Do ARTs affect the incidence of monozygotic twinning?

STUDY QUESTION: Does the manipulation of gametes or embryos during ARTs increase the risk for monozygotic twinning (MZT)? SUMMARY ANSWER: Frozen embryo transfer (ET) is associated with a lower MZT rate, while blastocyst culture is associated with an increased risk of monozygotic pregnancy. WHAT IS KNOWN ALREADY: Monozygotic twins have a higher risk for perinatal complications. Although an increased incidence of monozygotic pregnancies after ART has been previously reported, data regarding the possible impact of different laboratory procedures are conflicting. STUDY DESIGN, SIZE, DURATION: All clinical pregnancies after single ET carried out in our centre between 2004 and 2013 (n = 6096) were retrospectively analysed for the incidence of MZT. The effect of different laboratory procedures on the incidence of MZT was evaluated. PARTICIPANTS/MATERIALS, SETTING, METHODS: The following ART risk factors were assessed: maternal age, type of ET (fresh versus frozen), zona pellucida (ZP) manipulation (specifically, ICSI, embryo biopsy and assisted hatching), use of donor oocytes, embryo stage at time of ET (cleavage, compaction, early or advanced blastocyst) and culture media. MAIN RESULTS AND THE ROLE OF CHANCE: The overall MZT rate was 2.2% (136/6096). Frozen ET was associated with a significant reduction in MZT incidence (adjusted odds ratio (aOR) 0.48, 95% CI 0.29-0.80), while blastocyst transfer (early or advanced blastocyst) was associated with a significant increase in MZT risk (aOR 2.70, 95% CI 1.36-5.34; aOR 2.05, 95% CI 1.29-3.26, respectively). No significant differences were found between the MZT and singleton (non-MZT) groups regarding maternal age, the use of different ZP manipulation techniques, not type of culture media used. LIMITATION, REASONS FOR CAUTION: This study is limited by its retrospective nature and the fact that monozygosity was not confirmed by genetic testing. Furthermore, since monozygotic pregnancy is a rare event, other ART parameters that may influence its incidence could not be assessed during our analysis. WIDER IMPLICATION OF THE FINDINGS: Our findings warrant future studies designed to investigate the association between specific ART procedures and MZT, namely the potential risk of blastocyst transfer to increase MZT. STUDY FUNDING/COMPETING INTERESTS: No external funding was used for this study. There are no conflicts of interest.

Predictors of neonatal morbidity in fetuses with severe isolated congenital diaphragmatic hernia undergoing fetoscopic tracheal occlusion.

OBJECTIVES: To investigate neonatal morbidity in fetuses with severe congenital diaphragmatic hernia (CDH) treated with fetoscopic endoluminal tracheal occlusion (FETO) and compare it with historical controls with less severe forms of CDH that were managed expectantly. METHODS: This was a prospective, multicenter study on neonatal outcomes and prenatal predictors in 90 FETO survivors (78 left-sided, 12 right) and 41 controls from the antenatal CDH registry with either severe or moderate hypoplasia who were managed expectantly. We also investigated early neonatal morbidity indicators, including the need for patch repair, duration of mechanical ventilation and supplemental oxygen, age at full enteral feeding and incidence of pulmonary hypertension. RESULTS: Gestational age at delivery was predictive of duration of assisted ventilation (P = 0.046), days on supplemental oxygen (P = 0.019) and age at full enteral feeding (P = 0.020). When delivery took place after 34 weeks' gestation, neonatal morbidity of FETO cases was comparable with that of expectantly managed cases with moderate hypoplasia. CONCLUSIONS: Fetal intervention for severe CDH is associated with neonatal morbidity that is comparable with that of an expectantly managed group with less severe disease.

Outcome prediction in monochorionic diamniotic twin pregnancies with moderately discordant amniotic fluid.

