Reference data representative of normal findings at three-dimensional power Doppler ultrasound examination of the cervix from 17 to 41 gestational weeks

Maternal risk associated with the VACTERL association: A case-control study

Background

The VACTERL association (VACTERL) includes at least three of these congenital anomalies: vertebral, anal, cardiac, trachea‐esophageal, renal, and limb anomalies. Assisted reproductive techniques (ART), pregestational diabetes mellitus, and chronic lower obstructive pulmonary disorders (CLOPD) have been associated with VACTERL. We aimed to replicate these findings and were interested in additional maternal risk factors.

Methods

A case–control study using self‐administered questionnaires was performed including 142 VACTERL cases and 2,135 population‐based healthy controls. Multivariable logistic regression analyses were performed to estimate confounder adjusted odds ratios (aOR) and 95% confidence intervals (95%CI).

Results

Parents who used invasive ART had an increased risk of VACTERL in offspring (aOR 4.4 [95%CI 2.1–8.8]), whereas the increased risk for mothers with CLOPD could not be replicated. None of the case mothers had pregestational diabetes mellitus. Primiparity (1.5 [1.1–2.1]) and maternal pregestational overweight and obesity (1.8 [1.2–2.8] and 1.8 [1.0–3.4]) were associated with VACTERL. Consistent folic acid supplement use during the advised periconceptional period may reduce the risk of VACTERL (0.5 [0.3–1.0]). Maternal smoking resulted in an almost twofold increased risk of VACTERL.

Conclusion

We identified invasive ART, primiparity, pregestational overweight and obesity, lack of folic acid supplement use, and smoking as risk factors for VACTERL.

Women's Obstetric History and Midtrimester Cervical Length Measurements by 2D/3D and Doppler Ultrasound

OBJECTIVE

 The aim of the present study was to compare the obstetric history and both two- and tri-dimensional ultrasound parameters according to different cervical lengths.

METHODS

 The present cross-sectional study analyzed 248 midtrimester pregnant women according to cervical length and compared the data with the obstetric history and 2D/3D ultrasound parameters. Patients were divided into 3 groups according to cervical length: The Short Cervix group for cervical lengths ≥ 15 mm and < 25 mm (n = 68), the Very Short Cervix group for cervical lengths < 15 mm (n = 18) and the Control group, composed of 162 pregnant women with uterine cervical lengths ≥ 25 mm.

RESULTS

 When analyzing the obstetric history of only non-nulliparous patients, a significant association between the presence of a short cervix in the current pregnancy and at least one previous preterm birth was reported (p = 0.021). Cervical length and volume were positively correlated (Pearson coefficient = 0.587, p < 0.0001). The flow index (FI) parameter of cervical vascularization was significantly different between the Control and Very Short Cervix groups. However, after linear regression, in the presence of volume information, we found no association between the groups and FI. Uterine artery Doppler was also not related to cervical shortening.

CONCLUSION

 The present study showed a significant association between the presence of a short cervix in the current pregnancy and at least one previous preterm birth. None of the vascularization indexes correlate with cervical length as an independent parameter. Uterine artery Doppler findings do not correlate with cervical length.

Cervical modifications after pessary placement in singleton pregnancies with maternal short cervical length: 2D and 3D ultrasound evaluation

INTRODUCTION

The use of a pessary proved to prevent preterm birth in asymptomatic women with mid-trimester short cervical length (CL); however, the precise mechanisms by which the pessary confers its benefit remain unclear. The aim of this study was to evaluate multiple cervical characteristics assessed by 2-dimensional and 3-dimensional ultrasound before and after placement of a cervical pessary to ascertain its mechanism of action.

MATERIAL AND METHODS

In this prospective cohort study, we assessed the cervical characteristics in singleton pregnancies with maternal short CL and compared them with matched reference women with normal CL. The variables evaluated were: CL, uterocervical angles, cervical consistency indices (cervical consistency index and CL consistency index), cervical volume and vascular indices. All variables were re-assessed immediately after pessary placement and 4-6 weeks later in all participants. Mann-Whitney U test was used to assess differences between groups and paired samples t test for comparisons in two different examinations in the same women. The aim of this study was to evaluate multiple cervical ultrasound variables before and after the placement of a cervical pessary and compare the evolution of these variables with a reference group with normal CL to better understand the device's mechanism of action.

