español al inglés Medicina Medicina (general) Clinical Trials

This is a sentence from a document describing the procedures and requirements of a hospital ethics committee that evaluates and approves clinical research proposals:

"El CEI considera que la periodicidad del seguimiento del estudio corresponde una vez al año reportando de manera general lo acontecido con relación al reclutamiento de pacientes, eventos adversos, consentimientos informados y adquisición de nueva información. *En su defecto cuando el estudio así lo amerite*."

Basically, I don't understand what "en su defecto" refers to in the text before it.

I think that "en su defecto" means "in the absence" of something, or "failing ... (something) ... " But here, I don't understand ... in the absence of (or failing) what?

There are places where this document is not clear, there are misspellings and there seem to be missing words. In this case, I don't know if I'm missing something or if the text is missing something.

(The text is from Colombia.)

Thanks for your suggestions and ideas.