Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Advanced: How to evaluate sharp safety-engineered devices

  • Comment

Authors Joanna L. Ford, PhD, BSc, is research and development officer; Pete Phillips, MRPharmS, BPharm, is director; both at surgical material testing laboratory, Princess of Wales Hospital, Bridgend.

Abstract Ford, J. (2008) How to evaluate sharp safety-engineered devices. Nursing Times; 104:
36, 42–45.

With increasing concerns of occupational exposure to bloodborne viruses in healthcare settings, NHS trusts are under pressure to consider opting for safer sharps devices that are designed to protect users from needlestick injuries. However, with an ever-increasing range of ‘sharp safety’ devices on the market, deciding what to purchase is a complex issue. In addition, evidence shows that purchasing safety devices alone will not eliminate the problem of needlestick injuries. This article discusses the criteria that should be taken into account when trusts consider introducing sharp safety devices into their workplace.

Needlestick injuries are a common occupational hazard for healthcare workers in the NHS. A sharps injury from a blood-contaminated needle can put staff at risk of bloodborne viruses such as hepatitis B, hepatitis C and HIV. Eleven occupationally acquired cases of hepatitis C and five cases of HIV that have led to seroconversions were reported to the Health Protection Agency between 1997 and 2005 (HPA, 2006).

There are many sharps devices on the market that have features designed to reduce the risk of needlestick injuries. Examples of these include needles with shields and retractable needles. There are sharp safety alternatives to many medical devices including hypodermic needles, blood collection systems, IV cannulas, scalpels, sutures and sharps disposal systems. Also available are needle-free connectors that provide injection ports which can be accessed without needles.

In July 2006, the European Parliament voted to approve a report that requires the European Commission to bring forward a legislative proposal aimed at protecting healthcare workers from needlestick injuries. The report states ‘on the basis of risk assessments, moves should be made towards ensuring that appliances with safety features, where they exist, are used’ (European Parliament, 2006). However, we would like to see the European legislative proposal use a form of wording such as ‘ensuring that appropriate and demonstrably effective devices with safety features, where they exist, are used’.

The effectiveness of different designs of sharp safety device (SSD) can vary considerably (Centers for Disease Control and Prevention, 1997) and some ‘safety’ designs have even been shown to cause injuries (United States General Accounting Office, 2000), so there is a requirement for devices to be thoroughly evaluated before they are introduced. The Scottish NHS carried out extensive evaluations of a range of SSDs throughout Scotland in 2003 and reported that some of them had caused injuries to users (Paterson and Elder, 2003).

The Federal Drug Administration in the US has issued a series of recommendations to manufacturers regarding the design of SSDs (FDA, 2005). The FDA recommendations include the following:

  • It should be obvious when the device has been activated;

  • Activation of the safety feature should not be reversible;

  • It is best if a device can be activated using one hand only;

  • Needle shields should cover the needle when they are activated and prevent finger access.

Box 1 summarises some of the criteria that should be taken into account when considering the introduction of SSDs.

Box 1. Questions to consider when introducing devices

  • Is the device reliable?

  • Is the device clinically suitable for your workplace?

  • Will the device be used appropriately?

  • Are there any additional infection control issues to consider?

  • Will the device change the patient experience?

  • How much training will the device require?

  • Will the device be comfortable for healthcare workers to use?

  • What laboratory/clinical data is available about the device?

  • What are the economic considerations of introducing the device?

Device reliability

SSDs are usually more complex than their conventional counterparts and usually contain additional mechanisms and design features.

Reliability of an SSD is essential as a malfunction in the protective mechanism of an SSD may cause injury because users assume they are protected once it is activated.

An example of this is a device whose safety feature is supposed to engage with an audible click; if this does not happen on every occasion, the user may lose confidence in the device and be unsure whether it is safe.

If a device does not work properly, the user may have to dispose of it and try again, which is a waste of resources.

Examples of faulty SSDs, include: cases of retractable needles failing to retract completely into the barrel of the syringe upon activation (ECRI, 2003); and disengagement of a needle and a dental syringe during assembly (Porteous and Terezhalmy, 2004).

During evaluations of SSDs, questions such as ‘was the device reliable?’, ‘did you hear the audible click when the safety feature engaged?’ or ‘did the safety feature activate first time?’ should be included in order to assess the issue of device reliability.

Clinical suitability and efficacy

SSDs must be compatible with existing systems used in the workplace. For example, a new safety blood evacuation needle must be compatible with blood evacuation tubes and blood culture bottles in use there.

