The thymic-thoracic ratio in fetal heart defects: a simple way to identify fetuses at high risk for microdeletion 22q11

Comparative sonographic measurement of the fetal thymus size in singleton and twin pregnancies

OBJECTIVES

The aim of this study was to compare the size of the thymus gland of healthy fetuses in twin and singleton pregnancies using the thymic-thoracic ratio (TTR). As a second objective, the TTR difference between monochorionic and dichorionic twin thymus size was examined. Finally, a possible correlation between thymus size and gestational age (GA) at birth in twin pregnancies was investigated.

METHODS

The TTR was measured retrospectively using the plane of three-vessel view in prenatal ultrasound examinations. Images of 140 healthy twin fetuses (33 monochorionic and 107 dichorionic) between 19+0 and 33+2 weeks of gestation were utilized and compared to 248 healthy singleton fetuses.

RESULTS

A significant difference in thymus size could be observed between healthy fetuses from singleton and twin pregnancies (p<0.001). Thymus size in monochorionic and dichorionic fetuses did not differ. If only comparing fetuses after 37+0 weeks of pregnancy, the difference in the TTR was no longer significant. In addition, an association between prematurity and larger thymus was established. However, the effect size of this association was small.

CONCLUSIONS

The results indicate that factors related to preterm birth, rather than the number of fetuses, are likely to influence the TTR. Utilizing fetal thymus size in ultrasound screening may hold potential for predicting adverse events like preterm birth in both singleton and twin pregnancies, but only in addition to other variables.

Ultrasonographic Evaluation of the Fetal Thymic-Thoracic Ratio in Pregnant Women With Asthma

PURPOSE

To investigate the thymic-thoracic ratio (TTR) in pregnant women with asthma to determine whether fetal thymus size is affected in this condition.

METHODS

A total of 139 patients, 69 patients diagnosed with asthma and 70 controls were prospectively included in the study at a single tertiary center. Eighteen of the patients diagnosed with asthma experienced at least one asthma attack, while 51 patients did not have any asthma attacks during pregnancy. TTR was calculated from the anterior-posterior dimensions of the thymus and intrathoracic mediastinal measurements.

RESULTS

TTR was found to be statistically significantly lower in patients with asthma compared to the controls (p < 0.001). The rate of neonatal intensive care unit admission was higher and the TTR value was lower among the cases presenting with an asthma attack during pregnancy compared to patients without asthma attack and controls (p = 0.043 and p = 0.001, respectively). A statistical difference was found between patients with and without asthma attacks regarding the use of medication for asthma (p < 0.05).

CONCLUSION

The fetal thymus has been found to be affected in patients with asthma. The TTR is lower in patients who have asthma attacks during pregnancy and in patients taking medication for treatment, which may be related to chronic inflammatory process as well as to the use of exogenous steroids.

Assessment of fetal thymus size in pregnancies of underweight women

OBJECTIVES

The aim of this study was to compare the fetal thymus size measured in the second and third trimester of pregnancy in underweight women and women with normal weight. We hypothesized that the low maternal weight would affect the fetal thymus size, as maternal health and nutrition during pregnancy affect fetal development, including that of the fetal immune system.

METHODS

The fetal thymus size was retrospectively assessed by determining the thymic-thoracic ratio in 77 pregnancies of underweight women (study group) and 85 pregnancies of women with normal weight (control group) between the 19th and 34th week of pregnancy. The anteroposterior thymic diameter and the intrathoracic mediastinal diameter were measured in the three-vessel view acquired from routine echocardiograms. The thymic-thoracic ratio was calculated by dividing the anteroposterior thymic diameter with the intrathoracic mediastinal diameter. Additionally, we compared the descriptive data between the two groups, such as gestational age at screening and at birth, birth weight, umbilical artery pH and APGAR-score after 5 min.

RESULTS

The mean fetal thymic-thoracic ratio in underweight women was not significantly different to that in normal weight pregnancies (0.374 vs. 0.363). However, the average gestational age at birth, birth weight and APGAR-score at birth were lower in the group of underweight women.

CONCLUSIONS

There is no evidence that low maternal weight influences fetal thymus size during pregnancy. The differences we observed concerning fetal weight at birth, gestational age at delivery, APGAR-Score and birth weight percentile confirm the results of previous studies.

The Effects of Maternal Subclinical Hypothyroidism on Fetal Thymus Size: A Prospective Study

Objective: This study investigated the impact of maternal subclinical hypothyroidism on fetal thymus size and development and explored how inadequate thyroid hormone production in pregnant women affects the fetal thymus. Methods: Conducted at the Giresun Obstetrics, Gynecology, and Pediatrics Training and Research Hospital, this case-control study involved 86 pregnant women, 43 with hypothyroidism and 43 without. Maternal thyroid function was assessed using TSH and free T4 levels, and fetal thymus size and thymus-thorax ratio were measured using ultrasound. Exclusion criteria were chronic hypertension, gestational hypertension or eclampsia, multiple pregnancies, infectious diseases, renovascular diseases, diagnosed with hypothyroidism prior to pregnancy and other endocrine disorders, fetal cardiac diseases, and morbid obesity. Data collected included maternal age, gestational week, number of pregnancies, parity, number of living children, thyroid-stimulating hormone (TSH) and Free thyroxine 4 (T4) levels, and fetal thymus measurements (transverse diameter and thymus/thorax ratio). Statistical analyses were performed using the Mann-Whitney U test and logistic regression analysis. The relationships between TSH, thymus diameters, thorax diameters, and the thymus-thorax ratio were evaluated using Spearman's correlation coefficient. Results: The thymus-thorax ratio was significantly reduced in the hypothyroid group (p = 0.003). Logistic regression analysis identified TSH as an independent risk factor for a low thymus-thorax ratio, with each unit increase in TSH associated with a 1.345-fold higher likelihood of having a low thymus-thorax ratio. A significant negative correlation was found between TSH levels and the TTR ratio (Spearman's correlation coefficient r = -0.338, p = 0.001). Conclusions: An association was identified between maternal TSH levels and the thymus-thorax ratio, with increasing TSH levels correlating with a decrease in the thymus-thorax ratio. Regular monitoring of thyroid hormone levels during pregnancy and appropriate replacement treatment in cases of deficiency are crucial for optimal fetal thymus development. Further multicenter studies are needed to confirm these findings and investigate the long-term implications of altered fetal thymus development.

Assessment of the fetal thymic-thoracic ratio in pregnant women with intrahepatic cholestasis: a prospective case-control study

OBJECTIVES

To examine the fetal thymic-thoracic ratio (TTR) in intrahepatic cholestasis of pregnancy (ICP).

METHODS

This prospective case-control study was conducted in a single tertiary center. The sample consisted of 86 pregnant women at 28-37 weeks of gestation, including 43 women with ICP and 43 healthy controls. TTR was calculated for each patient using the anterior-posterior measurements of the thymus and intrathoracic mediastinal measurements.

RESULTS

The median TTR value was found to be smaller in the ICP group compared to the control group (0.32 vs. 0.36, p<0.001). The ICP group had a greater rate of admission to the neonatal intensive care unit (NICU) (p<0.001). Univariate regression analysis revealed that lower TTR values increased the possibility of NICU admission six times (95 % confidence interval: 0.26-0.39, p=0.01). A statistically significant negative correlation was detected between TTR and the NICU requirement (r: -0.435, p=0.004). As a result of the receiver operating characteristic analysis, in predicting NICU admission, the optimal cut-off value of TTR was determined to be 0.31 with 78 % sensitivity and 67 % specificity (area under the curve=0.819; p<0.001).

CONCLUSIONS

We determined that the fetal TTR may be affected by the inflammatory process caused by the maternal-fetal immune system and increased serum bile acid levels in fetal organs in the presence of ICP. We consider that TTR can be used to predict adverse pregnancy outcomes in patients with ICP.

