Prenatal visualization of the fetal uterus in routine 2D ultrasound examination.

Objective: To establish a new technique to easily identify the fetal cervix-uterus complex in normal female fetuses from 20 to 40 weeks of gestation.

Material And Methods: The study was performed in routine examination in normal fetuses by two observers. Twenty-five consecutive cases per gestational week were assessed between 20 and 40 weeks.

How to understand and report heterogeneity in a meta-analysis: The difference between I-squared and prediction intervals.

In any meta-analysis it is important to report not only the mean effect size but also how the effect size varies across studies. A treatment that has a moderate clinical impact in all studies is very different than a treatment where the impact is moderate on average, but in some studies is large and in others is trivial (or even harmful). A treatment that has no impact in any studies is very different than a treatment that has no impact on average because it is helpful in some studies but harmful in others.

Avoiding common mistakes in meta-analysis: Understanding the distinct roles of Q, I-squared, tau-squared, and the prediction interval in reporting heterogeneity.

In any meta-analysis, it is critically important to report the dispersion in effects as well as the mean effect. If an intervention has a moderate clinical impact on average we also need to know if the impact is moderate for all relevant populations, or if it varies from trivial in some to major in others. Or indeed, if the intervention is beneficial in some cases but harmful in others.