We have identified efforts by research ers to investigate interventions which seek to improve information delivery and consideration of information to enhance  informed consent .
The interventions used consistently improve patient knowledge , an important prerequisite for informed consent .
This is encouraging and these measures could be widely employed although we are not able to say with confidence which types of interventions are preferable .
Our results should be interpreted with caution due to the high levels of heterogeneity associated with many of the main analyses although we believe there is broad evidence of beneficial outcomes for patients with the pragmatic application of interventions .
BACKGROUND Achieving informed consent is a core clinical procedure and is required before any surgical or invasive procedure is undertaken .
However , it is a complex process which requires patients be provided with information which they can underst and and retain , opportunity to consider their options , and to be able to express their opinions and ask questions .
There is evidence that at present some patients undergo procedures without informed consent being achieved .
OBJECTIVES To assess the effects on patients , clinicians and the healthcare system of interventions to promote informed consent for patients undergoing surgical and other invasive healthcare treatments and procedures .
AUTHORS ' CONCLUSIONS Informed consent is an important ethical and practical part of patient care .
Use of videotapes for viewing at home to inform choice in Down syndrome screening: a randomised controlled trial.
A r and omised trial was carried out to assess the effect of a  Down syndrome screening video on test uptake , knowledge and psychological stress .  A total of 2000 women referred for antenatal care were allocated to two equal groups : one to be sent a video to their home , before their hospital booking visit , and a control group . All women also received screening information in the form of a leaflet before booking and from a midwife at booking . The video had no effect on the screening uptake rate : 638/993 ( 64.2 % ) and 652/1007 ( 64.7 % ) in the video and control groups , respectively . Women were requested to return the video for reuse in other pregnancies and 612 ( 62 % ) did so . A subset of 1200 women were selected to be posted at 17 - 19 weeks ' gestation a self-completed question naire to assess the psychological endpoints . Knowledge of screening was increased in the video group with a mean score of 7.3 compared with 6.7 in the controls , a statistically significant difference ( t=3.24 , p=0.0005 ) . There were no significant differences between the groups in specific worries about abnormalities in the baby , and general anxiety . We conclude that a video can increase knowledge without affecting the uptake of the test , or psychological stress
We have identified efforts by research ers to investigate interventions which seek to improve information delivery and consideration of information to enhance  informed consent .
The interventions used consistently improve patient knowledge , an important prerequisite for informed consent .
This is encouraging and these measures could be widely employed although we are not able to say with confidence which types of interventions are preferable .
Our results should be interpreted with caution due to the high levels of heterogeneity associated with many of the main analyses although we believe there is broad evidence of beneficial outcomes for patients with the pragmatic application of interventions .
BACKGROUND Achieving informed consent is a core clinical procedure and is required before any surgical or invasive procedure is undertaken .
However , it is a complex process which requires patients be provided with information which they can underst and and retain , opportunity to consider their options , and to be able to express their opinions and ask questions .
There is evidence that at present some patients undergo procedures without informed consent being achieved .
OBJECTIVES To assess the effects on patients , clinicians and the healthcare system of interventions to promote informed consent for patients undergoing surgical and other invasive healthcare treatments and procedures .
AUTHORS ' CONCLUSIONS Informed consent is an important ethical and practical part of patient care .