RESULTS

Thirty-three women with short CL and 24 reference women with normal CL were enrolled. At the time of enrollment, gestational age and maternal baseline characteristics did not differ between groups. Immediately after pessary placement, CL increased, uterocervical angles were narrower and cervical consistency increased significantly. When the magnitude of change in cervical variables was compared over time between the reference group and the study group, median CL had increased in the study group (1.47 mm) but it had shortened in the reference group (-2.56 mm). These inverse trends were statistically significant (P = 0.006).

CONCLUSIONS

Cervical pessary reduces both uterocervical angles and corrects cervical angulation by pushing the cervix up toward the uterus. Maintaining the cervix aligned to the uterine axis leads to reduced cervical tissue stretch, so avoiding further cervical shortening. All these changes were present after pessary placement; however, the clinical implications of these findings remain unknown.

The role of three-dimensional ultrasound in pregnancies submitted to cerclage

OBJECTIVE

Cervical cerclage is the standard treatment for cervical incompetence (CI); however, there is still a high risk of preterm birth for women who undergo this treatment. The aim of this study was to longitudinally evaluate findings on two-dimensional transvaginal ultrasonography (2DTVUS) and three-dimensional transvaginal ultrasonography (3DTVUS) that could be related to gestational age at birth.

METHODS

A total of 68 pregnant women who were treated with cerclage were evaluated by 2DTVUS and 3DTVUS in the second and third trimesters of pregnancy. Log-rank tests and Cox regression analyses were used to identify significant findings related to gestational age at delivery.

RESULTS

A cervical length lower than 281 mm (p= 0.0083), a proximal cervical length lower than 10 mm (p= 0.0151), a cervical volume lower than 18.17 cm3 (p= 0.0152), a vascularization index (VI) under 2.153 (p= 0.0044), and a vascularization-flow index (VFI) under 0.961 (p= 0.0059) in the second trimester were all related to earlier delivery. In the third trimester, a cervical length lower than 20.4 mm (p= 0.0009), a VI over 0.54 (p= 0.0327) and a VFI over 2.275 (p= 0.0479) were all related to earlier delivery. Cervical funnelling in the second and third trimesters and proximal cervical length in the third trimester were not related to gestational age at birth. The COX regression analyses showed that cervical volume in the second trimester; FI and VFI in the third trimester were significantly associated with gestational age at birth.

CONCLUSION

In women treated with history-indicated cerclage or ultrasound-indicated cerclage, 2nd trimester cervical volume and 3rd trimester FI and VFI are independent significant sonographic findings associated with time to delivery.

The association between maternal parity and birth defects

BACKGROUND

Previous studies observed that first birth is associated with an increased risk of some categories of birth defects. However, multiple statistical tests were conducted and it was unclear which of these associations would be replicated in a larger study. We used a large database to assess the association between maternal parity and 65 birth defects including birth defects that have not been previously studied.

METHODS

Using data from the Texas Birth Defects Registry for years 1999-2009, the risk of a birth defect occurring in a first, third, or fourth or higher birth was compared to the risk of a birth defect occurring in a second birth.

RESULTS

Women having their first birth had significantly increased odds of having an infant with 24 of 65 categories of birth defects when compared to women having their second birth. We also observed associations between first birth and an increased risk of five birth defects not previously reported (small penis, preaxial polydactyly, anomalies of the thoracic vertebrae, anomalies of the lumbar vertebrae, and sacroccygeal anomalies). Women having their third or fourth or higher birth had significantly increased odds of giving birth to infants with five of 65 birth defects when compared to second births.

CONCLUSIONS

Our observations regarding the categories of birth defects that were associated with first births were highly consistent with observations from two previous studies. Research into biological, behavioral, and environmental factors that may increase the risk of specific birth defects among first births is needed to further explore these associations.

