Surgical Equipment to Contain RFID

This seems like a really clever use of RFID. The idea is to embed chips in surgical equipment, and then wave a detector over surgical patients to make sure the doctors didn't accidentally leave something inside the body.

Posted on July 25, 2006 at 7:19 AM • 35 Comments


Darren KulpJuly 25, 2006 7:40 AM

*dons tinfoil hat*

Uh-huh. Or to make sure they *did* leave something inside you so They can track you ...

*doffs tinfoil hat, grins nervously*

Erik V. OlsonJuly 25, 2006 8:10 AM

Make certian it is tinfoil. Aluminum foil amplifies the beams, that's why they took real tinfoil out of the markets.

I've always thought another correct place for RFID is airline luggage tags. You can put RFID scanners on the belts and at the pod loading stations, and set them to beep loudly if the wrong bag is put on the belt.

This doesn't solve the "bag doesn't make the plane" problem, but it does help with the most common reason for the bag not making the plane -- the bag gets put on the wrong cart and goes somewhere else.

Airlines have tried similar systems based on barcode scans and hand tracking, and they don't work well -- too much time is spend making sure the barcodes are visible, etc. RFID, being bascially unidirectional, makes automatic scanning much easier.

Of course, right now, the cost per tag is probably a bit too high, but that's dropping rapidly.

tim fininJuly 25, 2006 8:19 AM

This was one of the use cases we had for a DOD sponsored research project. We encountered two issues: tag size and reading problems. You need tiny passive tags to make this work on the small items that might be left inside a patient. Smaller tags have smaller antennas and are harder to read. A second problem is that RFID signals are attenuated or blocked by metal and liquids. This is a problem since the surical equipment that might be tagged includes lot of metalic items and, to a first approximation, human bodies are bags of water. I'm not sure if the current generation of RFID is going to work for this use case. These kinds of problems is a motivation for developing new tagging technologies like RuBee.

Ian RingroseJuly 25, 2006 8:29 AM

The tags could also be used to automate the counting of used surgical equipment. E.g. if the holder for both the unused equipment and the used equipment had tag readers in them, they system could then give a warning if an item of equipment is “missing��?, e.g. left in the person.

SteveJuly 25, 2006 8:29 AM

The article says this is a 1 in 10,000 problem. If ther surgeon swipes before sewing you up, you'd hope that this scheme will reduce it to a (1 in 10,000 * the probablity of the swipe not being done) problem, which is very rare indeed.

But the factors which cause a surgeon to leave a sponge in your chest cavity will be somewhat correlated with him forgetting to swipe you with the wand. So although this scheme would presumably reduce the incidence, in many cases it provides only a rapid means of disagnosing the problem when you have complications after the surgery, rather than preventing it from occuring.

This still sounds clever, but how harmful is a false negative (e.g. a fritzed RFID tag, or too much of your body in the way)? You're left with a sponge in your heart and a bunch of doctors who think there's nothing in you. The failure rate for the tags therefore has to be (a) low, and (b) well-understood by doctors.

NumnumJuly 25, 2006 8:32 AM

Problem is, the exposure to radio waves on injured soft tissue as you scan from within and without is something that we haven't fully researched. Might be more harmful than envisaged.

The ideal would be for a visual placement inventory check at the end of the ops - any gaps in the racks would indicate missing items.

MarcelJuly 25, 2006 8:38 AM

Hey, what about counting tools before and after a surgery? It could be so easy...

MyCatJuly 25, 2006 9:05 AM

"Or a metal detector?"

Surgeons sometimes intentionally leave metal inside patients. Often in bones though.

Carlo GrazianiJuly 25, 2006 9:23 AM

I'm with Marcel on this one. This is a hi-tech -- and relatively expensive -- solution to a problem better-solved by low-tech accounting procedures. One trained nurse with a spreadsheet, keeping track of clamps, sponges, etc., is what is really required here.

