Cold coagulation - heat treatment

Cold coagulation is a way to treat abnormal cells on the cervix (neck of the womb) by destroying the abnormal cells with a heated probe. It is not suitable for everyone. Your doctor or nurse will discuss if it is the right treatment for you.

Cold coagulation is also done for some people who have delicate soft cells on their cervix, which bleed easily when touched. These patients do not necessarily have an abnormality on their cervix.

The procedure cauterises (burns) the soft cells, so that they become hardened and less likely to bleed when touched.

Benefits of cold coagulation

We do this procedure for 1 of these reasons:

  • To destroy the abnormal cells on your cervix. These were identified during your colposcopy (detailed examination of your cervix).
  • To harden the soft cells that are causing you to bleed (possibly after you have sex). You will already have had a colposcopy.  

Risks of having cold coagulation


It is normal to have some light bleeding and discharge for up to 4 weeks after the treatment. At first, we would expect you to have a mucky-looking discharge (brown from the iodine used). You may also notice some greyish-looking specks from the area we treat.

You might also have a yellow discharge from the paste that we apply to help stop bleeding. All of this is to be expected.

You might get a very watery, blood-stained discharge, which is produced from the area of your cervix we have treated. It is similar to having a burn on your hand which weeps as it heals.

We do not expect you to have heavy bleeding.


Signs of an infection are:

  • vaginal discharge which has an offensive (bad) smell
  • high temperature (fever)
  • severe, ongoing lower abdominal (tummy) pain

If you have any of these, go to your GP, who might prescribe antibiotics.

If you are still bleeding after 4 weeks, please contact the colposcopy unit as this could be a sign of infection. We might advise you to go to your GP for an examination of your cervix.

Narrowing (stenosis) of the cervical os (the small opening of the cervix)

After cold coagulation to your cervix there is a small risk (less than 2 out of every 100 cases) that the cervical os will close over. You can help prevent this by allowing your period to come as normal after the procedure. If you take a 21-day contraceptive pill, you should not run 2 packs without a break between them. Instead, you should make sure you leave a week (the 7-day break) between finishing one pack and starting the next.

Coils (IUCD or IUD) or Mirena (IUS)

If you have a coil or Mirena fitted, the clinician might take it out when you have the treatment. In many cases we can leave it in place.

A coil can usually be refitted 4 weeks after your treatment. The best time to fit your new coil will have to be agreed with your GP or family planning clinic.

You should use an additional method of contraception (such as condoms) as well as the coil, or not have sex, for 7 days before your planned procedure.


Having cold coagulation should not affect your ability to become pregnant. Cold coagulation has not been associated with any increased risk of premature birth.

If you are pregnant

It is not possible for us to do surgery on your cervix if you are pregnant. To make sure that you are not pregnant on the day of your surgery, we ask that you have protected sex for 7 days before your operation date. We will also ask you about dates of your last period. If there is any chance you are pregnant, please tell the doctor or nurse. We might ask you for a sample of pee (urine) to do a pregnancy test. 

If you are pregnant when you are due to have the procedure, we will delay your treatment until after you have had your baby. You should let us know your expected date of delivery when you come to see us.

The doctor or nurse looking after you might want to monitor the abnormal cells throughout your pregnancy. They will do this by asking you to come for another colposcopy while you are pregnant, but this does not harm your baby.

You will be asked to come back to the colposcopy unit 12 weeks after giving birth, so that we can have another look at your cervix. We might also carry out the treatment at this time.

Other treatment options

The other treatment available is only suitable for patients with an abnormality on their cervix. This is called a loop diathermy. If you decide to have this treatment, you will need to discuss this with the doctor or nurse caring for you. 

If you are having the procedure to treat bleeding from the soft cells on your cervix, the loop diathermy is not a suitable option. The alternative is to monitor your symptoms. 

Asking for your permission (consent)

We want to involve you in all the decisions about your care and treatment. If you decide to go ahead under local anaesthetic, you will be asked to agree verbally (spoken) to the procedure.

If you decide to have the procedure under general anaesthetic you will be asked to sign a consent form. This states that you understand what it involves and you agree to have the treatment.

Remember, it is your decision. You can change your mind at any time, (as long as this is before the procedure is started), even if you have signed the consent form. Let staff know immediately if you change your mind. Your wishes will be respected at all times. If you would like more information about our consent process, please speak to a member of staff caring for you.

You can read more about giving your consent.

Going on holiday

If you are planning on going abroad and we have sent you an appointment for treatment, please call us to let us know. We would normally suggest that you do not travel abroad for at least 2 weeks after the treatment. This is because of the risk of bleeding and other complications.

Preparing for cold coagulation

If you are having local anaesthetic

If you are having a local anaesthetic, you can continue as normal before the procedure. It is important that you eat and drink before the procedure and do not starve yourself.

It can be helpful to bring someone with you so that they can take you home after the procedure, but it is not essential.

If you are having a general anaesthetic

If you are having a general anaesthetic, we will give you instructions in your admission letter about when you need to stop eating and drinking certain liquids (fasting) depending on the time of your operation. Fasting means that you cannot eat or drink anything (except water) for 6 hours before surgery. We will give you clear instructions on when to start fasting.

It is important to follow these instructions. If there is food or liquid in your stomach during the anaesthetic it could come up to the back of your throat and damage your lungs.

You can read more about having local and general anaesthetic.

Having cold coagulation

If you are having local anaesthetic

You will be seen in the same department where you had previous colposcopy appointments. This is the colposcopy unit which is located in the gynaecology outpatients department (McNair Centre, Guy’s Hospital).