Prenatal cardiac findings and 22q11.2 deletion syndrome: Fetal detection and evaluation

Clinical features of 22q11.2 microdeletion syndrome (22q11.2DS) are highly variable between affected individuals and frequently include a subset of conotruncal and aortic arch anomalies. Many are diagnosed with 22q11.2DS when they present as a fetus, newborn or infant with characteristic cardiac findings and subsequently undergo genetic testing. The presence of an aortic arch anomaly with characteristic intracardiac anomalies increases the likelihood that the patient has 22q11.2 DS, but those with an aortic arch anomaly and normal intracardiac anatomy are also at risk. It is particularly important to identify the fetus at risk for 22q11.2DS in order to prepare the expectant parents and plan postnatal care for optimal outcomes. Fetal anatomy scans now readily identify aortic arch anomalies (aberrant right subclavian artery, right sided aortic arch or double aortic arch) in the three-vessel tracheal view. Given the association of 22q11.2DS with aortic arch anomalies with and without intracardiac defects, this review highlights the importance of recognizing the fetus at risk for 22q11.2 deletion syndrome with an aortic arch anomaly and details current methods for genetic testing. To assist in the prenatal diagnosis of 22q11.2DS, this review summarizes the seminal features of 22q11.2DS, its prenatal presentation and current methods for genetic testing.

Enlarged cavum septum pellucidum and small thymus as markers for 22q11.2 deletion syndrome

BACKGROUND

Enlarged cavum septum pellucidum (CSP) and hypoplastic thymus are proposed extra-cardiac fetal markers for 22q11.2 deletion syndrome. We sought to determine if they were part of the fetal phenotype of our cohort of fetuses with 22q11.2 deletion syndrome.

METHODS

Case-control study of fetuses evaluated from 2016 to 2022. The study group included fetuses with laboratory confirmation of 22q11.2 deletion syndrome. The control group included pregnancies with conotruncal cardiac anomalies with normal microarray as well as structurally normal fetuses with normal microarray. The CSP and thymus were routinely measured during anatomical ultrasound in all patients at their initial visit at 27.1 ± 4.7 weeks. The CSP and thymus measurements were classified as abnormal if they were >95% or <5% for gestational age, respectively. The groups were compared using analysis of variance or Kruskal-Wallis for continuous variables and Fisher's exact test for categorical variables. Logistic regression was performed, and a Receiver Operating Characteristic (ROC) curve was constructed.

RESULTS

We identified 47 fetuses with 22q11.2 deletion syndrome and compared them to 47 fetuses with conotruncal anomalies and normal microarray and 47 structurally normal fetuses with normal microarray. 51% (24/47) of fetuses with 22q11.2 deletion syndrome had an enlarged CSP compared to 6% (3/47) of fetuses with a conotruncal anomaly and normal microarray and none of the structurally normal fetuses (p < 0.001). Of the fetuses with 22q11.2 deletion syndrome, 83% (39/47) had a hypoplastic or absent thymus compared to 9% (4/47) of the fetuses with a conotruncal anomaly and normal microarray and none of the structurally normal fetuses (p < 0.001). 87% (41/47) of the fetuses with 22q11.2 deletion syndrome had conotruncal cardiac anomalies. Logistic regression revealed that both enlarged CSP and hypoplastic/absent thymus were associated with 22q11.2 deletion syndrome. The area under the ROC curve for the two markers was 0.94.

CONCLUSION

An enlarged CSP and hypoplastic/absent thymus appear to be part of the fetal phenotype of 22q11.2 deletion syndrome. These markers are associated with conotruncal anomalies in the setting of 22q11.2 deletion syndrome but not in normal controls or fetuses with conotruncal defects and normal microarrays.

Evaluation of fetal thymus size in maternal autoimmune diseases: systemic lupus erythematosus, Sjögren's syndrome and antiphospholipid antibody syndrome

PURPOSE

To investigate the effect of inflammation on the fetal thymus-thoracic ratio (TTR) in pregnant women with systemic lupus erythematosus (SLE), Sjögren's syndrome (SS) and antiphospholipid antibody syndrome (APS).

METHOD

This prospective case-control study included 45 pregnant women with SLE, SS, and APS and 90 gestational age-matched healthy pregnant women between 24 and 37 gestational weeks. The ratio of the anteroposterior fetal thymus length to the transverse mediastinal length was calculated as the TTR in the study groups.

RESULTS

Fetal TTR was significantly lower in the case group (p < 0.001). Fetal TTR in the APS group was significantly lower than SS group (p = 006). The patients using hydroxychloroquine (HCQ) had significantly higher fetal TTR compared to patients not using HCQ (p = 0.004). A moderate negative correlation was found between the disease duration and fetal TTR (r =  - 0.552, p < 0.001). In predicting admission to the neonatal intensive unit care (NICU), a value of 0.31 was found for the fetal TTR with a sensitivity of 83.3% and a specificity of 69% CONCLUSION: Maternal inflammation in pregnancies with autoimmune diseases may affect the intrauterine milieu of the fetus and cause a lower fetal TTR. Additionally, the lower level of fetal TTR may be more effective and beneficial for the clinician if combined with other risk factors in predicting NICU admission.

Decreased fetal thymus size in pregnancies after assisted reproductive technologies

OBJECTIVE

To compare the size of the fetal thymus, using both fetal thymic-thoracic ratio and fetal thymus transverse diameter values in Assisted reproductive technologies (ART) or naturally conceived pregnancies.

METHODS

In this retrospective study, fetal thymic-thoracic ratio and fetal thymus transverse diameter were evaluated in 204 pregnant women. Patients were examined in two groups. The study included 58 Intracytoplasmic sperm injection (ICSI) patients (study group) and 146 healthy pregnant women (control group).

RESULTS

Fetal thymic-thoracic ratio in ART pregnancies were found to be statistically significantly lower than that of the control group (p = .001). Also, the fetal thymus transverse diameter value was found to be statistically significantly lower in ART pregnancies compared to that of the control group (p = .001).

CONCLUSIONS

The size of the fetal thymus, manifested with a decrease in both fetal thymic-thoracic ratio and thymus transverse diameter values, decreased in ART pregnancies.

Small fetal thymus and adverse perinatal outcome in maternal vasculitis: A prospective case-control study

BACKGROUND

Ultrasonographic evaluation of fetal thymus size may be used to predict the adverse perinatal outcome in pregnant women with vasculitis.

AIM

To compare fetal thymus size in pregnant women with vasculitis and healthy pregnant women and to evaluate whether fetal thymus size predicts the adverse perinatal outcome.

METHODS

Twenty-two pregnant women with previously diagnosed vasculitis, 18 of them with Behçet's disease, three with Takayasu arteritis, and one with Wegener's granulomatosis, were included in the case group. The control group comprised 66 healthy pregnant women whose gestational ages matched the case group. Thymic thoracic ratio (TTR) was measured to assess fetal thymus size in the view of three vessels and trachea.

RESULTS

In the case group, fetal TTR was significantly lower (0.32 ± 0.03 vs. 0.36 ± 0.02, p = < 0.001). Fetal TTR was significantly lower in those using prednisone than those not (p = .001) in the case group. There was no significant difference in fetal TTR between colchicine used and not used (p = .078) in the case group. Also, for the TTR, a sensitivity of 100% and a specificity of 92% were achieved with a cut-off value of 0.33 for predicting adverse perinatal outcomes.

CONCLUSION

The fetuses of pregnant women with maternal vasculitis had a smaller TTR. The small fetal thymus may alert clinicians to possible adverse perinatal outcomes and, with other supporting risk factors, may help predict adverse perinatal outcomes in pregnant women with vasculitis.

Assessment of fetal thymus size in pregnant women with rheumatic diseases: A case-control study

PURPOSE

To investigate the fetal thymic-thoracic ratio (TT-ratio) in pregnancies diagnosed with rheumatoid arthritis (RA) and ankylosing spondylitis (AS).

METHODS

Thirty-two pregnant women with rheumatic disease and 96 low-risk pregnant women between 20 and 37 weeks were included in the study. Three control patients were randomly selected for each study patient. TT-ratio was calculated by measuring the anterior-posterior diameter of the thymus and the intrathoracic mediastinal diameter. Data were compared between the study group, including RA and AS, and the control group.

RESULTS

Thirty-two pregnant women with arthritis, 19 diagnosed with RA and 13 with AS, were evaluated. The mean value of the study group TT-ratio was 0.33; control group, 0.36; a statistically significant difference was found (p < 0.001). Perinatal outcomes were not different when compared with control patients. There was a negative correlation between disease duration, maternal C-reactive protein, erythrocyte sedimentation rate, and TT-ratio.

