Ultrasound assessment of the peri-implantation uterus: a review.

Emerging evidence suggests that early embryo implantation is a more active maternal process than hitherto appreciated, involving active encapsulation of the implanting blastocyst by maternal decidual cells and coordinated changes in the underlying inner myometrium, known as the junctional zone. These concepts raise the possibility that early ultrasound markers predictive of adverse pregnancy outcome could be identified. In this review we assess the role of ultrasound in predicting the likelihood of different pregnancy outcomes and highlight potential novel markers that could be tested.

Standardized approach for imaging and measuring Cesarean section scars using ultrasonography.

Incomplete healing of the scar is a recognized sequel of Cesarean section (CS) and may be associated with complications in later pregnancies. These complications can include scar pregnancy, a morbidly adherent placenta, scar dehiscence or rupture. To date there is uncertainty relating to the factors that lead to poor scar healing and how to recognize it. In recent years, there has been an increase in studies using ultrasound that describe scars as deficient, or poorly, incompletely or inadequately healed with few data to associate the morphology of the scar with the functional integrity of the lower segment of the uterus. There have been multiple attempts to describe CS scars using ultrasonography. Different terminology, methods and results have been reported, yet there is still no consensus regarding the prevalence, clinical significance or most appropriate method to describe the appearances of these scars. Developing a test that can predict the likelihood of women having problems associated with a CS scar is becoming increasingly important. On the other hand, understanding whether the ultrasound appearances of the scar can tell us anything about its integrity is not well supported by the research evidence. In this article we present an overview of ultrasound-based definitions and methods used to describe CS scars. We also present information relating to the performance of alternative techniques used to evaluate CS scars. Having examined the current evidence we suggest a standardized approach to describe CS scars using ultrasound so that future studies can be meaningfully compared.

PGD for a complex chromosomal rearrangement by array comparative genomic hybridization.

Patients carrying a chromosomal rearrangement (CR) have an increased risk for chromosomally unbalanced conceptions. Preimplantation genetic diagnosis (PGD) may avoid the transfer of embryos carrying unbalanced rearrangements, therefore increasing the chance of pregnancy. Only 7-12 loci can be screened by fluorescence in situ hybridization whereas microarray technology can detect genome-wide imbalances at the single cell level. We performed PGD for a CR carrier with karyotype 46,XY,ins(3;2)(p23;q23q14.2),t(6;14)(p12.2;q13) using array comparative genomic hybridization. Selection of embryos for transfer was only based on copy number status of the chromosomes involved in both rearrangements. In two ICSI-PGD cycles, nine and seven embryos were analysed by array, leaving three and one embryo(s) suitable for transfer, respectively. The sensitivity and specificity of single cell arrays was 100 and 88.8%, respectively. In both cycles a single embryo was transferred, resulting in pregnancy following the second cycle. The embryo giving rise to the pregnancy was normal/balanced for the insertion and translocation but carried a trisomy 8 and nullisomy 9 in one of the two biopsied blastomeres. After 7 weeks of pregnancy the couple miscarried. Genetic analysis following hystero-embryoscopy showed a diploid (90%)/tetraploid (10%) mosaic chorion, while the gestational sac was empty. No chromosome 8 aneuploidy was detected in the chorion, while 8% of the cells carried a monosomy for chromosome 9. In summary, we demonstrate the feasibility and determine the accuracy of single cell array technology to test against transmission of the unbalanced meiotic products that can derive from CRs. Our findings also demonstrate that the genomic constitution of extra-embryonic tissue cannot necessarily be predicted from the copy number status of a single blastomere.

A model and scoring system to predict outcome of intrauterine pregnancies of uncertain viability.

