Investigations in Diabetic Foot
Investigations in Diabetic Foot
What are Investigations in diabetic foot?
These are tests done to find out how severe is the diabetic foot problem and how far it has spread, for example, X-ray, doppler, MRI. But, depending upon the individual situation, one may need more tests. Please do remember, that these tests need to be done strictly under the direct supervision of a professional, in this case a diabetic foot specialist.
Following Topics Are Covered Briefly Here:
- Investigations to know the spread of the infection/gangrene
- Investigations to check the blood supply to the foot
- Investigations to know sensation and neuropathy and pressure testing:
- Investigations to find nature of infection:
- Investigations for fitness and related medical issues like kidney, diabetes, heart and fitness for surgery:
- Investigations to rule out similar-looking problems:
- Investigations at Regular check-up:
Investigations to know the spread of the infection/gangrene:
These investigations like X-ray and MRI, help to find exact extent of disease and infection so that all infection areas can be cleansed
(a) X-ray foot – It’s like any other plain X-ray. Separate x-ray needed for foot, ankle and legs.
Procedure – Usually at least 2 views are taken, like from front and side. Sometimes an oblique view is added. Because X-rays are two-dimensional and we need three-dimensional information. That’s why multiple views are taken.
What information it provides – It can tell about the spread of infection to the bones or joints. It also helps to show how the bones are placed and any major pressure points. It is these pressure points that create problems like ulcers.
Note – A digital, good quality X-ray can be very helpful. Also, certain changes in bones can take a month to appear. So usually, X-rays need to be supplemented with MRI or CT scan.
(b) MRI scan–
o What is it– MRI or magnetic resonance imaging is usually considered the gold standard for checking the foot infection. It is a kind of modern scan. There is no radiation (So, no exposure to harmful X-rays) but there is a magnetic field. No Injection or tablets are required to be taken before. It may take approximately half an hour. Please let doctor know of any implants or previous operations.
o What information it provides – Human foot has literally more than a hundred pockets. Looking at the surface of foot and leg, it is difficult to tell in which pockets the infection has spread. In the hands of an experienced radiologist and a foot doctor, it can tell in detail about the spread of the infection into the bones, joints, fascias, muscles, tendons and any other problems in the foot and leg. It tells of any pus, abscess, and dead tissues.
o Procedure – It’s a big machine, where one has to put the leg inside it. MRI can be done with contrast injection, but in diabetic foot usually it is not required, thereby making it safe for kidneys and also no chance of any reaction. It may take approximately half an hour.
o NOTE – It is important to let the reporting doctor(raknow where the problem is so that he can advise the technicians to take photos of appropriate parts in detail. I always ask patients to send photos of the foot problem to the radiologist before doing the scan. It’s too late once the scan is done and the patient has gone home. Otherwise, technicians may take standard photos not being aware of the wound, thereby missing the main diagnosis. This is a common situation in the diabetic foot. Also, most Radiologist (those who report MRI scans), is not used to report MRI foot on a routine basis, since it is not yet routinely performed. Hence it is important that the treating foot doctor and the reporting radiologist communicate with each other.
Investigations to check blood supply to foot
These investigations like doppler and angiography, tell us how good is the blood flow of the leg and foot. Most diabetics have some circulation problem, but in 10-15 % diabetics, it is very poor to endanger the foot. Knowing blood supply helps in –
o Healing of the wound
o Planning further treatment to improve circulation
o Problems of blood flowing back from foot (Venous circulation problems) need a different kind of treatment.
A good examination of foot usually will clarify the need of investigations. If the pulses in feet are well felt, it is considered that usually the circulation is adequate.
The common investigations that are done to check circulation are
(a) Doppler test
What is it – A non – invasive test where blood vessels are located at certain superficial points and the sound signals give an idea how good is the blood flow or circulation.
What information Doppler test provide
o Arterial flow – Whether enough blood is flowing into the foot, is there any block, how important is the block in circulation.
o Venous flow – Whether blood is flowing back properly – This includes varicose veins, reflux problem and clots in veins. The treatment of these problems is very different than that of a diabetic foot,
o Need of further investigations like Angiography, CT SCAN
Procedure It is a painless and simple test. It doesn’t need any preparation or injection. It is done on OPD basis. A small machine probe is placed on certain parts of foot and leg, and signals are heard and seen on screen as well as waves. In the report, you will get a chart with blood flow figures and some images.
Note
A Doppler test is essential in most diabetic foot patients. Usually, it is enough in more than 90% of cases to decide whether an angiography will be required or not.
(b) Angiography of the leg (peripheral angiography)
What is it? – Literally it means visualization of blood flow in vessels. ‘Angio’ stands for blood vessels and ‘graphy’ stands for seeing. Usually a good Doppler test gives enough idea if angiography is required or not. Angiography is a highly specialized test done to know the blood flowing into the leg and the foot. It can be done by different methods like Digital subtraction angiography (DSA), CT angiography (CT scan of blood vessels) MR angiography (MRI scan of blood vessels), and CO2 angiography.
What information it provides? – It tells exactly where the blood is not flowing and where are the blocks. This helps in the next step of angioplasty or bypass surgery
What information does it provide? – It tells exactly where the blood is not flowing and where are the blocks. This helps in the next step of angioplasty or bypass surgery
Because of different methods available, one can just do angiography in the first setting. This is relatively cheaper. The decision can be taken later whether to do angioplasty (depending upon urgency of the situation).
