Tissue Viability

Maggot therapy

What is maggot therapy?

Maggot therapy involves the use of maggots of the green-bottle fly, which are introduced into a wound to remove necrotic, sloughy and/or infected tissue. Maggots can also be used to maintain a clean wound after debridement if a particular wound is considered prone to re-sloughing.

The technique, which has been used for centuries, has been reintroduced into modern medicine by doctors and tissue viability specialists who have found that maggots are able to cleanse wounds much more rapidly than conventional dressings.

While maggots should not be regarded as a cure for all types of wounds, by removing dead tissue and any associated bacteria, in most instances they will improve the condition of a wound and allow the process of healing to begin.

How does maggot therapy work?

The processes by which larvae clean wounds are very complex, but in simple terms they physically feed on dead tissue and release special chemicals into the wound that breakdown dead tissue into a liquid form that the maggot can easily remove and digest. During this process the actively feeding larvae also take up bacteria, which are then destroyed within their gut. This process is so effective that larvae can often clean a wound within a few days.

How big are the maggots?

The maggots that are applied to your wound are very small, only a few millimetres in length, smaller than a grain of rice. During the treatment time they will increase in size as they clean the wound, to a maximum of 12mm.

How are the maggots applied?

There are two methods of application:

  • BioBag dressing: The maggots are sealed within a dressing which is a finely woven net pouch containing a small piece, or pieces of foam, which aid the growth of the maggot and manage exudate. The BioBag dressings come in varying sizes and are applied according to the nature and size of the wound being treated. The maggots remain sealed within the dressing throughout the treatment.
  • Free range maggots: The maggots are applied directly onto the wound and retained within a special dressing system. The exact nature of this is determined by the size and location of the area to be treated.

How long does the treatment last?

This can vary with each treatment of maggots and the method of application being used. BioBag dressings can be left in place for up to four days—it is possible for the dressing to be removed on a daily basis to allow inspection of the wound site.

‘Free range’ maggots are generally left in place for up to three days before being removed from the wound site. With both application methods, it is impossible to predict how long a course of treatment will take. Sometimes a wound is completely cleansed by a single application of larvae but other wounds may require two or more treatments to achieve the desired effect.

Will I notice anything different during maggot therapy?

During maggot therapy you may notice some changes in the wound:

  • The wound may become a little wetter than usual or show the presence of a dark red or pink discharge. This is due to the action of the maggot breaking down the dead tissue.
  • Sometimes a wound that contains a lot of dead tissue will develop a characteristic smell during treatment. This is nothing to worry about, it is just due to the activity of the maggots and should disappear when the dressing is changed.
  • Most people are unaware of the maggots presence, although a small number of patients claim that they can feel the larvae moving but only describe this as a tickling sensation.
  • Some patients, particularly those with poor circulation report that their wounds become more painful during larval therapy but this can generally be controlled with medication.
  • Some patients have found that the pain associated with infected wounds is reduced following maggot therapy.

Will Maggots bury into healthy tissue?

The maggots used in wound management will not attack or bury into healthy tissue, they only remove dead tissue.

Will the maggots multiply in my wound?

Only adult flies can lay eggs, so the maggots cannot reproduce or multiply within the wound. 

Where do the maggots come from?

Maggots are produced in a special unit by highly trained staff at Biomonde, a company with many years of experience in wound management.

Are there any activities that should be avoided during treatment?

Although it is possible for the patient to carry out most normal activities while undergoing maggot therapy, they should ideally not bathe or immerse the wound in water.

It is also not a good idea to sit with the wound too close to a source of heat eg fire or radiator as the maggots may dry out. Similarly, sitting or walking on a wound treated with maggots should also be avoided as much as possible.

Why use maggot therapy instead of a conventional dressing?

Clinical experience with maggots has shown that they can clean wounds in a fraction of the time taken by more conventional dressings, which could potentially speed up healing times. They are also useful in the management of infected wounds containing bacteria that are difficult to kill with more conventional treatments. Maggot therapy has also been shown to be successful at eliminating MRSA from wounds.

