Use of shear wave elastography on the maternal cervix to recognise cervical insufficiency using a transabdominal ultrasound approach.

INTRODUCTION: The ramifications of preterm birth on society and the role of cervical length in identifying cervical insufficiency are well known. The main goal of this work was to apply shear wave elastography to the maternal cervix to assess the stiffness of the cervix and identify cervical insufficiency, using a transabdominal ultrasound approach. METHODS: Measurements of shear wave speed were obtained using a transabdominal ultrasound approach, at the anterior and posterior portions of the internal and external cervical os on 504 participants. A total of 455 participants were contacted following the expected date of birth of the fetus and birth details were obtained. RESULTS: The anterior and posterior portions of the internal os showed a significant correlation between shear wave speed and time until delivery of the fetus for women who gave birth spontaneously, with R 2 Linear being 0.024 (P = 0.012) and 0.017 (P = 0.05) respectively, and these correlations increased for the group of participants that were scanned between the 18th and end of the 20th week of pregnancy to R 2 Linear = 0.043 (P = 0.001) and 0.021 (P = 0.040) respectively. A ratio of internal os/external os anteriorly also showed a correlation of R 2 Linear = 0.030 (P = 0.009). CONCLUSION: A transabdominal ultrasound technique has identified a reduction in shear wave speeds at the internal os in the mid-trimester, in women who had a subsequent preterm birth.

Shear Wave Elastography of the Maternal Cervix: A Comparison of Transvaginal and Transabdominal Ultrasound Approaches.

OBJECTIVES: This work aimed to compare the use of shear wave elastography on the maternal cervix with transvaginal (TV) and transabdominal (TA) ultrasound approaches to assess differences in shear wave speeds (SWSs) obtained for possible clinical use. METHODS: In both TV and TA ultrasound approaches, SWS measurements were attempted at the anterior and posterior portions of the internal and external cervical os on 38 gravid participants. RESULTS: A larger number of SWS measurements were obtained at the anterior portion of the cervix by both approaches. The numbers of reliable measurements of the SWS obtained at the anterior and posterior portions of the internal and external os were 99, 65, 103, and 77 in the TA approach and 93, 53, 110, and 87 in the TV approach, respectively. The mean difference in -the SWS obtained between the TV and TA ultrasound approaches was statistically significant at the anterior and posterior portions of the internal os, with differences of 0.67 and 0.52 m/s (P < .05). Differences were not significant at the external os both anteriorly and posteriorly, with differences of 0.15 and - 0.07 m/s (P > .05). CONCLUSIONS: Both TA and TV ultrasound approaches may be used to obtain SWSs in the maternal cervix. This study has shown that SWSs obtained by each approach need to be considered independently, as the TV approach produced significantly greater SWSs at the internal os compared to the TA approach, but the values were similar at the external os.

Reliability Indicators for 2-Dimensional Shear Wave Elastography.

Ultrasound (US) shear wave technology providers have either point shear wave elastography (SWE) or 2-dimensional SWE available on their US systems. With 2-dimensional SWE, larger regions of interest can be interrogated, with both the main acoustic radiation pulses and the resultant shear waves potentially being affected by US artifacts. Some providers assist the operator with elastographic maps indicating the reliability or precision of the shear wave propagation. This Technical Innovation explores the importance of the consideration of the precision maps and standard deviation output available on some devices and the implications for conversion of shear wave speed to pressure.

Shear wave elastography of the maternal cervix: A transabdominal technique.

INTRODUCTION: Reduced cervical length as seen on transvaginal ultrasound is a strong indicator of spontaneous preterm birth in the high-risk population. In low-risk women the appropriate method to assess this risk is still debatable. Ultrasound elastography has been used to assess cervical strength. This research aimed to assess the accuracy of shear wave speeds (SWS) obtained deep to echo free fluid-filled structures, and the use of two-dimensional shear wave on the maternal cervix using a transabdominal ultrasound approach. METHOD: Agreement of SWS measurements obtained through fluid and directly onto an ultrasound phantom was assessed for accuracy. Speed measurements were obtained in the anterior and posterior portions of the internal and external cervical os on 50 gravid participants in the mid-trimester of pregnancy. RESULTS: No difference in SWS was obtained in the phantom with either direct contact or through the saline water-bath (P > 0.05). In 50 participants, measurements were obtainable at the external os anterior and posterior in 49 and 38 participants, respectively, and in 47 and 42 participants for internal os anterior and posterior. The mean speed obtained at the external os anterior and posterior was 2.01 ± 0.51 and 2.38 ± 0.47 m/s, respectively, and at the internal os anterior and posterior, 2.49 ± 0.50 and 2.58 ± 0.41 m/s. CONCLUSION: Shear wave speed measurements can be obtained in the maternal cervix using a transabdominal approach with a moderately full maternal bladder in most patients, with a larger number of shear wave measurements obtained in the anterior cervix compared to posterior.

