Hyunjung Kim, Han Sung Hwang
Department of Obstetrics and Gynecology, Research Institute of Medical Science, Konkuk University School of Medicine, Seoul, Korea

The cervix is a cylindrical structure that is proximally connected to the uterus and distally to the vaginal cavity. The Bishop score has been used to evaluate the cervix during pregnancy. However, alternatives have been evaluated because the Bishop score is uncomfortable for patients, relies on a subjective examination, and lacks internal os data. Elastography has been used to assess the cervix, as it can estimate tissue stiffness. Recent articles on elastography for cervical assessment during pregnancy have focused on its usefulness for prediction of preterm birth and successful labor induction. There is a clinical need for cervical elastography, as an evaluation of biomechanical factors, because cervical length only assesses morphological changes. However, until now, cervical elastography has been studied in the limited fi and not shown a uniformed methodological technique. In this review, the current status, limitations, and future possibility of cervical elastography were discussed. Future studies should focus on overcoming the limitations of cervical elastography. Although the cervical elastography is presently an incompletely defi technique, it needs to be improved and evaluated as a method for use in combination with cervical length.

Keywords: Cervix uteri; Elastography; Labor induction; Premature birth

Introduction

The cervix is a cylindrical structure that is proximally con- nected to the uterus and distally to the vaginal cavity. The cervix is composed of fi ous connective tissue and the uterus is composed mainly of smooth muscle, and they are therefore distinct organs [1]. The cervix can change significantly over a short time period. It is a closed, fi structure during early pregnancy, and undergoes softening later in pregnancy. Cervi- cal effacement and dilatation are active, dynamic processes, and adequate effacement allows passage of the fetus and enables successful delivery [2]. Cervical integrity is essential in pregnancy. Preterm cervical dilatation may predict preterm de- livery. On the other hand, a cervix that remains fi after term may increase induction or cesarean section rates [3].
Traditionally, the Bishop score has been used to evaluate the cervix during pregnancy. It assesses cervical status based on dilatation, effacement, consistency, fetal head station, and position [4]. However, alternatives have been evaluated be- cause the Bishop score is uncomfortable for patients, relies on a subjective examination, and lacks internal os data. Cervical elastography is one of the alternatives. Elastography was fi introduced about 20 years ago as an adjunct to routine so- nography [5]. Since then, elastography has been used for the diagnosis and characterization of various tumors or cancers in the breast, prostate, and thyroid gland [6,7]. Recently, elas- tography has been used to assess the cervix, as it can estimate tissue stiffness. This article reviews the use of elastography to assess the cervix during pregnancy, in order to clarify its cur- rent status, limitations, and need for further research.

Received: 2016.9.12. Revised: 2016.10.13. Accepted: 2016.10.18. Corresponding author: Han Sung Hwang
Department of Obstetrics and Gynecology, Konkuk University School of Medicine, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea
Tel: +82-2-2030-7747 Fax: +82-2-2030-7748