[Transvaginal echography. An application in the diagnosis of cervical incompetence]

It has already been demonstrated that abdominal ultrasound is an adequate method for measuring the cervix in pregnancy. The use of the vaginal route for such measurement is new. We have been using for the vaginal approach an ultrasound transducer of 5 mHZ with an angle of sweep of 240 degrees. The study was carried out on 23 pregnant women at the 28th week of pregnancy who had been admitted because of threatened premature labour with possible cervical incompetence; and on 20 cases of normal pregnancy also at the 28th week, which is the time when we do glucose estimations normally in our antenatal clinics. The result of our work shows that this ultrasonic method through the vagina gives us much more accurate measurements of the cervix than digital vaginal examination does. A mean difference of 12.3 mm in the length of the cervix was found in normal pregnancies (46.3 mm) and in cases where there was a question of cervical incompetence (34 mm). Furthermore the phenomena of shortening, dilatation of the cervix and a funnel-shape of the internal os are ultrasound signs of value in diagnosing incompetent cervix. Further advantages of the transvaginal approach are that there is no need for the bladder to be filled previously, and that the organs are nearer which improves the ultrasound picture. All the same, it is to be emphasized that transvaginal ultrasound can only be a factor to be added to clinical examination in the diagnosis of the incompetent cervix.