OBJECTIVE: The aim of this study was to identify predictors of twin-to-twin transfusion syndrome (TTTS) and selective intrauterine growth restriction (sIUGR) in monochorionic diamniotic (MCDA) twin pregnancies with moderate amniotic fluid discordance (mAFD). METHODS: Monochorionic twins with mAFD (n = 45; gestational age, 15-29 weeks) were assessed for extent of fluid discordance, fetal growth discordance and fetal cardiac dysfunction, and were followed longitudinally. A prediction algorithm was constructed for TTTS and sIUGR and validated in an unrelated cohort (n = 52). RESULTS: Cardiac dysfunction could not predict TTTS or sIUGR. Twins below 20 weeks of gestation with a fluid discordance of ≥ 3.1 cm had a risk of TTTS of 85.7%. Sensitivity for TTTS was nevertheless only 55%. An intertwin weight discordance of ≥ 25% had 63% sensitivity and 76% specificity for sIUGR without TTTS. CONCLUSION: The outcome of MCDA twins with mAFD remains unpredictable, yet high-risk and low-risk subgroups for TTTS can be identified based on severity of fluid discordance and gestational age.

Maternal hyperoxygenation test in fetuses undergoing FETO for severe isolated congenital diaphragmatic hernia.

OBJECTIVES: To predict neonatal survival and pulmonary hypertension by measurement of fetal pulmonary artery reactivity to maternal hyperoxygenation in fetuses with severe congenital diaphragmatic hernia treated by fetoscopic endoluminal tracheal occlusion (FETO). METHODS: Thirty-eight fetuses underwent FETO at around 28 weeks' gestation and the balloon was removed at 34 weeks in most cases. We performed a hyperoxygenation test and measured the lung-to-head ratio of each fetus before and after each procedure. Outcome measures were neonatal survival, occurrence of pulmonary hypertension and its response to inhaled nitric oxide (iNO). RESULTS: Fetuses that survived had a larger increase in lung size and decrease of resistance in the first branch of the main pulmonary artery than did those that died. Both measures were also predictive of pulmonary hypertension unresponsive to iNO. The hyperoxygenation test and lung-to-head ratio were both best predictive for neonatal survival when measured following removal of the balloon (P < 0.002). Discriminant analysis confirmed that these two parameters are independent predictors of outcome. CONCLUSIONS: In fetuses undergoing FETO, pulmonary vascular reactivity in relation to oxygen and lung size are independent predictors of neonatal survival and pulmonary hypertension. The hyperoxygenation test merits further study in expectantly managed cases.

Fetal cerebral blood flow velocities in congenital diaphragmatic hernia.

OBJECTIVES: Left ventricular cardiac output is decreased in fetuses with congenital diaphragmatic hernia (CDH). Our aim was to assess whether this alters cerebral perfusion or growth in utero. METHODS: Fetal head circumference, biparietal diameter, lung-to-head ratio and middle cerebral artery (MCA) Doppler flow patterns were assessed by ultrasonography in 103 fetuses with prenatally diagnosed CDH. Total fetal lung volume and cerebral volume were measured using magnetic resonance imaging. Values were transformed to gestational age-independent scores (multiples of the median (MoM)) and compared with controls. Subanalyses were made according to whether the CDH was left- (n = 86) or right-sided (n = 17) and to whether it was isolated (n = 86) or associated with other anomalies (n = 17). RESULTS: MCA flow velocity was significantly lower in fetuses with CDH than in healthy fetuses (0.79 ± 0.19 MoM; P < 0.0001) but MCA pulsatility index was unchanged (0.99 ± 0.25 MoM; P = 0.79). Cranial biometry and cerebral volume in CDH fetuses fell in the normal range. Gestational age-adjusted lung area was correlated with MCA peak systolic velocity, which was in turn correlated with brain volume. CONCLUSIONS: Fetal cerebral blood flow velocities are decreased in CDH yet cranial and cerebral growth are conserved. Further work will be needed to address whether part of the neurologic impairment observed in long-term survivors of CDH finds its origin in the prenatal period.

