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.

Predicting successful vaginal birth after Cesarean section using a model based on Cesarean scar features examined by transvaginal sonography

OBJECTIVE

To develop a model to predict the success of a trial of vaginal birth after Cesarean section (VBAC) based on sonographic measurements of Cesarean section (CS) scar features, demographic variables and previous obstetric history.

METHODS

We used transvaginal sonography (TVS) to examine the CS scar of 320 consecutive pregnant women. TVS was carried out at 11-13, 19-21 and 34-36 weeks' gestation and prospective measurements of the scar were recorded at each visit according to a defined protocol. A logistic regression model to predict success of VBAC was developed for those patients with a visible scar on ultrasound and only one previous CS. The model was evaluated using bootstrap validation.

RESULTS

There were 131 women with one previous CS and a visible scar, of whom 10 underwent CS prior to labor and were excluded from analysis. Successful VBAC was achieved in 74/121 (61%) of the remaining cases. The prediction model developed was based on patient age, previous history of VBAC, residual myometrial thickness (RMT) and the change in RMT from the first to the second trimester (ΔRMT). The internally validated area under the receiver-operating characteristics curve was 0.62 when measurements of RMT and ΔRMT were excluded, but 0.94 when scar information was incorporated into the model.

CONCLUSION

Ultrasound measurements of CS scar, namely RMT and the change in RMT from the first to the second trimester of pregnancy, when incorporated into a mathematical model, can predict accurately a successful trial of labor in patients with one previous CS.

Changes in Cesarean section scar dimensions during pregnancy: a prospective longitudinal study

OBJECTIVES

To describe changes in Cesarean section (CS) scars longitudinally throughout pregnancy, and to relate initial scar measurements, demographic variables and obstetric variables to subsequent changes in scar features and to final pregnancy outcome.

METHODS

In this prospective observational study we used transvaginal sonography (TVS) to examine the CS scar of 320 consecutive pregnant women at 11-13, 19-21 and 32-34 weeks' gestation. For scars visible on TVS, the hypoechoic part was measured in three dimensions and the residual myometrial thickness (RMT) was also measured. Analyses were carried out using one-way repeated measures ANOVA and mixed modeling. The incidence of subsequent scar rupture was recorded.

RESULTS

The CS scar was visible in 284/320 cases (89%). Concerning length and depth of the hypoechoic part of the scar and RMT, the larger the initial scar measurement, the larger the decrease observed during pregnancy. For the hypoechoic part of the scar, the width increased on average by 1.8 mm per trimester, while the depth and length decreased by 1.8 and 1.9 mm, respectively (false discovery rate P < 0.0001). Mean RMT in the first trimester was 5.2 mm and on average decreased by 1.1 mm per trimester. Two cases (0.62%) of uterine scar rupture were confirmed following a trial of vaginal delivery; these had a mean RMT of 0.5 mm at second scan and an average decrease of 2.6 mm over the course of pregnancy.

CONCLUSION

This study establishes reference data and confirms that the dimensions of CS scars change throughout pregnancy. Scar rupture was associated with a smaller RMT and greater decrease in RMT during pregnancy. There is the potential to test absolute values and observed changes in CS scar measurements as predictors of uterine scar rupture and outcome in trials of vaginal birth after Cesarean section.

Does the presence of a Caesarean section scar affect implantation site and early pregnancy outcome in women attending an early pregnancy assessment unit?

STUDY QUESTION

Are there any differences in the location and distance to the internal cervical ostium of the implantation site of the intrauterine gestation sacs, early pregnancy symptoms and pregnancy outcome at 12 weeks gestation between women with and without a previous Caesarean section (CS)?

SUMMARY ANSWER

The presence of a CS scar affects the site of implantation, and the distance between implantation site and the scar is related to the risk of spontaneous abortion. WHAT IS KNOWN ALREADY?: Little is known about the impact of a CS scar on implantation other than the risk of Caesarean scar pregnancy (CSP). Furthermore, there is a paucity of information on how the proximity of implantation to the scar impacts on pregnancy outcome in the first trimester.

