She was referred to another obstetrician and underwent an endometrial tissue biopsy in March of that year. The specimen was identified and labeled by Kaiser laboratory staff, then sent to an outside laboratory for testing. The complaint alleges that another patient's tissue sample was labeled as hers. The result came back positive for an aggressive, high-grade endometrial cancer. The complaint states that the specimen showing aggressive endometrial cancer belonged to another woman who did have the disease.