Twin growth discrepancy in early pregnancy

The prognostic role of CRL discordance in first trimester ultrasound

OBJECTIVES

In the first trimester, intertwin crown-rump length (CRL) discordance has emerged as a notable factor linked to adverse perinatal health effects. It is frequently employed as a basis for counseling parents regarding potential adverse pregnancy outcomes. Despite its established association with adverse outcomes, the significance of CRL discordance in substantially predicting pregnancy problems and its efficacy in pregnancy screening remain subjects of ongoing discussion. The aim of this manuscript is to present current knowledge on CRL discordance.

METHODS

PubMed was searched for related articles with terms "Crown-Rump length", "Prenatal Screening", "Twin pregnancy", "Discordance".

RESULTS

Twenty-two studies were included in our study with six reporting data on monochorionic and 16 assessing the correlation between CRL discordance and adverse pregnancy outcomes. Fetal loss at the 20th and 24th week of the pregnancy, SGA neonates, pre-term delivery (32 weeks), perinatal death (24 weeks) are all reported adverse outcomes associated with CRL discordance. The reported cut-off for increased risk of adverse perinatal outcomes is a discordance of at least 10% or more.

CONCLUSIONS

Increased CRL (>10 %) discordance is linked to a higher risk of sFGR in both monochorionic and dichorionic pregnancies, fetal loss, and preterm delivery.

Drosophila CASK regulates brain size and neuronal morphogenesis, providing a genetic model of postnatal microcephaly suitable for drug discovery

BACKGROUND

CASK-related neurodevelopmental disorders are untreatable. Affected children show variable severity, with microcephaly, intellectual disability (ID), and short stature as common features. X-linked human CASK shows dosage sensitivity with haploinsufficiency in females. CASK protein has multiple domains, binding partners, and proposed functions at synapses and in the nucleus. Human and Drosophila CASK show high amino-acid-sequence similarity in all functional domains. Flies homozygous for a hypomorphic CASK mutation (∆18) have motor and cognitive deficits. A Drosophila genetic model of CASK-related disorders could have great scientific and translational value.

METHODS

We assessed the effects of CASK loss of function on morphological phenotypes in Drosophila using established genetic, histological, and primary neuronal culture approaches. NeuronMetrics software was used to quantify neurite-arbor morphology. Standard nonparametric statistics methods were supplemented by linear mixed effects modeling in some cases. Microfluidic devices of varied dimensions were fabricated and numerous fluid-flow parameters were used to induce oscillatory stress fields on CNS tissue. Dissociation into viable neurons and neurite outgrowth in vitro were assessed.

RESULTS

We demonstrated that ∆18 homozygous flies have small brains, small heads, and short bodies. When neurons from developing CASK-mutant CNS were cultured in vitro, they grew small neurite arbors with a distinctive, quantifiable "bushy" morphology that was significantly rescued by transgenic CASK+. As in humans, the bushy phenotype showed dosage-sensitive severity. To overcome the limitations of manual tissue trituration for neuronal culture, we optimized the design and operation of a microfluidic system for standardized, automated dissociation of CNS tissue into individual viable neurons. Neurons from CASK-mutant CNS dissociated in the microfluidic system recapitulate the bushy morphology. Moreover, for any given genotype, device-dissociated neurons grew larger arbors than did manually dissociated neurons. This automated dissociation method is also effective for rodent CNS.

CONCLUSIONS

These biological and engineering advances set the stage for drug discovery using the Drosophila model of CASK-related disorders. The bushy phenotype provides a cell-based assay for compound screening. Nearly a dozen genes encoding CASK-binding proteins or transcriptional targets also have brain-development mutant phenotypes, including ID. Hence, drugs that improve CASK phenotypes might also benefit children with disorders due to mutant CASK partners.

