-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 WLhpNM/XfNg56kOLZP0QKpVKiEmTSHchpiVd2bWApL7KmTQXvx9uPIVN/EjYmps4
 o0Xalm4dIDqWKBrofgflNQ==

<SEC-DOCUMENT>0001239724-03-000008.txt : 20030916
<SEC-HEADER>0001239724-03-000008.hdr.sgml : 20030916
<ACCEPTANCE-DATETIME>20030916132830
ACCESSION NUMBER:		0001239724-03-000008
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030915
FILED AS OF DATE:		20030916

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SONTRA MEDICAL CORP
		CENTRAL INDEX KEY:			0001031927
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTROMEDICAL & ELECTROTHERAPEUTIC APPARATUS [3845]
		IRS NUMBER:				411649949
		STATE OF INCORPORATION:			MN
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		58 CHARLES STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02141
		BUSINESS PHONE:		6174945337

	MAIL ADDRESS:	
		STREET 1:		58 CHARLES STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02141

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	CHOICETEL COMMUNICATIONS INC/MN/
		DATE OF NAME CHANGE:	20020701

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	SONTRA MEDICAL CORP
		DATE OF NAME CHANGE:	20020701

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	CHOICETEL COMMUNICATIONS INC /MN/
		DATE OF NAME CHANGE:	19970625

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			KOHLER GARY S
		CENTRAL INDEX KEY:			0001045714

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-23017
		FILM NUMBER:		03897232

	BUSINESS ADDRESS:	
		STREET 1:		3033 EXCELSIOR BLVD.
		STREET 2:		SUITE 300
		CITY:			MINNEAPOLIS
		STATE:			MN
		ZIP:			55416
		BUSINESS PHONE:		612-253-6027

	MAIL ADDRESS:	
		STREET 1:		3033 EXCELSIOR BLVD.
		STREET 2:		SUITE 300
		CITY:			MINNEAPOLIS
		STATE:			MN
		ZIP:			55416
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>

<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2003-09-15</periodOfReport>


    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001031927</issuerCik>
        <issuerName>SONTRA MEDICAL CORP</issuerName>
        <issuerTradingSymbol>sontc</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001045714</rptOwnerCik>
            <rptOwnerName>KOHLER GARY S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3033 EXCELSIOR BLVD.</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 300</rptOwnerStreet2>
            <rptOwnerCity>MINNEAPOLIS</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55416</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>

        <derivativeTransaction>
            <securityTitle>
                <value>Series A Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2003-09-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>33334</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2003-09-15</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>33334</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>33334</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>

        <derivativeTransaction>
            <securityTitle>
                <value>Common Stock Purchase Warrants(right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.5</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2003-09-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>33334</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2003-09-15</value>
            </exerciseDate>
            <expirationDate>
                <value>2008-09-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>33334</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>33334</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>

    </derivativeTable>

    <footnotes>
        <footnote id="F1">The shares of the Series A Convertible Preferred Stock are not convertible until the Company obtains shareholder approval.</footnote>
        <footnote id="F2">There is no expiration date.</footnote>
        <footnote id="F3">The Common Stock Purchase Warrants are not exercisable until the Company obtains shareholder approval.</footnote>
    </footnotes>


    <ownerSignature>
        <signatureName>/s/ Sean F. Moran</signatureName>
        <signatureDate>2003-09-16</signatureDate>
    </ownerSignature>

</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----