It kind of reminds me of electronic voting, in that people seem enamored of the hi-tech approach to a problem that is perfectly solvable (and frequently solved in most democracies) using paper and pencil. The fact that there are catastrophic failure modes of e-voting that simply don't exist in paper elections doesn't seem to bother its proponents.

I guess some people are just hypnotized by tech.

RCJuly 25, 2006 9:29 AM

The main security weakness in any system is people. You can't completely move that liability to technology. Suggestions such as these (rfid surgerical instruments, electronic voting) tend to ignore the human factor.

Bruce SchneierJuly 25, 2006 9:35 AM

"Hey, what about counting tools before and after a surgery? It could be so easy..."

They do that now. The problem is, well the problem is that people miscount far too often. Think of this as defense in depth.

DannyJuly 25, 2006 9:37 AM

@Carlo, @Marcel,

Keeping track of foreign objects that are inserted/removed in a body is standard procedure during medical operations. The only problem is that the person counting the objects is a human being and therefore prone to make mistakes.

Nobody, least of all doctors, *wants* to leave things in a patient, but errors do occur.

averyJuly 25, 2006 9:44 AM

The leaving bits inside a patient is a nice "looks good in a news article" use for the tag, but the ability to ID an instrument without a tiny little engraved serial number has a lot of uses. Simple example - where has this been? If "in a patient" is the last entry on the list, I don't want it used on me. (See Lister, et al.)

Carlo GrazianiJuly 25, 2006 11:00 AM

Quoth Bruce: "The problem is, well the problem is that people miscount far too often. Think of this as defense in depth."

I'll admit up front that I know nothing of OR procedure.

It still looks more like a Maginot Line than like a defense in depth to me. That is, this is potentially a technical "fix" that allows people to think of the problem as solved, so that there is no need to pursue further the harder but (IMO) higher-payoff avenue of tightening up existing human-based accounting procedures.

The thing is, none of the people in the OR are likely to have a suitably skeptical outlook concerning negative readings by the wand. A little green light will come on,everyone will nod, and they'll sew the guy up, without anyone wondering about sensitivity, environmental effects, signal attenuation, or any of the other effects that would seriously concern an electrical engineer.

Since this technology is defending against a rare type of failure, most of the time that green light will be correct, and OR personnel will learn to trust that wand without any real basis for that trust.

There is no real reason to believe that human accounting can't be made nearly foolproof, given proper design of the relevant procedures. You can train groups of people to make correct decisions reliably, and to verify redundantly that those decisions are correct. It works in missile silos, there's no reason it can't be made to work in a hospital. But it won't be, if operations research people at hospitals believe their technical fix has solved the problem once and for all.

bobJuly 25, 2006 11:33 AM

I dont believe an actual implementation of this would involve manual "wanding" of the patient; it would have to be some sort of scanner built into the gurney or OR ceiling or something that takes place automatically.

jmmJuly 25, 2006 11:37 AM

I find it quite likely that the comments about using the system to count the items /not/ in the body are dead on, and reporting to the contrary is simply misreporting.
The problem with human counts is that the person doing the counting knows what the right answer is, and will tend to get that answer. At 1 in 10,000, they will (conciously or unconciously) assume that it's more likely that they miscounted.

EDAJuly 25, 2006 12:23 PM

If we're going to solve this problem with technology, I'd rather see technology used to augment the manual process of counting the articles used during the surgery, rather than scanning the patient for articles.

Let's RFID tag all the articles used in the surgery, and store them in a containers that have embedded RFID readers. Each time the container is opened and closed, the reader takes an inventory of the contents and stores it. Any sharps containers, waste containers, etc, should also have embedded readers and should function the same way.

At the end of the surgery, before the patient is "closed up", the readers in all the containers are queried for their inventory and compared with the starting inventory, and if anything is missing, a search can be mounted for the missing article(s).

This takes care of the concerns about radio exposure to human tissue, and any signal degredation issues related to tags being embedded in living bodies, and seems like it wouldn't be a great change to OR procedure.

