Ultrasound assessment of the cervix.

Ultrasound of the Cervix—Techniques Initial attempts at evaluating the cervix used transabdominal ultrasound (TAU). Unfortunately, this technique was found to be imperfect, because of (1) fetal parts obscuring the cervix, especially after 20 weeks, (2) the requirement of bladder filling, which can elongate the cervix and mask funneling, and (3) long distance from the probe to the cervix. Translabial (also known as transperineal) ultrasound, first used in France in the early 1980s, proved to be more useful. This technique involves having the patient lie on table with the hips and knees flexed, while a gloved transducer is positioned on the perineum in a sagittal orientation between the patient’s labia majora. Elevation of the patient’s hips with a cushion is sometimes used to improve visualization. Compared with TAU, this technique is not impaired by obstruction by fetal parts, and does not require bladder filling, achieving close to 100% visualization. Other advantages of this technique are that the transducer is closer to the cervix, but does not enter the vagina (so no pressure can be exerted on the cervix), it Correspondence: Vincenzo Berghella, MD, Division of Maternal–Fetal Medicine, Department of Obstetrics and Gynecology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania. E-mail:[email protected] CLINICAL OBSTETRICS AND GYNECOLOGY Volume 46, Number 4, 947–962 © 2003, Lippincott Williams & Wilkins, Inc.