Preventing recurrence of endometriosis by means of long-acting progestogen therapy

Endometriosis is a painful condition and many sufferers require surgery to remove areas of endometriosis in order to relieve pain. Repeated surgery can lead to health complications, which is why BCU researchers are comparing the effectiveness of different treatment options to advise sufferers and health professionals. 

Endometriosis treatment project large


Research team

Middleton LJ, Daniels JP, Weckesser A, Bhattacharya S; Denny, E, Jones, G, and PRE-EMPT trial collaborative group.

Research background

Endometriosis occurs in 6-10% of women of reproductive age. The condition is painful and can have a serious impact on their lives. Many will need surgery to remove areas of endometriosis in order to relieve pain. However, symptoms of endometriosis tend to return and women need to go through repeated surgery including removal of their womb and ovaries. Previous research has suggested that medicines containing female hormones (progestogens) can reduce the chances of symptoms returning. Treatments in this class are contraceptives and include a coil, injections, or the pill. However, these studies were done with small numbers of participants and were unable to provide definitive results.

Research aims 

The aim of this study is to compare the effectiveness of these different treatment options in women undergoing surgery for endometriosis. Additionally, it seeks to understand women’s experiences of different endometriosis treatments.

Research methods

Women were randomised to two, three or four treatment options provided. An interview and focus group-based qualitative study were carried out to explore women’s experiences of endometriosis treatment and the acceptability of this RCT.


The qualitative study found that women were strongly influenced by previous experience and personal circumstances in their decision to enter the PRE-EMPT trial. This decision was facilitated by the ability to 'opt out' of the treatment arm(s) they found unacceptable. This element of choice offered patients a sense of control in the randomisation process and has important implications for clinical trial design and recruitment.

The substantial RCT has not yet been completed.  The pilot trial has been completed and found that multi-arm studies are potentially efficient as they can answer multiple questions simultaneously but are difficult to recruit to if there are strong patient or clinician preferences. A flexible approach to randomisation in a pilot phase can be used to assess the feasibility of such studies and modify a trial design based on chosen recruitment options, but trialists should consider carefully any practical arrangements should groups need to be dropped during a study.