The Association between Intertwin Difference in First Trimester Crown-Rump Length, Nuchal Translucency, and Birth Weight Discordance in Twin Pregnancies: A Retrospective Cohort Study

Background. Discordant birth weight in twins is linked to poor outcomes and predicting this discrepancy may lead to enhanced screening and surveillance. Our purpose was to quantify the relationship between intertwin nuchal translucency (NT) and crown-rump length (CRL) discordance with birth weight discrepancies ≥ 20%. Methods. We conducted a retrospective cohort study of 887 live twin births delivering at a Canadian tertiary care center over a 7-year period who opted for integrated prenatal screening. Categorical data are presented as numbers and percentages, and continuous data are expressed as means and standard deviations. Chi-square tests, Fisher’s Exact tests, or $T$ -test were performed as appropriate. We then used published data and receiver operating curves to determine the optimal thresholds for predicting birth weight discordance based on first trimester intertwin NT differences. These values were used in multivariate logistic regression models accounting for known confounders. Results. Roughly 16% of twin pairs exhibited ≥ 20% difference in birth weight. Twin pairs with a CRL discordance greater than 10% have nearly a 4 times greater likelihood of having a birth weight discordance greater than 20% (OR 3.71, CI 2.24-6.14) while controlling for chorionicity, maternal age, gestational age at delivery, maternal body mass index (BMI), and parity. In these models, intertwin NT discordance ≥ 20% (OR 1.16, CI 0.77-1.77) and NT discordance ≥ 14% (OR 1.08, CI 0.73-1.60) were not statistically significant predictors of twin birth weight differences. However, when evaluating the effect of the larger intertwin NT value corresponding to the 95th percentile, an NT difference ≥ 0.9 mm was predictive of birth weight discordance ≥ 20% (OR 2.53, CI 1.21-5.29). Conclusion. Although intertwin CRL and NT discordance measured via ultrasound between 11-14 weeks gestation are related to birth weight discordance, there is uncertainty as to whether twin birth weight differences are related to adverse pregnancy outcomes in this population.

Screening for aneuploidy in twins

All pregnant women should be offered screening for aneuploidy. Twin pregnancies present unique challenges in aneuploidy screening. This review describes available aneuploidy screening options and their benefits and limitations in twin pregnancy, along with describing special circumstances, such as vanishing twins and diagnostic testing in twin pregnancy. No method of aneuploidy screening is as accurate in twin pregnancies as singleton pregnancies. Cell-free DNA screening should be considered a first-line approach; however, this option may not be available or may have limitations in certain clinical scenarios, such as vanishing twins. If cell-free DNA screening is not available, nuchal translucency and/or maternal serum marker screening can be offered.

Ultrasound for diagnosis of birth weight discordance in twin pregnancies

BACKGROUND

There is a need to standardize monitoring in obstetric research of twin pregnancies. Identification of birth weight discordance (BWD), defined as a difference in the birth weights of twins, is a well-documented phenomenon in twin pregnancies. Ultrasound for the diagnosis of BWD informs complex decision making including whether to intervene medically (via laser photo coagulation) or deliver the twins to avoid fetal morbidities or even death. The question is, how accurate is this measurement?

OBJECTIVES

To determine the diagnostic accuracy (sensitivity and specificity) of ultrasound estimated fetal weight discordance (EFWD) of 20% and 25% using different estimated biometric ultrasound measurements compared with the actual BWD as the reference standard in twin pregnancies.

SEARCH METHODS

The search for this review was performed on 15 March 2019. We searched CENTRAL, MEDLINE (Ovid), Embase (Ovid), seven other databases, conference proceedings, reference lists and contacted experts. There were no language or date restrictions applied to the electronic searches, and no methodological filters to maximize sensitivity.

SELECTION CRITERIA

We selected cohort-type studies with delayed verification that evaluated the accuracy of biometric measurements at ultrasound scanning of twin pregnancies that had been proposed for the diagnosis of estimated BWD, compared to BWD measurements after birth as a reference standard. In addition, we only selected studies that considered twin pregnancies and applied a reference standard for EFWD for the target condition of BWD.