CONCLUSION

This is the first study to prospectively evaluate the fetal TT-ratio in patients with RA and AS. Systemic inflammation appears to affect fetal thymus size. Appropriate management of maternal rheumatic diseases is essential for developing the thymus, a vital immune system component.

Fetal Thymus Size at 19-22 Weeks of Gestation: A Possible Marker for the Prediction of Low Birth Weight?

INTRODUCTION

The purpose was to compare thymus size measured during second trimester screening of fetuses who were subsequently small for gestational age at birth (weight below 10th percentile, SGA group) with fetuses with normal birth weight (control group). We hypothesized that measuring the fetal thymic-thoracic ratio (TT-ratio) might help predict low birth weight.

METHODS

Using three-vessel view echocardiograms from our archives, we measured the anteroposterior thymus size and the intrathoracic mediastinal diameter to derive TT-ratios in the SGA (n = 105) and control groups (n = 533) between 19+0 and 21+6 weeks of gestation. We analyzed the association between TT-ratio and SGA adjusted to the week of gestation using logistic regression. Finally, we determined the possible TT-ratio cut-off point for discrimination between SGA and control groups by means of receiver operating characteristics (ROC) curve analysis.

RESULTS

The TT-ratio was significantly higher in the SGA group than in the control group (p < 0.001). An increase of the TT-ratio by 0.1 was associated with a 3.1-fold increase in the odds of diagnosing SGA. We determined that a possible discrimination cut-off point between SGA and healthy controls was achieved using a TT-ratio of 0.390 (area under the ROC curve 0.695).

CONCLUSION

An increased TT-ratio may represent an additional prenatal screening parameter that improves the prediction of birth weight below the 10th percentile. Prospective studies are now needed to evaluate the use of fetal thymus size as predictive parameter for adverse fetal outcome.

[Prenatally detected aortic arch anomalies and their consequences after birth]

INTRODUCTION

Aortic arch anomalies are frequently associated with cardiac or extracardiac malformations, chromosomal aberrations and postpartum esophagus/trachea compression.

OBJECTIVE

We aimed to establish the prevalence of associated cardiac and extracardiac malformations, the frequency of chromosomal aberrations in fetuses with the diagnosis of aortic arch anomalies and to assess the pregnancy and the postnatal outcome.

METHOD

Retrospective cohort study of all fetuses with aortic arch anomalies and genetic diagnosis in a tertiary referral obstetric and fetal cardiology centre between 2016 and 2020. Postpartum data were collected within 24 months after birth.

RESULTS

In a cohort of 11.380 pregnant women, the prevalence of aortic arch anomalies was 0.25%. Among 28 cases of right aortic arch anomalies, in 27 fetuses prenatal genetic diagnosis was available. We diagnosed 4 fetuses with mirror-image branching (right sided V-sign) and 23 fetuses with U-sign (4 fetuses with complete double aortic arch). 18 cases (66%) were isolated. Associated anomalies were cardiac in 3 cases and extracardiac in 7 cases (33%). The most frequent cardiac anomaly was tetralogy of Fallot (2/27), the extracardiac anomalies were thymus hypoplasia, single umbilical artery and subclavian artery malformations. In 1 case (3.7%), fluorescent in situ hybridization diagnosed 22q11.2 microdeletion. 75% of fetuses with right sided V-sign were associated with conotruncal malformations. Pregnancy and postpartum outcome were known in 24 pregnancies. Postnatal diagnosis was different from prenatal in 2 cases, the concordance rate was 93%. Isolated cases resulted in live birth in 17/18 pregnancies (93%). The frequency of postpartum trachea/esophagus compression was 42,9% (9 cases) due to vascular ring, in 6 children (28,6%) operation was necessary.

CONCLUSION

Fetal aortic arch anomalies are multidisciplinary diseases to be diagnosed by proper prenatal ultrasound examination. Associated fetal anomalies necessitate extended obstetric and cardiac sonography, invasive prenatal testing should be offered, and thorough postnatal long-term follow-up is recommended. Orv Hetil. 2023; 164(28): 1111-1120.

Clinical Course and Outcome of Prenatally Detected 22q11.2 Deletion Syndrome-A Retrospective Analysis

The 22q11.2 deletion syndrome (22q11.2 DS) is known as the most common microdeletion syndrome. Due to its variable clinical phenotype, prenatal diagnosis can be challenging. The aim of this retrospective study was to evaluate the clinical course and pregnancy outcome of cases with prenatally diagnosed 22q11.2 deletion syndrome (DS) as well as to evaluate the role of prenatal magnetic resonance imaging (MRI) and postmortem examination. In total, 21 cases who underwent prenatal ultrasound examination and pregnancy care at the Department of Obstetrics and Gynecology at the Medical University of Vienna between 2012 and 2022 were included. The majority of the cases were genetically diagnosed using fluorescent in situ hybridization (FISH). The median gestational age (GA) at genetic diagnosis was 23.0 weeks (IQR 21.4-24.8 weeks). CHDs were detected in all fetuses and the most common extracardiac manifestation was thymus hypo/aplasia followed by genitourinary anomalies. Prenatal magnetic resonance imaging (MRI) revealed additional diagnostic information in three of ten cases. Overall, 14 patients opted for drug-induced TOP, of which 9 cases had a feticide prior to the induction of labor. The majority of craniofacial malformations were only detected by autopsy. In conclusion, the majority of cases prenatally diagnosed with 22q11.2 DS had an absent or hypoplastic thymus noted antenatally in addition to the detected CHD, and almost half of the cases had another extracardiac malformation of predominantly genitourinary origin. Furthermore, prenatal MRIs confirmed previously detected malformations, but only provided additional diagnostic information in three out of ten cases, whereas postmortem examination diagnosed most of the craniofacial anomalies and should always be conducted, serving as an important quality indicator for prenatal imaging.

Fetal thymic-thoracic ratio in pregnancies with familial Mediterranean fever

OBJECTIVE

To investigate the thymic-thoracic ratio (TTR) in fetuses of pregnant women with familial Mediterranean fever (FMF).

STUDY DESIGN

This prospective case-control study was conducted with 43 pregnant women diagnosed with FMF and 43 gestational age-matched healthy controls. Pregnant women between 28 and 40 weeks who applied for antenatal care were included in the study. Healthy pregnant women whose age and gestational week matched were defined as the control group.

RESULTS

TTR was significantly lower in the FMF group compared to the control group. The mean TTR value was 0.34 ± 0.03 in the FMF group and 0.36 ± 0.02 in the control group (p < 0.001). TTR was significantly lower in those with FMF duration of ten years or more than those with FMF of less than ten years (p < 0.001). In addition, pregnant women who had an attack during pregnancy had lower TTR (p < 0.001). TTR was significantly associated with white blood cell count, neutrophil count, monocyte count, platelet count, mean platelet volume, C-reactive protein, red cell distribution width, and platelet‑to‑lymphocyte ratio.

CONCLUSION

Besides the inflammation during the FMF attacks, the ongoing subclinical inflammation between the attacks might affect the fetal thymus size. Since TTR is an easily applicable method, it can be used to evaluate fetal inflammation.

Prenatal Screening and Diagnostic Considerations for 22q11.2 Microdeletions

Diagnosis of a chromosome 22q11.2 microdeletion and its associated deletion syndrome (22q11.2DS) is optimally made early. We reviewed the available literature to provide contemporary guidance and recommendations related to the prenatal period. Indications for prenatal diagnostic testing include a parent or child with the 22q11.2 microdeletion or suggestive prenatal screening results. Definitive diagnosis by genetic testing of chorionic villi or amniocytes using a chromosomal microarray will detect clinically relevant microdeletions. Screening options include noninvasive prenatal screening (NIPS) and imaging. The potential benefits and limitations of each screening method should be clearly conveyed. NIPS, a genetic option available from 10 weeks gestational age, has a 70-83% detection rate and a 40-50% PPV for most associated 22q11.2 microdeletions. Prenatal imaging, usually by ultrasound, can detect several physical features associated with 22q11.2DS. Findings vary, related to detection methods, gestational age, and relative specificity. Conotruncal cardiac anomalies are more strongly associated than skeletal, urinary tract, or other congenital anomalies such as thymic hypoplasia or cavum septi pellucidi dilatation. Among others, intrauterine growth restriction and polyhydramnios are additional associated, prenatally detectable signs. Preconception genetic counselling should be offered to males and females with 22q11.2DS, as there is a 50% risk of transmission in each pregnancy. A previous history of a de novo 22q11.2 microdeletion conveys a low risk of recurrence. Prenatal genetic counselling includes an offer of screening or diagnostic testing and discussion of results. The goal is to facilitate optimal perinatal care.

