A Dutch In Vitro Fertilization (IVF) lab has announced an investigation on Tuesday after discovering that 26 women may have been fertilized by the wrong sperm cells.

Nearly half of the women who underwent treatment mid-April 2015 and mid-November 2016 may have been fertilized by sperm cells from the wrong man.

According to the University Medical Centre (UMC) in Utrecht, Netherlands, a ‘procedural error’ occurred during IVF treatment.

“During fertilization, sperm cells from one treatment couple may have ended up with the egg cells of 26 other couples,” said UMC.

in-vitro-fertilization“For some of the 26 couples, frozen embryos are still available but the chance remains that they (too) have been fertilized by the sperm from a man other than the intended father,” UMC added.

The medical institution said there is a small chance, that would happen, but they cannot exclude the possibility.

The UMC have informed all the couples and said, “The UMC’s board regrets that the couples involved had to receive this news and will do everything within its powers to give clarity on the issue as soon as possible.”

Meanwhile, sperm mix-up does happen, most notably the incident in 2012 when a mother sued a clinic in Singapore for negligence after they accidentally mixed up her husband’s sperm with a stranger.