-----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,
 A5WtK/WQUAZYrDDqB+cVSrh3286TL07TJoIZ0k0FK5x+bsbei1wTgSJkvSZI4uex
 Zi8A52CXMV2VfatHIXDTPw==

<SEC-DOCUMENT>0001179110-04-019602.txt : 20041008
<SEC-HEADER>0001179110-04-019602.hdr.sgml : 20041008
<ACCEPTANCE-DATETIME>20041008175027
ACCESSION NUMBER:		0001179110-04-019602
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20041007
FILED AS OF DATE:		20041008
DATE AS OF CHANGE:		20041008

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ESSEX WOODLANDS HEALTH VENTURES FUND IV L P
		CENTRAL INDEX KEY:			0001110080
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-23017
		FILM NUMBER:		041072924

	BUSINESS ADDRESS:	
		STREET 1:		190 S LASALLE ST
		STREET 2:		STE 2800
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60603

	MAIL ADDRESS:	
		STREET 1:		10001 WOODLOCH FOREST DR
		STREET 2:		STE 175
		CITY:			WOODLOCH
		STATE:			TX
		ZIP:			77380

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:		10 FORGE PARKWAY
		CITY:			FRANKLIN
		STATE:			MA
		ZIP:			02038
		BUSINESS PHONE:		508 553-8850

	MAIL ADDRESS:	
		STREET 1:		10 FORGE PARKWAY
		CITY:			FRANKLIN
		STATE:			MA
		ZIP:			02038

	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
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-10-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001110080</rptOwnerCik>
            <rptOwnerName>ESSEX WOODLANDS HEALTH VENTURES FUND IV L P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>10001 WOODLOCH FOREST DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 175</rptOwnerStreet2>
            <rptOwnerCity>THE WOODLANDS</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77380</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-10-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>155343</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1298086</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Partial distribution by reporting person to its partners.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Martin P. Sutter, Managing Director of Essex Woodlands Health Ventures Fund IV, L.L.C., as general partner of the Reporting Person</signatureName>
        <signatureDate>2004-10-08</signatureDate>
    </ownerSignature>
</ownershipDocument>

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