see - sc.judiciary.gov.ph/jurisprudence/2013/july2013/179786.pdf
"x x x.
3. Josielene argues that since Johnny admitted in his answer to the petition before the RTC that he had been confined in a hospital against his
will and in fact attached to his answer a Philhealth claim form covering that confinement, he should be deemed to have waived the privileged character of its records. Josielene invokes Section 17, Rule 132 of the Rules of Evidence that provides:
SEC. 17. When part of transaction, writing or record given in evidence, the remainder admissible.— When part of an act, declaration, conversation, writing or record is given in evidence by one party, the whole of the same subject may be inquired into by the other, and when a detached act, declaration, conversation, writing or record is given in evidence, any other act, declaration, conversation, writing or record necessary to its understanding may also be given in evidence.
But, trial in the case had not yet begun. Consequently, it cannot be said that Johnny had already presented the Philhealth claim form in evidence, the act contemplated above which would justify Josielene into requesting an inquiry into the details of his hospital confinement. Johnny was not yet bound to adduce evidence in the case when he filed his answer.
Any request for disclosure of his hospital records would again be premature.
x x x."