Sibling eggs

Sibling eggs, typically from the same patient and often collected in the same cycle, serve as experimental controls. For instance, in a study comparing ICSI and conventional IVF, a patient with 20 eggs may have 10 treated with ICSI and the remaining 10 with IVF, and these are considered sibling eggs.

Using sibling eggs minimizes variability in the experiment, because the eggs are coming from the same patient (instead of from different patients).