Finding the best method for screening for gestational diabetes mellitus: fetal thymic-thoracic ratio or fetal thymus transverse diameter

OBJECTIVE

The aim of this study was to compare the efficiency of fetal thymic-thoracic ratio and fetal thymus transverse diameter measurements in gestational diabetes mellitus.

METHODS

Fetal thymic-thoracic ratio and fetal thymus transverse diameter were assessed in 360 pregnant women. Patients were examined in two groups: 180 gestational diabetes mellitus (study group) and 180 healthy pregnant women (control group).

RESULTS

There were no statistically significant differences between the cases with gestational diabetes mellitus and the control group in terms of fetal thymus transverse diameter; however, the fetal thymic-thoracic ratio was found to be significantly lower in cases with gestational diabetes mellitus compared to that in the control group (p<0.001).

CONCLUSION

The fetal thymic-thoracic ratio is superior to the fetal thymus transverse diameter in evaluating the fetal thymus size.

Utility of Measuring Fetal Cavum Septum Pellucidum (CSP) Width During Routine Obstetrical Ultrasound for Improving Diagnosis of 22q11.2 Deletion Syndrome: A Case-Control Study

Objective

To evaluate the utility of measuring fetal cavum septum pellucidum (CSP) width during routine, mid-pregnancy ultrasound for improving diagnosis of 22q11.2 deletion syndrome amongst fetuses with and without conotruncal anomalies.

Patients and Methods

This was a retrospective case-control study (2005–2016). Fetuses and newborns with 22q11.2 deletion and/or conotruncal cardiac anomalies were identified using a regional, clinical database. A control group was assembled in a 2:1 ratio to create three groups for comparison: i) 22q11.2 deletion syndrome; ii) isolated conotruncal anomalies; and iii) controls. Eligibility was restricted to those with stored ultrasound images between 18–22 weeks’ gestation and a minimum biparietal diameter of 40 mm. Post-processing measurement of CSP width was performed in a standardized fashion by two blinded and independent study personnel. Descriptive and inferential statistics, regression modeling, and receiver operator curves (ROC) were used to compare outcomes between groups and evaluate sensitivity/specificity of CSP width as a marker of 22q11.2 deletion syndrome.

Results

Twenty-nine cases of 22q11.2 deletion and 64 cases of isolated conotruncal anomalies were matched to 186 healthy controls. Cases with 22q11.2 deletion syndrome had significantly larger CSP widths (5.36 mm; SD=1.2) compared to those with isolated conotruncal anomalies (3.75 mm; SD=1.11) and healthy controls (2.93 mm; SD=0.57; p<0.0001). There was no difference in CSP width amongst those with 22q11.2 deletion irrespective of the presence/absence of a conotruncal anomaly (p=0.362), or by type of conotruncal anomaly (p=0.211). Using a CSP width cutoff >4.3 mm, fetuses with 22q11.2 deletion can be accurately identified with good sensitivity (89.7%) and specificity (84%).

Conclusion

Fetuses with 22q11.2 deletion syndrome have dilated CSPs when compared to those with isolated conotruncal anomalies or controls. Because CSP dilation can be evaluated during routine mid-pregnancy ultrasound using standard images of the fetal head, measurement could easily be incorporated to enhance prenatal diagnosis of this phenotypically diverse condition.

Decreased fetal thymus size at 24 weeks gestation by ultrasound measurement in gestational diabetes mellitus fetal thymus examination for diabetes

AIM

This study aimed to evaluate the difference in fetal thymus diameter, which we measured ultrasonographically, between the healthy pregnant group and the pregnant group with gestational diabetes.

METHOD

Fetal thymus and thymus/thorax ratio parameters were assessed in this case-control study. Patients were examined in two groups. They included 49 diabetics (study group) women and 71 nondiabetic (control group). We performed a binary logistic regression analysis to determine the predictive value of ultrasonographic measurements. We completed the receiver curve characteristic analysis to evaluate the cut-off thymus diameter.

RESULTS

The median age of pregnant women was 27. Thymus diameter and thymus-thorax ratio were smaller in fetuses of diabetic mothers than in the nondiabetic group (p <0.05). Thymus diameter was found to be more predictive of gestational diabetes prediction (p: 0.019). There was no correlation between fasting blood glucose and thymus diameter.

CONCLUSION

Decreased fetal thymus anterior-posterior diameter seems to be associated with diabetic pregnancy.

Ultrasonographic evaluation of the fetal thymic-thoracic ratio and its association with conotruncal heart defects

OBJECTIVE

To evaluate the thymic-thoracic ratio (TT ratio) on fetal ultrasound and its association with conotruncal heart defects.

METHODS

A case control study was carried out to retrospectively assess the TT ratio on fetal echocardiograms performed between 19 and 39 weeks of gestation, showing congenital heart defects, from January to December 2018. The control group was comprised of fetuses with no echocardiogram evidence of congenital cardiac malformations. Cases of multiple pregnancies and patients where the TT ratio could not be established have been excluded.

RESULTS

A total of 338 pregnancies have been analysed. Fifty-two pregnancies were diagnosed with fetal heart defects (15%), 17 of which showed conotruncal heart defects (32.7%). The TT ratio in normal fetuses (286 pregnancies) increased with gestational age, and had an average of 0.43 ± 0.06. Compared to the control group (normal fetuses), fetuses with conotruncal heart defects had significantly lower mean TT ratio (0.33 ± 0.07). Those that were diagnosed with nonconotruncal heart defects did not show any statistically significant difference in the TT ratios compared with the control group (0.40 ± 0.09 vs. 0.43 ± 0.06, respectively).

CONCLUSION

The TT ratio was significantly lower in fetuses with conotruncal heart defects compared with both the control group (normal fetuses) and the fetuses with nonconotruncal heart defects.

Assessment of the fetal thymus gland: Comparing MRI-acquired thymus volumes with 2D ultrasound measurements

OBJECTIVES

The fetal thymus gland has been shown to involute in response to intrauterine infection, and therefore could be used as a non-invasive marker of fetal compartment infection. The objective of this study was to evaluate how accurately 2D ultrasound-derived measurements of the fetal thymus reflect the 3D volume of the gland derived from motion corrected MRI images.

STUDY DESIGN

A retrospective study was performed using paired ultrasound and MRI datasets from the iFIND project (http://www.ifindproject.com). To obtain 3D volumetry of the thymus gland, T2-weighted single shot turbo spin echo (ssTSE) sequences of the fetal thorax were acquired. Thymus volumes were manually segmented from deformable slice-to-volume reconstructed images. To obtain 2D ultrasound measurements, previously stored fetal cine loops were used and measurements obtained at the 3-vessel-view (3VV) and 3-vessel-trachea view (3VT): anterior-posterior diameter (APD), intrathoracic diameter (ITD), transverse diameter (TD), perimeter and 3-vessel-edge (3VE). Inter-observer and intra-observer reliability (ICC) was calculated for both MRI and ultrasound measurements. Pearson correlation coefficients (PCC) were used to compare 2D-parameters with acceptable ICC to TV.

RESULTS

38 participants were identified. Adequate visualisation was possible on 37 MRI scans and 31 ultrasound scans. Of the 30 datasets where both MRI and ultrasound data were available, MRI had good interobserver reliability (ICC 0.964) and all ultrasound 3VV 2D-parameters and 3VT 3VE had acceptable ICC (>0.75). Four 2D parameters were reflective of the 3D thymus volume: 3VV TD r = 0.540 (P = 0.002); 3VV perimeter r = 0.446 (P = 0.013); 3VV APD r = 0.435 (P = 0.110) and 3VT TD r = 0.544 (P = 0.002).

CONCLUSIONS

MRI appeared superior to ultrasound for visualization of the thymus gland and reproducibility of measurements. Three 2D US parameters, 3VV TD, perimeter and 3VT APD, correlated well with TV. Therefore, these represent a more accurate reflection of the true size of the gland than other 2D measurements, where MRI is not available.

