Published online by Cambridge University Press: 04 August 2010
Ultrasound is an essential diagnostic tool in gynecologic and obstetric practice and is of special importance for management of infertile patients. With the advancement of ultrasound technology and ultrasound machines and with introduction of 3D technology as well, detailed examination of the uterine cervix, anatomy, and accurate measurements have become possible (1). This has broadened the uses of sonographic examination in infertile patients as well as in pregnancy, mainly due to the importance of uterine cervix examination for prediction of preterm labor (2).
MORPHOLOGY OF THE UTERINE CERVIX
The cervix is the cylindrical portion of the uterus, which enters the vagina and lies at right angles to it. It measures 2–4 cm in length. The point of junction to the uterus is called the isthmus. Branches of the uterine arteries are situated lateral to the cervix and can be seen by color Doppler at transvaginal ultrasound (3).
By transvaginal ultrasound, the cervix is seen in the sagittal plane as a cylindrical, moderately echogenic structure with a central canal (Figure 16.1). The internal os is better identified during pregnancy. The cervical mucus is more prominent during pregnancy, facilitating the recognition of the cervical canal (Figure 16.2). The cervical gland area is an area surrounding the cervical canal, which is either hypo- or hyperechoic; its absence has been related to preterm labor (4–6).