Shear Wave Elastography on the Uterine Cervix: Technical Development for the Transvaginal Approach.

OBJECTIVES: This research aimed to identify biological and technical confounders in the nonpregnant cervix when applying shear wave elastography with an endovaginal transducer. METHODS: Cervical speed measurements were obtained at the internal and external os in the anterior and posterior portions of the cervix using a transvaginal approach in 69 nongravid patients. RESULTS: Reliable measurements were obtained at the external os and internal os, anteriorly and posteriorly, in 63, 55, 55, and 26 patients, respectively. The mean speed obtained at the external os, anteriorly and posteriorly, was 2.52 ± 0.49 m/s and 2.87 ± 0.63 m/s, respectively, and at the internal os, anteriorly and posteriorly, 3.29 ± 0.79 m/s and 4.10 ± 1.11 m/s, respectively. The difference in speed between all regions was statistically significant (P < .05). CONCLUSION: Ultrasound-induced artifacts appear to affect the transmission of the elastographic main pulse, with cervical position contributing to suboptimal shear wave production in the posterior cervix. Reliable shear wave propagation can be achieved in the anterior cervix in most patients.

A comparison of ultrasonic measurement techniques for the maternal cervix in the second trimester.

Introduction: The appropriate ultrasound technique to assess the maternal cervical length in women at low risk of preterm birth is yet to be established. This study aimed to determine the accuracy of different ultrasound approaches for measuring the maternal cervix in patients between 17 and 22 weeks gestation. Methods: The prospective study recruited 50 patients who were at a low risk of preterm birth. All measurements were acquired by one operator who was blind to the measurements being acquired in all approaches. The cervical length was registered using the transabdominal approach with a full and empty bladder, the transperineal approach and the transvaginal. The transvaginal approach was used as the reference measurement. Results: The transabdominal full bladder, post void, transperineal and transvaginal measurements were obtainable in 50, 49, 45 and 50 participants respectively. The transabdominal post void measurements showed a bias of -0.06 mm from perfect agreement with transvaginal. The transperineal measurements showed a bias of -0.16 mm. The transabdominal full bladder measurements were positively biased by 14.05 mm (p < 0.05). All transabdominal post void cervical lengths of 30 mm or greater registered a transvaginal cervical length greater than 25 mm in this study. Conclusion: The cervix should not be assessed in the transabdominal approach with a full maternal bladder due to overestimation of cervical length. Transvaginal cervical length can be reproduced accurately by post void transabdominal cervical length in most cases. Transperineal cervical length should be considered if transvaginal cervical length is contraindicated.

Cervical length for predicting preterm birth and a comparison of ultrasonic measurement techniques.

Introduction: Preterm birth is the leading cause of neonatal morbidity and mortality not attributable to congenital anomalies or aneuploidy. It has been shown that a shortened cervix is a powerful indicator of preterm births in women with singleton and twin gestations - the shorter the cervical length, the higher the risk of spontaneous preterm birth. Ultrasound measurements of the cervix are a more accurate way of determining cervical length (CL) than using a digital method. Background: There are three approaches that may be used to perform ultrasound measurements of the cervix; these are the transabdominal (TA), transperineal (TP) and the transvaginal (TV) approach. The TV approach is considered to be the gold standard. In women who are considered to be at a high risk of preterm birth it is now recommended that the cervix is measured at the mid-trimester ultrasound using the TV ultrasound approach. For women considered to be at a historical low risk the TV scan is not recommended, however it has been found that many women who deliver a preterm baby have no known risk factors. Conclusion: There is contradictory evidence in the literature with regard to the correlation between TA, TP and TV measurements. This article provides an overview of these three approaches with a focus on the clinical value for the assessment of the maternal cervix.