Polyhydramnios is associated with postnatal dysphagia determining short-term prognosis of the newborn with 22q11.2 deletion syndrome - A case series analysis

OBJECTIVE

We experienced a case of 22q11.2 deletion syndrome (22qDS), with severe polyhydramnios, and dysphagia, which prompted us to review prognosis in neonates with 22qDS, with a focus on dysphagia.

CASE REPORT

A patient was referred to our hospital at 35 gestational weeks because of polyhydramnios. After amniotic fluid reduction, labor was induced at 38 weeks. The neonate had serious dysphagia, and 22qDS was diagnosed postnatally by fluorescent in situ hybridization analysis. This prompted a retrospective analysis of 9 cases with 22qDS experienced in our facility. Three out of these nine cases showed polyhydramnios, and had severe dysphagia postnatally. In total, 4 cases had dysphagia, while mortality was observed in 2 of these 4 cases. Additionally, 5 cases without dysphagia had normal development and no major complications.

CONCLUSION

Polyhydramnios associated with postnatal dysphagia might be a risk factor related to short-term prognostic outcomes in newborns with 22qDS.

Correlation of first-trimester thymus size with chromosomal anomalies

OBJECTIVES

The aim of this study was to investigate the correlation between fetal thymus size measured during first-trimester screening and chromosomal anomalies.

METHODS

This study is a retrospective evaluation, in which the anterior-posterior diameter of the thymus in a midsagittal plane was measured in first-trimester ultrasound between 11⁺⁰ and 13⁺⁶ weeks of gestation in 168 fetuses with chromosomal anomalies (study group) and 593 healthy fetuses (control group). The included cases were subdivided into six groups: (1) trisomy 21, (2) trisomy 18, (3) trisomy 13, (4) Turner syndrome, (5) triploidy and (6) normal controls. Thymus size measurements were adjusted to the week of gestation, which was determined by ultrasound using crown-rump-length (CRL), by calculating a ratio between CRL and thymus size (CRL-thymus-ratio). Each study group was compared with the control group separately.

RESULTS

Thymus size in fetuses affected by trisomy 18 or trisomy 13 was noticeably smaller compared to the control group (1.4 mm [1.3, 1.5] and 1.3 mm [1.2, 1.4] vs. 1.8 mm [1.6, 2.1]; all p<0.001; respectively). The thymus size of fetuses with trisomy 21 and Turner syndrome did not differ from healthy fetuses. Between the CRL-thymus-ratios of the separate study groups no statistically noticeable differences could be found.

CONCLUSIONS

Fetal thymus size appeared to be smaller in pregnancies affected by trisomy 18 and trisomy 13. The predictive value of fetal thymus size in first-trimester screening should be evaluated prospectively.

Prenatal sonographic and cytogenetic/molecular findings of 22q11.2 microdeletion syndrome in 48 confirmed cases in a single tertiary center

PURPOSE

We aimed to present the fetal ultrasound, cytogenetic/molecular testing and postmortem or postnatal clinical findings of cases with 22q11.2DS diagnosed prenatally.

MATERIALS AND METHODS

A retrospective medical record review of 48 prenatal cases diagnosed with 22q11.2DS were evaluated in our institution. Detailed ultrasound examination was performed on all fetuses. Postmortem and postnatal examinations were evaluated. The microdeletions were detected by karyotyping or microarray, then confirmed by FISH. Descriptive statistical analysis was performed.

RESULTS

Demographic data of 48 prenatal cases including 46 singletons and 1 dichorionic diamniotic twin pregnancy were evaluated. The most common extracardiac anomaly was skeletal system anomalies (25%), in which PEV was the most frequent one (20.8%). Polyhydramnios rate was detected as 31%, in 6.6% as an isolated finding. Microdeletion has been detected by karyotyping in 13 cases (13/47, 27.7%) (including 2 unbalanced translocations), by FISH in 28 cases (28/48, 58.3%), by microarray/a-CGH testing in 7 cases. Microarray analysis showed that in one case with unbalanced translocation had two consecutive deletions; one was proximal and other one distal to critical region and not encompassing TBX1 gene but CRKL and LZTR1 genes.

CONCLUSION

The current study demonstrates the whole spectrum of atypical phenotypic and genotypic variations of 22q11.2DS in the largest prenatal case series reported to date. Therefore, differential diagnosis should be considered not solely in CHD, but also in the presence of isolated clubfeet and polyhydramnios. Establishing the diagnosis in the prenatal period may allow a postnatal multidisciplinary approach, as well as affect the actual prevalence of the disease.

Initial validation of the diagnostic performance of Thymic-Thoracic Ratio as a marker of conotruncal abnormalities and for prediction of surgical prognosis in fetuses without 22q11.2 deletion

AIM

The present study aimed to perform an initial validation of the Thymic-Thoracic Ratio as a sonographic marker of conotruncal defects in non-syndromic fetuses and to assess the possible correlation between the grade of thymic hypoplasia and the severity of conotruncal defects.

METHODS

The study was conducted between January and June 2018 on singleton pregnant women who underwent fetal echocardiography at our institution. Fetuses with a diagnosis of conotruncal defects without 22q11.2 deletion composed the study group, while healthy appropriate for gestational age fetuses composed the control group. The Thymic-Thoracic Ratio was measured in all included fetuses and compared between the study and control group. A ROC curve analysis to evaluate the diagnostic performance of Thymic-Thoracic Ratio toward the diagnosis of conotruncal defects was performed, with determination of sensitivity, specificity, PPV, NPV, positive likelihood ratio, and negative likelihood ratio. The severity of conotruncal defects was defined with the Aristotle score in each newborn who underwent a surgical operation. The correlation between Thymic-Thoracic Ratio and Aristotle score was assessed.

RESULTS

During the study period, 23 fetuses with conotruncal defects without 22q11.2 deletion constituted the study group, and 67 healthy appropriate for gestational age fetuses were included in the control group. The T-T ratio of the study group was significantly lower than the control group (0.32 ± 0.08 vs. 0.41 ± 0.08, p < .001). The ROC curve analysis showed an AUC of 0.80 (95% CI, 0.71-0.89, p < .001) and a T-T ratio cutoff value of 0.35 for the identification of a CTD, with a sensibility of 73.9% (95% CI: 51.6-89.8%), a specificity of 79.1% (95% CI: 67.4-88.1%) a PPV of 54.8% (95% CI: 41.8-67.3%), a NPV of 89.8% (95% CI: 81.5-94.7), a positive likelihood ratio of 3.54 (95% CI 2.09-5.98), and a negative likelihood ratio of 0.33 (95% CI 0.16-0.66). A negative correlation between Aristotle score and T-T ratio was found, with a Kendall-Tau coefficient of -0.41, p = .04.

CONCLUSION

T-T ratio measurement could be useful to identify fetuses at higher risk of conotruncal heart diseases, even without chromosomic deletion, with a cutoff of 0.35. Since a lower T-T ratio seems to be related to a worse surgical neonatal prognosis, it could be possible to provide effective counseling and refer patients to high-specialized centers for fetal echocardiography and cardiac surgery.

Prenatal screening of DiGeorge (22q11.2 deletion) syndrome by abnormalities of the great arteries among Thai pregnant women

Objective

22q11.2DS (deletion syndrome) is one of the common serious anomalies resulting in high perinatal morbidity and mortality rate. Nevertheless, prenatal diagnosis of 22q11.2DS in Southeast Asia has never been described and its prevalence in prenatal series has never been explored. The objective of this study was to describe the experience of prenatal diagnosis of 22q11.2DS in the Thai population and to determine its prevalence among fetuses prenatally diagnosed with abnormalities of the great arteries.

Methods

A prospective study was conducted on pregnant Thai women prenatally diagnosed with abnormalities of the great arteries in the second trimester. The recruited cases were investigated for fetal 22q11.2 deletion by in situ hybridization with a probe specific to the DiGeorge/VCFS TUPLE 1 region located on chromosome 22 for the locus D22S75, and 22qter for a telomere specific sequence clone as the control region.

Results

Five out of the 42 (11.9%) fetuses with abnormalities of the great arteries meeting the inclusion criteria were proven to have 22q11.2DS. The most common abnormalities were the tetralogy of Fallot (or variants) and right-sided aortic arch, followed by a thymic hypoplasia.