OBJECTIVES: To define the incidence and outcome of intrauterine pregnancy of uncertain viability (PUV) and to develop and assess the performance of a model and a scoring system to predict ongoing viability. METHODS: Of 1881 consecutive women undergoing transvaginal ultrasonography, a cohort of 493 women with an empty gestational sac < 20 mm in mean diameter, gestational sac < 25 mm in mean diameter and containing yolk sac only or an embryonic pole < 6 mm in maximum length and without visible heart activity were followed until the end of the first trimester. Women with multiple pregnancies or who underwent termination of pregnancy were excluded. Outcome measures were pregnancy viability at initial 7-14-day follow-up and first-trimester viability at 11-14 weeks. The data were split randomly into two sets (two-thirds and one-third, respectively) in order to first develop and then test a mathematical model and a 'simple' model in the prediction of viability at each outcome point, based on maternal demographics, ultrasound features and symptoms. The performance of each system was assessed by receiver-operating characteristics (ROC) curve analysis and calibration plots on a test dataset. RESULTS: The incidence of PUV in this population was 29.2% (549/1881). Of the 493 pregnancies with initial (7-14 days) follow-up available, 307 (62.3%) were viable at this time and of the 444 pregnancies with follow-up at the end of the first trimester, 225 (50.7%) were still viable. Initial (7-14-day) viability was predicted by the model with an area under the ROC curve (AUC) of 0.837 (95% CI, 0.791-0.884) in the training dataset and 0.821 (95% CI, 0.756-0.885) in the test dataset. First-trimester (11-14-week) viability was predicted by the model with an AUC of 0.788 (95% CI, 0.734-0.842) in the training dataset and 0.774 (95% CI, 0.701-0.848) in the test dataset. The scoring system performed slightly worse than did the model, but had the advantage of being easily applicable. CONCLUSIONS: When early pregnancy viability cannot be established immediately with ultrasound, use of either a logistic regression model or a scoring system allows an individualized prediction of first-trimester outcome.

Gestational sac and embryonic growth are not useful as criteria to define miscarriage: a multicenter observational study.

OBJECTIVES: We studied changes in mean gestational sac diameter (MSD) and embryonic crown-rump length (CRL) in intrauterine pregnancies of uncertain viability (IPUVs). We aimed to establish cut-off values for MSD and CRL growth that could be definitively associated with either viability or miscarriage, and to establish the relationship between growth in MSD and appearance of embryonic structures in the gestational sac. METHODS: One thousand and sixty consecutive IPUVs were recruited prospectively from four London University hospitals: 462 with no yolk sac or embryo, 419 with a yolk sac but no embryo, and 179 with an embryo but no heartbeat visible. IPUV was defined as an empty gestational sac with or without a yolk sac but no embryo seen with MSD < 20 or < 30 mm (depending on center) or an embryo with no heartbeat and CRL < 6 mm or < 8 mm (depending on center). Scans were repeated 7-14 days later. The endpoint was viability at first-trimester screening ultrasonography between 11 and 14 weeks. Change in MSD and CRL between the first and second scans of each pregnancy was compared with respect to viability and appearance of embryonic structures using the two-sample t-test. RESULTS: The study included 359 pregnancies in which a gestational sac with or without embryo was identified at the follow-up scan 7-14 days later. Of these, 192 were viable and 167 non-viable at the 11-14-week scan. MSD growth was significantly higher in viable than non-viable pregnancies (mean 1.003 vs. 0.503 mm/day; P < 0.001, 95% CI of difference 0.403-0.596). A difference in CRL growth was found between the two groups (mean 0.673 vs. 0.148 mm/day; P < 0.001, 95% CI of difference 0.345-0.703). MSD growth of 0.6 mm/day was associated with a specificity for diagnosing miscarriage of 90.1%, a sensitivity of 61.7% and 19 false-positive test results. A cut-off of CRL growth rate of 0.2 mm/day gave a sensitivity of 76.3% and there were no false-positive test results for miscarriage. On repeat scan the failure of either a yolk sac or embryo to be visualized was always associated with miscarriage. CONCLUSION: There is an overlap in MSD growth rates between viable and non-viable IPUV. No cut-off exists for MSD growth below which a viable pregnancy could be safely excluded. A cut-off value for CRL growth of 0.2 mm/day was always associated with miscarriage. These data suggest that criteria to diagnose miscarriage based on growth in MSD and CRL are potentially unsafe. However, finding an empty gestational sac on two scans more than 7 days apart is highly likely to indicate miscarriage, irrespective of growth.

Limitations of current definitions of miscarriage using mean gestational sac diameter and crown-rump length measurements: a multicenter observational study.

