Developing and implementing a core outcome set for caesarean scar ectopic pregnancy research (COSCAR)

Studies evaluating caesarean scar ectopic pregnancy report many different outcomes and often define and measure success or complications of various treatments in different ways. This variation in reporting of results leads to heterogeneity and an inability to compare results of studies directly or reliably.

We will develop a core outcome set to ensure outcomes important to all stakeholders are collected all the time to ensure future research in caesarean scar ectopic pregnancy is consistent.

The core outcomes will not be limited to a particular study type given the relative rarity of caesarean scar ectopic pregnancy. The core outcome set will be defined for all treatment options for caesarean scar ectopic pregnancy, including expectant, medical, and surgical management. Recommendations for the diagnosis of caesarean scar ectopic pregnancy in studies are not within the scope of COSCAR, this will require a separate process.

A core outcome set for research in ‘ectopic pregnancy’ was published in 2023. However, caesarean scar ectopic pregnancy is a distinct disease in comparison to all other ectopic pregnancies, both in terms of aetiology, the natural disease progression and associated morbidity; therefore, a distinct core outcome set needs to be developed.

Caesarean scar ectopic pregnancy is the only type of ectopic pregnancy where there is potential for the pregnancy to progress to viability (albeit with significant morbidity) and therefore treatment options centre around terminating the pregnancy (which is not usually offered to any other type of ectopic pregnancy) or expectant management (with the potential of a live baby). Caesarean scar ectopic pregnancy is associated with both maternal morbidity (loss of future fertility, uterine rupture, bladder injury, obstetric hysterectomy, placenta accreta syndrome) and fetal morbidity (second trimester loss, prematurity, neonatal morbidity). As expectant management is one treatment option for caesarean scar ectopic pregnancy, any core outcome set for caesarean scar ectopic pregnancy must include the aforementioned outcomes that occur beyond the first trimester. In comparison other ectopic pregnancies do not generally progress beyond the first trimester, so these late outcomes are not covered by the previously published core outcome set for ‘ectopic pregnancy’. We will therefore develop an add-on core outcome set for caesarean scar ectopic pregnancy.

Contributors

Principal investigator:
Dr. Simrit Nijjar (Department of Obstetrics and Gynaecology, University College Hospital, London, United Kingdom)


Supervisors:
Miss Cecilia Bottomley
Professor Davor Jurkovic
(Department of Obstetrics and Gynaecology, University College Hospital, London, United Kingdom)

Further Study Information

Current Stage: Ongoing
Date: November 2023 - April 2025
Funding source(s): No funding


Health Area

Disease Category: Gynaecology

Disease Name: Ectopic pregnancy

Target Population

Age Range: 18 - 50

Sex: Female

Nature of Intervention: Any

Stakeholders Involved

- Charities
- Clinical experts
- Consumers (patients)
- Patient/ support group representatives
- Researchers
- Service providers
- Service users

Study Type

- COS for clinical trials or clinical research

Method(s)

- Consensus meeting
- Delphi process
- Focus group(s)
- Interview
- Literature review
- Systematic review

A mixed-method consensus approach will be used as informed by the COMET handbook. Potential core outcomes will be identified through a comprehensive literature review and semi-structured interviews with individuals with a lived experience of caesarean scar ectopic pregnancy. We will establish an international steering group of key stakeholders, including healthcare professionals, researchers, patients and patient representatives. The resulting list of potential outcomes will be entered into a 2-round modified Delphi process. Finally, the resulting core outcomes will be presented to a consensus meeting of key to develop the final core outcome set.