Sonographic assessment of the cervix before, during and after a uterine contraction is effective in predicting the course of labor

Growth-profile configuration for specific deformations of tubular organs: A study of growth-induced thinning and dilation of the human cervix

Growth is a significant factor that results in deformations of tubular organs, and particular deformations associated with growth enable tubular organs to perform certain physiological functions. Configuring growth profiles that achieve particular deformation patterns is critical for analyzing potential pathological conditions and for developing corresponding clinical treatments for tubular organ dysfunctions. However, deformation-targeted growth is rarely studied. In this article, the human cervix during pregnancy is studied as an example to show how cervical thinning and dilation are generated by growth. An advanced hyperelasticity theory called morphoelasticity is employed to model the deformations, and a growth tensor is used to represent growth in three principle directions. The computational results demonstrate that both negative radial growth and positive circumferential growth facilitate thinning and dilation. Modeling such mixed growth represents an advancement beyond commonly used uniform growth inside tissues to study tubular deformations. The results reveal that complex growth may occur inside tissues to achieve certain tubular deformations. Integration of further biochemical and cellular activities that initiate and mediate such complex growth remains to be explored.

Automatic evaluation of progression angle and fetal head station through intrapartum echographic monitoring

Labor progression is routinely assessed through transvaginal digital inspections, meaning that the clinical decisions taken during the most delicate phase of pregnancy are subjective and scarcely supported by technological devices. In response to such inadequacies, we combined intrapartum echographic acquisitions with advanced tracking algorithms in a new method for noninvasive, quantitative, and automatic monitoring of labor. Aim of this work is the preliminary clinical validation and accuracy evaluation of our automatic algorithm in assessing progression angle (PA) and fetal head station (FHS). A cohort of 10 parturients underwent conventional labor management, with additional translabial echographic examinations after each uterine contraction. PA and FHS were evaluated by our automatic algorithm on the acquired images. Additionally, an experienced clinical sonographer, blinded regarding the algorithm results, quantified on the same acquisitions of the two parameters through manual contouring, which were considered as the standard reference in the evaluation of automatic algorithm and routine method accuracies. The automatic algorithm (mean error ± 2SD) provided a global accuracy of 0.9 ± 4.0 mm for FHS and 4° ± 9° for PA, which is far above the diagnostic ability shown by the routine method, and therefore it resulted in a reliable method for earlier identification of abnormal labor patterns in support of clinical decisions.

Uterine contractions in asymptomatic pregnant women with a short cervix on ultrasound

OBJECTIVE

To estimate the incidence of uterine contractions in asymptomatic pregnant women with a short cervix on transvaginal ultrasound.

METHODS

Asymptomatic women with a short cervix on transvaginal ultrasound between 14 and 23(6/7) weeks of pregnancy were instructed to undergo uterine monitoring immediately. Women without available tracings were excluded. Women with and without contractions were compared with regard to demographics, risk factors, and outcomes.

RESULTS

One hundred and one women with a short cervix and available tracings were identified. Eighty-six (85%) had contractions and 15 (15%) did not have contractions immediately after identification of the short cervix. The median number of contractions per hour per woman was 4 (range 0-31). These two groups did not differ in demographics, risk factors, or outcomes, except for the fact that 33% of women with contractions versus 73% of women without uterine contractions had a prior second trimester loss (p = 0.004).

CONCLUSIONS

In this study, 85% percent of pregnant women with a short cervix on transvaginal ultrasound between 14 and 24 weeks of pregnancy are having asymptomatic uterine contractions. This information is important for further investigation of the short cervix and preterm delivery.

Cervical diameter in relation to uterine and cervical EMG activity in early postpartum dairy cows with retained placentas after PGF2alpha induced calving

The cervix must regain its normal diameter after parturition. Until now, little has been known about the pattern of cervical closure and the possible influences of myometrial and cervical contractions in this process. We continuously measured the cervical diameter with ultrasound cervimetry during the first 48h after calving in six cows with retained fetal membranes, while uterine (n=6) and cervical outer muscular layer (n=4) electromyographic (EMG) activity was measured with bipolar EMG electrodes. We found that the cervical diameter which was 6.2cm (+/-0.7) at 1.4h after calving, initially increased to 9.0cm (+/-1.0) during the first 14.8h (+/-2.8) postpartum. After this time, the diameter decreased gradually to 5.3cm (+/-1.0) at 48h after calving. The overall EMG activity after parturition decreased by 59% (+/-6) and 35% (+/-17) for the uterus and cervix, respectively. The decrease in EMG activity was due to a 50% (+/-7) decrease in EMG amplitudes of the myometrium; the EMG amplitudes of the cervix decreased by only 8% (+/-21) (P>0.05). At the same time in the cervix, burst frequency decreased by 69% (+/-17), while the decrease in burst frequency of the myometrium was only 11% (+/-5) (P>0.05). Uterine myometrial and cervical EMG activity after parturition showed burst patterns. These contractions of the uterus and cervix were accompanied by and correlated with transient dilatations of the caudal cervix. This could have functional relevance in the evacuation of the uterus.