Genetic and nongenetic etiology of nonsyndromic anorectal malformations: a systematic review

Congenital anorectal malformations (ARMs) are one of the most frequently observed birth defects of the digestive system. However, their etiology remains elusive. Therefore, we aim to summarize and critically appraise all existing literature on the genetic and nongenetic etiology of nonsyndromic ARM and to conclude with unifying hypotheses and directions for future research. A structured literature search on English language human studies was conducted in PubMed and Embase up to October 1, 2013, resulting in 112 included articles. Research on the identification of genes underlying nonsyndromic ARM is remarkably scarce. Most studies were focused on screening of candidate genes for mutations or single-nucleotide polymorphisms, which did not yield any substantial evidence. Nongenetic factors fairly consistently found to be associated with ARM are assisted reproductive techniques, multiple pregnancy, preterm delivery, low birth weight, maternal overweight or obesity, and preexisting diabetes. This review provides indications for the involvement of both genes and nongenetic risk factors in the etiology of ARM. In future studies, large cohorts of patients with ARM from national and international collaborations are needed to acquire new hypotheses and knowledge through hypothesis-generating approaches. Challenges for future studies may also lie in the investigation of gene-gene and gene-environment interactions.

Maternal reproductive history and the risk of congenital heart defects in offspring: a systematic review and meta-analysis

Epidemiological studies have reported conflicting results on the association of congenital heart defect (CHD) risk in offspring with a maternal history of prior pregnancies and abortions, but no meta-analysis has been reported. We searched MEDLINE and EMBASE from their inception to April 14, 2014, for relevant studies that assessed the association between maternal reproductive history and CHD risk. Two authors independently assessed eligibility and extracted data. Fixed-effects or random-effects models were used to calculate the pooled odds ratios (ORs). Among 1,599 references, 17 case-control studies and one nested case-control study were included in this meta-analysis. The summary OR for the ever versus nulligravidity was 1.18 (95% CI 1.03-1.34). A dose-response analysis also indicated a positive effect of maternal gravidity on CHD risk, and the summary OR for each increment in number of pregnancies was 1.13 (95% CI 1.08-1.18). A history of abortion was associated with a 24% higher risk of CHD, OR = 1.24 (95% CI 1.11-1.38). When stratified by abortion category, CHD risk increased by 18 and 58% with a history of spontaneous abortion and induced abortion, respectively. The summary OR for each increment of one abortion was 1.28 (95% CI 1.18-1.40). In summary, this study provides evidence that increased maternal gravidity was positively associated with a risk of CHDs in offspring. Meanwhile, our results demonstrate a positive association of any history of abortion with an increased risk of CHDs.

Maternal parity and the risk of congenital heart defects in offspring: a dose-response meta-analysis of epidemiological observational studies

Background

Epidemiological studies have reported conflicting results regarding maternal parity and the risk of congenital heart defects (CHDs). However, a meta-analysis of the association between maternal parity and CHDs in offspring has not been conducted.

Methods

We searched MEDLINE and EMBASE for articles catalogued between their inception and March 8, 2014; we identified relevant published studies that assessed the association between maternal parity and CHD risk. Two authors independently assessed the eligibility of the retrieved articles and extracted data from them. Study-specific relative risk estimates were pooled by random-effects or fixed-effects models. From the 11272 references, a total of 16 case-control studies and 3 cohort studies were enrolled in this meta-analysis.

Results

The overall relative risk of CHD in parous versus nulliparous women was 1.01 (95% CI, 0.97–1.06; Q = 32.34; P = 0.006; I² = 53.6%). Furthermore, we observed a significant association between the highest versus lowest parity number, with an overall RR = 1.20 (95% CI, 1.10–1.31; (Q = 74.61, P<0.001, I² = 82.6%). A dose–response analysis also indicated a positive effect of maternal parity on CHD risk, and the overall increase in relative risk per one live birth was 1.06 (95% CI, 1.02–1.09); Q = 68.09; P<0.001; I² = 80.9%). We conducted stratified and meta-regression analyses to identify the origin of the heterogeneity among studies. A Galbraith plot was created to graphically assess the sources of heterogeneity.

