SONTRA MEDICAL CORPORATION

LIMITED POWER OF ATTORNEY


	This statement confirms that the undersigned has authorized and
designated each of Sean F. Moran, Thomas B. Rosedale and Kevin P. Lanouette
his attorney-in-fact to (i) prepare, execute and file on behalf of the
undersigned Form ID in order to obtain access codes for the undersigned
to permit filing on EDGAR, and (ii) prepare, execute and file on behalf
of the undersigned all Forms 3, 4 and 5 (including any amendments thereto)
that the undersigned may be required to file with the U.S. Securities and
Exchange Commission as a result of the undersigned's ownership of or
transactions in securities of Sontra Medical Corporation.  The authority
of such attorneys under this Power of Attorney shall continue until the
undersigned is no longer required to file Forms 3, 4 and 5 with regard to
the undersigned's ownership of or transactions in securities of Sontra
Medical Corporation, unless earlier revoked in writing.  The undersigned
acknowledges that such attorneys are not assuming any of the undersigned's
responsibilities to comply with Section 16 of the Securities Exchange Act
of 1934, as amended, or any of the undersigned's liabilities for failure
to comply with such requirements.


Date: May 4, 2005			/s/ Barry Marston
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					Barry Marston