Conclusion

As observed in the western countries, we have documented that, among pregnant Thai women, 22q11.2DS is highly prevalent in fetuses with abnormalities of the great arteries (approximately 12%). This information is important when counselling couples to undergo prenatal testing for 22q11.2DS, since this information is vital in the patients' decision of termination or continuation of pregnancy and in a well-prepared management of the affected child.

The Fetal 3-Vessel Views: An Illustrative Case-Based Tutorial

In 2018, the American Institute of Ultrasound in Medicine revised its obstetric Practice Parameter for the second-trimester fetal anatomic survey. The 2018 Practice Parameter recommends incorporation of the 3-vessel view and 3-vessel and trachea view "if technically feasible." Sonographers and other medical providers may require additional training and education to develop greater proficiency in obtaining and interpreting these views. This pictorial essay, including ultrasound images alongside their respective schematic diagrams, provides an up-to-date, practical, and clinically oriented review of the 3-vessel view and 3-vessel and trachea view and their most common presentations in the context of congenital heart disease.

DiGeorge syndrome chromosome region deletion and duplication: Prenatal genotype-phenotype variability in fetal ultrasound and MRI

OBJECTIVE

The aim of the study was to assess genotype-phenotype correlation of prenatally diagnosed fetal DGS and dup22q11 syndrome by fetal molecular genetic analysis, fetal ultrasound, and/or MRI.

METHODS

In this retrospective consecutive case series, pregnant women were screened for fetal anomalies during a period of 10 years. Fetal genotype was assessed in 72 cases upon the occurrence of five prenatal fetal phenotypic features: cardiac anomalies, hypo/aplastic thymus, craniofacial malformations, urinary abnormalities, or IUGR; genotype-phenotype correlation was tested to potentially improve prenatal diagnosis of fetal DGS and dup22q11 syndrome.

RESULTS

Fetal genotypes of deletions or duplications in proximal clusters of LCR22s (A-B) were associated with fetal cardiac anomalies in combination with hypo/aplastic thymus and craniofacial malformations, suggesting a correlation with deleted HIRA. TOF associated with aplastic thymus in combination with renal defects indicated a relevant correlation with TBX1 deletion. Deletions in central LCR22s (B-D) with the loss of CRKL supposed a trend of genotype-phenotype correlation with fetal urinary abnormalities.

CONCLUSION

Genotype-phenotype correlation might improve prenatal diagnosis of fetal DGS and dup22q11 syndrome. Hence, prenatal screening and counseling is highly enhanced by a combination of fetal molecular genetic analysis, fetal ultrasound, and/or MRI. The implications of these findings remain to be explored.

[Isolated right aortic arch: prenatal diagnosis characteristics, pregnancy outcomes and systematic review]

OBJECTIVE

To investigate prenatal diagnosis characteristics and pregnancy outcomes associated with isolated right aortic arch (RAA).

METHODS

A retrospective study including fetuses with isolated RAA, managed between January 2010 and February 2018. Cases were identified from the ultrasound databases of the expert pediatric cardiologists, who made the aforementioned diagnosis. All fetuses were examined by a fetal medicine imaging expert to exclude any extracardiac abnormality. A systematic review was performed to assess the prenatal diagnosis and outcomes of fetuses with isolated RAA.

RESULTS

Fifty-six fetuses were diagnosed with an isolated RAA. An isolated double aortic arch (DAA) was diagnosed in one fetus. Mean gestational age at diagnosis was 24 weeks. The sex ratio (boy/girl) was 0.89. No significant abnormality was detected in invasive tests (karyotype and FISH or microarray). Only one fetus was misdiagnosed with isolated RAA. He was the only symptomatic (stridor) newborn baby and was later diagnosed with DAA. Four studies were included in our systematic review representing 115 cases of isolated RAA. One significant chromosomal abnormality was detected: a 22q11 deletion in a newborn baby who had a postnatal finding of a soft palate cleft. There was one major obstetric complication: an intrauterine fetal demise at 41 gestational weeks.

CONCLUSION

Diagnosis of isolated RAA can be challenging. Invasive tests are to be discussed. The diagnosis of isolated RAA should not change obstetric monitoring. Nevertheless, an echocardiography should be performed systematically in these new newborn babies within their first month of life.

Measuring fetal thymus size: a new method for diabetes screening in pregnancy

Objective: To investigate the correlation between fetal thymus size and diabetes in pregnancy.Method: Fetal thymus size was assessed in 160 pregnant women with gestational age of 19-39 weeks. They included 80 diabetic (investigation group) and 80 nondiabetic (control group) women. Fetal thymus size was measured by thymic-thoracic ratio. We did this with dividing the thymus' anteroposterior diameter by anteroposterior of mediastinum.Results: Thymic-thoracic ratio was significantly smaller in fetuses of diabetic mothers compared to the nondiabetic group (p = .001). It remained significant after subgrouping diabetic mothers into overt diabetes, insulin-dependent gestational diabetes, and noninsulin-dependent gestational diabetes.Conclusion: Although thymus size was smaller in fetuses of diabetic pregnant women compared to nondiabetic pregnant women, it seems that thymic-thoracic ratio can be a predictor of diabetes and its other related adverse effects during pregnancy.

Expanding the fetal phenotype: Prenatal sonographic findings and perinatal outcomes in a cohort of patients with a confirmed 22q11.2 deletion syndrome

22q deletion syndrome (22q11.2DS) is most often correlated prenatally with congenital heart disease and or cleft palate. The extracardiac fetal phenotype associated with 22q11.2DS is not well described. We sought to review both the fetal cardiac and extracardiac findings associated with a cohort of cases ascertained prenatally, confirmed or suspected to have 22q11.2DS, born and cared for in one center. A retrospective chart review was performed on a total of 42 cases with confirmed 22q11.2DS to obtain prenatal findings, perinatal outcomes and diagnostic confirmation. The diagnosis was confirmed prenatally in 67% (28/42) and postnatally in 33% (14/42). The majority (81%) were associated with the standard LCR22A-LCR22D deletion. 95% (40/42) of fetuses were prenatally diagnosed with congenital heart disease. Extracardiac findings were noted in 90% (38/42) of cases. Additional findings involved the central nervous system (38%), gastrointestinal (14%), genitourinary (16.6%), pulmonary (7%), skeletal (19%), facial dysmorphism (21%), small/hypoplastic thymus (26%), and polyhydramnios (30%). One patient was diagnosed prenatally with a bilateral cleft lip and cleft palate. No fetus was diagnosed with intrauterine growth restriction. The average gestational age at delivery was 38 weeks and average birth weight was 3,105 grams. Sixty-two percentage were delivered vaginally and there were no fetal demises. A diagnosis of 22q11.2 deletion syndrome should be considered in all cases of prenatally diagnosed congenital heart disease, particularly when it is not isolated. Microarray is warranted in all cases of structural abnormalities diagnosed prenatally. Prenatal diagnosis of 22q11.2 syndrome can be used to counsel expectant parents regarding pregnancy outcome and guide neonatal management.

Foetal thymus size in pregnancies after assisted reproductive technologies

PURPOSE

The aim of our study was to compare thymus sizes in foetuses conceived using assisted reproductive technologies (ART) to those conceived naturally (control group).

METHODS

Sonographic foetal thymus size was assessed retrospectively in 162 pregnancies conceived using ART and in 774 pregnancies conceived naturally. The anteroposterior thymic and the intrathoracic mediastinal diameter were measured to calculate the thymic-thoracic ratio (TT-ratio). The ART cases were subdivided into two groups: (1) intracytoplasmic sperm injection (ICSI; n = 109) and (2) in vitro fertilisation (IVF; n = 53).

RESULTS

The TT-ratio was smaller in pregnancies conceived using ART (p < 0.001). In both ART subgroups (ICSI and IVF), the TT-ratio was lower compared to the control group (p < 0.001). However, no difference between the two subgroups could be detected (p = 0.203).

CONCLUSIONS

Our data show reduced thymus size in foetuses conceived using ART compared to controls. These findings indicate that the use of ART may lead to certain deviations in organogenesis.

