Lapses in procedure and human error were the reasons behind the mix-up of sperm used in an in-vitro fertilisation treatment at Thomson Medical Centre (TMC), Health Minister Khaw Boon Wan said yesterday.

Pipettes used at its fertility centre were reused instead of being discarded, as is standard protocol, and there was no second layer of checks to ensure specimens were put in the correct receptacles.

Describing the incident as indirectly affecting Singapore's reputation as a regional medical hub, Mr Khaw told Parliament that the National Medical Ethics Committee (NMEC) was also consulted on the matter.

It acknowledged the complexity of the issues involved, and on the matter of the "rights" of the sperm donor, held that TMC would have a duty to inform him he was the father should he ask.

"But it should not volunteer the information, taking into account the impact it may have on the baby," he said.

Mr Khaw said his ministry had completed its investigation into the mix-up, which was first reported in The Straits Times.

In October this year, a Singaporean Chinese woman and her Caucasian permanent resident husband discovered that their baby's blood group did not match theirs. The baby's complexion was also markedly different from theirs.

More bad news was to follow when a DNA test showed that the baby wasn't biologically related to the husband.

Thomson Medical Centre, which carried out the IVF procedure in January, apologised when the incident was made public.

Responding to Health Government Parliamentary Committee (GPC) chairman Lam Pin Min, who wanted an update on the matter, Mr Khaw told the House that to eliminate the risk of any mix-up, assisted reproduction centres follow procedures in accordance with international best practices.

First, the embryologist will work on the specimens of only one individual or one couple, at one workstation at a time.

Second, he will carefully label all the receptacles and instruments with the couple's or the individual's name.

Third, he will discard disposable instruments such as pipettes after each use, to avoid any contamination.

Fourth, at every critical step, a second operator will counter-check that the specimens are transferred to the correct receptacles.

It was found that TMC's IVF centre had deviated from some procedures.

"At the time of the incident, the embryologist was processing semen specimens of two individuals at the same workstation at the same time," Mr Khaw said.

"The pipette used for transferring the specimen was reused, instead of being discarded after each step.

"Even though it was reused only for handling the specimens from the same individual, it unnecessarily raised the risk of human error.

"This was particularly risky as there was no second person to counter-check that the specimens were transferred to the correct receptacles at every critical stage. These lapses in procedure contributed to the occurrence of a human error, and both led to the IVF mix-up in this case."

He did not give further details on how the mistake actually took place.

In response to Dr Lam's question about the rights of the baby's biological father, Mr Khaw said his ministry had consulted the medical ethics committee, which met to discuss the matter.

The committee noted that many parties were involved and TMC had a duty to every one.

However, in fulfilling all those duties, other problems may be caused to some of the parties.

The committee's advice was that the rights of the baby - the most vulnerable of all parties - should take priority.

Elaborating on this last night, the ministry said the NMEC meeting was chaired by acting chairman Dr Yeoh Swee Choo.

The committee also recommended that to protect the interests of the child, information on the mix-up as well as any other that might lead to identifying the child should not be conveyed to the unintended genetic father without prior consent from the biological mother and her husband.

Following the IVF mix-up, the ministry directed all assisted reproduction Centres to strictly follow the correct procedures, if they have not been doing so. TMC was also banned from taking in new cases.

Mr Khaw said TMC has been responsive and has cooperated fully in the investigation.

"The incident has no doubt impacted the reputation of the TMC IVF Centre and indirectly affected Singapore's reputation as a regional medical hub," he said.

"They are determined to recover from this incident. The key is full disclosure of the facts and immediate correction of any systemic inadequacies to ensure that similar errors will not recur. This is the way to regain patients' confidence and trust."