DATA COLLECTION AND ANALYSIS

We screened all titles generated by electronic database searches. Two review authors independently assessed the abstracts of all potentially relevant studies. We assessed the identified full papers for eligibility, and extracted data to create 2 × 2 tables. Two review authors independently performed quality assessment using the QUADAS-2 tool. We excluded studies that did not report data in sufficient detail to construct 2 × 2 tables, and where this information was not available from the primary investigators. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included 39 eligible studies with a median study sample size of 140. In terms of risk of bias, there were many unclear statements regarding patient selection, index test and use of proper reference standard. Twenty-one studies (53%) were of methodological concern due to flow and timing. In terms of applicability, most studies were of low concern. Ultrasound for diagnosis of BWD in twin pregnancies at 20% cut-off Twenty-two studies provided data for a BWD of 20% and the summary estimate of sensitivity was 0.51 (95% CI 0.42 to 0.60), and the summary estimate of specificity was 0.91 (95% CI 0.89 to 0.93) (8005 twin pregnancies; very low-certainty evidence). Ultrasound for diagnosis of BWD in twin pregnancies at 25% cut-off Eighteen studies provided data using a BWD discordance of 25%. The summary estimate of sensitivity was 0.46 (95% CI 0.26 to 0.66), and the summary estimate of specificity was 0.93 (95% CI 0.89 to 0.96) (6471 twin pregnancies; very low-certainty evidence). Subgroup analyses were possible for both BWD of 20% and 25%. The diagnostic accuracy did not differ substantially between estimation by abdominal circumference and femur length but femur length had a trend towards higher sensitivity and specificity. Subgroup analyses were not possible by sex of twins, chorionicity or gestational age due to insufficient data.

AUTHORS' CONCLUSIONS

Very low-certainty evidence suggests that EFWD identified by ultrasound has low sensitivity but good specificity in detecting BWD in twin pregnancies. There is uncertain diagnostic value of EFWD; this review suggests there is insufficient evidence to support this index as the sole measure for clinical decision making to evaluate the prognosis of twins with growth discordance. The diagnostic accuracy of other measures including amniotic fluid index and umbilical artery Doppler resistive indices in combination with ultrasound for clinical intervention requires evaluation. Future well-designed studies could also evaluate the impact of chorionicity, sex and gestational age in the diagnostic accuracy of ultrasound for EFWD.

First trimester ultrasonographic parameters in prediction of the course and outcome of monochorionic twin pregnancies

BACKGROUND/AIM

The aim of the study was to evaluate the association and the potential predictive value of first trimester ultrasonographic parameters on the course and outcome of monochorionic diamniotic twin pregnancies.

MATERIALS AND METHODS

A prospective cohort study was undertaken of 39 healthy women with consecutive monochorionic diamniotic twin pregnancies. During first-trimester screening, crown-rump length (CRL) and nuchal translucency (NT) were measured. The intertwin discordance in CRL and NT was determined. As pregnancy outcomes we assessed twins' live-born rates, Apgar scores, birth weight, pregnancy complications, and gestational week of delivery.

RESULTS

None of the assessed pregnancy outcomes significantly correlated with standard CRL discordance ≥10%. The newly established cut-off was 3.75 mm for CRL and 1.3 mm for NT. Monochorionic diamniotic twins were delivered in a later gestational week and had better chance of survival if CRL intertwin difference was <3.75 mm. Apgar scores significantly negatively correlated only with NT of corresponding twins. When intertwin NT difference was ≥1.3 mm, twins had lower birth weight and pregnancy complications were more frequent. Regression models show that intertwin CRL difference <3.75 mm is a significant predictor of live-born monochorionic diamniotic twins.

CONCLUSION

CRL and NT in monochorionic diamniotic twin pregnancies could indicate pregnancy complications and outcomes.

Intertwin estimated fetal weight or crown rump length discordance and adverse perinatal outcome

AIM

In the current review study, we present recent data regarding the importance of intertwin estimated fetal weight (EFW) and crown rump length (CRL) discordance for the prediction of adverse perinatal outcome both in monochorionic and in dichorionic diamniotic gestations.

RESULTS

Twins with significant weight disparity are associated with higher rates of perinatal morbidity and mortality, regardless of gestational age at delivery. However, there is no agreement regarding as to the cut off value above which the perinatal outcome is unfavorably affected and the threshold range from 10 to 30%. On the other hand, CRL discrepancy has proved to be a weak predictor of adverse outcomes, such as fetal or neonatal death in fetuses without chromosomal and structural abnormalities. In clinical practice, decisions about obstetric surveillance of discordant twin gestations, frequency of fetal sonographic monitoring and time of delivery are usually based on amniotic fluid volume and Doppler assessments on a weekly basis.

