Guidance

Cervical screening: implementation of DySIS as additional colposcopic technique for examination of the uterine cervix

Published 1 October 2012

1. Overview

The Dynamic Spectral Imaging System (DySIS) is a digital video colposcope. A colposcope is a large magnifying glass that a doctor or specialist nurse (colposcopist) uses to closely look at the skin-like covering of the cervix. By looking through it, the colposcopist can see changes that may be too small to see with the naked eye.

DySIS is used to evaluate the acetowhitening phenomenon (the whitening of skin or mucous membrane after application of acetic acid solution) and to detect cancerous and pre-cancerous cervical tissue.

It produces a measurement of the rate, extent and duration of the acetowhitening effect that is summarised in a graphical display, called DySISmap, overlaid on a live image of the cervix. DySISmap therefore provides the colposcopist with additional information that helps in the selection of biopsy sites.

DySIS should be used according to the standard colposcopic guidelines and process, but additional training is required to make sure users understand the correct use and interpretation of the DySISmap. DySISmap should be used in addition to standard colposcopic indicators.

The National Institute for Health and Care Excellence (NICE) and the NHS cervical screening programme (CSP) evaluated the DySIS system and concluded the technology was suitable for use in NHS colposcopy clinics.

Clinical trials demonstrated that, when combined with all other usual colposcopic indicators, DySIS colposcopy can detect high-grade lesions with 88% sensitivity, compared to the 55% achieved by conventional colposcopy.

This publication sets out practical requirements for using DySIS in addition to conventional colposcopy in the NHS CSP in England.

2. Equipment

2.1 Components

DySIS is a CE-marked class IIa digital colposcope. It consists of:

• wheeled base with braking system for moving the device and stabilising the unit
• central pole with 2 positioning arms for moving the imaging head
• onboard computer for data processing and image storage
• touchscreen monitor for image viewing and user interface
• imaging head that incorporates the illumination source, high definition digital camera, speculum connection point and acetic acid applicator

Upgraded software packages and a range of accessories are also available, including a large 19-inch medical grade monitor to help with viewing live and recorded examination images.

The 12-inch touchscreen monitor is used for all data entry, instrument control and image viewing activities.

A range of control options are displayed on the right hand side of the DySIS touchscreen monitor including:

• magnification (x6 to x27)
• brightness control
• green and blue filters
• contrast control
• image (snapshot) capture
• biopsy point annotation
• biopsy video recording

Standard colposcopic examinations can be performed using these DySIS functions.

An acetic acid applicator is included and can be attached to either side of the imaging head of DySIS. It consists of a syringe holder, acetic acid container, tubing, spray nozzle, and pre-aligned mount. Its function is to make sure a measured amount of acid is delivered in a homogeneous pattern onto the cervix. In line with colposcopy guidelines, 3% to 5% acetic acid should be used with DySIS.

2.2 Specula

DySIS requires the use of specific specula, which are available in small, medium and large sizes, as well as in normal and wide-billed widths.

DySIS specula are similar to standard instruments but have an additional extension shaft that enables connection to the DySIS imaging head during the examination, allowing stable images to be captured for the production of the DySISmap.

When integrating DySIS into a clinical service, consideration should be given to the number and size of DySIS specula needed for the colposcopy clinic.

2.3 Manoeuvrability

The wheeled based allows the device to be moved within and between rooms in the clinical setting. A foot-operated brake mechanism can be engaged to provide greater stability during the examination. DySIS needs a mains power supply but is supplied with a long power cable, allowing it to be positioned in any area of the clinic room.

DySIS occupies about the same floor area as a conventional colposcope. It can be set up to the left or right of the examination chair and operated with the left or right hand. The touchscreen monitor can also be positioned to accommodate left or right-handed practitioners, and the display angle can be further adjusted and tilted using a locking joint, so the necessary functions and operations can be accessed.

Two positioning arms allow both vertical and horizontal movement, so the imaging head can be positioned to ensure optimal visualisation of the cervix. The arm that supports the imaging head can be folded when not in use.

Training and familiarisation may be needed so individual users can set up DySIS in a suitable ergonomic position to perform colposcopic examinations.

2.4 Duration of DySIS examination

The examination time for DySIS compares favourably with that for conventional colposcopy. DySIS measures the acetowhitening process over the 2 to 3-minute development time and then automatically produces a DySISmap of the cervix. For patients with a clear presentation, the mapping process can be halted prematurely if necessary, but no DySISmap will then be stored in the patient record system.

3. Training

DySIS Medical provides product training. The cost of this is included in equipment procurement. Individuals operating DySIS must be trained and certified by a company representative or product trainer. The training programme includes device set-up and maintenance, operating instructions and procedures and troubleshooting.

New users can be trained in the use of DySIS, and in interpreting the DySISmap, in 2 to 4 hours. However, there is an initial learning curve as individuals become accustomed to using the system. During this initial familiarisation period, estimated to last 2 to 4 weeks, it may be necessary for clinics to reduce the number of patients seen.

4. Patient database, image storage, IT connectivity and reports

4.1 Onboard database

DySIS includes an onboard patient database that enables practitioners to maintain a record for each patient, including patient details, medical history, images collected during the examination, biopsy annotations, histology results, and the post-treatment management plan.

DySIS stores all high-definition images and video clips produced during the patient examination so these can be reviewed at a later time. The images stored include a baseline/reference image of the cervix, the acetowhitening sequence, biopsy annotations and video, and the DySISmap.

4.2 IT connectivity

Patient records and images can be manually or automatically imported/exported via a USB stick (for manual transfers) or via ethernet (for automatic transfers). Protocols regarding the confidentiality of sensitive or patient identifiable information must be observed.

DySIS has a standard software interface through which electronic medical record (EMR) systems may connect and exchange information. Patient examination data and images produced and stored in DySIS can be exported and integrated into existing colposcopy databases. IT work may be required to enable DySIS to connect with these databases.

Achieving connectivity between DySIS and colposcopy databases ensures that use of DySIS will not interfere with the production of data reports required for quality assurance purposes.

4.3 Reports and patient records

At any point after an examination, DySIS can create a standardised patient report, containing patient details, medical information, and a summary of the examination data. Specific images can be selected and included by the user. The report can be printed directly or exported to a USB storage device as a PDF file.

5. Treatment

After users have been trained, they may be able to use DySIS to perform colposcopy treatments, such as LLETZ. However, because the DySIS imaging head is a different shape to a traditional colposcope, DySIS operators will need to learn new techniques to manipulate biopsy forceps and treatment wands. Because the cervix is viewed on a 2D screen, treatment procedures are similar to those of endoscopy practice. The optical working distance for DySIS is reported to be 30cm, equivalent to most traditional colposcopes.

Some colposcopists may prefer to use DySIS solely for diagnostic purposes. In such cases, either clinics will need to be configured into diagnostic and treatment sessions, or a conventional colposcope will need to be available to allow treatment. In both scenarios, the need to provide enough clinical space must be considered.

6. Service and maintenance

The DySIS colposcope needs basic daily maintenance. No part of the system other than the speculum is intended to come into contact with the patient. Standard cleaning and disinfecting procedures are outlined in the DySIS user manual.

DySIS reusable specula require cleaning and decontamination/sterilisation between uses. The manufacturer provides instructions, which follow standard Medicines and Healthcare Products Regulatory Agency (MHRA) requirements for Hospital Sterilisation and Decontamination Unit (HSDU) sterilisation.