A conditional standard for the customized fetal growth trajectory in twin pregnancy.

BACKGROUND: The difference in the birth weights between twins and singletons grows with advancing gestation. Although many fetal weight standards based on ultrasonographic measurements have been created for tracking fetal growth in twin pregnancies, their applicability to other groups is limited by the fact that they are population specific. OBJECTIVE: This study aimed to generate conditional centiles for growth assessment of twin fetuses and to compare them with other population-based growth standards for singleton and twin fetuses. STUDY DESIGN: This was a retrospective, longitudinal study of ultrasound-based estimated fetal weight data of normal twin fetuses delivered after 34 weeks of gestation. Linear mixed effects models that adjusted for maternal characteristics, fetal gender, and chorionicity were used to evaluate the relationship between estimated fetal weight and gestational age. The estimated fetal weight reference values were calculated using conditional centile based on the estimated fetal weight at an earlier gestational age. To compare our results with previous studies, fetal growth curves were generated using a formula we created that included maternal characteristics and the estimated fetal weight at 24 weeks of gestation in these studies. In a subgroup analysis of our low-risk twin babies born at full term, we calculated the number of fetuses who were reclassified as being in the bottom 10th percentile using each of the previous population-based standard. RESULTS: A total of 2644 ultrasounds with a median of 4 scans per fetus from 572 twin pregnancies were included in this analysis. In the cohort, 36% of the fetuses were monochorionic. Maternal age, body mass index, and the interaction between fetal gender and chorionicity were significantly associated with estimated fetal weight. The predicted growth curves matched the growth standard for twins. In our low-risk group, when the singleton standard was used, the incidence of estimated fetal weight <10th percentile was above 20% from gestational week 24 to 38, and this incidence varied when reclassified using other population-based twin standards. CONCLUSION: This conditional growth chart was specifically designed to assess fetal growth in twin pregnancies, but it is generalizable to other populations.

Ablative effect of the interstitial laser setting in the human placental model.

AIM: To assess the impact of laser power and time on interstitial ablation generated by neodymium-doped yttrium aluminium garnet (Nd:YAG) and diode laser in the human placental model. METHODS: The experiment was carried out in a simulation model of interstitial laser ablation on ex-vivo placental tissue. One-hundred and forty-four pieces of fresh placentae were interstitially ablated with Nd:YAG or diode laser at various power (15, 20, 25, 30 W)-time (5, 10, 15 s) combinations. The ablation tissues were evaluated using both sonographic and histopathologic measurements. RESULTS: Laser generator, power, and time significantly affected the ablation size (p < 0.001). The coagulation zone continuously increased with extending time at the power of 15, 20, and 25 W. When adjusting to the power of 30 W, increased time from 10 to 15 s did not induce the larger coagulation diameter. The maximal diameter was obtained at the laser power of 20 W for 15 s. The ablation from the diode laser was greater than that from Nd:YAG laser. The sonographic evaluation overestimated the ablation size by an average of 24%. CONCLUSION: Diode laser destroys greater tissue than Nd:YAG laser. Different power settings of interstitial laser ablation produce diverse patterns of correlation between laser time and coagulation size.

Reference values for fetal Doppler-based cardiocirculatory indices in monochorionic-diamniotic twin pregnancy.

BACKGROUND: Placental anastomoses in monochorionic diamniotic (MCDA) twin pregnancy have a major impact on fetal circulation. This study was designed to define reference ranges of cardiac and vascular Doppler indices in MCDA twin pregnancies. METHODS: This cross-sectional study included 442 uncomplicated MCDA twin fetuses undergoing Doppler ultrasonography at 18-35 weeks of gestation. Left and right myocardial performance index (LV-MPI, RV-MPI), E/A ratio of atrioventricular valves, pulsatility indices of umbilical artery, middle cerebral artery (MCA), and ductus venosus (DV), cerebroplacental ratio, peak systolic velocity of MCA, S/a ratio of DV, and early diastolic filling time of ductus venosus (DV-E) were evaluated under standardized settings. The equation models between Doppler indices and gestational age (GA) were fitted. After adjustment for GA, the correlations between MPI and fetal heart rate (FHR), and between MPI and DV indices were analyzed. RESULTS: Estimated centiles of Doppler indices were derived as a function of GA, being distinct in values from those of singletons. There was no correlation between GA-adjusted MPI and FHR. DV-E was inversely related to LV-MPI. CONCLUSIONS: MCDA twins showed significant changes in some Doppler indices throughout gestation with quantitative differences from singletons, emphasizing the importance of MC twin-specific reference values for clinical application. Further adjustment of MPI for FHR was unnecessary. DV-E is a vascular index indirectly representing fetal diastolic function.

A 10-Year Retrospective Review of Prenatal Applications, Current Challenges and Future Prospects of Three-Dimensional Sonoangiography.

