Palacio 2006

Methods	RCT.
Participants	Singleton gestations; PTL at 24 to 35 6/7 weeks. N = 149.
Interventions	TVU CL knowledge or not (the control group did receive TVU CL, but results were blinded to managing physicians). Time TVU CL results available: not specified. Protocol for TVU knowledge group: yes.
Outcomes	Primary: hospital length of stay.
Notes	Only abstract published; 7 women lost to follow up; only singletons; protocol for management of TVU CL group. Short TVU CL (< 25 mm): 22/75 (29%) in knowledge group; 20/74 (27%) in the control group.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomization not described.
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Women and physicians knew which group was randomized to 'knowledge' or 'no knowledge'.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported.
Incomplete outcome data (attrition bias) All outcomes	High risk	5% of data removed from final analysis.
Selective reporting (reporting bias)	Unclear risk	Length of hospital stay primary outcome.
Other bias	Unclear risk	Abstract only. Data limited.

CL: cervical length FFN: fetal fibronectin PPROM: preterm premature rupture of membranes PTL: preterm labor RCT: randomized controlled trial TVU: transvaginal ultrasound US: ultrasound