Quantitative strain elastography of the uterine cervix assessed by the GE Voluson E10 system in combination with a force-measuring device.

OBJECTIVE: During pregnancy, the stiffness of the cervical tissue decreases long before the cervical length decreases. Therefore, several approaches have been proposed in order to ensure a more objective assessment of cervical stiffness than that achieved by digital evaluation. Strain elastography has shown promising results. This technique is based on an ultrasound assessment of the tissue deformation that occurs when the examiner applies pressure on the tissue with the ultrasound probe. However, the results are only semi-quantitative as they depend on the unmeasured force used by the examiner. We, therefore, hypothesized that a force-measuring device applied to the handle of the ultrasound probe may render the technique quantitative. With this approach, the stiffness is the force (measured by the device) divided by the compression (measured by the elastography platform). One perspective is the early identification of women at risk of preterm birth in whom cervical stiffness may decrease long before cervical shortening. Another perspective is cervical evaluation when planning labor induction. In this feasibility study, we aimed to evaluate how quantitative strain elastography performs when a commercially available strain elastography platform (by which the algorithm is unavailable) is combined with a custom-made, force-measuring device. We studied how the assessments were associated with the gestational age in women with uncomplicated pregnancies and how they were associated with cervical dilatation time from 4 to 10 cm in women undergoing labor induction. METHODS: In the analysis, we included quantitative strain elastography assessments from 47 women with uncomplicated singleton pregnancies, with gestational age between 12+0 and 40+0, and from 27 singleton term-pregnant women undergoing labor induction. The force-measuring device was mounted on the handle of a transvaginal probe. The strain values (i.e. the compression of the cervical tissue) were obtained by the elastography software of the ultrasound scanner (GE Voluson E10). The region of interest was placed within the central part of the anterior cervical lip. Based on the force data and strain values, we calculated the outcomes cervical elastography indexGE (CEIGE) and the cervical strength indexGE (CEIGE x cervical length: CSIGE). RESULTS: The average CEIGE was 0.24 N at week 12 and 0.15 N at week 30-34. For CSIGE these figures were 8.2 and 4.7 N mm, respectively (p = 0.002). Among women undergoing labor induction, the CEIGE was associated with a cervical dilatation time (4-10 cm) beyond 7 h. For nulliparous women, this area under the ROC curve was 0.94. CONCLUSION: Quantitative strain elastography may constitute a tool for the evaluation of a uterine cervix with normal length in women at risk of preterm birth and in women undergoing labor induction. The performance of this tool deserves evaluation in larger clinical trials.

Seasonal variation in the hypertensive disorders of pregnancy in Denmark.

INTRODUCTION: Hypertensive disorders of pregnancy, including gestational hypertension and preeclampsia, are leading causes of morbidity and mortality for both mother and fetus. It has been proposed that vitamin D affects a number of biological processes involved in the pathogenesis of hypertensive disorders of pregnancy. Therefore, a seasonal variation in the risk of these disorders might be expected in areas such as Denmark with marked seasonal variation in sunlight exposure. In this study, we aimed to evaluate the existence of this association. MATERIAL AND METHODS: We used information from a cohort of 50 665 previously healthy, nulliparous women with singleton pregnancies. All women gave birth between 1989 and 2010 at Aarhus University Hospital, Denmark. Logistic regression analyses combined with the cubic spline method were used to estimate the seasonal variation for each outcome: gestational hypertension and preeclampsia, after adjusting for calendar time. RESULTS: Of the 50 665 women included, 8.5% were diagnosed with a hypertensive disorder of pregnancy. The overall tendency was towards increasing risk when conceiving during spring and early summer, peaking midsummer, and subsequently decreasing steadily during late summer and fall to reach the nadir by winter. Seasonal variation was found for; gestational hypertension (P = .01); preeclampsia (P = .001) and early-onset preeclampsia (P = .014). CONCLUSIONS: We found a seasonal variation in the risk of the hypertensive disorders of pregnancy in a large cohort of Danish nulliparous women. The highest risk was seen in women with the estimated date of conception in June and August, that is, during summer. Seasonal variation in vitamin D status may explain this association.

Seasonal variation of dystocia in a large Danish cohort.

BACKGROUND: Dystocia is one of the most frequent causes of cesarean delivery in nulliparous women. Despite this, its causes are largely unknown. Vitamin D receptor (VDR) has been found in the myometrium. Thus, it is possible that vitamin D affects the contractility of the myometrium and may be involved in the pathogenesis of dystocia. Seasonal variation of dystocia in areas with distinct seasonal variation in sunlight exposure, like Denmark, could imply that vitamin D may play a role. This study examined whether there was seasonal variation in the incidence of dystocia in a Danish population. METHOD: We used information from a cohort of 34,261 nulliparous women with singleton pregnancies, spontaneous onset of labor between 37 and 42 completed gestational weeks, and vertex fetal presentation. All women gave birth between 1992 and 2010 at the Department of Obstetrics and Gynecology, Aarhus University Hospital, Skejby. Logistic regression combined with cubic spline was used to estimate the seasonal variation for each outcome after adjusting for calendar time. RESULTS: No evidence for seasonal variation was found for any of the outcomes: acute cesarean delivery due to dystocia (p = 0.44); instrumental vaginal delivery due to dystocia (p = 0.69); oxytocin augmentation due to dystocia (p = 0.46); and overall dystocia (p = 0.91). CONCLUSION: No seasonal variation in the incidence of dystocia was observed in a large cohort of Danish women. This may reflect no association between vitamin D and dystocia, or alternatively that other factors with seasonal variation and influence on the occurrence of dystocia attenuate such an association.