Personalized charts for the fetal corpus callosum length

Objective: To personally customize the antenatal ultrasound charts for the fetal corpus callosum (CC) length. Methods: A retrospective analysis of fetal neuro-sonography scans. Cases were grouped as normal neuro-sonographic evaluation (normal) or as high risk and suspected brain anomaly (abnormal). The normal group was subcategorized according to Cignini's CC length charts. Data of fetuses with a CC length between the 5th-95th percentile served for creating new charts, describing the ratio of the CC length to the major biometric parameters as a function of gestational age (GA). Results: A total of 410 measurements were included. Of them 255 were normal and 155 abnormal. The CC length/estimated fetal weight (EFW) ratio had the strongest linear association with GA (R² = 0.929). Applying charts using this ratio to the normal group, significantly increased the percent of CC length measurements defined as normal from 84.7 to 94.5% (p < .001). Conversely, applying these charts to the abnormal group nonsignificantly decreased the number of measurement defined as normal from 89 to 83.2% (p = .137) Conclusions: The CC length/EFW ratio is strongly and linearly associated with GA. Using this personalized ratio may improve the diagnostic accuracy of CC evaluation by adjusting the CC length to the fetus natural proportions.

Correlation Between the Thymic-Thoracic Ratio and Cardiac Axis in Healthy Fetuses

OBJECTIVES

The aim of this study was to assess the correlation between the thymic-thoracic ratio and cardiac axis in healthy fetuses.

METHODS

The fetal thymic-thoracic ratio and cardiac axis were measured in 220 healthy fetuses. The normal ranges of the fetal thymic-thoracic ratio and cardiac axis for each gestational week were established. The Pearson correlation coefficient was calculated to analyze the relationship between the thymic-thoracic ratio and cardiac axis.

RESULTS

The mean fetal thymic-thoracic ratio increased slightly throughout the pregnancy, from 0.33 at 17 weeks' gestation to 0.37 at 37 weeks. No statistically significant correlation was found between the thymic-thoracic ratio and cardiac axis in healthy fetuses.

CONCLUSIONS

In healthy fetuses, the thymus occupies an increasingly larger portion of the upper mediastinum when the pregnancy advances. The cardiac axis is not affected by the thymic-thoracic ratio in healthy fetuses.

Fetal thymus size in pregnant women with diabetic diseases

AIM

The aim of our study was to assess fetal thymus size in diabetic pregnancies compared with normal pregnancies.

METHODS

Sonographic fetal thymus size was retrospectively assessed in 161 pregnancies with maternal diabetes and in 161 uncomplicated pregnancies matched by gestational age. The anteroposterior thymic and the intrathoracic mediastinal diameter were measured and the quotient was calculated [thymic-thoracic ratio (TT-ratio)]. In addition, we defined the quotient of the anteroposterior thymic diameter and the head circumference as thymus-head ratio (TH-ratio). The maternal diabetes cases were subdivided into three groups: (1) diet-controlled gestational diabetes, (2) insulin-dependent gestational diabetes and (3) preexisting maternal diabetes.

RESULTS

TT-ratio and TH-ratio were smaller in pregnancies with maternal diabetes (P<0.001 and P<0.001, respectively). In all three maternal diabetes subgroups, the TT-ratio and the TH-ratio were lower compared with the control group (P<0.001 for each group).

CONCLUSIONS

Reduced fetal thymus size seems to be associated with diabetic pregnancy. We introduce fetal thymus size as a new potential prognostic parameter for maternal diabetes.

Cardio-STIC Based Reference Ranges of Fetal Thymus Size in Singleton Pregnancies

OBJECTIVES

To establish the reference ranges of the fetal thymus size among Thai fetuses.

METHODS

The database of spatio-temporal image correlation (cardio-STIC) was assessed to obtain the volume data sets for offline analysis. The volume data sets acquired at 16 to 38 weeks were measured for the thymus transverse diameter (TD) and the thymus/thoracic (TT) ratio at the three-vessel view. The measured values were regressed to identify the best-fitted model.

RESULTS

A total of 622 volumes were successfully measured and the reference ranges of TD and TT ratio were established. Although TT was relatively constant or increased minimally with gestational age (GA), TD was significantly increased with gestational age. The predicted mean TD (mm) =  -31.206 + 2.854 × GA - 0.028 × GA² (r = 0.891; P < .001) and predicted standard deviation (SD) of TD (mm) = 0.837 + 0.073 × GA (r = 0.038; P < .001). Centile charts for predicting TD and equations for z-score calculation were also provided. Interobserver variability in TD measurement was better than that in TT ratio and thymic perimeter measurement.

CONCLUSIONS

Reference ranges of fetal TD and TT ratio have been provided. These normative data may be a useful tool in the assessment of thymus-associated conditions. For clinical purposes, we recommend measurements of the TD rather than TT ratio or perimeter because of its reproducibility and simplicity.

Fetal right aortic arch: associated anomalies, genetic anomalies with chromosomal microarray analysis, and postnatal outcome

OBJECTIVES

The aim of the study was to assess the associated prenatal findings, genetic anomalies with chromosomal microarray analysis (CMA) and postnatal outcome of fetal right aortic arch (RAA).

METHODS

This retrospective study reviewed 92 fetuses diagnosed with RAA and the findings of CMA using Affymetrix CytoScan HD array in our institution between 2013 and 2016.

RESULTS

Postnatal data were not available for six cases, and genetic data were not available for 26 cases. Tetralogy of the Fallot was the most frequently associated anomaly. Among the 60 fetuses with known karyotype, one was 46, X, Yqh+, der(13)t(8;13)(q22.3;q33.2), one was 47, XYY and the remaining were normal. Our study showed that CMA could detect uncertain significant copy number variants in 5.2% of fetal RAA and pathogenic copy number variants in 5.2%, all of which were microdeletion in chromosome 22q11.21. The genetic anomalies, gestational age at delivery and postnatal death were not significantly different between RAA-no intracardiac anomalies and RAA-intracardiac anomalies group. One infant with aberrant left subclavian artery needed to perform a surgery for respiratory symptom.

CONCLUSIONS

A right aortic arch is associated with 22q11.2 deletion syndrome in approximately 5% of cases, and, therefore, prenatal testing, preferably using CMA, should be offered. © 2017 John Wiley & Sons, Ltd.

Sonographic measurement of fetal thymus size in uncomplicated singleton pregnancies

PURPOSE

To establish sonographic reference ranges of the normal fetal thymus size between 17 and 38 weeks of gestational age (GA).

METHODS

The study was conducted between April 1 and December 31, 2013. Low-risk singleton pregnancies without obstetrical and medical complications at the GAs between 17 and 38 weeks were recruited for thymus measurement. The fetal thymus was identified on transabdominal sonography at the three-vessel view. Maximal transverse diameter, perimeter, and thymus/thoracic ratio were measured. The best-fit models in predicting thymic dimensions as a function of GA and biparietal diameter (BPD) were determined using regression analysis, and percentile charts for predicting thymic dimensions were constructed.

RESULTS

A total of 296 singleton pregnancies were recruited in this study. Maximal transverse diameter, perimeter, and thymus/thoracic ratio increased throughout pregnancy. The regression equation for maximal transverse diameter of the thymus as a function of GA was as follows: Predicted mean thymus diameter (mm) = -25.904 + 2.476 × GA - 0.019 × GA² (r = 0.915; p < 0.001) with predicted standard deviations of thymus diameter (mm) = 1.428 + 0.044 × GA (r = 0.017; p < 0.001).

CONCLUSIONS

Sonographic reference ranges of the normal fetal thymic dimensions between 17 and 38 weeks of GA have been established. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:150-159, 2017.

Chromosomal microarray analysis in fetuses with aberrant right subclavian artery

OBJECTIVE

To evaluate the association between aberrant right subclavian artery (ARSA), with or without additional risk factors for aneuploidy or ultrasound abnormality, and results of chromosomal microarray analysis (CMA).

METHODS

This was a multicenter study of fetuses diagnosed with ARSA that underwent genetic analysis by CMA, all samples being analyzed in the same laboratory. Clinical investigation included nuchal translucency measurement, first- and second-trimester maternal serum screening, early and late second-trimester fetal anatomy scans and fetal echocardiography. Comparative genomic hybridization microarray analysis or single-nucleotide polymorphism array technology was used for CMA of DNA samples obtained from amniotic fluid.