What is the ethical position relating to the use of larvae?

The use of larvae in wound management has a sound basis in literature. It appears to be free of any serious or significant side effects and can have major advantages over conventional treatments for certain types of wounds. Provided that a specific patient has no objection to the use of larvae there appear to be no ethical barriers to their use.

Preventing pressure ulcers

What is a pressure ulcer?

A pressure ulcer is damage that occurs to the skin and underlying tissue. The skin can become red, broken or ulcerated. Pressure ulcers are caused by:

  • Pressure- The weight of the body pressing down on the skin
  • Shearing- The layers of the skin are forced to slide over one another or over the deeper tissues, e.g. when you slide down, a bed or chair.
  • A combination of pressure and shear.

 Who is at risk?

Anyone can be at risk of a pressure ulcer, but some are at greater risk than others. Those who are particularly at risk are people:

  • Who have problems moving and need help to change position
  • Whose skin is continually moist e.g. incontinence
  • Who have a poor diet and do not drink enough fluids
  • Who have problems feeling pain or sensation
  • Who are seriously unwell
  • Who are very old or very young
  • Who have or have had pressure ulcers in the past

Your nurses will assess your risk. This will include assessing your skin.

Where do pressure ulcers develop?

Pressure ulcers usually develop over bony areas of the body. The most common site of pressure ulcers are:

  • Bottom
  • Heel
  • Back

Other sites are shown below. Pressure ulcers can also develop under equipment such as masks or tubing, so it is important to check these areas too. 

What are the signs of pressure ulceration?

Early signs of damage may be redness or discolouration over bony areas. This can be more difficult to see in darker skin tones. Stinging and burning may also be felt in the skin.

We categorise the severity of skin damage. From category 1(a), Skin that is red, that does not go pale when pressed; to category 4(b), where there is severe skin damage that leaves an open wound extending to the muscle or bone. 



Preventing pressure ulcers

There are several important aspects to preventing pressure ulcers. These include: 

  • Repositioning- Changing your position regularly allows sufficient blood flow to get to your skin to keep it healthy. If you are unable to move yourself, staff will assist you to do so. If you are mobile, walk around as often as you can. If you are in bed or sitting in a chair, you will be advised to turn and change your position.

Skin assessment

Staff will assess your skin for signs of damage. If you notice pain, discomfort or discolouration, please inform your nurse or other member of the healthcare professional team.


It is important your skin is kept clean and dry. Skin that is moist is more at risk of breaking down. This may be due to incontinence, sweating or a weeping wound.

Staff will provide care to manage moisture on the skin. Please discuss with your nurse.


Eating well and drinking enough is very important. Your diet will be assessed and this will be discussed with you. If needed, you will be referred to a dietician.


All of our mattresses help to reduce pressure when you are in bed. If you have a significant risk and have limited movement in bed you may be provided with an air mattress. If you have problems moving your legs you will be encouraged and supported to keep your heels off the surface of the bed with pillows under your legs or a special boot.

Using an air mattress does not remove the need for you to reposition. When sitting out of bed a pressure reducing foam or air cushion may be provided to help reduce pressure when seated.

Managing pressure ulcers

Pressure ulcer management is complex. This can be complicated by any underlying health issues. You may therefore have different members of the clinical team give advice and support.

Depending on the severity of the pressure ulcer, you may require various dressings or therapies to help support wound healing. It is important to continue to change your position regularly, eat well and keep your skin healthy. You may need additional equipment such as pressure-relieving air mattresses or specialist seating.

Please discuss your individual plan of care with your health care professional team.

Topical Negative Pressure (TNP)


This leaflet is intended to provide you with information on the technique and give answers to some of the questions you might have about the therapy. If the treatment was initiated by the Tissue Viability team please contact the service below otherwise speak with the ward manager

What is Topical Negative Pressure therapy?