Angioplasty – It means actually doing something to increase the blood flow, like widening the blood vessel or putting a stent in the blood vessel. Angioplasty is expensive. It has got its own side effects.
Note – One needs to be very careful before doing angioplasty on a diabetic foot-
o In diabetes, by the time a person gets a foot problem, the diabetes has been there uncontrolled for many years. Hence the damage to the blood vessels has happened all over the body, in multiple places and in all organs.
o Even in the leg itself, there may be multiple blocks all the way up to the small blood vessels of the toes. Hence, removing a block at knee level may not always help if there are blocks further down in the foot.
o Most doctors can do angioplasty only in the leg and not in the foot, because the blood vessels in foot are small (modern advances are changing this field fast)
o In a few selected cases, angioplasty/bypass surgery can help to save the foot.
o IMPORTANT – In diabetic patients, owing to uncontrolled diabetes for many years, there are multiple hardened calcified long blocks from head to toe in all blood vessels. Most people may not get benefitted even if circulation is poor, because, even if one block is removed, there are likely to be many blocks beyond it. This procedure itself is costly and has complications. It definitely has a place in poor circulation but is useful in very select cases and it should be used wisely.
(c) Bypass surgery – Similar to the bypass in heart, it can be done even in legs and can help in very selected cases. Here again the blocked part of the blood vessel is bypassed. Nowadays it is done rarely.
Investigations to know sensation and neuropathy and pressure testing:
These tests tell how much sensation is lost. This helps in deciding how to protect the foot from further damage and how to promote healing. It also helps in making the appropriate customized diabetic footwear.
(a) 10g monofilament test – A special calibrated nylon filament is used to test sensation in different areas of foot. If not available a cotton wool or gauze piece can be used.
(b) Biothesiometry – A specialized test to check sensation in different parts of the body to vibrations
(c) Harris mat – Foot print is taken on paper to get ideas about pressure areas
(d) Computerized pressure monitoring – Foot is scanned for pressures on different areas. This information helps to prepare specialized plasters and shoes.
Investigations to find nature of infection:
It tells us about the small bugs (microorganisms) like bacteria or fungi and what antibiotics will work on them.
(a) Culture and sensitivity (c/s) – It has two parts
The first one is culture; it is about the nature of bacteria (culture report). Knowing the nature of bacteria helps to decide the nature of the treatment, how aggressive one has to be and what medicines to give.
Second one is sensitivity; it is about the exact antibiotics that will work against them (sensitivity report).
o Sometimes one has to check for different bugs like fungus.
o Normally, the doctor/nurse will take a small sample on a stick (a swab stick) or still better, a very small piece of infected part in a small bottle filled with saline. In septic or serious patients, even blood needs to be cultured to find the bacteria in the blood.
o Please note, these samples have to be processed ideally within a few hours (2 hours is better). Hence, please check with the microbiology lab if it will be processed immediately. Very few labs do it on time. Delayed processing may give the wrong report. This will end up being given wrong antibiotics that are either inappropriate and hence won’t work or unnecessary.
Investigations for fitness and related medical issues like kidney, diabetes, heart and fitness for surgery:
For any treatment, the whole body needs to be in a fit condition and hence all other health conditions need to be stabilized. All these diabetic foot patients have diabetes and possibly other medical issues that need investigation and treatment.
o Routine blood test – Blood sugar, liver, kidney, cholesterol
o Heart, kidney related special tests – 2D ECHO, ultrasound.
o Viral infection tests – HIV and hepatitis are routinely checked
Note – There is no end to the number of tests one can do in a diabetic. But a good doctor, after doing a good examination, can do focused investigations relevant to the problem at hand. A test is done to confirm or ruling out certain suspicions. It is not a good practice to do a full body checkup randomly and do all the tests.
Investigations to rule out similar looking problems:
Sometimes a diabetic may have problem that is totally different than usual ones. Unless one is aware, it can be missed. For example, diabetics may have ulcer because of different problems than infection, say cancer. Or, patient may still have loss of sensation or ulcer because of some other problem like leprosy. This may then need a totally different set of tests depending upon what is suspected. For example,
Back problem –It can cause of loss of sensation. Investigation – MRI spine
Abdominal problem – It can cause blockage of blood vessels or pressure on nerves Inv – Ultrasound or CT of abdomen,
Syphilis, leprosy, cancer – Different blood tests, biopsy, etc.
Investigations at Regular check up:
One may simply need a proper examination and nothing else. A good clinical examination by a good doctor will reduce the risk of unnecessary investigations. One may do some simple investigations like-
Sensation check for nerve damage – It can be done using simple cotton or a special nylon wire (10g SW monofilament). A more sophisticated instrument called Biothesiometry will detect the loss of sensation at an earlier stage
Circulation test – Doppler test – This can help to check the blood flowing into the foot (arterial circulation). It can also check for any problems in the flow of the blood coming back from the foot (varicose veins, reflux, and deep vein thrombosis)
Pressure points check – This is done to see if there are any points in foot getting too much pressure. High pressure points eventually cause ulcers.
Please note, all the tests to be done under the supervision of a diabetic foot specialist
Please read…..
Advanced and modern treatment in diabetic foot
Contact us, for more information
Call – 7506420648
Address – DOL CLINIC, 105, Soham Plaza, Manpada, Ghodbunder road,Thane