It is also important to determine whether the device performs the role for which it is designed.

A study that evaluated safety single-use blood lancets found that one of the models produced insufficient blood volume in 68% of the cases, indicating that this particular lancet was not performing effectively (Fruhstorfer, 2000).

Questions such as ‘did the device take a sufficient volume of blood?’ (for phlebotomy products) or ‘did the device inject all the medication?’ (for hypodermic syringes/needles) should be included in evaluations to assess their efficacy.

Appropriate use

Some users may handle an SSD with less caution than a conventional device because it has a ‘safety’ label.

A common example of SSDs not being appropriately used is failure of the user to activate the safety mechanism after use. This can be investigated by observing users, auditing the contents of sharps bins (which is a risk-prone procedure itself) or asking users to estimate the percentage of safety devices they did not activate. There are problems with each of these methods.

Three studies that audited the contents of sharps bins showed that 40% of safety syringe/needles (Mulherin et al, 1996), 30% of safety phlebotomy devices (Centers for Disease Control and Prevention, 1997) and 17% of shielded safety butterfly needles (Mendleson et al, 2003) had not been activated after use.

These issues may be addressed by training but reliance on training will inevitably miss some staff.

Some SSDs can be made safe passively (such as some safety IV cannulas, where the shield is engaged as the needle is withdrawn from the cannula) and these are considered the best design because no additional action is required by users to engage the safety feature. However, very few passive SSDs are currently available.

Infection control

Whenever a new medical device is introduced into a clinical setting, infection control issues must be considered.

Typical considerations may include whether there are more connectors on the device, whether the user has to make increased contact with the device in order to use it or whether it produces blood splash-back following activation. Cases of blood splash-back upon activation of some safety syringes and IV cannula devices have been reported (Adams and Elliott, 2003; Asai et al, 2002).

A number of hospitals have published the results of trials where needle-free connectors have been used and bloodstream infection rates during their use calculated. The results have been mixed – some show no increase in blood stream infections with the use of needle-free connectors (Zafar et al, 1999; Mendelson et al, 1998), while other reports show that bloodstream infection rates have increased following the introduction of a needle-free connector (Cookson et al, 1998; McDonald et al, 1998; Kellerman et al, 1996).

A recent US study swapped one model of needle-free connector they had been using on central venous catheters for 10 years in ICU to another model (Maragakis et al, 2006). However, they stopped using the new connector due to an increase in bloodstream infections. Increases in bloodstream infection rates in these cases have been attributed to various factors such as a variation in clinical practice, unfamiliarity with the device (Cookson et al, 1998), the number of activations of the device (Danzig et al, 1995) and the device design (Maragakis et al, 2006).

ECRI (an American device evaluation organisation) has stated that most data on this issue is ‘anecdotal’ and that more scientific evidence is required before the use of needle-free connectors can be linked with increases in bloodstream infections (ECRI, 2006). A systematic review of needle-less systems came to a similar conclusion (Niel-Weise et al, 2006).

Patient experience

Some of the SSDs have attachments, such as shields, which may look daunting to a patient who is used to a conventional device. Some are activated with an audible click and others can be activated while the needle is still in the patient’s vein. All of these factors may affect the patient experience of discomfort and noise compared with conventional devices. Obtaining feedback from patients can increase the complexity of an evaluation, as ethics approval is usually required.


Although SSDs are often similar in appearance to conventional devices, it is a mistake to assume that they are used in an identical manner. As with any medical device, training is an essential part of the support provided by the supplier and it is important to consider how many users can be trained in a given timescale and the risks for users who do not or will not attend a training session.

Potential users may also wish to examine the instructions for use and labelling details. For example, is it clear from the packaging that the device is an SSD and are the instructions for use easy to understand? It must be emphasised that instructions can be very different for two models of the same type of device. For example, two safety blood collection sets currently on the market have retractable needles but one is activated by pressing a button while the other requires pulling the tubing to retract the needle.

User experience

When performing a procedure, SSDs should be comfortable to use. Ideally, other than the additional actions associated with the safety mechanism, the way the procedure is carried out should be no different from that for a conventional device. Through our experience of evaluating a range of SSDs in the Welsh NHS, some of the devices can be uncomfortable to hold because safety features obstruct the way the device would usually be held. Safety features in some devices can visually obstruct the needle tip, making venipuncture difficult.

Including questions such as ‘Is the device comfortable to use?’, ‘Can you see the needle tip when performing venipuncture?’ and ‘How many times did you use this device until you felt comfortable using it?’ in evaluation questionnaires is helpful.