TNP is short for Topical Negative Pressure Therapy which is a system that uses controlled negative pressure (vacuum) to help promote wound healing. Clinical studies demonstrate that TNP therapy also removes infectious materials and other fluid from the wound.

How does TNP therapy work?

The TNP therapy system consists of a computer controlled therapy unit, canister, sterile plastic tubing, foam dressing and clear drape. The foam dressing will go on or inside your wound. One end of the tube will connect to the foam using a T.R.A.C. pad ® the other end will connect to the canister, placed inside the TNP system. The wound area will be sealed with the clear plastic drape. The TNP system pulls infectious material and other fluids from your wound through the tube and collects inside the canister. Additionally TNP therapy enhances blood flow and can decrease swelling, thereby helping the wound to heal.

How does it feel when first applied?

When the TNP system is first turned on, you will feel a slight pulling sensation, if you have any feeling in the wound area. You must keep the system connected in order for it to work. Leaving the system off for longer than two hours per day may result in delayed healing.

How long will I be receiving TNP therapy?

The amount of time you require TNP therapy depends on the type and severity of the wound, your body’s ability to heal wounds and the type of outcome desired. Your clinician or Specialist Nurse will decide whether your wound will be taken to complete closure or ready for a flap or skin graft. However, studies have shown TNP therapy, in most cases, significantly reduces recovery time for patients, even in wounds previously considered non-responsive. Please note that failure to comply and to follow advice could hinder your wound healing.

How many hours a day does the VAC system need to be on?

It is recommended that you remain on the TNP therapy for 24 hours a day, otherwise your wound is not receiving the full benefit of TNP therapy, and you may be at greater risk of complications. If the system is turned off for longer than two hours the dressing must be removed and a new dressing put in place.

How does it feel during treatment?

Patients placed on TPN therapy describe it as a “mild pulling sensation” that is generally not noticeable after around 10-15 minutes. Certainly the level of comfort will vary from patient to patient. Please contact the nurse if discomfort persists.

How often does the dressing need to be changed?

This will depend on the size and type of wound. Usually most TNP dressings will be applied and stay insitu for three days. However, some wounds may be 5-7 days. Your Nurse Specialist or clinician will prescribe a treatment plan.

How will I know if the TPN dressing is working?

The TPN dressing will “wrinkle” when therapy is working and will shrink and mould to the size of the wound.

Is TPN therapy safe?

Yes. TPN has been providing therapy to thousands of patients with acute and chronic wounds. TPN therapy is an excellent method to help promote wound healing. It allows the caregiver to monitor delivery of the Vacuum Therapy at the wound site to ensure controlled, consistent and safe therapy.

Can you move around while on TNP therapy?

This depends on the location of the wound and the 

treatment plan prescribed. Please ask your Clinician or Specialist Nurse.

What happens if the system alarms?

The system has both audible and visual alarms that describe the nature of the problem. Please consult your nurse if you are an inpatient in hospital. If you are discharged with TNP, a full list of problems will be explained to you upon discharge.

Please consult the nurse immediately if:

  • If you notice a significant change in colour or consistency in the fluid.
  • You see excessive bleeding under the clear drape, tubing or in the canister
  • You observe redness or odour from the wound
  • You experience increased pain
  • The alarm will not shut off
  • If the therapy has been turned off for more than two hours

As a family member, how can you help?

As a family member or friend of someone receiving TNP therapy you can remind the patient of the importance of using TNP. In addition, when asked, and properly trained, you can assist in changing the dressing and canisters, responding to alarms and monitoring the therapy. Remember, your support and encouragement can make a difference in a speedy recovery!

What happens if I change my mind?

You are entitled to change your mind at any time during your treatment. Simply speak to a member of the Nurse specialists. The dressing will be removed and a conventional dressing will be applied. Should you require any further information please discuss with your nurse or doctor. 

Contact information

Tissue Viability Service
Chelsea and Westminster: 020 3315 5235
West Middlesex: 020 8321 5312