The Health, Labor and Welfare Ministry plans to demand that hospitals across the country that carry out fertilization treatment conduct strict checks.

By doing so, the ministry hopes to prevent a recurrence of such mishaps as a recent mixup over patients' eggs, ministry sources said Thursday.

The ministry plans to revise guidelines in April at the earliest to require checks by two or more doctors to avoid errors, and to set up ethics committees at such facilities, they said.

The guidelines set requirements for hospitals that receive state subsidies for patients who undergo fertilization treatment.

Facilities that fall short of these conditions may be denied funding.

Before amending the guidelines, the ministry plans to soon send questionnaires to some 600 designated hospitals across the nation to survey how they try to ensure the safety of fertilization treatment, including in vitro fertilization, the sources said.

Treatment fees are subsidized for patients who receive in vitro fertilization or other forms of fertility treatment at any of the some 600 hospitals designated by local prefectural governments based on the ministry guidelines.

The conventional guidelines set standards for equipment and personnel but do not include safety measures.

Kagawa Prefecture said last week that Kagawa Prefectural Central Hospital in Takamatsu last September implanted in a woman a fertilized egg believed to be from another patient.

The woman became pregnant, but had an abortion nine weeks later at the hospital after she was informed of the mistake.

Only one doctor was involved in carrying out the operation.