CONCLUSION

Significant EFW discordance leads to adverse perinatal outcome, although the cut-off value has not yet been estimated. CRL discrepancy is not correlated well with adverse perinatal outcome. However, increased monitoring of women with EFW and CRL discrepancy is suggested.

Intertwin crown-rump length discordance in the prediction of fetal anomalies, fetal loss and adverse perinatal outcome

OBJECTIVE

To assess the risks of fetal anomalies, fetal loss and adverse perinatal outcome in a cohort of first-trimester intertwin crown-rump length (CRL) discordant twins, stratified by chorionicity and the degree of CRL discordance.

METHOD

Four-hundred-and-seventy-one twin pregnancies were scanned during an 8-year period at 11-14 weeks, and those with an intertwin CRL discordance ≥10% were compared with concordant twins. Outcomes were also compared between monochorionic and dichorionic twins and between moderate (10-16%) and severe (>16%) discordance.

RESULTS

Four-hundred-and-five twin pregnancies, 65 discordant and 340 concordant, were follow-up. Discordant twin pregnancies were at significant higher risk of chromosomal (OR = 11.42; 95% CI: 2.78-46.94) and structural anomalies (OR = 5.91; 95% CI: 2.25-15.54), spontaneous fetal loss (OR = 4.23; 95% CI: 1.79-10.01), birthweight discordance (OR = 2.8; 95% CI: 1.48-5.65) and small-for-gestational age (OR = 3.48; 95% CI: 1.78-6.79). Similar differences (except for birthweight discordance) were observed among dichorionic twins. Among monochorionic, increased frequencies were only seen for structural anomalies, birthweight discordance and small newborns. Severe CRL discordance presented with higher rates of structural anomalies, stillbirth, birthweight discordance and small newborns.

CONCLUSION

Intertwin CRL discordance (≥10%) results in an increased risk of fetal anomalies and growth restriction that increases in severe CRL discordance (≥16%).

First-trimester Ultrasound and Aneuploidy Screening in Multifetal Pregnancies

First-trimester ultrasound provides valuable information to help optimize the management of multifetal pregnancies. First trimester ultrasound the use of ultrasound and screening for aneuploidy has been well studied in singleton pregnancies. While evidence supporting the use of ultrasound in multiple gestations is well established, aneuploidy screening continues to evolve and its role in the prenatal setting has been less well studied. We review the importance of early first trimester ultrasound in assessing gestational age and chorionicity and early identification of anomalies, and review the various methods and limitations of aneuploidy screening and invasive diagnostic procedures in multiples.

The association of crown-rump length discrepancy with birthweight discordance in spontaneous versus IVF monochorionic twins: a multicenter study

OBJECTIVE

The objective of this study was to compare the associations of crown-rump length (CRL) discrepancy with birthweight discordance in spontaneous versus in vitro fertilization (IVF) monochorionic (MC) twin pregnancies.

METHOD

This is a multicenter retrospective study on women with twin pregnancies assessed for nuchal translucency between January 1997 and July 2013. The study group was subdivided into MC twins conceived spontaneously and after IVF. Pregnancies with later fetal death or twin transfusion syndrome were excluded. A large-weight discordance was defined as a difference of birthweights of >15%.

RESULTS

The study group included 171 pregnancies; of them, 142 (83%) were spontaneous and 29 (17%) were IVF conceived. In the entire cohort, we found a significant correlation between birthweight discordance and CRL discrepancy (r = 0.173, P < 0.05). While a significant correlation was found between CRL discrepancy and birthweight discordance in spontaneous-conceived pregnancies (n = 142, r = 0.24, P = 0.005), such correlation was not present in IVF pregnancies (n = 29, r = -0.7, P = 0.724). A logistic regression analysis found significant odds of larger-weight discordance for each increase of 1% in CRL discrepancy among spontaneously conceived pregnancies (odds ratio = 1.1, confidence interval = 1.03-1.2, P = 0.005). A receiver operating characteristic (ROC) for large-weight discordance in the spontaneously conceived pregnancies demonstrated an area under the ROC curve of 0.613 (P = 0.039).