Pat CahalanJuly 25, 2006 1:19 PM

This has an additional advantage if you look at it in audit terms. It's not just defense in depth, it's leveraging the ability of third parties to audit the surgical procedure.

Counting surgical implements after a surgery is something that can only be done effectively at the end of the surgery (after which point, trays are put away, things are sterilized, etc), so only the surgical team can effectively audit the process. Having RFID tags on the instruments enables non-surgical people to perform an audit on the surgery team, which is a function not possible under a hand counting procedure.

You have a surgery. Doc and nurse on surgical team (a) leave something inside you (b) also make an error in inventory and (c) fail to scan you with the reader or scan you incorrectly with the reader.

You're checked in to recovery. Two hours later you're in trouble. Non-surgical recovery nurse can pick up an RFID scanner and scan you, and say, "Boy, did those surgery guys screw up this time." Even if the RFID scanning technology isn't available to recovery nurses, you can be wheeled back to surgery and a different team can audit the previous team using the reader. It would be very difficult for them to audit the previous team using an equipment checklist if anyone had used the room after the initial surgery.

This seems like an altogether good thing. I imagine the relative cheapness of RFID tags (and the huge influx of RFID readers in the hospital environment) would mean that implementing this would certainly cost less than the malpractice suits that the hospital might suffer...

JJuly 25, 2006 4:52 PM

Classic case of a solution looking for a problem. Classic case of people wanting a good press release without thinking through. Classic case of trying to find a technical solution to human error.

Carlo GrazianiJuly 25, 2006 5:08 PM

The other thing is, "solutions" like this one are part of the reason that health care costs in the USA are totally out of control.

Apparently there is nobody at the hospitals with an incentive to compare the marginal cost of ugrading all surgical gear to "RFID aboard" to the benefit of preventing this kind of error in a tiny number of cases. The costs are passed on to the insurance companies, who pass them on to employers, who...

Stefan WagnerJuly 25, 2006 5:43 PM

Surgeon: "Inventory reference?"
Assistant: "7 clips, 3 scalpels, ..."
Surgeon: "Inventory actual?"
Assistant: "11 clips, 4 scalpels, ..."
Surgeon: "Oohm? Let's put that scalpel and the 4 clips back - inconspicuously ... "

Pat CahalanJuly 25, 2006 5:58 PM

@ Carlo

Health care costs are completely out of control for a lot of reasons, but that's too complicated an issue to cover here.

A great many inventory control systems currently in use in hospitals already include an RFID element. Of course, I know very little about surgical instruments, but a quick google ( shows some of them to be on the order of a few hundred dollars. RFID tags range in price, but some are on the order of a few cents per tag ( Given the fact that the inventory system is likely to already be RFID-ized and the tags are cheap, this doesn't seem like a very expensive program to implement.

Mrs. RobinsonJuly 25, 2006 6:28 PM

re: Erik Olsen's proposal for tagging luggage:

My Tumi luggage is built with RFID right in it -- it came pre-chipped, just like my border collie. Anybody with an RFID reader (say, a lost baggage office, or a police station) can blip up an ID number, along with contact info (phone and website, I presume) for Tumi's lost baggage service. Tumi will then contact me and hook me back up with my lost or stolen bag. This is a perk that comes with all Tumi bags.

Since the mfr has already tagged each bag tagged a unique number, why not use this same chip and number to track bags through the transport process, just like UPS and FedEx track packages now? As Erik proposes: the RFIDs can either be built into the bags, or added as a tag.

This strikes me as an extremely low-cost way to streamline baggage handling and reduce both lost and stolen baggage.

Filias CupioJuly 25, 2006 7:19 PM

It seems to me that RFID is overkill for this. RFID provides many bits of information. All you need is one - presence or absence. Couldn't you do something much cheaper with conductive fibres of a very specific length? Then they would (I hope) strongly reflect radio waves at specific frequencies, and much more weakly at others. All you'd need to do is a multi-frequency scan to look for objects with the the right frequency response.

