Darwish 2018.

Study characteristics
Methods	Randomised controlled trial (described as single‐blinded) Setting: Assuit Women's Health Hospital, Egypt
Participants	Women with primary atonic PPH following vaginal delivery and not responding to standard treatment protocol. PPH was not defined, and nor was there a systematic method of diagnosis (the trial report states that, "Failure to use an accurate measure of blood loss estimation in patients and relying on indirect methods of estimation like HB before and after the intervention is a weak point of this study." p757, Darwish 2018). Exclusions: traumatic PPH, caesarean section, placental abruption, placenta praevia, chorioamnionitis, pregnancy complications (e.g. pre‐eclampsia, diabetes, anaemia, rheumatic heart disease) or women known to have coagulation problems. (Women were put under general anaesthetic before recruitment into the trial, "Under general anesthesia, traumatic lesions and placental remnants were properly excluded." p748, Darwish 2018). 100 potentially eligible women were identified but only 66 were randomised (34 refused to participate). Mean age 28 years, mean body mass index was 27.35. Mean parity was 3.0.
Interventions	Intervention: Bakri balloon (33 women) "Bakri balloon is connected to a 24 French, 54 cm long silicone catheter. The Bakri balloon was well‐inserted inside the uterine cavity. After proper positioning, the balloon was initially inflated with 150 mL of sterile normal saline. Then the surgeon put his thumb and index finger around the cervix to keep the partially inflated balloon above the cervix. Bakri balloon was further inflated up to 400‐500 mL until the blood draining through the catheter is considerably decreased" p 748 Control: condom‐loaded Foley catheter (33 women) inflated in the same way as the Bakri balloon. All women in both groups also received IV cephradine 1 g every 12 hours after balloon insertion.
Outcomes	Primary outcome: number of women requiring surgical intervention to stop bleeding Secondary outcomes Time between insertion and stoppage of bleeding (minutes)* Hysterectomy Blood transfusion* Fever (post‐insertion)* Disseminated intravascular coagulopathy* The following outcomes were reported but were not prespecified in the registration (NCT02430155) protocol: Referral to ICU* Successful procedure Pulse rate, systolic and diastolic blood pressure Urine output Haemoglobin and haematocrit levels (pre/post intervention) * These outcomes are only reported for those women who were successfully treated by balloon tamponade, and did not include women who had treatment failure.
Notes	Trial authors' declarations of interest: "The authors report no conflicts of interest" p 752. Sources of trial funding: not mentioned. Trial dates: October 2014 until December 2015. Informed consent obtained?: Ethics approval obtained?: yes, from the ethical board of the Faculty of Medicine of the Assiut University. Did we attempt to contact the trial authors?: no
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Randomization was done using a computer‐generated random table" p 748
Allocation concealment (selection bias)	Low risk	"Allocation concealment was done using serially numbered closed opaque envelopes" p 748
Blinding of participants and personnel (performance bias) All outcomes	High risk	Trial reported as single‐blind but unclear who was blinded. Women were under general anaesthesia so presumably effectively blinded whilst being operated on. Given the description in the study report, it is likely that personnel were not blinded, because the interventions would clearly look different when handled by clinicians. On this basis we assess this as high risk of performance bias due to likely lack of clinician blinding which could have affected clinical decision‐making
Blinding of outcome assessment (detection bias) All outcomes	High risk	Trial reported as single‐blind but unclear who was blinded; no mention of blinding of outcome assessors in trial report. It is possible that non‐independent blinded providers have biased the outcomes assessments
Incomplete outcome data (attrition bias) All outcomes	High risk	Data on use of blood transfusion, intensive care unit referral and coagulopathy were not reported for those who had 'treatment failures' in each group. Rather than the denominator of 66 women recruited, the denominator for these outcomes is 58
Selective reporting (reporting bias)	Unclear risk	Trial was registered NCT02430155 but checking the outcomes in the protocol against the trial report there are some differences. We note that the following reported outcomes were not listed in the study protocol: referral to intensive care unit, successful procedure, pulse rate, systolic and diastolic blood pressure, urine output, haemoglobin and haematocrit levels (pre/post intervention)
Other bias	Low risk	No sources of other bias identified