EMG activity of the muscular and stromal layer of the cervix in relation to EMG activity of the myometrium and cervical dilatation in PGF2α induced parturition in the cow

The goal of this study was to quantify and characterize the electromyographic (EMG) activities in the cervical outer muscular layer and in the cervical stromal layer, and to characterize their relationship with myometrial EMG activity and cervical dilatation during PGF2alpha-induced parturition in term pregnant cows. We continuously measured the EMG activity of the uterine myometrium and cervical outer muscular layer as well as the cervical stromal layer in five cows using bipolar electrodes while at the same time measuring changes in the cervical diameter with ultrasound cervimetry. This we did from the moment a prostaglandin analogue was injected until the expulsion of the calf. In contrast to the cervical stromal layer, the cervical outer muscular layer showed distinct EMG activity, which began to increase at about the same time as the EMG activity of the myometrium, i.e. some 12 h before the start of cervical dilatation. However, the rate of this increase was lower than in the myometrium and it was not characterized, like in the myometrium, by an increase in maximum EMG amplitude. Although the cervical outer muscular layer showed contracture and contraction like EMG activity in unison with in the myometrium, it was also characterized by a more irregular EMG activity, which occurred independently from the myometrium. These data suggest that while the outer muscular layer of the cervix may be considered to be a caudal continuation of the myometrium, it also displays activity independently from the myometrium. The physiological relevance of this activity remains to be explored.

Prediction of labor and delivery by transperineal ultrasound in pregnancies with prelabor rupture of membranes at term

OBJECTIVE

To evaluate whether engagement of the fetal head or cervical length in women with premature rupture of membranes (PROM) at term, are associated with time from PROM to delivery or need for operative delivery.

METHODS

A transperineal ultrasound examination was performed in 152 women with a single live fetus in cephalic presentation after PROM (at > 37 gestational weeks). The shortest distance from the outer bony limit of the fetal skull to the skin surface of the perineum was measured in a transverse view, and the cervical length was measured in a sagittal view. The time from PROM to delivery was tested in a Cox regression analysis with ultrasound measurements, parity, maternal age, body mass index and birth weight as possible predictive factors.

RESULTS

The head-perineal distance was associated with the time from PROM to delivery (log rank test, P < 0.001). Thirty-six hours after PROM, 32% (95% CI, 15-49) of women with a short head-perineal distance (< 45 mm) and 43% (95% CI, 24-62) of women with a long distance (> or = 45 mm) were still in labor. Women with a short head-perineal distance had fewer Cesarean sections, less use of epidural analgesia and a shorter time in active labor, and their babies had a higher pH in the umbilical artery. The measured cervical length was not associated independently with time to delivery.

CONCLUSION

Transperineal ultrasound measurements of fetal head engagement may help clinicians to predict the course of labor in women with PROM.

Cervical Sonography in Women with Symptoms of Preterm Labor

In the last few years, ultrasound of the cervix during pregnancy has been the focus of much research. Significant advances have been made in its technique and in understanding the proper role of this procedure in several clinical settings. This article reviews the evidence for the clinical role of transvaginal cervical assessment in women with symptoms of preterm labor.

Abnormalities of the First and Second Stages of Labor

Abnormalities of the first and second stages of labor refer for the most part to abnormal progression of labor. This article discusses the risk factors, diagnoses, management options, and outcomes of the various categories of labor abnormalities, and provides an evidence-based approach where one exists. The article concentrates on the term, healthy woman carrying a singleton, vertex, normally grown fetus with no anomalies.

Dynamic cervical change during real-time ultrasound: prospective characterization and comparison in patients with and without symptoms of preterm labor

OBJECTIVES

To compare the incidence of dynamic cervical change (spontaneous real-time cervical shortening) in singleton patients with and without symptoms of preterm labor (PTL).

METHODS

A total of 109 patients between 23 and 34 weeks' gestation with and without PTL symptoms underwent cervical length ultrasound and contraction monitoring over a 10-min period. Cervical length measurements were taken at 1-min intervals. Exclusion criteria included ruptured membranes, dilation > 3 cm or cerclage. Following the examination, the sonographer made a subjective assessment as to whether noticeable dynamic cervical change had occurred. A measurement was then made during the application of fundal pressure. The initial cervical length, shortest length, maximum change in length and incidence of dynamic change were compared between patients with and without PTL symptoms. The shortest cervical length was compared to the presence and timing of uterine contractions and the measurement during the application of fundal pressure.

RESULTS

A total of 43 asymptomatic patients and 66 symptomatic patients were studied. Compared to asymptomatic patients, patients with PTL symptoms had shorter initial lengths, nadir lengths and mean lengths over time as well as a greater amount of maximum change. Dynamic cervical change was more frequently seen in symptomatic patients (48% vs. 9%, P < 0.001) and was associated with uterine contractions (odds ratio 4.6, 95% CI 1.9-10.8). Fundal pressure was not able to reproduce the shortest cervical length that occurred spontaneously during the observation period.

CONCLUSIONS

Dynamic cervical change (real-time cervical shortening) is common in patients with PTL symptoms and is associated with uterine contractions. Whether this finding enhances the ability to predict preterm delivery remains to be elucidated.