OBJECTIVES: There is significant variation in cut-off values for mean gestational sac diameter (MSD) and embryo crown-rump length (CRL) used to define miscarriage, values suggested in the literature ranging from 13 to 25 mm for MSD and from 3 to 8 mm for CRL. We aimed to define the false-positive rate (FPR) for the diagnosis of miscarriage associated with different CRL and MSD measurements with or without a yolk sac in a large study population of patients attending early pregnancy clinics. We also aimed to define cut-off values for CRL and MSD that, on the basis of a single measurement, can definitively diagnose a miscarriage and so exclude possible inadvertent termination of pregnancy. METHODS: This was an observational cross-sectional study. Data were collected prospectively according to a predefined protocol. Intrauterine pregnancy of uncertain viability (IPUV) was defined as an empty gestational sac or sac with a yolk sac but no embryo seen with MSD < 20 or < 30 mm or an embryo with an absent heartbeat and CRL < 6 mm or < 8 mm. We recruited to the study 1060 consecutive women with IPUV. The endpoint was presence or absence of a viable pregnancy at the time of first-trimester screening ultrasonography between 11 and 14 weeks. The sensitivity, specificity, positive and negative predictive values were calculated for potential cut-off values to define miscarriage from MSD 8 to 30 mm with or without a yolk sac and from CRL 3 to 8 mm. RESULTS: Of the 1060 women with a diagnosis of IPUV, 473 remained viable and 587 were non-viable by the time of the 11-14-week scan. In the absence of both embryo and yolk sac, the FPR for miscarriage was 4.4% when an MSD cut-off of 16 mm was used and 0.5% for a cut-off of 20 mm. There were no false-positive test results for miscarriage when a cut-off of MSD ≥ 21 mm was used. If a yolk sac was present but an embryo was not, the FPR for miscarriage was 2.6% for an MSD cut-off of 16 mm and 0.4% for a cut-off of 20 mm, with no false-positive results when a cut-off of MSD ≥ 21 mm was used. When an embryo was visible with an absent heartbeat, using a CRL cut-off of 4 mm the FPR for miscarriage was 8.3%, and for a CRL cut-off of 5 mm it was also 8.3%. There were no false-positive results using a CRL cut-off of ≥ 5.3 mm. CONCLUSIONS: These data show that some current definitions used to diagnose miscarriage are potentially unsafe. Current national guidelines should be reviewed to avoid inadvertent termination of wanted pregnancies. An MSD cut-off of > 25 mm and a CRL cut-off of > 7 mm could be introduced to minimize the risk of a false-positive diagnosis of miscarriage.

Clinical implications of intra- and interobserver reproducibility of transvaginal sonographic measurement of gestational sac and crown-rump length at 6-9 weeks' gestation.

OBJECTIVES: To assess intra- and interobserver agreement of routinely performed measurements-crown-rump length (CRL) and mean gestational sac diameter (MSD)-for assessing the likelihood of miscarriage in the first trimester of pregnancy using transvaginal sonography. METHODS: A cross-sectional study of CRL and gestational sac measurements in first-trimester pregnancies was conducted in a fetal medicine referral center with a predominantly Caucasian population. Gestational age ranged from 6 to 9 weeks. All patients underwent a transvaginal ultrasound examination using a high-resolution ultrasound machine. Two measurements of CRL and measurements of three diameters of the gestational sac were obtained by two observers. Agreement within and between observers for CRL and between observers for MSD was analyzed using 95% prediction intervals, Bland-Altman plots with 95% limits of agreement and the intraclass correlation coefficient (ICC). RESULTS: In total 54 patients were included in the study, with measurements obtained by both observers in 44 of these. Intra- and interobserver ICCs were high for CRL measurements, with values of 0.992 and 0.993 for intraobserver agreement and 0.993 for interobserver agreement. For the MSD, the interobserver ICC was 0.952. Limits of agreement were ± 8.91 and ± 11.37% for intraobserver agreement of CRL and ± 14.64% for interobserver agreement of CRL. For MSD, the interobserver limits of agreement were ± 18.78%. For an MSD measurement of 20 mm by the first observer, the prediction interval for the second observer was 16.8-24.5 mm. For a CRL measurement of 6 mm, the prediction interval for the second observer was 5.4-6.7 mm. CONCLUSION: For dating purposes, there is reasonable reproducibility of CRL measurements using transvaginal ultrasonography at 6-9 weeks' gestation. When diagnosing miscarriage based on measurements of CRL care must be taken for values close to any decision boundary. The higher interobserver variability that we observed for MSD has implications for the diagnosis of miscarriage based on this measurement in the absence of a visible embryo or yolk sac.