Contribution of intrapulmonary artery Doppler to improve prediction of survival in fetuses with congenital diaphragmatic hernia treated with fetal endoscopic tracheal occlusion.

OBJECTIVE: To evaluate the contribution of intrapulmonary artery Doppler in predicting the survival of fetuses with congenital diaphragmatic hernia (CDH) treated with fetoscopic tracheal occlusion (FETO). METHODS: A cohort of 41 fetuses (between 24 and 28 weeks of gestation) with CDH was treated with FETO. The observed/expected lung-to-head ratio (O/E-LHR), pulmonary artery pulsatility index (PI), peak early diastolic reversed flow (PEDRF) and peak systolic velocity (PSV) were evaluated before FETO, and their isolated and combined value to predict survival using multiple logistic regression and decision-tree analysis was assessed. RESULTS: O/E-LHR and intrapulmonary artery PI and PEDRF were significantly associated with the probability of survival (O/E-LHR > or = 26%, OR 14.2; PI < 1 Z-score, OR 8.4; and PEDRF < 3.5 Z-scores, OR 5.7). Decision-tree analysis showed that O/E-LHR was the best initial predictor of prognosis (O/E-LHR > or = 26%, 90% survival; O/E-LHR < 26%, 45% survival). For fetuses with an O/E-LHR of < 26%, Doppler parameters allowed discrimination of cases with moderate (66-71% survival) and very poor (0% survival) prognosis. CONCLUSION: Intrapulmonary artery Doppler evaluation helps to refine the prediction of survival after FETO in fetuses with severe CDH.

Lung tissue perfusion in congenital diaphragmatic hernia and association with the lung-to-head ratio and intrapulmonary artery pulsed Doppler.

OBJECTIVE: To evaluate lung tissue perfusion in fetuses with congenital diaphragmatic hernia (CDH) and to explore the association of lung tissue perfusion with the lung area to head circumference ratio (LHR) and intrapulmonary artery pulsed Doppler. METHODS: Fetuses with isolated left CDH were evaluated and compared with a group of fetuses without CDH, which were sampled from our general population and matched by gestational age at inclusion. Lung tissue perfusion measured using fractional moving blood volume (FMBV), the observed to expected (O/E) LHR and pulsed Doppler of the proximal intrapulmonary artery were evaluated in the lung contralateral to the side of the hernia. Doppler waveform analysis included the pulsatility index (PI), the peak early diastolic reversed flow (PEDRF) and the peak systolic velocity (PSV). All Doppler parameters were converted into Z-scores for gestational age. The associations between FMBV and O/E-LHR and between FMBV and intrapulmonary arterial Doppler parameters were analyzed using multiple linear regression, adjusted by gestational age. RESULTS: A total of 190 fetuses (95 with CDH and 95 controls) were evaluated. Fetuses with CDH showed significantly lower lung FMBV (26.8 (SD 8.4) vs. 37.9 (SD 8.1)%; P < 0.001) than controls. Lung tissue perfusion correlated positively with O/E-LHR (r = 0.37; P < 0.001) and negatively with intrapulmonary artery PI (r = - 0.31; P < 0.001), PEDRF (r = - 0.43; P < 0.001) and PSV (r = - 0.18; P = 0.03). CONCLUSIONS: Fetuses with CDH have decreased lung tissue perfusion, which is associated with decreased lung growth and increased intrapulmonary artery impedance.

Left ventricular cardiac function in fetuses with congenital diaphragmatic hernia and the effect of fetal endoscopic tracheal occlusion.

