[Transvaginal ultrasound biometry of crown-rump length in the 1st trimester].

The embryonary crown-rump-length (CRL) in 225 pregnant women between the 6th and 13th week of gestation was measured by the technique of transvaginal sonography. A curve and a rate of growth was determined. The investigation showed that the CRL can already be measured in the 6th week of gestation when using transvaginal sonography, whereas transabdominal sonography makes a CRL measurement in the 7th week possible. A comparison of results and growth rates revealed a deviation up to 12th week of gestation age in both ultrasound methods. The known tabels with embryonary data, obtained by transabdominal technique, should not be used any longer for CRL determination, when prefering the technique of transvaginal sonography.