STUDY DESIGN, SIZE, AND DURATION

A prospective cohort study conducted over 15 months in the early pregnancy unit of a London Teaching Hospital. Three hundred and eighty women underwent a transvaginal scan at 6-11 weeks of gestation. A total of 170 women had undergone ≥1 CS, and 210 women had no history of CS.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The 380 women were recruited as consecutive non-selected cases. The relationship between the implanted sac and the CS scar was assessed by quantifiable measures and by subjective impression. Logistic regression analysis was used to determine the influence of the presence of a CS scar on pregnancy outcome. The final outcome of the study was the viability of the pregnancy at 12 weeks.

MAIN RESULTS AND THE ROLE OF CHANCE

Implantation was most frequently posterior (53%) in the CS group and fundal in the non-CS group (42%). Gestation sac implantation was 8.7 mm lower in the CS group (95% confidence interval (CI) 6.7-10.7, P < 0.0001). Presenting complaints differed in women with and without a previous CS (P = 0.0009). More frequent vaginal bleeding [73 versus 55%, difference -18, 95% CI (-27 to -8%] yet no clearly increased spontaneous abortion rates were noted in the CS group compared with the non-CS group (adjusted odds ratio = 1.1, 95% CI 0.6-1.9, P = 0.74). Subjective impression showed that in eight cases the implantation site crossed the scar, seven of which resulted in spontaneous abortion, while the remaining case survived to term complicated by placenta praevia and post-partum haemorrhage. The subjective impression of the examiner was supported by the measurements of distance between implantation site and CS scar.

LIMITATIONS, REASONS FOR CAUTION

A weakness of the study is the lack of a reference technique to verify the location of implantation.

WIDER IMPLICATIONS OF THE FINDINGS

This study adds further support to the hypothesis that the presence of a CS on the uterus impacts on the implantation site of a future pregnancy. The possibility that the CS scar has an impact on the risk of spontaneous abortion should be further studied. Caution must be exercised when implantation occurs near to, and crosses, a CS scar as this is not always associated with the diagnosis of CSP. A potential limitation of the study is that we did not examine scar dimensions and morphology.

Improving strategies for diagnosing ovarian cancer: a summary of the International Ovarian Tumor Analysis (IOTA) studies

In order to ensure that ovarian cancer patients access appropriate treatment to improve the outcome of this disease, accurate characterization before any surgery on ovarian pathology is essential. The International Ovarian Tumor Analysis (IOTA) collaboration has standardized the approach to the ultrasound description of adnexal pathology. A prospectively collected large database enabled previously developed prediction models like the risk of malignancy index (RMI) to be tested and novel prediction models to be developed and externally validated in order to determine the optimal approach to characterize adnexal pathology preoperatively. The main IOTA prediction models (logistic regression model 1 (LR1) and logistic regression model 2 (LR2)) have both shown excellent diagnostic performance (area under the curve (AUC) values of 0.96 and 0.95, respectively) and outperform previous diagnostic algorithms. Their test performance almost matches subjective assessment by experienced examiners, which is accepted to be the best way to classify adnexal masses before surgery. A two-step strategy using the IOTA simple rules supplemented with subjective assessment of ultrasound findings when the rules do not apply, also reached excellent diagnostic performance (sensitivity 90%, specificity 93%) and misclassified fewer malignancies than did the RMI. An evidence-based approach to the preoperative characterization of ovarian and other adnexal masses should include the use of LR1, LR2 or IOTA simple rules and subjective assessment by an experienced examiner.

Imaging in gynecological disease (7): clinical and ultrasound features of Brenner tumors of the ovary

OBJECTIVES

To describe clinical and ultrasound features of Brenner tumors of the ovary.