You will have a consultation with the colposcopist. You will be taken to the examination area where you will be asked to undress from the waist down (a loose skirt does not need to be removed). The nurse who will be looking after you and assisting the colposcopist will help you to get into the right position on the examination couch.

If you are having general anaesthetic

You will have an appointment in the colposcopy unit or McNair Centre at Guy’s Hospital. This will be to discuss the operation with a doctor and sign your consent form. You will also be seen in the McNair Centre for your pre-assessment appointment. You will have your actual treatment done in Lambeth Theatres (day surgery) at St Thomas’ Hospital. 

The consultant, or one of their team, will talk to you before your operation and they will recheck the consent form with you. The nursing team will look after you. You will be asked to undress completely and put on a hospital gown. You will be taken to the operating theatre where your general anaesthetic will be given and where you will be treated while you are asleep.

During the procedure

The procedure usually takes 15 to 20 minutes. During the examination an instrument called a speculum is inserted into your vagina to hold back the vaginal walls so the clinician can see your cervix. The colposcopist then uses the colposcope to examine your cervix. They might apply some liquid to the cervix to show any abnormal-looking areas. The area is then numbed if you are having the procedure under local anaesthetic (if you are having a general anaesthetic you will already be asleep).

When the local anaesthetic has taken effect, the colposcopist will proceed with the treatment. They will use a heated probe on the cervix. This will be positioned in one place for up to 30 seconds. This application might be repeated several times, and the probe might be repositioned to make sure all affected areas are treated.

After the procedure, the speculum will be taken out and you will be asked to rest on the examination couch for a few minutes. The nurse will tell you when to get up and dressed. When you are dressed you will go back to see the colposcopist who will talk to you about the procedure.


You should not feel any pain during the procedure. If you are having a general anaesthetic you will be asleep. Local anaesthetic is given before the treatment, so you should not feel any pain during the procedure, but you might feel some pressure on your cervix.

It is unusual to feel discomfort after the treatment. You might get a mild period-like pain. If this happens you should take your regular painkillers.

After cold coagulation

If you had local anaesthetic

We ask you to stay in the department for about 20 minutes after the procedure. During this time a nurse will check on you, go through the aftercare instructions, and answer any questions you have. We advise that you bring someone with you, so that they can take you home after the procedure. You can eat and drink as normal.

If you had general anaesthetic

You will need to stay in the day surgery unit for at least 2 hours after the procedure. You must have someone who can take you home after a general anaesthetic, and a responsible adult (over 18 years of age) needs to stay with you overnight.

You can read more about about having surgery at our hospitals.

After you leave hospital

We advise that you go home after the procedure and rest for the remainder of the day. If you have had a local anaesthetic you should be able to go to work the next day. If your appointment is late in the afternoon, you might want to book the next day off work.

If you have had a general anaesthetic, you should rest on the day of your operation. You do not need to stay in bed the next day, but we would advise that you have a restful day. Ideally, we would recommend that you have someone staying with you for the first 24 hours.

With local and general anaesthetics, we recommend that you return to work depending on how you feel and how physical your job is. You should be able to self-certify your absence from work for 7 days. Please avoid any heavy lifting (at home or at work) for the next 2 weeks.

In the first 48 hours after surgery we advise you:

  • do not drive a car or ride a bike
  • do not operate machinery
  • do not cook, use sharp objects or pour hot liquids
  • do not drink alcohol
  • do not smoke
  • do not take sleeping tablets
  • do not make important decisions or sign contracts

We recommend that you avoid swimming until the vaginal discharge has stopped, ideally for at least 4 weeks. Please do not go to a gym or do any strenuous exercise, for 2 weeks after your procedure. After this time you can slowly build up to your usual fitness routine. If you start to bleed during or after a gym session, do not go again for a week.

When you get your menstrual period, only use sanitary towels. Do not use tampons or have sex for 4 weeks after your treatment. This allows time for the cervix to heal and reduces the risk of infection and bleeding.

You can bathe as normal after your treatment. We would advise you to shower where possible, however if you do not have access to a shower, please have a warm bath (not hot).

Go to your nearest emergency department (A&E) if:

  • you have heavy bleeding, which is heavier than your normal period, or if you are passing blood clots.

Follow-up appointments

It is very important that you have your first cervical screening test (smear test) and human papilloma virus (HPV) 6 months after your treatment. These might be done in the colposcopy clinic or you might be asked to see your GP.  More information on these tests will be given to you in the clinic after your procedure.

If you have had cold coagulation to treat the soft cells on your cervix, we might discharge you after the treatment. We will tell you where you need to have your next cervical cytology test taken in your results letter. If you do not get your results letter within 8 weeks after your treatment, please ring the colposcopy unit.

More information

We have listed some useful websites which we believe have the most detailed information and we hope will answer more of your questions. It does not mean that you have cancer.

Cancer Research UK, Support line, phone: 0808 800 4040 

Macmillan cancer support Support line, phone: 0808 808 00 00
Support and information about all types of cancers

Cervical cancer screening
Information from Gov.uk about the UK's cervical cancer screening programme

British society for colposcopy and cervical pathology
Information about screening and treatment

Resource number: 3100/VER6
Published date: November 2023
Review date: November 2025

Contact us

If you have any questions, please contact the Colposcopy unit

phone: 020 7188 3691, Monday to Friday, 9am to 5pm.

Appointments and cancellations 
email: [email protected]@gstt.nhs.uk

Clinical questions
email: [email protected]

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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