CONCLUSION

The significant correlation between CRL discrepancy and birthweight discordance in spontaneous versus IVF MC twin pregnancies might suggest differential monozygotic twinning process.

Ultrasound imaging in the management of bleeding and pain in early pregnancy

Bleeding and pain are experienced by 20% of women during the first trimester of pregnancy. Although most pregnancies complicated by pain and bleeding tend to progress normally, these symptoms are distressing for woman, and they are also associated with an increased risk of miscarriage and ectopic pregnancy. Ultrasound is the first and often the only diagnostic modality that is used to determine location of early pregnancy and to assess its health. Ultrasound is an accurate, safe, painless and relatively inexpensive diagnostic tool, which all contributed to its widespread use in early pregnancy. Pain and bleeding in early pregnancy are sometimes caused by concomitant gynaecological, gastrointestinal, and urological problems, which could also be detected on ultrasound scan. In women with suspected intra-abdominal bleeding, ultrasound scan can be used to detect the presence of blood and provide information about the extent of bleeding. In this chapter, we comprehensively review the use of ultrasound in the diagnosis and management of early pregnancy complications. We include information about the diagnosis of gynaecological and other pelvic abnormalities, which could cause pain or bleeding in pregnancy. We also provide a summary of the current views on the safety of ultrasound in early pregnancy.

Crown-rump length discordance in the first trimester: a predictor of adverse outcome in twin pregnancies?

OBJECTIVES

To evaluate the usefulness of first-trimester crown-rump length (CRL) discordance in predicting adverse outcome in twin pregnancies.

METHODS

This retrospective study included a large cohort retrieved from local ultrasound databases at 14 obstetric departments in Denmark, comprising all twin pregnancies with two live fetuses scanned between 11 and 14 weeks' gestation during the period 1 January 2004 to 31 December 2006. The association between CRL discordance ≥ 10 % and adverse outcome was evaluated.

RESULTS

Among 1993 twin pregnancies, 1733 were dichorionic (156 (9%) discordant; 1577 (91%) concordant) and 260 were monochorionic (32 (12%) discordant; 228 (88%) concordant). In dichorionic twin pregnancies we found an association between CRL discordance ≥ 10% and preterm delivery before 34 weeks' gestation (P=0.007), birth weight discordance (P=0.001) and mean birth weight (P=0.033). In monochorionic twin pregnancies we found an association between CRL discordance ≥ 10% and birth weight discordance (P=0.02) and mean birth weight (P=0.03). To evaluate CRL discordance as a predictor of fetal loss and preterm delivery before 34 weeks' gestation, receiver-operating characteristics curves were created for each outcome. For CRL discordance ≥ 10% as a predictor of fetal loss and preterm delivery in dichorionic twin pregnancies, sensitivity was 0.17 (95% CI, 0.06-0.28) and 0.14 (95% CI, 0.10-0.18), respectively, and in monochorionic twin pregnancies it was 0.10 (95% CI, 0.03-0.22) and 0.16 (95% CI, 0.06-0.26), respectively.

CONCLUSIONS

CRL discordance in twin pregnancies is associated with, but is not a strong predictor of, adverse outcome.

Perinatal complications of monochorionic diamniotic twin gestations with discordant crown-rump length determined at mid-first trimester

AIM

The aim of this study was to investigate the value of discordance of crown-rump length (DCRL) at mid-first trimester to predict adverse outcomes in monochorionic diamniotic twin gestations (MD).

MATERIAL AND METHODS

This was a retrospective cohort study of the perinatal outcome in MD pregnancies managed from the first trimester onward. DCRL was evaluated between 8 and 10 weeks of gestation. The association between DCRL and perinatal complications, including fetal death, twin-twin transfusion syndrome, severe discordant birthweight (DB), and twin anemia-polycythemia sequence, was assessed.