METHODS

In this retrospective study, the databases of the International Ovarian Tumor Analysis (IOTA) studies and one tertiary center were searched to identify patients who had undergone an ultrasound scan before surgery for an adnexal mass that proved to be a Brenner tumor. Twenty-eight patients with 29 Brenner tumors were included, most of which had been collected within the framework of the IOTA studies. An experienced ultrasound examiner reviewed available ultrasound images (available for 14 tumors), searching for a pattern specific to Brenner tumors.

RESULTS

Most patients were postmenopausal and asymptomatic. Twenty-four (83%) tumors were benign, two (7%) were borderline and three (10%) were malignant. Most benign tumors (17/24, 71%) contained solid components and manifested no or minimal blood flow on Doppler examination (19/24, 79%). Information about calcifications was available for 15 benign tumors, and in 13 (87%) calcifications were present. The five borderline and invasively malignant tumors contained solid components less often than did the benign ones (3/5, 60%) and were more richly vascularized on Doppler examination. Information about calcifications was available for four borderline or invasively malignant tumors, and in three (75%) calcifications were present.

CONCLUSION

We failed to demonstrate ultrasound features specific to Brenner tumors. A prospective study is needed to determine if ultrasound features of calcifications can discriminate between Brenner tumors and other types of ovarian tumor.

Impact of ovulation and implantation timing on first-trimester crown-rump length and gestational age

OBJECTIVE

To determine the impact of ovulation and implantation timing on first-trimester crown-rump length (CRL) and the derived gestational age (GA).

METHOD

One hundred and forty-three women who were trying to conceive were recruited prospectively. The timing of ovulation and implantation and the ovulation to implantation (O-I) interval were established in 101 pregnancies using home urinary tests for luteinizing hormone and human chorionic gonadotropin. In 71 ongoing pregnancies, GA determined by measurement of fetal CRL at 10-14 weeks' gestation was compared with GA based on ovulation and implantation day. First-trimester growth was determined by serial ultrasound scans at 6-7, 8-9 and 10-14 weeks.

RESULTS

The median ovulation and implantation days were 16 and 27, respectively, with an O-I interval of 11 days. GA estimated from CRL at 10-14 weeks was on average 1.3 days greater than that derived from ovulation timing. CRL Z-score was inversely related to O-I interval (ρ= -0.431, P=0.0009). There was no significant relationship between CRL growth rate and the difference between observed CRL and expected CRL based on GA from last menstrual period (ρ=0.224, P=0.08).

CONCLUSIONS

Early implantation leads to a larger CRL and late implantation to a smaller CRL at 10-14 weeks, independent of CRL growth rate. Implantation timing is a major determinant of fetal size at 10-14 weeks and largely explains the variation in estimates of GA in the first trimester derived from embryonic or fetal CRL.

Visibility and measurement of cesarean section scars in pregnancy: a reproducibility study

OBJECTIVES

To evaluate the visibility of cesarean section (CS) scars by transvaginal sonography (TVS) in pregnant women, to apply a standardized approach for measuring CS scars and to test its reproducibility throughout the course of pregnancy.

METHODS

In this observational cohort study, 320 consecutive pregnant women with a previous cesarean delivery were examined to assess scar visibility by two independent examiners. TVS was carried out at 11-13, 19-21 and 34-36 weeks' gestation. A scar was defined as visible when an area of hypoechogenicity representing myometrial discontinuity at the anterior wall of the lower uterine segment was identified. In a subset of patients (n = 111), visible scars were measured by two independent examiners in three dimensions: scar width, depth and length as well as the residual myometrial thickness (RMT). Descriptive analysis was used to assess scar visibility, and the intraclass correlation coefficient (ICC) was calculated to show the strength of absolute agreement between two examiners for scar measurements. For RMT, a cut-off of 2.4 mm was used and measurement agreement was assessed using Cohen's kappa coefficient.

