For all standards (not just IEC 60601-1) the following minimum requirements can be derived from the law (MDD):
- a report showing compliance with the standard, or pointing to alternate solutions for each and every requirement in a harmonized standard not applied;
- the report should be prepared by person(s) that are appropriately qualified and experience in the scope of tests
- the reports should show results of tests, calculations etc (in sufficient detail to to be audited by the notified body)
- there should be records of traceability for any equipment used to make measurements
It is not necessary for a third party lab or certified report, and it is very common not to use a lab, especially for the less popular standards.
For popular standards like IEC 60601-1 it is usually efficient to use a third party lab as they have the experience, equipment and are set up for the reporting. However, IEC 60601-1 these days is very broad and includes subjective areas. It can be more efficient to limit the test lab to objective, well established tests and exclude parts of the standard which are highly subjective (e.g. PEMS). The excluded parts then need to be covered by report(s) prepared by the manufacturer, and for completeness there should be a cover report which ties the sub-reports together and provides an overall statement of compliance with the standard.