Conclusion

In summary, this meta-analysis provided a robust estimate of the positive association between maternal parity and risk of CHD.

Role of 3-dimensional power Doppler sonography in differentiating pregnant women with threatened preterm labor from those with an asymptomatic short cervix

OBJECTIVES

To compare cervical volumes and vascularization indices using 3-dimensional power Doppler sonography among singleton pregnancies with threatened preterm labor and an asymptomatic short cervix.

METHODS

Three hundred asymptomatic healthy pregnant women between 24 and 34.6 gestational weeks were prospectively scanned for cervical length. If cervical length was short, defined as below the 10th percentile for gestational age, the cervical volume and vascularization indices (vascularization index [VI], vascularization-flow index [VFI], and flow index [FI]) were measured. Women receiving any treatment for preterm delivery prevention were excluded. During this period, the same sonographic parameters were measured among patients with threatened preterm labor admitted to our institution during the first 24 hours after admission. Multiple pregnancies and fetal or maternal pathologic conditions, were exclusion criteria. Data on body mass index, maternal age, smoking, parity, family history of preterm birth, mother who was born preterm, and previous preterm birth among the pregnant women were recorded. Sonographic and medical history parameters were compared between the two groups.

RESULTS

Twenty-nine asymptomatic healthy women (9.6%) had a short cervix. Additionally, 71 pregnancies with threatened preterm labor were scanned. There were no statistically significant differences between the groups in medical history parameters or cervical length. The cervical volume was smaller in threatened preterm cases (12.90 versus 17.168 cm(3); P = .005). The VI and VFI were lower in women with an asymptomatic short cervix (VI, 4.369% versus 15.939%; P < .001; VFI, 1.514 versus 4.878; P < .001). The FI was higher in the short cervix group (33.581 versus 30.311; P = .006).

CONCLUSIONS

Three-dimensional transvaginal sonography reveals differences in cervical volume and vascularization indices between pregnancies with an asymptomatic short cervix and cases with threatened preterm labor, although cervical length is similar in both groups.

System-level biomechanical approach for the evaluation of term and preterm pregnancy maintenance

Preterm birth is the primary contributor to perinatal morbidity and mortality, with those born prior to 32 weeks disproportionately contributing compared to those born at 32-37 weeks. Outcomes for babies born prematurely can be devastating. Parturition is recognized as a mechanical process that involves the two processes that are required to initiate labor: rhythmic myometrial contractions and cervical remodeling with subsequent dilation. Studies of parturition tend to separate these two processes rather than evaluate them as a unified system. The mechanical property characterization of the cervix has been primarily performed on isolated cervical tissue, with an implied understanding of the contribution from the uterine corpus. Few studies have evaluated the function of the uterine corpus in the absence of myometrial contractions or in relationship to retaining the fetus. Therefore, the cervical-uterine interaction has largely been neglected in the literature. We suggest that a system-level biomechanical approach is needed to understand pregnancy maintenance. To that end, this paper has two main goals. One goal is to highlight the gaps in current knowledge that need to be addressed in order to develop any comprehensive and clinically relevant models of the system. The second goal is to illustrate the utility of finite element models in understanding pregnancy maintenance of the cervical-uterine system. The paper targets an audience that includes the reproductive biologist/clinician and the engineer/physical scientist interested in biomechanics and the system level behavior of tissues.

Is maternal parity an independent risk factor for birth defects?

BACKGROUND

Although associations between maternal parity and birth defects have been observed previously, few studies have focused on the possibility that parity is an independent risk factor for birth defects. We investigated the relation between levels of parity and a range of birth defects, adjusting each defect group for the same covariates.

METHODS

We included infants who had an estimated delivery date between 1997 and 2007 and participated in the National Birth Defects Prevention Study, a multisite case-control study. Cases included infants or fetuses belonging to 38 phenotypes of birth defects (n = 17,908), and controls included infants who were unaffected by a major birth defect (n = 7173). Odds ratios (ORs) were adjusted for 12 covariates using logistic regression.