OBJECTIVES: The pre-existing compression of the left ventricle in congenital diaphragmatic hernia (CDH) could be aggravated by the amplified lung growth after fetoscopic endoluminal tracheal occlusion (FETO). Our aim was to document left ventricular (LV) size and function in fetuses with isolated left-sided CDH and to document the effect of FETO on the fetal heart. METHODS: We determined cardiac axis, LV diameters, ejection fraction, shortening fraction, mitral E/A index and myocardial performance index (MPI) in 27 fetuses with isolated left-sided CDH, and compared these with values in a reference population (n = 117). In fetuses with severe CDH that subsequently underwent FETO and/or reversal of occlusion, additional measurements were obtained 24 h before and after each fetal intervention. We recorded fetal electrocardiograms non-invasively in six CDH fetuses and compared the duration of the QRS complex with data obtained from 12 controls. RESULTS: LV end-diastolic diameter was 32% smaller in CDH fetuses than in controls (P < 0.0001) but LV function was comparable. QRS duration was no different between CDH and control fetuses. FETO did not affect cardiac size but reduced the MPI (P = 0.004). Reversal of FETO had no significant effect on cardiac size and function. CONCLUSIONS: CDH fetuses have a smaller left ventricle than do healthy fetuses. There is no overall adverse impact of CDH and FETO on LV cardiac function.

Severe diaphragmatic hernia treated by fetal endoscopic tracheal occlusion.

OBJECTIVES: To examine operative and perinatal aspects of fetal endoscopic tracheal occlusion (FETO) in congenital diaphragmatic hernia (CDH). METHODS: This was a multicenter study of singleton pregnancies with CDH treated by FETO. The entry criteria for FETO were severe CDH on the basis of sonographic evidence of intrathoracic herniation of the liver and low lung area to head circumference ratio (LHR) defined as the observed to the expected normal mean for gestation (o/e LHR) equivalent to an LHR of 1 or less. RESULTS: FETO was carried out in 210 cases, including 175 cases with left-sided, 34 right-sided and one with bilateral CDH. In 188 cases the CDH was isolated and in 22 there was an associated defect. FETO was performed at a median gestational age of 27.1 (range, 23.0-33.3) weeks. The first eight cases were done under general anesthesia, but subsequently either regional or local anesthesia was used. The median duration of FETO was 10 (range, 3-93) min. Successful placement of the balloon at the first procedure was achieved in 203 (96.7%) cases. Spontaneous preterm prelabor rupture of membranes (PPROM) occurred in 99 (47.1%) cases at 3-83 (median, 30) days after FETO and within 3 weeks of the procedure in 35 (16.7%) cases. Removal of the balloon was prenatal either by fetoscopy or ultrasound-guided puncture, intrapartum by ex-utero intrapartum treatment, or postnatal either by tracheoscopy or percutaneous puncture. Delivery was at 25.7-41.0 (median, 35.3) weeks and before 34 weeks in 65 (30.9%) cases. In 204 (97.1%) cases the babies were live born and 98 (48.0%) were discharged from the hospital alive. There were 10 deaths directly related to difficulties with removal of the balloon. Significant prediction of survival was provided by the o/e LHR and gestational age at delivery. On the basis of the relationship between survival and o/e LHR in expectantly managed fetuses with CDH, as reported in the antenatal CDH registry, we estimated that in fetuses with left CDH treated with FETO the survival rate increased from 24.1% to 49.1%, and in right CDH survival increased from 0% to 35.3% (P < 0.001). CONCLUSIONS: FETO in severe CDH is associated with a high incidence of PPROM and preterm delivery but a substantial improvement in survival.

Reference ranges for middle cerebral artery peak systolic velocity in monochorionic diamniotic twins: a longitudinal study.