(This could also work for recycling. If recyclable objects were tagged in such a way, with different frequencies for different materials, you could dump all your recyclables into a single bin, and have them cheaply sorted at the depot.)

Stephen DedalusJuly 25, 2006 7:51 PM

EDA has the correct line on this. Partial counts are made (by the OR nursing and scrub tech) intermittently throughout a surgical procedure and final counts are made prior to closing. If you added RFID to the equation, it would be implemented on the *outside* as a means to externally verify the count. Once the manual count is complete, an audit would be initiated, which would identify any materials that had "gone rogue" (i.e. were not in their appropriate tray, rack or receptacle). The surgeons and OR staff would then have to locate anything that was not accounted for by the audit. Ideally, there would be a penalty for having to run the audit more than once or twice to prevent anyone from relying on the audit to the neglect of the manual count.

@Carlo: I think the (insured) consumers that respond to hospital promotions of RFID-enhanced patient safety when making decisions about where to have surgery performed bear some of the blame for the high costs of medical care.

Stuart YoungJuly 25, 2006 10:39 PM

Re: Erik Olsen and Mrs. Robinson on RFID and Luggage.

Hong Kong airport uses RFID for it's luggage shipping operations already. They obviously think the price per tag is worth it. I did note however that they did NOT put on a new tag when I returned through the airport the second time, so if there is a tag present already, it's one less to deploy. Of course, this could be a problem if you're trying to ship RFID tags. *grin*

The big problem however, is that there are a number of frequency bands available for RFID, and they are country dependant, which means that tags built for one location won't necessarily work in another. This means that a bag would need more than one tag per region if this was a global effort, which does increases the cost per bag.

Christoph ZurniedenJuly 26, 2006 12:02 PM

It seems, as if the procedure of an OP is not known to us sufficiently enough to analyse the tagging of the instruments with RFID tags. I do not know it either, so I asked a physician and a nurse and here are the most interresting findings in no special order (valid in Germany, but I don't think that these procedures differ a lot in world).

- the number of instruments used is not known beforehand.
Simplest reason: the surgeon dropped the last scalpel on the floor and needs a new one, but there are a lot of other reasons like the need for another size or similar. There is even a special nurse for such incidents who passes instruments between septic (e.g. storeroom) and aseptic (the OP-room) areas.

- instruments may break in pieces.
Obviously only one of these pieces has the tag.

- some instruments are very small and cannot hold a tag, e.g. a needle.

- it might be difficult to tag something like a swab.
A swab is probably the most forgotten surgical equipment.

And with this in mind and knowing a bit about the RFID technique I cannot see much use for tagging surgical instruments in parts beside easier storage- and desinfection managment for the patient but the advantage of have no false positives if the patient itself is "wanded" (is there no word for "checking for a RFID-tag with this curious thingamabob"?): if the "wand" detects an RFID tag in the body, there is an RFID-tag in the body.
If you check the equipment for completeness, you'll get at most a complete inventory of all the RFID-tags and nothing more (things may break, some things are not tagged at all, and so on): false positives are possible (there is equipment left in the body despite the correct number of RFID-tags detected). A nurse would see if instruments are broken, would know which equipment is not tagged and handcount them, and so on.

All implementations of such a technique would need a lot of approvement stamps which makes it significantly more expensive.

It's very easy to wave the "wand" over the patient to detect a left RFID if it is detectable (no false positives, but, depending on the kind of RFID technique a lot of false negatives). A RFID-chip has some metal build in and is, depending on the size quite easily detectable with x-ray (some materials are not or at least badly visible with medical x-ray) if some equipment is missed.

So, it has some significant advantages for the patient and might be cheap enough to get implemented if somebody finds a good argument for the hospital because "good for the patient" is not sufficient. Ah, "it makes stealing more difficult" might be a good argument if nobody asks for an actual measurement of "more difficult".