RESULTS

Among 126 cases, a single fetal demise occurred in two (2%) and demise of both fetuses occurred in eight (6%). Five pregnancies (4%) were complicated with twin-twin transfusion syndrome; one case (1%) was twin anemia-polycythemia sequence and 13 (10%) were DB. Neonatal death occurred in one pair. At 28 days of age, in 115 cases (91%) both twins were alive. In 117 cases (93%), at least one twin survived until 28 days of age. DCRL >12.0% was not related to any perinatal complications but DB (P < 0.01; relative risk: 1.40; 95% confidence interval: 1.06-1.84).

CONCLUSIONS

DCRL in MD during the mid-first trimester might be useful for predicting DB.

Crown-rump length discordance and adverse perinatal outcome in twins: analysis of the Southwest Thames Obstetric Research Collaborative (STORK) multiple pregnancy cohort

OBJECTIVE

Evidence for the role of first-trimester ultrasound in predicting outcome in twin pregnancies is conflicting. The aim of this study was to determine the association between crown-rump length (CRL) discordance and adverse perinatal outcome in twin pregnancies.

METHODS

This was a retrospective study of all twin pregnancies of known chorionicity from a large regional cohort over a 10-year period. Terminations of pregnancy, cases with fetal or chromosomal abnormalities and monoamniotic pregnancies were excluded. Receiver-operating characteristics (ROC) curve and logistic regression analyses were performed to evaluate the association between CRL discordance and stillbirth, neonatal mortality, intrauterine growth restriction, preterm birth (PTB) at < 34 weeks' gestation and birth weight (BW) and ultrasound estimated fetal weight (EFW) discordance of ≥ 25%.

RESULTS

A total of 2155 twin pregnancies were analyzed, of which 420 were monochorionic (MC) and 1735 dichorionic (DC). There were 42 fetal losses before 24 weeks' gestation and 23 perinatal deaths. CRL discordance was poorly predictive for fetal loss at < 24 weeks (area under the ROC curve (AUC), 0.54 (95% CI, 0.46-0.62)), perinatal loss (AUC, 0.52 (95% CI, 0.41-0.64)), BW discordance (AUC, 0.61 (95% CI, 0.56-0.65)), BW < 5(th) centile (AUC, 0.56 (95% CI, 0.53-0.59)), EFW discordance (AUC, 0.55 (95% CI, 0.51-0.60)) and PTB at < 34 weeks (AUC, 0.50 (95% CI, 0.47-0.54)). Overall mortality was significantly higher in MC (5.0%) than in DC (2.6%) twins (P = 0.016). Logistic regression analysis demonstrated that chorionicity (odds ratio 2.09 (95% CI, 1.06-4.10); P = 0.033) independently contributed to determining mortality, while CRL discordance (P = 0.201) did not. Adjusting for chorionicity did not improve the detection of adverse outcomes using CRL discordance.

CONCLUSION

In the absence of aneuploidy or structural fetal abnormality, CRL discordance is of poor predictive value for adverse perinatal outcome in both MC and DC twin pregnancies. CRL discordance should not be used routinely to identify twin pregnancies at high risk of adverse perinatal outcome.

First-trimester growth discordance and adverse pregnancy outcome in dichorionic twins

OBJECTIVE

To evaluate the association between first-trimester growth discordance and adverse pregnancy outcome in dichorionic twin pregnancies.

METHODS

This was a retrospective cohort study of consecutive women with dichorionic twin pregnancies undergoing an ultrasound scan at our institution between 7 and 14 weeks' gestation. Study groups were defined by the presence or absence of ≥ 11% crown-rump length (CRL) discordance. Pregnancies were excluded if one twin was dead on initial ultrasound or if a termination was performed. The primary outcome was loss of one or both fetuses before 20 weeks. Secondary outcomes included fetal anomaly, fetal demise after 20 weeks (stillbirth), small-for-gestational-age (SGA) at birth, admission to the neonatal intensive care unit (NICU) and preterm delivery before 34 weeks.