OBJECTIVES: The role of middle cerebral artery (MCA) peak systolic velocity (PSV) has become established in the management of fetal anemia. To date, singleton reference ranges have also been used in twin pregnancies. However, in monochorionic twin pregnancies, normal ranges for cerebral blood flow may differ from those in singletons owing to intertwin blood exchange. We aimed to establish gestational age-specific reference ranges for MCA-PSV in monochorionic diamniotic (MCDA) twin pregnancies, to compare them with previously reported singleton reference ranges, and to establish terms for calculating conditional reference intervals appropriate for individual serial measurements. METHODS: In a prospective longitudinal study we examined 50 uncomplicated MCDA pregnancies that were recruited between 11 and 14 weeks of gestation. Fetal MCA Doppler waveforms were assessed biweekly from 15 weeks of gestation onwards. Multilevel modeling was used to estimate gestational age-specific reference ranges for MCA-PSV and terms for conditional reference intervals were established. RESULTS: Based on 824 observations in 100 fetuses, normative ranges from 15 to 37 weeks of gestation were constructed. Median MCA-PSV increased with advancing gestational age. Measurements between 18 and 37 weeks were comparable to those in singletons. However, before 18 weeks MCA-PSV values were higher in MCDA twin pregnancies compared with singleton references. CONCLUSIONS: Between 18 and 37 weeks of gestation, reference ranges of singletons can be used to assess fetal anemia in MCDA twin pregnancies. Prior to 18 weeks the application of singleton references may lead to an increased number of false-positive diagnoses of presumed fetal anemia in MCDA twin pregnancies.

Fetal mesenchymal stem cells: isolation, properties and potential use in perinatology and regenerative medicine.

The fetus is a source of nonembryonic stem cells (SC), with potential applications in perinatal medicine. Cells derived from the placenta, membranes, amniotic fluid or fetal tissues are higher in number, expansion potential and differentiation abilities compared with SC from adult tissues. Although some obstacles keep SC biology at distance from clinical application, the feasibility of using (homologous) SC for tissue engineering for the fetus with a congenital birth defect has been demonstrated. Also, other pathologies may benefit from SC technology.

Instrumental requirements for minimal invasive fetal surgery.

Minimal invasive intrauterine interventions have gained their place in fetal medicine. Interventions on the placenta, umbilical cord, fetal membranes or on the fetus require special endoscopes with their respective sheaths, cannulas and additional instruments. Instruments for fetal therapy are purpose designed for the procedure of interest and most gynaecologists are therefore not familiar with them. We review the currently available instrumentation used during operations for complicated monochorionic multiple pregnancies, congenital diaphragmatic hernia, amniotic band syndrome, urinary tract obstruction and hydrothorax.

Prenatal prediction of survival in isolated diaphragmatic hernia using observed to expected total fetal lung volume determined by magnetic resonance imaging based on either gestational age or fetal body volume.

OBJECTIVES: To compare the predictive value of the prenatal observed to expected (o/e) lung volume as measured by fetal magnetic resonance imaging (MRI), based on an algorithm using either the gestational age or fetal body volume (FBV), for neonatal survival of fetuses with isolated congenital diaphragmatic hernia (CDH). METHODS: We included 53 fetuses with a prenatal diagnosis of isolated CDH, 26 without and 27 with prenatal tracheal occlusion, who were assessed by fetal MRI, liveborn after 32 weeks, and in whom follow-up until discharge from the neonatal care unit was available. Measurements of lung volumes were expressed as a percentage of the appropriate mean (o/e total fetal lung volume (TFLV) x 100) either for gestational age or for FBV. Measurements of FBV were expressed as a percentage of the appropriate mean (o/e FBV x 100) for gestation. Fetuses with prenatal intervention were all assessed > or = 24 h after balloon removal. Regression analysis was used to examine the effect on postnatal survival of either o/e TFLV based on gestational age or based on FBV, gestation at delivery, side of CDH, intrathoracic position of the liver and prenatal intervention. Receiver-operating characteristics (ROC) curves were constructed for the prediction of survival by o/e TFLV based on gestational age and o/e TFLV based on FBV, for all fetuses, as well as for those with o/e FBV between 90 and 110% and those with values beyond that range. A power calculation for the number of fetuses needed to show a difference between the ROC curves was performed. RESULTS: Regression analysis demonstrated that o/e TFLV based on gestational age and on FBV were the only independent predictors of postnatal survival. The area under the ROC curve for prediction of postnatal survival from the o/e TFLV based on gestational age was 0.811, and for that based on FBV it was 0.868 (P < 0.001 for both). For fetuses with o/e FBV between 90 and 110%, and those with values < 90% and > 110%, the area for measurements based on gestational age was 0.895 and 0.733, respectively; when based on FBV it was 0.906 and 0.833 (P < 0.01 for all). A minimum of 273 patients would be needed to provide a probability of 90% of detecting a difference between the areas under both ROC curves. CONCLUSIONS: In fetuses with isolated CDH, lung volume as measured by fetal MRI was significantly correlated with survival. Prediction tended to be better by o/e TFLV based on FBV rather than gestational age. The difference in the prediction of survival between o/e TFLV based on FBV or gestational age was dependent on fetal biometry.

