UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                  SCHEDULE 13G


                    Under the Securities Exchange Act of 1934


                           Sontra Medical Corporation
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                                (Name of Issuer)

                     Common Stock, par value $0.01 per share
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                         (Title of Class of Securities)

                                    83568W109
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                                 (CUSIP Number)

                               September 15, 2003
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             (Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule
13G is filed:

         [ ] Rule 13d-1(b)
         [X] Rule 13d-1(c)
         [ ] Rule 13d-1(d)

*The  remainder of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for any  subsequent  amendment  containing  information  which  would  alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934 ("Act") or otherwise  subject to the liabilities of that section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
Notes).




CUSIP No. 83568W109
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(1)  Names of Reporting  Persons.  I.R.S.  Identification  Nos. of Above Persons
     (entities only):

      Brown Simpson Asset Management, LLC

      13-3954392
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(2) Check the Appropriate Box if a Member of a Group (See Instructions)  N/A
        (a)
        (b)
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(3)     SEC Use Only
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(4)     Citizenship or Place of Organization:  New York, United States
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Number of Shares  Beneficially Owned by Each
   Reporting Person With                      (5) Sole Voting Power:          *
                                              (6) Shared Voting Power:        *
                                              (7) Sole Dispositive Power:     *
                                              (8) Shared Dispositive Power:   *

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 (9) Aggregate Amount Beneficially Owned by Each Reporting Person:

        600,000*
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(10) Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See
     Instructions):  N/A
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(11) Percent of Class Represented by Amount in Row (9):  6.0%*
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(12) Type of Reporting Person (See Instructions): IA
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*Brown  Simpson  Asset  Management,  LLC, a New York limited  liability  company
("BSAM"), serves as investment  manager for each of Xmark Fund, L.P., a Delaware
limited  partnership  ("Xmark  LP"),  and Xmark  Fund,  Ltd.,  a Cayman  Islands
exempted  company ("Xmark Ltd").  In such capacity,  BSAM possesses the power to
vote and direct the  disposition  of all  securities  held by Xmark LP and Xmark
Ltd.  Xmark LP is the holder of (i)  108,500  shares  (the  "Xmark LP  Preferred
Shares") of Series A Convertible Preferred Stock, par value $0.01 per share (the
"Series A Preferred"),  of Sontra Medical Corporation,  a Minnesota  corporation
(the "Company"),  which, subject to certain restrictions  contained therein, may
be converted into Common Stock,  par value $0.01 per share (the "Common Stock"),
of the Company, at a conversion price of $1.00 per share, which conversion price
is  subject  to  adjustment  as set forth in the  Series A  Preferred,  and (ii)
warrants  (the  "Xmark LP  Warrants")  which,  subject to  certain  restrictions
contained  therein,  entitle  Xmark LP to purchase up to an aggregate of 108,500
shares of Common Stock at an exercise  price of $1.50 per share,  which exercise
price is subject to adjustment as set forth in the Xmark LP Warrants. Xmark Ltd
is the  holder of (i)  191,500  shares of Series A  Preferred  (the  "Xmark  Ltd
Preferred  Shares,"  and  together  with the  Xmark  LP  Preferred  Shares,  the
"Preferred Shares"),  which, subject to certain restrictions  contained therein,
may be converted  into Common Stock,  at a conversion  price of $1.00 per share,
which  conversion  price is subject to  adjustment  as set forth in the Series A
Preferred,  and (ii) warrants (the "Xmark Ltd  Warrants,"  and together with the
Xmark LP  Warrants,  the  "Warrants")  which,  subject to  certain  restrictions
contained  therein,  entitle Xmark Ltd to purchase an aggregate of up to 191,500
shares of Common Stock at an exercise  price of $1.50 per share,  which exercise
price is  subject  to  adjustment  as set forth in the Xmark Ltd  Warrants.  The
Preferred  Shares and the  Warrants  provide that the  Preferred  Shares are not
convertible  and the  Warrants are not  exercisable  prior to the receipt by the
Company of  shareholder  approval of the issuance of the Common Stock
upon the  conversion  of the  Preferred  Shares  and upon  the  exercise  of the
Warrants,  as required by NASDAQ Marketplace Rule 4350 (the "NASDAQ  Approval").
As of the date hereof, the NASDAQ Approval has not been obtained.  However,  the
Company has scheduled a shareholders'  meeting for September 30, 2003.  Thus, as
of September 15, 2003, for the purposes of Reg. Section  240.13d-3,  BSAM may be
deemed to beneficially own 600,000 shares of Common Stock, or 6.0% of the Common
Stock deemed issued and outstanding as of that date.