Stefan WagnerJuly 26, 2006 6:41 PM

I think putting an rfid-chip into a swab should be possible.
Not every rfid-chip is as big as this one (wm-ticket):

Needles are small - so you would check the 'rfid-tagged stuff + 3 needles'.

Broken tools should be rare enough to be mentioned although.

Aren't the costs of the chips in the area of cents?
Having 1$ spent on wasted one-way-equipment per operation doesn't look expensive.

Having international manufactors, a way of standardisation is needed: All pieces should respond to the same system, and all systems should detect all pieces.
Initiation of the technic might be difficult: As long as not all equipment is tagged, having multiple concurrent validation systems is annoying.

Buying the machines while little tools are tagged?
Buying perhaps more expensive tools with tags, while the scanning-system isn't used?
Throwing away a repository filled with tag-less equipment?

Steve GeistJuly 27, 2006 6:23 PM

RFID tags on surgical supplies and instruments strikes me as a tremendous opportunity to turn sterile items into non-sterile items.

Can the tags be autoclaved? Typically, this is done with super-heated steam and a cycling of vacuum and pressure - the vacuum is to remove air from items such as the bore of a needle. If the tags aren't 100% sealed, they'll be cooked.

Autoclaving is a really tough process for anything to endure - even stainless steel and tungsten instruments get worn down - especially any sort of mechanisim such as scissors or forceps - the hinge area erodes gradually.

If they can't be autoclaved, someone has to add the otherwise-sterilized tags to the autoclaved items resulting in a really "weak link" in infection control.

I'd much rather see dual custody of the instrument count: One scrub nurse counts things entering the OR, and another counts things leaving.

MilaJuly 27, 2006 9:47 PM

This might be one of the better uses for RFID. Recently, I read an article on CNN I believe about using RFID for ePassports. The government is trying to start issuing these to Americans in late August, despite the security concerns of many experts.
RFID should be used for something helpful - like in surgery, as described in your blog - not for ePassports which are susceptible to security breaches.

Jon MinerJuly 31, 2006 10:09 AM

I still contend that this is solving the wrong problem.

You are looking to solve the problem of surgeons leaving tools inside of a patient. This is a procedural problem. Doctors are not maliciously leaving tools inside patients, they are rushed/tired/overworked/etc.

So, how about solving the root problem instead: make the doctors less rushed/tired/overworked/etc.

But, no, this greatly increases costs for insurance companies, hospitals and HMOs that are constantly pushing doctors to work longer hours and see more patients. Tagging the instruments is a good-PR plan for the hospitals/HMOs, moving the "blame" to the doctors. It also creates an extra charge that they can legitimately put on the bill "RFIDs for instruments" versus "more rest for doctor."

There are simpler methods for making sure that tools have returned to their proper container (weight, for example) that aren't as "sexy" but will work just as well, I prediect.


techMarch 30, 2007 1:13 AM

how would you setirlize the chip that is the major problem infection in healthcare take x-ray when working deep in abdomen or any cavitiy have count

AnonymousApril 5, 2007 8:18 AM

RFID can be used to track the entire operational process associated with surgical instruments - which batch they were sterilized in, which tray they were on, which patients they were used on or in, which staff handled them, etc.

With that type of scope, you make gains in a variety of diciplines with stakes in the CSP process working as prescribed.

cherylMay 22, 2007 5:40 PM

Tracking surgical instruments is a critical problem, not only because they get left behind, very rarely, but because the cleaning of instruments is a issue. 24% of clinicians will tell you that they have very little confidence in the sterilization process. this being the case, there is a high chance of cross contamination, and therefore important you know who you need to contact. Can RFID with stand temperatures of 134deg Celcius? this is the temperature that instruments are cooked at.Also, how do you embed this into a stainless steel instrument, and then make sure that is cab not be destroyed by CT scan, Xray etc. Worrying about the cross infection, not the left behind instrument. A simple count is the best way to prevent this.

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