Data interpretation

Reviewing published evaluations of safety devices is essential before embarking on device trials in a hospital. ECRI has evaluation data on its website ( and other independent device evaluations have also been published.

Some companies can provide their own data related to the clinical effectiveness of their device and published independent studies of the devices may also be available.

However, when papers (cited by companies or independent investigators) discuss ‘reduction in injury rates’, the sample sizes and time scales used can make the results appear better than they actually are, while the way studies are described may be misleading.


As is usually the case with advances in medical technology, one of the most important barriers to implementation is cost.

Trusts must take into account both the costs of using the SSD and the costs saved if injuries are prevented as a result of introducing the SSD.

The costs saved from ‘injuries prevented’ usually includes ‘hidden’ costs such as blood tests, sickness absence and counselling.

Calculating such costs usually relies on the reduction in rates reported in studies demonstrating the clinical effectiveness of the device. An NHS Scotland document reported the following (NHS Scotland, 2000):

  • An needlestick injury leading to seroconversion costs approximately £10,000–20,000 per case;

  • A high-risk needlestick injury that does not lead to seroconversion costs around £3,000–5,000;

  • An needlestick injury where the source patient is unknown costs approximately £1,000–2,000;

  • Low-risk needlestick injury costs approximately £50–100 per case.

Some companies provide computer packages for calculating the costs, which may be useful in determining the financial considerations of implementing such a change.

Personal injury claims are not included in this costing and have increased in recent years.

Other costs (such as the cost of additional sharps bins for a device that takes up more space) are more difficult to calculate.

Decision-makers should bear in mind that cost may not be an acceptable reason to prevent the purchase of such devices.


Trusts should adopt a systematic approach when considering the different SSDs. The Welsh NHS is tackling this issue collectively, and is running a project coordinated by the Surgical Material Testing Laboratory and Welsh Health Supplies.

Box 2 summarises advice for conducting evaluations of safety devices, drawn from the experience of the Welsh NHS over the past three years.

Box 2. Recommendations for evaluating safety devices
  • Limit each evaluation to one group of safety devices (for example, safety IV cannulas or safety phlebotomy products)

  • Ask companies for a few samples of their product and shortlist devices by assessing them around the table with a small group of experts

  • Only eliminate devices that are inappropriate for your workplace or if you have serious concerns about them

  • Recruit a small number of users in a range of clinical areas to take part in evaluations

  • Clearly document the involvement of the companies who agree to take part (for example, limit company involvement to training users in a one-off session)

  • Create a timetable for user training and evaluations and try to stick to it

  • Ensure users evaluate one model of safety device at a time and only fill in the evaluation form for that device when they have tried it a number of times

  • Ask users to compare and rank safety devices with each other at the end of the evaluation period

The All Wales Sharps Safety Project involves the evaluation of different groups of safety devices in turn. First, a bench-top assessment of all safety products within a group is performed and devices eliminated from the process if they are not suitable for inclusion in an evaluation (because of incompatibility with equipment or clinical practice, for example). Following this, trust-based evaluations of devices take place in the workplace, by approximately five users in each participating trust. Laboratory tests are conducted on devices where considered appropriate. Users fill in a common All Wales evaluation form after they evaluate each type of device and, at the end of the evaluation period, they fill in a different questionnaire that asks them to compare safety devices with each other. Results are collated and analysed by SMTL. Full details of some All Wales safety device evaluations will be published later this year.

Evaluation forms for different SSDs are available to the NHS (TDICT, 1998, for example) which trusts may find helpful, or trusts can devise their own questionnaires to gather information on the performance of a sharp safety device. The authors caution against uncritical use of manufacturers’ questionnaires because of the potential for bias.

The introduction of these devices alone will not eliminate sharps injuries (United States General Accounting Office, 2000), and should be accompanied by other measures such as training in safe and appropriate disposal methods and raising awareness of correct procedures as part of an overall sharps safety strategy.

The Scottish NHS concluded that 52% of sharps injuries could have been prevented if the necessary guidance had been adhered to (Cullen et al, 2006). An analysis of incidence reports carried out in Wales in 2005 (data unpublished) concluded that approximately 50% of injuries are preventable if the necessary guidance is adhered to.

There is a large range of SSDs available on the market designed to protect the user from sharps injuries and choosing the appropriate devices for your workplace is complex. Trusts are strongly advised to consider the issues raised in this article when making decisions about the introduction of SSDs and to evaluate them in the workplace before adopting them.