Relationship between lung area at ultrasound examination and lung volume assessment with magnetic resonance imaging in isolated congenital diaphragmatic hernia.

OBJECTIVES: To prospectively examine the relationship between contralateral lung area measured by two-dimensional (2D) ultrasound examination and contralateral and total fetal lung volume (FLV) estimated by magnetic resonance imaging (MRI) in the assessment of fetuses with congenital diaphragmatic hernia (CDH). METHODS: Sixty-six fetuses with isolated CDH were entered in this prospective study. Contralateral fetal lung area was measured by 2D ultrasonography using the longest axis method. Ipsilateral, contralateral and total FLV were measured using multiplanar axial T2-weighted MRI. Regression analysis was used to determine the significance of associations between contralateral lung area and contralateral and total FLV, and the predicted total FLV was subsequently calculated using the regression equation. Univariate regression analysis was used to investigate the effect on the proportionate difference between the predicted and the observed total FLV of gestational age, proportionate volume of ipsilateral vs. total FLV, side of CDH, intrathoracic herniation of the liver and intratracheal presence of a balloon. RESULTS: The 66 fetuses underwent a total of 191 paired 2D ultrasound and MRI examinations at a median gestational age of 30 (range, 18-38) weeks. It was possible to visualize and measure the contralateral lung area by 2D ultrasound, as well as both the ipsilateral and contralateral lung volumes by MRI, in all instances. There was a significant association between contralateral lung area and contralateral lung volume (r = 0.86; P < 0.001) and with total FLV (r = 0.84; P < 0.001). Univariate regression analysis showed that the proportionate difference between the predicted and the observed total FLV was significantly associated with the proportionate volume of ipsilateral vs. total FLV but not with gestational age, side of CDH, intrathoracic herniation of the liver or intratracheal presence of the balloon. CONCLUSIONS: In CDH, contralateral lung area measurement by 2D ultrasound correlates well with the total FLV estimated by MRI, irrespective of gestational age, liver herniation or side of herniation. Inconsistencies between the two measurements are attributable to the contribution of the ipsilateral lung to the total lung volume.

Comparison of fetal lung area to head circumference ratio with lung volume in the prediction of postnatal outcome in diaphragmatic hernia.

OBJECTIVES: To compare prediction of postnatal survival in isolated diaphragmatic hernia by prenatal two-dimensional (2D) versus three-dimensional (3D) sonographic assessment of the contralateral lung. METHODS: The lung area to head circumference ratio (LHR) of the contralateral lung was measured and expressed as a percentage of the normal mean for gestation (O/E) in 47 fetuses with isolated diaphragmatic hernia at 26 (range, 21-36) weeks of gestation. The lung area was measured by tracing the limits of the lungs (LHR trace) and by multiplying the longest diameter by its perpendicular (LHR diameters). The contralateral lung volume was measured by the Virtual Organ Computer-Aided anaLysis method and the O/E was calculated. Regression analysis was used to determine the significance of the LHRs and volume in the prediction of postnatal survival. RESULTS: The survival rate was 59.6% (28 of 47). There were significant associations between O/E LHR trace and O/E LHR diameters, and between each O/E LHR and O/E volume, but multiple regression analysis demonstrated that significant prediction of survival was provided only by O/E LHR trace and intrathoracic herniation of the liver. CONCLUSIONS: In diaphragmatic hernia prenatal prediction of postnatal outcome is better by 2D measurement of LHR trace than it is by 3D measurement of lung volume.