RESULTS

Compared with primiparous mothers, nulliparous mothers were more likely to have infants with amniotic band sequence, hydrocephaly, esophageal atresia, hypospadias, limb reduction deficiencies, diaphragmatic hernia, omphalocele, gastroschisis, tetralogy of Fallot, and septal cardiac defects, with significant ORs (1.2 to 2.3). Compared with primiparous mothers, multiparous mothers had a significantly increased risk of omphalocele, with an OR of 1.5, but had significantly decreased risk of hypospadias and limb reduction deficiencies, with ORs of 0.77 and 0.77.

CONCLUSIONS

Nulliparity was associated with an increased risk of specific phenotypes of birth defects. Most of the phenotypes associated with nulliparity in this study were consistent with those identified by previous studies. Research into biologic or environmental factors that are associated with nulliparity may be helpful in explaining some or all of these associations.

Cervical blood perfusion assessed using power Doppler-derived estimation of fractional moving blood volume: a reproducibility study

OBJECTIVE

To evaluate the reproducibility of estimation of power Doppler-derived fractional moving blood volume (FMBV) in the uterine cervix of women with uncomplicated pregnancies.

METHODS

Two experienced operators evaluated 30 uncomplicated singleton pregnancies at 20-24 weeks of gestation. The PDU box was positioned in a mid-sagittal view of the cervix, including the internal os and external os, in the same plane as that in which cervical length is measured. Two consecutive examinations were performed by each operator, in each of which the cervical length was measured and five consecutive good-quality images with PDU information were obtained. The region of interest (ROI) (cervix) was delineated offline and FMBV, which expresses the percentage of blood occupying the ROI, was calculated with purpose-designed software. Intra- and interobserver intraclass correlation coefficients (ICCs) and mean differences with 95% limits of agreement (LOA) were calculated.

RESULTS

The median gestational age at examination was 22 + 0 weeks. Measurements (median ± SD) obtained for cervical length and FMBV were as follows: Operator A: 37 ± 7.4 mm and 8.11 ± 2.9%; Operator B: 37.5 ± 9.3 mm and 7.9 ± 3.3%, respectively. The intra- and interobserver ICCs for FMBV were 0.88 (95% CI, 0.75-0.94) and 0.82 (95% CI, 0.64-0.94), respectively. There was a mean difference in FMBV measurement between operators of - 0.2 ± 1.75% (95% LOA, - 3.7 to 3.2%).

CONCLUSIONS

Reproducible assessment of cervical blood perfusion through estimation of FMBV can be achieved while cervical length is being measured.

Comparison of cervical parameters by three-dimensional ultrasound according to parity and previous delivery mode

BACKGROUND

We would like to find out that whether the patient's parity, previous delivery mode and previous labor could influence cervical parameters. Cervical length, volume and width were measured using two-dimensional (2D) and three-dimensional (3D) transvaginal ultrasound on normal pregnant women.

METHOD

This study was conducted between January 2009 and December 2010 in singleton pregnant women who were admitted for routine antenatal care at hospitals in affiliation with the Catholic University, Seoul, Korea. The study group was classified by parity (nullipara and multipara) and previous delivery mode (cesarean section group and vaginal delivery group). The previous cesarean section group was divided by elective group who did not undergo labor and labor group who underwent labor. Cervical parameters such as cervical length, volume and width were measured using 2D and 3D ultrasound examinations in the first and second trimesters and the results were analyzed between those groups mentioned above.

RESULTS

One hundred and twenty-one pregnant women in their 1st trimester and 233 pregnant women in their 2nd trimester (a total of 354) were enrolled in this study. Cervical parameters were not statistically significant from parity, nor previous delivery mode and previous labor in 1st trimester. Cervical volumes were not statistically significant from nullipara and elective cesarean section groups (35.96±9.81 vs. 34.73±9.75 cm3), but the nullipara groups were significantly lowered in the vaginal group (35.96±9.81 vs. 43.10±11.87 cm3) in 2nd trimester. For the nullipara group, cervical widths were not statistically significant in the elective cesarean section group but these were significantly lower than labor and previous vaginal group in the 2nd trimester.