Adams, D., Elliott, T. (2003) A comparative user evaluation of three needle-protective devices British Journal of Nursing; 12:
8, 470–474.

Asai, T. et al (2002) Efficacy of catheter needles with safeguard mechanisms. Anaesthesia; 57:
6, 572–577.

Centers for Disease Control and Prevention (1997) Evaluation of safety devices for the prevention of percutaneous injuries among health-care workers during phlebotomy procedures. Morbidity and Mortality Weekly Report; 46:
2, 21–25.

Cookson, S. et al (1998) Increased bloodstream infection rates in surgical patients associated with variation from recommended use and care following implementation of a needleless device. Journal of Infection Control and Hospital Epidemiology; 19: 1, 23–27.

Cullen, B. et al (2006) Potential for reported needlestick injury prevention among healthcare workers through safety device usage and improvement of guideline adherence: expert panel assessment. Journal of Hospital Infection; 63: 4, 445–451.

Danzig, L. et al (1995) Bloodstream infections associated with a needleless intravenous infusion system in patients receiving home infusion therapy. The Journal of the American Medical Association; 273: 23, 1862–1864.

ECRI (2006) Do positive fluid-displacement luer-activated devices increase infection rates? The jury is still out. Health Devices; 35: 9, 354–356.

ECRI (2003) Imperfect protection: syringe safety mechanisms can fail. Health Devices; 32: 5, 203–205.

European Parliament session document (2006) With recommendations to the Commission in Protecting European Healthcare Workers from Blood Borne Viruses Due to Needle Stick Injury.

Fruhstorfer, H. (2000) Capillary blood sampling: the pain of single-use lancing devices. European Journal of Pain; 4: 3, 301–305.

Federal Drug Administration (2005) Guidance for Industry and FDA Staff. Medical Devices with Sharps Injury PreventionFeatures. Rockville, MD: US Department of Health and Human Services (non-binding recommendations).

Health Protection Agency (2006) The Eye of the Needle: United Kingdom Survey of Significant Occupational Exposure to Blood Borne Viruses in Healthcare Workers, November 2006.

Kellerman, S. et al (1996) Bloodstream infections in home infusion patients: the influence of race and needleless intravascular access devices. The Journal of Pediatrics; 129: 5, 711–717.

Maragakis, L. et al (2006) Increased catheter-related bloodstream infection rates after the introduction of a new mechanical valve intravenous access port. Infection Control and Hospital Epidemiology; 27: 1, 67–70.

McDonald, L. et al (1998) Line-associated bloodstream infections in pediatric intensive-care-unit patients associated with a needleless device and intermittent intravenous therapy. Infection Control and Hospital Epidemiology; 19: 10, 772–777.

Mendelson, M. et al (2003) Evaluation of a safety resheathable winged steel needle for prevention of percutaneous injuries associated with intravascular-access procedures among healthcare workers. Infection Control and Hospital Epidemiology; 24: 2,

Mendelson, M. et al (1998) Study of a needleless intermittent intravenous-access system for peripheral infusions: analysis of staff, patient, and institutional outcomes. Infection Control and Hospital Epidemiology; 19: 6,

Mulherin, S. et al (1996) Initial worker evaluation of a new safety syringe. Infection Control Hospital Epidemiology;
17: 9, 593–594.

NHS Scotland (2000) Needlestick Injuries – Sharpen Your Awareness. A Report of the Short Life Working Group on Needlestick injuries in NHS Scotland.

Niel-Weise, B. et al (2006) Is there evidence for recommending needleless closed catheter access systems in guidelines: a systematic review of randomized controlled trials. Journal of Hospital Infection; 62: 4, 406–413.

Paterson, C., Elder, A. (2003) Safer Sharps Devices: an Evaluation of Utility in NHS Scotland. A Report for the Occupational Health and Safety Strategy Implementation Group, NHS Scotland.

Porteous, N., Terezhalmy, G. (2004) Use of the Septodont safety-plus syringe by dental school faculty and students – a pilot study. Texas Dental Journal; 121: 2, 138–143.

TDICT (Training for the Development of Innovative Control Technologies) (1998) Safety evaluation forms available from

United States General Accounting Office (2000) GA0-01–60R– Occupational Safety: Selected Cost and Benefit Implications of Needlestick Prevention Devices for Hospitals.

Zafar, A. et al (1999) Primary bacteremia and needleless safety devices. Infection Control and Hospital Epidemiology; 20: 1, 15.

  • Comment

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Links may be included in your comments but HTML is not permitted.