15935 women recruited.

The CORONIS Trial recruited 15,935 women from Argentina, Chile, Ghana, India: Delhi and Vellore, Kenya, Pakistan and Sudan to this fractional, factorial randomised controlled trial of caesarean section surgical techniques. The results were published on the 28th May 2013 in the Lancet (online first), and 19th July 2013 in print.

The CORONIS Trial is funded by the UK Medical Research Council, supported by the World Health Organisation. CORONIS is an international, fractional factorial randomised controlled trial and is being conducted in hospitals in the following seven countries: Argentina, Chile, Ghana, India, Kenya, Pakistan and Sudan. The collaborating institutions are centres with experience in conducting trials. These centres also have experience in detailed follow-up of large numbers of women.

The study will not alter or interfere with any treatment or care given routinely to women in the hospitals where the caesarean section takes place except on the interventions to be evaluated.


The objectives of the trial are to determine whether there are any differences in maternal morbidity when comparing the following five pairs of alternative surgical techniques undertaken during the time of caesarean section:

  1. Blunt versus sharp abdominal entry
  2. Exteriorisation of the uterus for repair versus intra-abdominal repair
  3. Single versus double layer closure of the uterus
  4. Closure versus non-closure of the peritoneum (pelvic and parietal)
  5. Chromic catgut versus Polyglactin-910 for uterine repair

Recruitment Target

The trial aims to recruit 15,000 women world-wide. Women will be recruited from 18 hospitals in the six participating countries.

Trial eligibility

Women ARE eligible for trial entry if:

  • they are undergoing delivery by lower segment caesarean section through a transverse abdominal incision, irrespective of fever in labour, gestational age or whether they have a multiple pregnancy.

Women are NOT eligible if:

  • there is a clear indication for a particular surgical technique or material to be used that prevents any of the allocated interventions being used,
    e.g. for a woman with a previous vertical abdominal incision it maybe considered inappropriate to do a transverse abdominal incision for this caesarean section. However, if a transverse incision is going to be performed the woman is eligible.
  • they have had more than one previous caesarean section.
  • they have already been recruited into the trial during a previous pregnancy.


All women will be followed-up six weeks after discharge from hospital. Six week follow-up will be carried out at hospital clinics, home visits or by telephone interview whichever is most appropriate. A long-term follow-up of all women is planned at 3 years after enrolment into the study.

Primary outcome

Death or maternal infectious morbidity (one or more of the following: antibiotic use for maternal febrile morbidity during postnatal hospital stay, antibiotic use for endometritis, wound infection or peritonitis); or further operative procedures or blood transfusion.

Trial Co-ordination

The trial is being co-ordinated through the International Co-ordinating Centre (ICC) at the NPEU. In each region of the six participating countries (seven regions) there is a Regional Trial Office working closely with the ICC in Oxford.