RESULTS

The scar was visible in 284/320 cases (88.8%). Visible scars were significantly associated with anteverted uteri (P < 0.0001). Both examiners had 100% agreement on scar visibility at 12 and 20 weeks' gestation, while agreement was 96% at 34 weeks. The intra- and interobserver agreements for scar measurements were generally good (ICC 0.86 and 0.89, respectively). The kappa coefficient for the RMT was 0.27 in the first trimester, compared with 0.51 and 0.72 in the second and third trimesters, respectively.

CONCLUSION

CS scars remain visible in the majority of women throughout pregnancy. They can be reproducibly measured in three dimensions when assessed by TVS in all trimesters of pregnancy. The agreement between two observers for CS scar measurement can be considered good for the first trimester, compared with relatively moderate agreement for the second and third trimesters.

Clinically oriented three-step strategy for assessment of adnexal pathology

OBJECTIVE

To determine the diagnostic performance of ultrasound-based simple rules, risk of malignancy index (RMI), two logistic regression models (LR1 and LR2) and real-time subjective assessment by experienced ultrasound examiners following the exclusion of masses likely to be judged as easy and 'instant' to diagnose by an ultrasound examiner, and to develop a new strategy for the assessment of adnexal pathology based on this.

METHODS

3511 patients with at least one persistent adnexal mass preoperatively underwent transvaginal ultrasonography to assess tumor morphology and vascularity. They were included in two consecutive prospective studies by the International Ovarian Tumor Analysis (IOTA) group: Phase 1 (1999-2005), development of the simple rules and logistic regression models LR1 and LR2, and Phase 2, a validation study (2005-2007).

RESULTS

Almost half of the cases (43%) were identified as 'instant' to diagnose on the basis of descriptors applied to the database. To assess diagnostic performance in the more difficult 'non-instant' masses, we used only Phase 2 data (n = 1036). The sensitivity of LR2 was 88%, of RMI it was 41% and of subjective assessment it was 87%. The specificity of LR2 was 67%, of RMI it was 90% and of subjective assessment it was 86%. The simple rules yielded a conclusive result in almost 2/3 of the masses, where they resulted in sensitivity and specificity similar to those of real-time subjective assessment by experienced ultrasound examiners: sensitivity 89 vs 89% (P = 0.76), specificity 91 vs 91% (P = 0.65). When a three-step strategy was applied with easy 'instant' diagnoses as Step 1, simple rules where conclusive as Step 2 and subjective assessment by an experienced ultrasound examiner in the remaining masses as Step 3, we obtained a sensitivity of 92% and specificity of 92% compared with sensitivity 90% (P = 0.03) and specificity 93% (P = 0.44) when using real-time subjective assessment by experts in all tumors.

CONCLUSION

A diagnostic strategy using simple descriptors and ultrasound rules when applied to the variables contained in the IOTA database obtains results that are at least as good as those obtained by subjective assessment of a mass by an expert.

Does the presence of a cesarean section scar influence the site of placental implantation and subsequent migration in future pregnancies: a prospective case-control study

OBJECTIVES

To describe placental location in the first trimester of pregnancy and subsequent placental migration in women with and without a history of previous cesarean delivery.

METHODS

In this prospective case-control study, placental location was defined according to five anatomical sites in relation to the endometrial cavity. Placental localization was carried out by transabdominal ultrasound between 11 and 14 weeks' gestation. We recruited 738 women who had undergone one or more previous cesarean sections (CS) and 1856 patients without previous cesarean delivery. Comparative analysis was performed of placental location between the two groups, and to assess placental migration of those classified as being low lying at 20 and 32 weeks' gestation.

RESULTS

There were significant differences in placental location between the two groups. In the CS group there were significantly more posterior and fewer fundal placentae than in the control group (47.2 vs 31.5% and 4.7 vs 15.5%, respectively). The number of previous cesarean deliveries did not have a significant effect on placental location. There was no significant difference in the incidence of anterior low-lying placenta between groups (1.5 vs 0.9%). Placental migration of the low-lying subtypes was similar in both groups (62 vs 64%).

CONCLUSION

The presence of CS scars in the uterus are associated with an increase in the number of posterior placentae and a reduced number that implant in the fundus of the cavity. Migration of a low-lying placenta is independent of the presence of a CS scar in the uterus.

