other ultra‑slim endoscopes that appear to fulfil a similar function to the SpyGlass, a full listing of which is outside the scope of this briefing.

Costs and use of the technology

The manufacturer was unable to provide a purchase price for the SpyGlass system. However, a poster presentation reported an operational cost of £1443 per procedure for the SpyGlass in Japan (Shibata et al. 2012).

A standard ERCP procedure needs to be performed before the SpyGlass can be used. If the NHS reference cost for minor diagnostic ERCP of £794 is added to the estimated cost of the SpyGlass procedure, the average cost per procedure is estimated as £2237. This is more than the weighted average cost (£1768) for all major therapeutic (GB05F‑H), intermediate therapeutic (GB06E‑H) and minor diagnostic (GB07Z) ERCP procedures (DOH 2013).

No other practical difficulties have been identified in using or adopting the technology. Boston Scientific offers training and ongoing in‑case support at no extra cost, as part of the device purchase.

Likely place in therapy

The SpyGlass can be used as a first‑ or second‑line procedure for the diagnostic and therapeutic management of indeterminate strictures and large stones of the biliary system when standard ERCP has been unsuccessful or is deemed to be inappropriate. The latter will be at the discretion of the clinician and may occur if MRI or CT findings indicate that ERCP is unlikely to be successful. The SpyGlass requires specialist training and is more expensive than standard ERCP, so it is currently available at only a limited number of centres (NHS Choices 2012b).

Specialist commentator comments

One specialist commentator stated that cholangioscopy with the SpyGlass is a technically demanding procedure which should only be performed by clinicians who carry out a large number of ERCPs annually. Another specialist commentator stated that the basic technical skills needed for both the SpyGlass and ERCP procedures are similar. Two specialist commentators stated that doing 1 or 2 procedures per month using the SpyGlass should be enough to maintain the skills of experienced clinicians who regularly perform ERCPs.

Two specialist commentators stated that ERCP is standard practice in the UK as the first‑line procedure for managing biliary strictures and stones. One specialist commentator stated that use of the SpyGlass would vary between a general and a specialist teaching hospital. In specialist units it is more likely that it would be carried out as a first‑line procedure because most people are referred from a general hospital after one or more failed attempts with ERCP. Nevertheless, since ERCP is the first step before introducing the cholangioscope, a case could be made that every procedure using the SpyGlass is initially intended as an ERCP session. One specialist commentator also noted that in his experience of working in a specialist unit, patients can be selected to have ERCP with the SpyGlass as a first‑line procedure after the clinicians have reviewed their MRI or CT scan findings. One specialist commentator stated that the SpyGlass is currently used in approximately 5% of all the ERCP procedures, but that this is likely to increase to 10% in the next 10 years.

One specialist commentator stated that the SpyGlass has been the most useful development in endoscopic technology for biliary disease in the last 10 years. In their opinion, the SpyGlass offers a relatively cheap and user‑friendly alternative to standard 'baby' endoscopes for patients with indeterminate biliary strictures and large stones. Without it, they would have needed repeated ERCPs, CT and MRI scans, biopsies and possibly surgery as a last resort. Without the SpyGlass direct lithotripsy, patients with large stones not managed with mechanical lithotripsy would have to have extracorporeal shock‑wave lithotripsy. Success of the latter procedure varies, and patients often need multiple sessions and repeat ERCPs to fully remove the stones. As a result, the number of patients having bile duct surgery or complex liver surgery for gallstones might have been larger had the SpyGlass not been used.

One specialist commentator noted that the studies included in this briefing are representative of UK clinical practice. They show that for approximately 80% of patients who needed cholangioscopy with the SpyGlass, there was a significant clinical and cost‑saving benefit compared with the alternative options mentioned above.

One specialist commentator noted that the main indications for cholangioscopy with the SpyGlass are for the treatment of difficult intraductal stones and assessment of indeterminate biliary strictures. The same commentator also noted that cholangioscopy will become the standard technique to provide a vehicle for other emerging diagnostic and treatment modalities such as confocal microscopy, other imaging techniques, and laser therapy.

One specialist commentator noted that, although the current version of the SpyGlass is the first single‑operator cholangioscopy system, it has significant limitations. Among these are the steep learning curve associated with using the equipment and interpreting images, the fragility of the SpyProbe and the poor image quality delivered by the fibre‑optic imaging. Two specialist commentators noted (and the manufacturer confirmed) that a new version of the SpyGlass is being developed which uses a micro videochip, and that this will address the current limitations to the SpyProbe.

Two specialist commentators noted that from their personal experience, cholangioscopy with the SpyGlass is safe. Although the fragility and deterioration of the SpyProbe is a common problem, it has never resulted in patient harm. One specialist commentator stated that from his clinical experience, the SpyProbe only lasts for 10 rather than 20 procedures.

Equality considerations

NICE is committed to promoting equality and eliminating unlawful discrimination. In producing guidance, NICE aims to comply fully with all legal obligations to:

  • promote race and disability equality and equality of opportunity between men and women

  • eliminate unlawful discrimination on grounds of race, disability, age, sex, gender reassignment, pregnancy and maternity (including women post‑delivery), sexual orientation, and religion or belief (these are protected characteristics under the Equality Act 2010).

No particular equalities issues were raised in the preparation of this briefing.