CONCLUSION

The cervical volume and width have an influence on parity, previous delivery mode and labor in the 2nd trimester.

Longitudinal examination of cervical volume and vascularization changes during the antepartum and postpartum period using three-dimensional and power Doppler ultrasound

OBJECTIVE

To assess longitudinally the changes in cervical volume and vascularization during the peripartum period using three-dimensional ultrasound (3D US) and power Doppler and to determine whether these measures change with gestational complications.

METHODS

Longitudinal measurements of cervical dimensions by transvaginal 3D US and power Doppler using the virtual organ computer-aided analysis program were performed at 11-14, 22-24, 32-34 weeks' gestation, and at 6 weeks' postpartum in 111 pregnant women. Comparisons were made between women who delivered at term (vs. preterm), nulliparous (vs. parous), with (vs. without) pre-eclampsia and those with (vs. without) gestational diabetes.

RESULTS

After establishing reference values for each peripartum period for cervical volume, vascularization index (VI) and flow index (FI), we found that the 2(nd) and 3(rd) trimester volume, 2(nd) trimester FI and postpartum VI were different in nulli- vs. multiparous women. Volume and vascularization parameters were unaffected by preterm labor. Second trimester VI and vascularization flow index values were lower in pre-eclamptic vs. non-pre-eclamptic women (P<0.05), but unaffected by gestational diabetes.

CONCLUSION

Cervical volume and vascularization parameters are not helpful in predicting preterm labor and gestational diabetes, but might be associated with pre-eclampsia.

Placental vascularization measured by three-dimensional power Doppler ultrasound at 11 to 13 + 6 weeks' gestation in normal and aneuploid fetuses

OBJECTIVE

To establish the potential role of three-dimensional (3D) power Doppler evaluation of the placental circulation in aneuploidy screening at 11 to 13 + 6 weeks of gestation.

METHODS

3D power Doppler ultrasound examination of the placenta was performed in 25 pregnancies with fetuses with abnormal karyotype and in 100 control pregnancies at 11 to 13 + 6 weeks of gestation. Using the same pre-established settings for all cases, the vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were calculated for the whole placenta.

RESULTS

In the chromosomally normal group all the vascular indices increased significantly with advancing gestation between 11 and 13 + 6 weeks (VI: r = 0.482, P < 0.001; FI: r = 0.295, P = 0.0029; VFI, r = 0.484, P < 0.001). In the chromosomally abnormal group, the flow indices were not significantly different from normal in cases with trisomy 21 (13 cases), but they were significantly reduced compared with normal in cases with trisomies 13 and 18 (VI: t = 8.321, P < 0.0001: FI: t = 12.934, P < 0.0001; VFI: t = 7.608, P < 0.0001).

CONCLUSIONS

3D power Doppler evaluation of the placental circulation is not useful in screening for trisomy 21, and unlikely to further increase the already high detection rate for trisomies 13 and 18. However, we provide normal ranges of placental vascular indices between 11 + 0 and 13 + 6 weeks of gestation, which may be useful in future research on placental vascularity in certain at-risk pregnancies.

Three-dimensional ultrasound power Doppler assessment of the cervix: comparison between nulliparas and multiparas

AIM

To assess the sonographic cervical characteristics between nulliparous and multiparous women.

SUBJECT AND METHODS

Transvaginal three-dimensional ultrasound and power Doppler using the virtual organ computer-aided analysis (VOCAL) program were performed on 71 nulliparas and 59 multiparas at a mean gestational age of 25.3+/-7.9 weeks. We compared the cervical volume and power Doppler vascularization index (VI), flow index (FI), and vascularization-flow index (VFI) between nulliparas and multiparas.

RESULTS

The mean cervical volume and mean VI, VFI, FI measurements were not significantly different between multiparas and nulliparas.

CONCLUSION

Our observations suggest that the morphological changes in the cervix of parous women are merely configurational without a change in cervical mass and vascularization. These configurational changes might result from the inevitable cervical stretching during labor and represent a healing process that does not involve a subsequent change in mass or vascularity.