RESULTS

Of 805 dichorionic twin pregnancies undergoing first-trimester ultrasound, 610 met the inclusion criteria. Eighty-six had ≥ 11% CRL discordance and, of these, nine (10.5%) had a fetal loss at < 20 weeks (risk ratio (RR) 7.8 (95% CI, 3.0-20.5)). In the surviving pregnancies, an increased risk of fetal anomalies was seen (27.3 vs 17.4%, RR 1.6 (95% CI, 1.1-2.4)). In surviving pregnancies unaffected by anomalies, no increased risk of stillbirth, SGA, NICU admission or delivery before 34 weeks was noted in the discordant group. A post-hoc power analysis demonstrated 80% power to detect a five-fold increase in the risk of stillbirth and 90% power to detect a two-fold increase in other outcomes.

CONCLUSION

Dichorionic pregnancies in which a CRL discordance of at least 11% is noted are at increased risk for fetal anomalies and fetal loss prior to 20 weeks' gestation. However, patients can be reassured that, in the absence of structural anomalies, CRL discordance does not appear to be associated with other adverse outcomes in continuing pregnancies, although the power to detect small increases in the risk of stillbirth may have been limited by the sample size.

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.

Prediction of outcome in dichorionic twin pregnancies at 6-10 weeks' gestation

OBJECTIVE

The objective of the study was to predict the outcome of dichorionic (DC) twin pregnancies at 6-10 weeks' gestation from intertwin discordance in crown-rump length (CRL), heart rate (HR), and gestational sac diameter (GSD).

STUDY DESIGN

Intertwin discordance in CRL, HR, and GSD, was compared in 3 groups of DC twin pregnancies with 2 live embryos at 6-10 weeks. In one group, there were 2 live births (n = 174), in another 1 live birth (n = 24), and in a third group there were no live births (n = 33). Regression analysis was used to determine the predictors of outcome.

RESULTS

Significant contributors to the prediction of 1 intrauterine death were discordance in CRL and GSD. The only predictor of 2 deaths was discordance in CRL. Detection rates of screening for single or double death, at 10% false-positive rate, were 79.2% and 27.3%, respectively.

CONCLUSION

In DC twins, intertwin discordance in CRL and GSD at 6-10 weeks can predict outcome.

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.

Relationship of intertwin crown-rump length discrepancy to chorionicity, fetal demise and birth-weight discordance

OBJECTIVES

To study the frequency and clinical significance of crown-rump length (CRL) discrepancy at 11-14 weeks of gestation in twin pregnancies from an unselected population.

METHODS

This was a retrospective analysis of all twin pregnancies that underwent a routine 11-14-week scan at a large teaching hospital. Fetal loss was defined as fetal demise of one or both twins after 14 weeks.

RESULTS

A total of 507 twin pregnancies were studied; 382 (75.3%) were dichorionic and 125 (24.7%) were monochorionic twins. The discrepancy in CRL was expressed as a percentage of the CRL of the larger twin. The 95(th) and 99(th) centile for CRL discrepancy in twins was 12.2% and 19.3%, respectively. The discrepancy in CRLs in monochorionic and dichorionic twins was not significantly different (Mann-Whitney U = 22,406, P = 0.302). In 39 twin pairs, there was subsequent intrauterine death of one or both twins. Fetal loss was more common in monochorionic twins (24/125) than in dichorionic twins (15/382) (chi-square = 30.9, P < 0.001). In monochorionic twins, the discrepancy in CRLs in the 24 cases with subsequent loss was significantly greater than in the 101 twin pairs with no subsequent loss (Mann-Whitney U = 896, P = 0.048). The discrepancy in CRLs in 15 dichorionic twins with subsequent loss was not different from that in the 367 twins with no loss (Mann-Whitney U = 2116.5, P = 0.129). The CRL discrepancy was significantly correlated with birth-weight discordance in twins (Spearman's rho = 0.128, P = 0.006). However, this was due to a significant correlation in dichorionic twins (Spearman's rho = 0.127, P = 0.016) but not in monochorionic twins (Spearman's rho = 0.145, P = 0.14).

CONCLUSIONS

Fetal loss is significantly associated with discrepancy in CRL at the 11-14-week scan in monochorionic twins and discordance in birth weights is significantly associated with discrepancy in CRL in dichorionic twins. However, intertwin CRL discrepancy is of limited value in screening for these adverse events.