RESULTS

CMA results were available for 63 fetuses with ARSA. In 36 fetuses, ARSA was an isolated finding, and no pathogenic variant was found. Additional ultrasound findings and/or risk factors for aneuploidy were present in 27 fetuses, five of which had pathogenic CMA results. Of these five, trisomy 21 was detected in a fetus with echogenic intracardiac focus (EIF), 22q11 deletion was detected in a fetus with EIF and an increased risk of trisomy 21 of 1:230 from maternal serum screening, 22q11 duplication was detected in a fetus with hypoplastic right kidney and choroid plexus cyst and 22q11 deletion was detected in a fetus with right aortic arch and clubfoot. The fifth fetus had increased nuchal translucency thickness (4 mm) and a ventricular septal defect, and CMA identified both 22q11 deletion and 1q21 duplication.

CONCLUSIONS

In fetuses with isolated ARSA, an invasive procedure for CMA is not indicated. However, CMA is recommended when additional ultrasound abnormalities or risk factors for aneuploidy are observed. The chromosomal findings in four of the five cases with an abnormal CMA result in our study would not have been detected by standard fetal chromosomal testing. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Neuropsychiatric aspects of 22q11.2 deletion syndrome: considerations in the prenatal setting

Most major neuropsychiatric outcomes of concern to families are not detectable by prenatal ultrasound. The introduction of genome-wide chromosomal microarray analysis to prenatal clinical diagnostic testing has increased the detection of pathogenic 22q11.2 deletions, which cause the most common genomic disorder. The recent addition of this and other microdeletions to non-invasive prenatal screening methods using cell-free fetal DNA has further propelled interest in outcomes. Conditions associated with 22q11.2 deletions include intellect ranging from intellectual disability to average, schizophrenia and other treatable psychiatric conditions, epilepsy, and early-onset Parkinson's disease. However, there is currently no way to predict how severe the lifetime expression will be. Available evidence suggests no major role in these neuropsychiatric outcomes for the congenital cardiac or most other structural anomalies that may be detectable on ultrasound. This article provides an outline of the lifetime neuropsychiatric phenotype of 22q11.2 deletion syndrome that will be useful to clinicians involved in prenatal diagnosis and related genetic counselling. The focus is on information that will be most relevant to two common situations: detection of a 22q11.2 deletion in a fetus or newborn, and new diagnosis of 22q11.2 deletion syndrome in a parent without a previous molecular diagnosis. © 2016 John Wiley & Sons, Ltd.

Intrathymic and other anomalous courses of the left brachiocephalic vein in the fetus

OBJECTIVE

The left brachiocephalic vein (LBCV), or innominate vein, connects the left jugular vein to the right superior vena cava. Its course is posterior to the thymus and directly anterior and superior to the aortic arch. Pediatric and adult cardiology studies have reported on the subaortic or retrotracheal courses of the LBCV and the presence of double LBCV. We observed recently in the fetus that the LBCV may have a course through the thymus (intrathymic) or be absent in the presence of a left superior vena cava. The aim of this study was to report the prevalence of isolated intrathymic and absent LBCV in normal fetuses undergoing second-trimester ultrasound screening, as well as the prevalence of other courses in association with cardiac anomalies.

METHODS

In the prospective part of this study, consecutive second-trimester ultrasound examinations were evaluated to assess the presence and course of the fetal LBCV. In the retrospective case-control part of this study, the databases of two fetal medicine centers were reviewed for cardiac anomalies and the pattern and prevalence of anomalous courses of the LBCV were reported.

RESULTS

One thousand four hundred and eighteen consecutive fetuses were examined prospectively. An intrathymic course of the LBCV with a typical bent shape was found in 1.76% (1 : 57) of cases and the absence of a LBCV in association with a persistent left superior vena cava (LSVC) was found in 0.28% (1 : 350). All fetuses with an isolated intrathymic course or absence of the LBCV had a normal outcome. Over a period of 4.5 years, a total of 1544 fetuses with cardiac malformations were reviewed at two centers. Among these, an anomalous course of the LBCV was noted in eight (0.5%) cases: six subaortic, one retrotracheal and one double LBCV.

CONCLUSION

An intrathymic LBCV is a common condition and appears to be a normal variant in the fetus. The prevalence of a LSVC in our screening population was similar to that reported in previous studies. Anomalous courses of the LBCV are seen occasionally in cases with cardiac malformation. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Risk of 22q11.2 deletion in fetuses with right aortic arch and without intracardiac anomalies

OBJECTIVE

To assess the risk of 22q11.2 deletion in fetuses with a prenatal diagnosis of right aortic arch without intracardiac anomalies (RAA-no ICA).

METHODS

This was a retrospective study of all fetuses with RAA-no ICA diagnosed prenatally at three referral centers, between 2004 and 2014. A detailed sonographic examination was performed in each case, including visualization of the thymus and of the head and neck vessels to identify the presence of an aberrant left subclavian artery (ALSA). Karyotyping and fluorescence in situ hybridization analysis for diagnosis of 22q11.2 deletion were always offered either prenatally or postnatally. Clinical and echocardiographic examinations were performed in livebirths and a postmortem examination in cases of termination of pregnancy.

RESULTS

During the study period, 85 fetuses were diagnosed prenatally with RAA-no ICA. Genetic or clinical data were not available for three cases and these were excluded from analysis. 22q11.2 deletion was found in 7/82 cases (8.5% (95% CI, 3.8-17.3%)). The thymus was small or non-visualized in all seven cases and additional abnormal sonographic findings were present in four.

CONCLUSION

22q11.2 deletion is present in a clinically significant proportion of fetuses with a prenatal diagnosis of RAA-no ICA. In such cases, a detailed sonographic examination, with assessment of the thymus in particular, may be useful to further define the level of risk for 22q11.2 deletion. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Ultrasonographic approach to diagnosis of fetal inflammatory response syndrome: a tool for at-risk fetuses?

Preterm parturition is a syndrome that may result from many underlying mechanisms. Infection and inflammation are the prominent ones. Intrauterine infection and inflammation have an effect akin to sepsis, and that is similar to systemic inflammatory response in adults. Indeed, there is evidence to support the association of a fetal inflammatory response syndrome (FIRS) to systemic infection and inflammation. The utilization of invasive procedures for the prenatal diagnosis of FIRS is associated with a risk for complications resulting from the invasive method. The progress in the imaging quality of obstetrical ultrasound and the development of novel methods for functional anatomical assessment of the fetal organs may help to identify, noninvasively, fetuses at risk for FIRS in patients presenting with preterm labor. We review the studies describing advanced sonographic modalities and the imaging findings in the heart, thymus, kidney, adrenal glands, and spleen of these fetuses.

Second-Trimester Sonographic Thymus Measurements Are Not Associated With Preterm Birth and Other Adverse Obstetric Outcomes

OBJECTIVES

Previous studies have demonstrated an association between adverse obstetric outcomes, such as preterm birth, and in utero inflammation. The fetal thymus, which can be visualized in the anterior mediastinum on obstetric sonography, may involute in response to such inflammation and thus may identify pregnancies at increased risk for these outcomes. We therefore sought to determine whether second-trimester fetal thymus measurements are associated with preterm birth.

METHODS

Transabdominal fetal thymus measurements were prospectively obtained in singleton pregnancies at gestational ages of 18 weeks to 23 weeks 6 days during a 5-month period. The transverse and anterorposterior thymus diameters and the thymic-thoracic ratio were measured. Delivery outcomes were collected from our clinical database. The primary outcome was preterm birth, which we defined as delivery between 24 weeks and 36 weeks 6 days. Small for gestational age (SGA) and pregnancy-related hypertension, which are adverse obstetric outcomes that may also be associated with in utero inflammation, were included as secondary outcomes.

RESULTS

We included 520 patients with thymus measurements and obstetric outcome data. The prevalence of preterm birth was 12.3% (n = 64). None of the thymus measurements were associated with preterm birth. Similarly, there was no association between thymus measurements and SGA or pregnancy-related hypertension.

CONCLUSIONS

Sonographic assessment of the second-trimester fetal thymus did not identify patients at increased risk for preterm birth, SGA, and pregnancy-related hypertension. Routine thymus measurements during the second-trimester anatomic scan are not clinically useful for prediction of preterm birth and other adverse outcomes.