Follicular aspiration using a syringe suction system may damage the zona pellucida.

The incidence of the formation of cracks in the zona pellucida during aspiration was assessed by comparing two methods of aspirating follicular contents by suction: manual aspiration by syringe and mechanical aspiration by pump. Of 36 patients whose follicles were evacuated manually using syringes, 18 had at least one damaged oocyte. Of 38 other patients whose follicles were aspirated by pump, only one had an oocyte with a cracked zona pellucida. Four patients had their oocytes aspirated by both syringe and pump. In all four, the oocytes were intact when aspirated by the pump, but one oocyte was damaged in three of four cases when the follicles were aspirated using syringes.