Cone biopsy and LLETZ

LLETZ and cone biopsy are both treatments to remove abnormal cells in cervical area. LLETZ stands for Large Loop Excision of the Transformation Zone.

Diagram of cone biopsy

LLETZ and cone biopsy are performed if you have abnormal cervical screening test results (changes in the cells covering the cervix).

During the investigation following your test result (called a colposcopy), a small sample of cells may be taken. The results may show CIN. CIN is cervical intraepithelial neoplasia. It is not cancer. There are 3 levels of CIN and they relate to how deep into the skin the abnormal cells have gone.

  • CIN 1 – up to one third of the thickness of the lining covering the cervix has abnormal cells
  • CIN 2 – between one third and two thirds of the skin covering the cervix has abnormal cells
  • CIN 3 – the full thickness of the lining covering the cervix has abnormal cells


In the LLETZ procedure a thin wire loop heated by an electrical current is used to remove the abnormal tissue from the cervix. It is a quick procedure, usually done under a local anaesthetic. The tissue sample is sent to a laboratory for examination. 

Cone biopsy

A cone biopsy is so called because a cone-shaped piece of tissue is surgically removed from the cervix. The cone biopsy is usually done under a general anaesthetic and involves a day or overnight stay in hospital. Results are usually available in a week. 

The risk of premature birth

Women who had have a cone biopsy or a LLETZ procedure, or any other procedure that involves the removal of cells from the cervix before pregnancy, are at higher risk of having a late miscarriage or premature birth (before 37 weeks).

The level of risk depends on the extent of the procedure that was carried out. Evidence shows that in cases where the excision is more than 10mm, or if more than one procedure has been carried out, then the risk is increased. 

It is important to let the midwife know at your first booking appointment if you have had any type of procedure performed on your cervix. 

More research is needed to assess the impact of these cervical procedures on pregnancy and at the moment there are no national guidelines on care, so different NHS trusts may offer different care.

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NHS Choices (accessed Nov 2016, Next review due: 15/12/2016) Colposcopy - Treatment

RCOG (2016) Reproductive Outcomes after Local Treatment for Preinvasive Cervical Disease, Royal College of Obstetricians and Gynaecologists, London

Cancer research UK (Accessed Nov 2016. Updated: 2 June 2014, No review date given) Pregnancy and abnormal cervical cells.

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    Last reviewed on December 14th, 2017. Next review date December 17th, 2020.

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