No influence of body mass index on first trimester fetal growth.

BACKGROUND: Our objective was to determine what effect maternal BMI has on fetal growth rate in the early first trimester. METHODS: This was a prospective observational study of singleton pregnancies with certain dates, initially presenting for a transvaginal scan (TVS) before 12 weeks of gestation. Maternal characteristics (BMI, ethnicity, maternal age, obstetric history, abdominal pain and vaginal bleeding) were recorded. Fetal crown-rump length (CRL) was measured at the initial scan, and at subsequent ultrasound assessments. In order to assess the fetal growth rates, women with at least two CRL measurements were included in the analysis. A mixed-linear effects model analysis was performed to determine whether BMI influences the rate of change in CRL. RESULTS: A total of 264 pregnancies were analysed. The median BMI was 23.55 (range 16-45), median age was 32 (17-44) and the proportion of white, black and Asian women was 61.0, 15.5 and 5.3%, respectively. Mean gestational age (GA) at first TVS was 56 (range 33-84) days. Studying CRL as a function of GA with a mixed-linear effects model showed that this relationship was neither significantly influenced by BMI when modelling BMI as a continuous variable (P = 0.7529), nor when modelling it as a categorical variable using the WHO criteria (P = 0.8904). CONCLUSIONS: Dating by CRL influences subsequent growth assessment and previous studies have suggested that first trimester fetal growth rates may be influenced by ethnicity and age. Our data however suggest that maternal BMI does not significantly influence early fetal growth.

New crown-rump length curve based on over 3500 pregnancies.

OBJECTIVES: The Robinson and Hadlock crown-rump length (CRL) curves are commonly used to estimate gestational age (GA) based on the CRL of an embryo or fetus. However, the Robinson curve was derived from a small population using transabdominal sonography and the Hadlock curve was generated using early transvaginal ultrasound equipment. The aim of this study was to use transvaginal and transabdominal ultrasound to study a large population of early pregnancies to assess embryonic or fetal size, and so create a new normal CRL curve from 5.5 weeks' gestation. We compared this with the Robinson and Hadlock CRL curves. METHODS: A retrospective database study of CRL in first-trimester embryos was conducted in a fetal medicine referral center with a predominantly Caucasian population. Linear mixed-effects analysis was performed to determine the relationship between CRL and GA. After internal validation of this curve, the CRL was compared with the expected CRL at a given GA according to both the Robinson and Hadlock models based on the paired t-test. Bland-Altman plots were constructed to compare the CRL measurements obtained in our study population with those predicted according to GA by both the Robinson and Hadlock curves. RESULTS: In total 3710 normal singleton pregnancies with a known last menstrual period were included in the study, corresponding to 4387 scans. Our data differed significantly from both the Robinson and the Hadlock curves (paired t-test, P < 0.0001). A mixed-effects model for CRL as a function of GA was developed on 70% of the data and internally validated with z-scores on the remaining 30%. The new curve extended from 5.5 to 14 weeks' gestation. Compared to our CRL curve, the Robinson curve gave a 4-day underestimation of GA at 6 weeks with a difference in CRL of 3.7 mm and a 1-day overestimation from 11 to 14 weeks with a difference in CRL of 0.9-1 mm. A comparison between our curve and the Hadlock curve showed a difference in CRL of 2.7 mm at 6 weeks, equivalent to an underestimation of 3 days, and a difference in CRL of 4.8 mm at 14 weeks, equivalent to an overestimation of 2 days. At 9 weeks all three curves were similar. CONCLUSION: The new CRL curve suggests differences in the range of CRL measurements compared with the Robinson and Hadlock curves. These differences are most significant at the beginning and the end of the first trimester, and may lead to more accurate estimations of GA.