Item 1(a).  Name Of Issuer:  Sontra Medical Corporation.
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Item 1(b).  Address of  Issuer's  Principal Executive Offices: 10 Forge Parkway,
            Franklin, Massachusetts 02038.
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Item  2(a).  Name of Person  Filing: Brown Simpson Asset Management,  LLC.
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Item 2(b).   Address of Principal Business Office or, if None, Residence: 152
             West 57th Street,  21st Floor, New York, New York 10019.
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Item 2(c).  Citizenship:  Brown Simpson Asset Management, LLC is a New York
            limited liability company.
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Item 2(d).  Title  of  Class  of  Securities:  Common Stock, par value $0.01 per
            share.
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Item 2(e).  CUSIP No.:  83568W109
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Item 3.     If This Statement Is Filed Pursuant to ss.ss.240.13d-1(b) or
            240.13d-2(b) or (c), check whether the Person Filing is a:

            Not Applicable.
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Item 4.  Ownership

         (a) Amount Beneficially Owned (as of September 15, 2003):     600,000*

         (b) Percent of Class (as of September 15, 2003):                  6.0%*

         (c) Number of Shares as to which the person has:

             (i)  sole power to vote or to direct the vote                  *

             (ii) shared power to vote or to direct the vote                *

            (iii) sole power to dispose or to direct the disposition of     *

             (iv) shared power to dispose or to direct the disposition of   *
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Item 5.  Ownership of Five Percent or Less of a Class

         Not Applicable.




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Item 6.  Ownership of More Than Five Percent on Behalf of Another Person

         Not Applicable.*
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Item 7.  Identification  and  Classification  of the  Subsidiary Which  Acquired
         the Security Being Reported on by the Parent Holding Company or Control
         Person

         Not Applicable.
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Item 8.  Identification and Classification of Members of the Group

         Not Applicable.
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Item 9.  Notice of Dissolution of Group

         Not Applicable.


Item 10.  Certification

          By signing  below I certify  that, to the  best  of  my knowledge  and
belief, the  securities  referred  to above were not  acquired  and are not held
for the purpose of or with the effect of changing  or  influencing  the  control
of  the  issuer  of  the  securities and  were  not acquired and are not held in
connection  with or  as  a participant in any transaction having that purpose or
effect.

- -----------
* Brown  Simpson Asset  Management,  LLC, a New York limited  liability  company
("BSAM"),  serves as investment manager for each of Xmark Fund, L.P., a Delaware
limited  partnership  ("Xmark  LP"),  and Xmark  Fund,  Ltd.,  a Cayman  Islands
exempted  company ("Xmark Ltd").  In such capacity,  BSAM possesses the power to
vote and direct the  disposition  of all  securities  held by Xmark LP and Xmark
Ltd.  Xmark LP is the holder of (i)  108,500  shares  (the  "Xmark LP  Preferred
Shares") of Series A Convertible Preferred Stock, par value $0.01 per share (the
"Series A Preferred"),  of Sontra Medical Corporation,  a Minnesota  corporation
(the "Company"),  which, subject to certain restrictions  contained therein, may
be converted into Common Stock,  par value $0.01 per share (the "Common Stock"),
of the Company, at a conversion price of $1.00 per share, which conversion price
is  subject  to  adjustment  as set forth in the  Series A  Preferred,  and (ii)
warrants  (the  "Xmark LP  Warrants")  which,  subject to  certain  restrictions
contained  therein,  entitle  Xmark LP to purchase up to an aggregate of 108,500
shares of Common Stock at an exercise  price of $1.50 per share,  which exercise
price is subject to adjustment as set forth in the Xmark LP Warrants.  Xmark Ltd
is the  holder of (i)  191,500  shares of Series A  Preferred  (the  "Xmark  Ltd
Preferred  Shares,"  and  together  with the  Xmark  LP  Preferred  Shares,  the
"Preferred Shares"),  which, subject to certain restrictions  contained therein,
may be converted  into Common Stock,  at a conversion  price of $1.00 per share,
which  conversion  price is subject to  adjustment  as set forth in the Series A
Preferred,  and (ii) warrants (the "Xmark Ltd  Warrants,"  and together with the
Xmark LP  Warrants,  the  "Warrants")  which,  subject to  certain  restrictions
contained  therein,  entitle Xmark Ltd to purchase an aggregate of up to 191,500
shares of Common Stock at an exercise  price of $1.50 per share,  which exercise
price is  subject  to  adjustment  as set forth in the Xmark Ltd  Warrants.  The
Preferred  Shares and the  Warrants  provide that the  Preferred  Shares are not
convertible  and the  Warrants are not  exercisable  prior to the receipt by the
Company of  shareholder  approval of the  issuance of the Common  Stock upon the
conversion  of the Preferred  Shares and upon the exercise of the  Warrants,  as
required by NASDAQ Marketplace Rule 4350 (the "NASDAQ Approval"). As of the date
hereof,  the NASDAQ  Approval has not been  obtained.  However,  the Company has
scheduled a shareholders'  meeting for September 30, 2003. Thus, as of September
15, 2003,  for the  purposes of Reg.  Section  240.13d-3,  BSAM may be deemed to
beneficially  own 600,000  shares of Common  Stock,  or 6.0% of the Common Stock
deemed issued and outstanding as of that date.



                                    SIGNATURE

          After reasonable inquiry and to the best of my  knowledge  and belief,
I certify that the information set forth in this statement is true, complete and
correct.


                                            September 25, 2003


                                            BROWN SIMPSON ASSET MANAGEMENT, LLC


                                            /s/ Mitchell D. Kaye
                                            ------------------------------------
                                            Mitchell D. Kaye, Manager


      Attention: Intentional misstatements or omissions of fact constitute
                Federal criminal violations (See 18 U.S.C. 1001)