INTRODUCTION
Preterm birth (PTB) is a major cause of neonatal morbidity and mortality, affecting 10% of births worldwide 1, 2. Long-term pulmonary or neurodevelopmental disabilities and the mortality risk of prematurity extend beyond the neonatal ICU, even into childhood and adolescence 3-5. The majority of births before term are spontaneous due to preterm labor (PTL), preterm prelabor rupture of membranes (PPROM), and cervical insufficiency, but the etiology is often unknown 6. Shortened cervical length (CL) is the target of several preventative interventions, such as progesterone supplementation and cervical cerclage, both of which have been shown to reduce PTB risk 7, 8. However, sonographic CL has variable sensitivity for screening, and its predictive value in the general obstetric population remains suboptimal7, 9, 10. The character of the cervical canal itself, specifically the cervical gland area (CGA), has been proposed as another useful reflection of cervical function 11-13.
The CGA is a hyper- or hypoechoic zone lining the cervical canal, distinct in echotexture from the cervical stroma, and corresponds to the histologic endocervical crypts (Figure 1) 14. This glandular tissue is responsible for maintaining the collagen, elastin, and proteoglycans that help impart the firm cervical consistency necessary to sustain a pregnancy, as well as producing endocervical mucus to help prevent ascending genital infections15-17. Normal and preterm cervical ripening is thought to be related to collagenolysis and changes in cervical water content that disrupt the structural integrity of these glands, resulting in softening, effacement, and insufficiency. The collagenolysis involved in cervical ripening may correspond to loss of a sonographically detectable CGA 12, 18, 19. However, CGA is not a widely known marker of cervical integrity in clinical practice. Exploring a relationship between the CGA, CL, and PTB could potentially facilitate beneficial interventions. The objective of our study is to sonographically characterize the CGA and determine if its evaluation at the time of routine CL screening can be useful for PTB prediction.