Functional linear discriminant analysis: a new longitudinal approach to the assessment of embryonic growth.

BACKGROUND: Functional linear discriminant analysis (FLDA) is a new growth assessment technique using serial measurements to discriminate between normal and abnormal fetal growth. We used FLDA to assess and compare growth in live pregnancies destined to miscarry with those remaining viable. METHODS: This was a prospective cohort study of women with ultrasound scans on at least two separate occasions showing live pregnancies. Serial crown-rump length (CRL), mean gestational sac diameter and mean yolk sac diameter measurements were recorded. The ability of FLDA to predict subsequent miscarriage was compared with that of a single CRL measurement. RESULTS: Of 521 included pregnancies, 493 (94.6%) remained viable at 14 weeks and 28 (5.4%) miscarried. The CRL growth rate was significantly lower in those that miscarried (one-sample t-test, P = 2.638E-22). The sensitivity of FLDA in predicting miscarriage from serial CRL measurements was 60.7% and specificity was 93.1% [positive predictive value (PPV) 33.3%, negative predictive value (NPV) 97.7%]. This was significantly better for predicting miscarriage than a single CRL observation of more than 2SD below that expected (sensitivity 53.6%, specificity 72.2%, PPV 9.9%, NPV 96.5%). CONCLUSIONS: FLDA discriminates between normal and abnormal growth to predict miscarriage with high specificity. FLDA predicts miscarriage better than a single observation of a small CRL.

The influence of weight gain patterns in pregnancy on fetal growth using cluster analysis in an obese and nonobese population.

OBJECTIVE: Excessive weight gain during pregnancy has an important influence on fetal growth and on weight development in future generations. DESIGN AND METHODS: A prospective cohort study of 325 obese and nonobese Caucasian women with naturally conceived, singleton pregnancies was performed. They were followed up until delivery for maternal weight gain and for fetal growth with ultrasound-based weight estimations and final birth weight. Using cluster analysis distinct profiles of maternal weight gain during pregnancy were obtained. Longitudinal regression analysis was performed to investigate the relationship of the maternal weight gain profile and BMI on fetal growth and final birth weight. RESULTS: Cluster analysis revealed four discernable maternal weight gain profiles: 12 cases (3.7%) ended up at their starting weight or decreased in weight (cluster 1), 16 cases (4.9%) who slightly increased in weight (maximum 4 kg) as compared to their initial weight (cluster 2), 114 cases (35.1%) who gained between 4 and 12 kg in weight (cluster 3), and 183 cases (56.3%) who showed the largest weight gain: more than 12 kg (cluster 4). There were statistically significant differences in fetal growth associated with weight gain cluster, which became apparent late in the second trimester and increased toward the end of pregnancy. Maternal BMI and maternal weight gain profile were independent predictors of fetal growth and birth weight. CONCLUSIONS: Therefore, the conclusion is that the cluster analysis permits to discern four gestational weight gain (GWG) patterns in obese and nonobese subjects and that both maternal BMI and maternal weight gain pattern during pregnancy positively influence fetal growth and birth weight.

Endometriosis, recurrent miscarriage and implantation failure: is there an immunological link?

Endometriosis is more frequently diagnosed in patients with infertility than in a normal population. The goal of this paper is to give an overview of the clinical and fundamental evidence for a possible link between endometriosis and (recurrent) miscarriage or implantation failure after treatment with assisted reproductive technology. According to the literature, there is insufficient evidence for an association between endometriosis and (recurrent) miscarriage, but there is, however, epidemiological evidence to support the link between endometriosis and recurrent implantation failure after assisted reproduction. This can possibly be explained by alterations in humoral and cell-mediated immunity in women with endometriosis. Humoral immunological changes include increased formation of antibodies against endometrial antigens, anti-laminin-1 auto-antibodies and other auto-immune antibodies (e.g. antiphospholipid). Cell-mediated immunological changes include alterations in peritoneal and follicular fluid immune cells and cytokines. The possible negative effect of these immunological changes on folliculogenesis, ovulation, oocyte quality, early embryonic development and implantation in women with endometriosis suggests that infertility in endometriosis patients may be related to alterations within the follicle or oocyte, resulting in embryos with decreased ability to implant.