Original Article Transvaginal grey scale histogram of the cervix at 20–25 weeks of pregnancy Marcio R. FURTADO, Claudio R. PIRES, Edward ARAUJO JU ´ NIOR , Eduardo de SOUZA, Luciano M.M. NARDOZZA and Antonio F. MORON Department of Obstetrics, São Paulo Federal University (UNIFESP), São Paulo, SP, Brazil Aim: To assess the echogenicity of the cervical stroma and area surrounding the cervical canal (cervical gland area – CGA) using grey scale histogram (GSH) in pregnancies between 20 and 25 weeks. Methods: Cross-sectional study involving 149 pregnancies in the second trimester. Transvaginal sonography was performed to measure cervical length (biometric evaluation), assess the CGA and detect cervical funnelling (morphologic evaluation). The GSH was used for the objective assessment of the cervical stroma and CGA in the mid portion of the cervix. Mean, minimum, maximum and standard deviation measurements were obtained on the GSH and the CGA ⁄ stroma ratio was calculated. Intra-observer and inter-observer reproducibility were assessed using the intraclass correlation coefficient (ICC). Results: Mean cervical length was 42.37 ± 7.05 mm (range 12–54 mm). Funnelling was detected in four women (2.7%) and one of these also had absent CGA. The mean GSH stroma value was 103 ± 25 (53–160) and the mean CGA value was 64.5 ± 23 (13–167). The mean CGA ⁄ stroma ratio was 0.62 ± 0.14 (0.24–1.29). Intra- and inter-observer reproducibility was excellent with ICC of 0.975 and 0.922 respectively. Conclusion: There are large differences in the texture of the cervical stroma and CGA on GSH allowing the objective differentiation of the two areas. The CGA ⁄ stroma ratio allows the objective assessment of the absence or presence of the CGA. Key words: cervix, histogram, pregnancy, transvaginal ultrasonography. Introduction Pre-term birth (PTB), delivery before the 37th week of pregnancy, is one of the main causes of perinatal mortality and is responsible for major immediate and long-term morbidity among survivors. 1–3 Most authors doing research in the area of PTB distinguish between early and late PTB with the objective of selecting the high-risk pre-term infants. A common cut-off used is birth before 32 or 34 weeks. In group with spontaneous PTB, 15% will have a previous history of PTB and 85% will have an unremarkable history and therefore warrants our endeavour to find effective screening programmes for all pregnant women. Prediction of PTB would allow the identification of women at risk for this outcome and therefore offer the possibility of prophylactic interventions. Transvaginal ultrasonography (TVUS) is an efficient and highly reliable method of assessing cervical biometry and morphology during pregnancy. Despite some controversies regarding cutoffs, many studies indicate that women with cervical lengths below 15–35 mm are at increased risk for spontaneous PTB. 4,5 The current publications with large samples indicate cutoff values to the cervical length where the risk increases exponentially: 15 mm for singletons and 25 mm for multiple pregnancies. 6 Cervical funnelling, dilation of the internal cervical os, is a morphological marker of PTB, but there are controversies on the utility of this sign in the prediction of spontaneous PTB. 7,8 The cervical gland area (CGA), another sonographic morphological marker, was first described on TVUS by Sekiya et al. 9 in 1998 as the sonographically hyperechoic or hypoechoic zone surrounding the cervical canal, which probably corresponds to the histological CGA. Subsequent studies confirmed that non-detection (absence) of the CGA on vaginal ultrasound could be a predictive sign of spontaneous PTB. 10–12 The grey scale histogram (GSH) is a graphic representation of the quantity, reflexivity and disposition of the ‘pixels’ in a specific area of interest selected on two- dimensional ultrasound. As the GSH is not affected by depth or gain and is not attenuated by maternal weight, this method allows an objective evaluation of any area of interest, with little intra-observer error. 13,14 One of the main concerns regarding the assessment of CGA is that it is a subjective sonographic maker. The objective differentiation between the echogenicity of the cervical stroma and glandular areas has not yet been described until now. The GSH could reduce Correspondence: Professor Edward Araujo Júnior, Rua Carlos Weber, 950 apto. 113 Visage, Alto da Lapa, CEP 05303-000, São Paulo – SP, Brazil. Email: araujojred@terra.com.br Received 16 September 2009; accepted 21 May 2010. 444 Ó 2010 The Authors Australian and New Zealand Journal of Obstetrics and Gynaecology Ó 2010 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists Australian and New Zealand Journal of Obstetrics and Gynaecology 2010; 50: 444–449 DOI: 10.1111/j.1479-828X.2010.01202.x Te Australian and New Zealand Journal of Obstetrics and Gynaecology