Rush 1984.

Methods	RCT. 20 January 1979 to 19 April 1982. Reproductive failure clinic at the Groote Schuur Maternity Centre, Peninsula Maternity and Neonatal Service, Capetown, South Africa. Women entered the study at 15 to 21 weeks' gestation.
Participants	Participants (N = 194):  high‐risk women for PTL or late abortion. Inclusion criteria: 2, 3 or 4 previous pregnancies which has ended spontaneously before 37 completed weeks' gestation; and at least 1 previous pregnancy which ended spontaneously between 14 and 36 completed weeks' gestation. Exclusion criteria: age > 35 years; smoking > 5 cigarettes/day; medical disorders (cardiac disease, hypertension, diabetes, thyroid disease); obstetric/gynaecological conditions (recurrent 1st trimester abortions, multiple gestation in present pregnancy, congenital uterine abnormality, uterine fibromyomata, previous cervical surgery – cone biopsy, trachelorrhaphy, cervical cerclage); cervix < 2.0 cm long or dilated at entry
Interventions	Cervical suture versus no suture
Outcomes	Not stated
Notes	Additional information and the data base for cross‐checking of the published results provided by the first author
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	“…patients were allocated at random either to have a cervical suture (96 patients) or to be managed without a suture (98 patients) by reference to a series of sealed envelopes.”
Allocation concealment (selection bias)	Unclear risk	“…reference to a series of sealed envelopes.”
Blinding of participants and personnel (performance bias) All outcomes	High risk	Impossible to blind to participants and personnel
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated if outcome assessors were blinded
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Loss of participants not stated.                                                          Exclusion of participants after randomisation not stated.  Intention‐to‐treat analysis: “All but two of 194 women entered into the trial received the management to which they were allocated.”
Selective reporting (reporting bias)	Low risk	Study protocol not available. The full database was provided by the authors, so any selective reporting unlikely
Other bias	Low risk	Study was not stopped early. Baseline imbalance: “Although the frequency of two or more previous second trimester abortions or preterm deliveries was somewhat greater in women allocated to cerclage, this difference was not statistically significant.”