Kavak 2013.

Study characteristics
Methods	"Randomised prospective single blind trial" (p 706) Setting: university hospital setting in Turkey
Participants	Women with complete placenta praevia and intractable bleeding (n = 13) following caesarean section. PPH was not defined. Exclusions: serious medical, haematological or surgical diseases; placental implantation anomalies such as placenta accreta/increta/percreta; history of thromboembolism; emergency CS; macrosomia; poly ‐hydramnios; preeclampsia; gestational diabetes; intrauterine growth retardation; and presence of multiple gestations.
Interventions	Intervention: Bakri balloon tamponade intraoperatively through uterine incision (7 women) ‐ was inflated with saline (100 mL to 200 mL) "according to the uterine size" p 706 Control: Endouterine haemostatic square suturing to the lower segment of the uterus (6 women). 4‐5 sutures were applied. All women were given prophylactic antibiotics.
Outcomes	Blood loss in the first 24 hours Operative time Hb pre and post operation Intraoperative blood loss Blood transfusion Postoperative blood loss
Notes	Trial authors' declarations of interest: the authors state that they have no conflicts of interest. Sources of trial funding: not reported. Trial dates: August 2011 to August 2012 Informed consent obtained? yes Ethics approval obtained? yes, from the local research ethics committee Did we attempt to contact the trial authors?: email to Dr Kavak on 25 Aug 2018 requesting data on blood loss following transfusion only (not total blood loss). No response as of 1 March 2019.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Trial report states "randomly divided" ‐ insufficient information provided
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	High risk	Reported to be a single‐blind trial but no further information explicitly provided, although women were under general anaesthesia so presumably effectively blinded whilst undergoing intervention. Assume blinding of surgical personnel not possible due to difference in intervention techniques between groups. (Blood loss during the operation calculated by the anaesthetist (evaluation of blood collected via suction plus weighing of absorbant pads) ‐ reasonably objective. During first 24 hours, postoperative blood loss measured by weighing pads worn by patients ‐ again, this is reasonably objective so we question the extent to which lack of blinding would matter ‐ it may have had lots of small impacts on clinical decision‐making)
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient information to assess ‐ reported to be a single‐blind trial but no further information provided
Incomplete outcome data (attrition bias) All outcomes	Low risk	No missing outcome data
Selective reporting (reporting bias)	Unclear risk	No protocol available
Other bias	Low risk	No other sources of bias identified