Detection of intracavitary uterine pathology using offline analysis of three-dimensional ultrasound volumes: interobserver agreement and diagnostic accuracy

OBJECTIVE

To estimate the diagnostic accuracy and interobserver agreement in predicting intracavitary uterine pathology at offline analysis of three-dimensional (3D) ultrasound volumes of the uterus.

METHODS

3D volumes (unenhanced ultrasound and gel infusion sonography with and without power Doppler, i.e. four volumes per patient) of 75 women presenting with abnormal uterine bleeding at a 'bleeding clinic' were assessed offline by six examiners. The sonologists were asked to provide a tentative diagnosis. A histological diagnosis was obtained by hysteroscopy with biopsy or operative hysteroscopy. Proliferative, secretory or atrophic endometrium was classified as 'normal' histology; endometrial polyps, intracavitary myomas, endometrial hyperplasia and endometrial cancer were classified as 'abnormal' histology. The diagnostic accuracy of the six sonologists with regard to normal/abnormal histology and interobserver agreement were estimated.

RESULTS

Intracavitary pathology was diagnosed at histology in 39% of patients. Agreement between the ultrasound diagnosis and the histological diagnosis (normal vs abnormal) ranged from 67 to 83% for the six sonologists. In 45% of cases all six examiners agreed with regard to the presence/absence of intracavitary pathology. The percentage agreement between any two examiners ranged from 65 to 91% (Cohen's κ, 0.31-0.81). The Schouten κ for all six examiners was 0.51 (95% CI, 0.40-0.62), while the highest Schouten κ for any three examiners was 0.69.

CONCLUSION

When analyzing stored 3D ultrasound volumes, agreement between sonologists with regard to classifying the endometrium/uterine cavity as normal or abnormal as well as the diagnostic accuracy varied substantially. Possible actions to improve interobserver agreement and diagnostic accuracy include optimization of image quality and the use of a consistent technique for analyzing the 3D volumes.

Do pocket-sized ultrasound machines have the potential to be used as a tool to triage patients in obstetrics and gynecology?

OBJECTIVES

To evaluate the performance and potential impact on patient management of a pocket-sized ultrasound machine (PUM) in comparison to high-specification ultrasound machines (HSUM).

METHODS

This was an observational cohort study with 204 unselected patients in three categories: 1) women with pain and bleeding in early pregnancy (101 patients); 2) women presenting for routine obstetric ultrasound assessment (53 patients); 3) women with possible gynecological pathology (50 patients). Scans were carried out transabdominally using a PUM. A second operator repeated the examination transvaginally and/or transabdominally, depending on the clinical indication, using an HSUM. The operators were blind to each other's findings.

RESULTS

In the early pregnancy group, there was good to very good agreement between the PUM and HSUM for identifying the presence or absence of an embryo, gestational sac, fetal heart motion, pregnancy location and final diagnostic outcome (kappa coefficients, 0.844, 0.843, 0.729, 0.785 and 0.812, respectively; P < 0.0001). In the obstetric ultrasound group there was good to very good agreement for fetal presentation, placental location and placental position (kappa coefficients, 0.924, 0.924 and 0.647, respectively; P < 0.0001). In the gynecological pathology group, there was very good agreement for final diagnosis and type of ovarian mass (low risk or complex) (kappa coefficients, 0.846 and 0.930, respectively; P < 0.0001). For the measured continuous variables, there was close agreement for crown-rump length, mean sac diameter, femur length and mean diameter of an ovarian mass, but not for endometrial thickness. Neither patient demographics (age, body mass index, ethnicity) nor operator experience and familiarity with a PUM had an impact on agreement between the two machines. If a PUM had been the only equipment available for an initial assessment, only two cases would have led to a suboptimal patient management plan.

CONCLUSION

The findings and final diagnosis in the three study groups were similar for both a PUM used transabdominally and an HSUM used transvaginally and/or transabdominally.

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.

Triaging women with ovarian masses for surgery: observational diagnostic study to compare RCOG guidelines with an International Ovarian Tumour Analysis (IOTA) group protocol

OBJECTIVE

To compare guidelines from the Royal College of Obstetricians and Gynaecologists (RCOG) based on the Risk of Malignancy Index (RMI) with a protocol based on logistic regression model LR2 developed by the International Ovarian Tumour Analysis (IOTA) group for triaging women with an ovarian mass as low, moderate, or high risk of malignancy.

DESIGN AND SETTING

Observational diagnostic study conducted between 2005 and 2007 at 21 oncology referral centres, referral centres for ultrasonography and general hospitals.

SAMPLE

In all, 1938 women undergoing surgery for an ovarian mass.

METHODS

RCOG guidelines use the RMI to triage women as low (RMI < 25), moderate (25-250), or high (above >250) risk. The IOTA protocol uses LR2s estimated probability of malignancy (<0.05 indicates low risk, ≥ 0.05 but <0.25 moderate risk, and ≥ 0.25 high risk).

MAIN OUTCOME MEASURE

Percentages of benign, borderline and invasive tumours classified as low, moderate or high risk.

RESULTS

The IOTA and RCOG protocols classified 71.1% and 62.1% of benign tumours as low risk, respectively (difference 9.0; 95% CI 6.2-11.9, P < 0.0001). Of invasive tumours, 88.6% and 73.6% were labelled high risk (difference 15.0; 10.6-19.4, P < 0.0001), and 3.0% and 5.2% were labelled low risk (difference -2.2; -4.6 to 0.2, P = 0.07) respectively by each protocol. Similar results were found after stratification for menopausal status.

CONCLUSIONS

The IOTA protocol was more accurate for triage than the RCOG protocol. The IOTA protocol would avoid major surgery for more women with benign tumours while still appropriately referring more women with an invasive tumour to a gynaecological oncologist.

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.

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.

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.

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.

Umbilical artery pulsatility index and fetal abdominal circumference in isolated gastroschisis

OBJECTIVES

To investigate changes in abdominal circumference (AC) and umbilical artery pulsatility index (UA-PI) with gestation in fetuses with isolated gastroschisis, and to determine whether a relationship exists between UA-PI and fetal AC.

METHODS

Data from 58 pregnancies with isolated gastroschisis diagnosed at between 24 and 36 weeks' gestation were included in the study. Z-scores were calculated with respect to expected UA-PI values in normal pregnancies after log-transformation. AC-Z-scores were calculated with respect to expected size in normal pregnancies according to a standard chart. Functional linear discriminant analysis (FLDA) was applied to generate 50(th), 5(th) and 95(th) percentile curves for changes in both AC and UA-PI with gestational age in fetuses with gastroschisis. These curves were compared with the standard curves, as were the means. UA-PI was also plotted against AC. For this relationship, a robust Spearman correlation coefficient was obtained with FLDA.

RESULTS

In fetuses with gastroschisis, there was a highly significant negative correlation between UA-PI and AC, normalized for gestation using Z-scores (median correlation coefficient, - 0.289; median P = 0.000023). Moreover, compared with standard curves AC was lower and UA-PI higher in the gestational-age range studied. Both the AC and UA-PI curves showed a significantly different rate of change with gestation compared with the normal ranges. The mean values for fetuses with gastroschisis compared with the standard AC and UA-PI range curves were significantly different for AC throughout gestation, and for UA-PI from 32 weeks' gestation.

CONCLUSIONS

In fetal gastroschisis, it is well known that AC tends to be smaller, though UA-PI has not been reported to be abnormal in any consistent way. There is a clear relationship between the fetus's AC for gestation and UA-PI, which is not the case for normally grown fetuses. The data suggest that the growth restriction seen in gastroschisis may be explained by hypoxia, and not simply by the classical explanation of extra-abdominal displacement of the abdominal viscera.