Realistic reconstruction of angioarchitecture within the morphological landmark with three-dimensional sonoangiography (three-dimensional power Doppler; 3D PD) may augment standard prenatal ultrasound and Doppler assessments. This study aimed to (a) present a technical overview, (b) determine additional advantages, (c) identify current challenges, and (d) predict trajectories of 3D PD for prenatal assessments. PubMed and Scopus databases for the last decade were searched. Although 307 publications addressed our objectives, their heterogeneity was too broad for statistical analyses. Important findings are therefore presented in descriptive format and supplemented with the authors' 3D PD images. Acquisition, analysis, and display techniques need to be personalized to improve the quality of flow-volume data. While 3D PD indices of the first-trimester placenta may improve the prediction of preeclampsia, research is needed to standardize the measurement protocol. In highly experienced hands, the unique 3D PD findings improve the diagnostic accuracy of placenta accreta spectrum. A lack of quality assurance is the central challenge to incorporating 3D PD in prenatal care. Machine learning may broaden clinical translations of prenatal 3D PD. Due to its operator dependency, 3D PD has low reproducibility. Until standardization and quality assurance protocols are established, its use as a stand-alone clinical or research tool cannot be recommended.

Factors affecting Thai pregnant women's decisions concerning prenatal diagnosis and termination of pregnancy for ß-thalassemia.

AIM: To investigate the factors influencing decisions concerning prenatal diagnosis (PND) and termination of pregnancy for ß-thalassemia in Thai pregnant women. METHODS: A total of 142 Thai Buddhist pregnant women waiting for PND were asked to undertake semi-structured interviews regarding their reasons for PND and their decisions and reasoning concerning pregnancy if the fetus was found to be affected. The interviews were analyzed using a thematic content approach. RESULTS: Thai pregnant women accepted PND for three reasons: to know whether their pregnancies were affected, to confirm that their pregnancies were unaffected and to terminate if their pregnancies were affected. Three decisions identified among the women were to terminate the pregnancy, to continue the pregnancy and undecided. The interview analysis identified five themes and nine sub-themes affecting pregnancy-related decision-making: (i) quality of life (suffering or no disability); (ii) burden (difficulty or acceptability); (iii) sense of motherhood (the best way for the child or I cannot hurt my child); (iv) significant others (support to terminate, support to continue or support to wait for the test result) and (v) conflict in deciding. CONCLUSION: An acceptance of PND in Thai pregnant women was not always associated with pregnancy termination. Multiple factors influenced the decision to terminate, but not their religious affiliation.

Morphology, intrafetal vascular pattern, and umbilical artery Doppler indices of acardiac twins.

BACKGROUND: Twin reversed arterial perfusion (TRAP) sequence consists of acardiac twin (A) paradoxically perfused by pump twin (P) through an umbilical artery (UA). We proposed characterization of acardiac twins with intrafetal vascular pattern (IVP), and assessed its correlation with morphology and UA Doppler indices. METHODS: We prospectively evaluated 21 cases of TRAP sequence. Morphology (acardia vs hemicardia) and IVP (simple vs complex) of acardiac twins were characterized with ultrasound and color Doppler. Twins weight ratio (A/P Wt) and UA Doppler indices of acardiac and pump twins including (1) difference of systolic/diastolic ratio (UA ∆S/D), (2) difference of resistance index (UA ∆RI), and (3) ratio of pulsatility index (UA PI A/P) were calculated. RESULTS: The median (min, max) gestational age at diagnosis was 18 (11, 27) weeks. Acardia (n = 14) were associated with simple IVP (n = 16) (P < .05). After exclusion of acardia with complex IVP (n = 1), the A/P Wt, UA ∆S/D, UA ∆RI, and UA PI A/P of acardia with simple IVP (n = 13), hemicardia with simple IVP (n = 3), and hemicardia with complex IVP (n = 4) were not significantly different (P > .05). CONCLUSIONS: Most of acardiac twins were acardia with simple IVP. Morphology and IVP of acardiac twins were not associated with UA Doppler indices.

Comparison of Mannequin Training Satisfaction with a Conventional Box Trainer and a Low-Fidelity Fetoscopic Surgical Simulator for Selective Fetoscopic Laser Photocoagulation.

BACKGROUND: A low-fidelity fetoscopic surgical simulator (FSS) for training of selective fetoscopic laser photocoagulation (SFLP) was developed. OBJECTIVE: To evaluate and compare training satisfaction with an FSS and with a conventional box trainer (BT). METHODS: The BT consisted of a cleaned human placenta attached to the inside of a plastic storage box with a watertight lock cover and an ultrasound-transparent rubber skin. The FSS consisted of the replica of a monochorionic twin placenta attached to the inside of a spherically shaped, ultrasound-transparent phantom. Tap water was used as an ultrasound conduction agent. Evaluation of the mannequin trainings was conducted on 8 junior maternal-fetal medicine (MFM) attending physicians and 22 MFM fellows. Training satisfaction was scored from 0 to 10 on 8 different domains. RESULTS: The mean satisfaction score (±SD) with the FSS was higher than with the BT in all domains (p < 0.05). The fellows' training satisfaction with the BT was greater than that of the attending physicians in 4 domains: tactile feedback, demonstration of chorionic vessels, feedback on performance, and overall value as learning aid (p < 0.05). CONCLUSIONS: As evaluated by a small group of trainees, our FSS is superior to the BT in mannequin training of SFLP. However, the BT may be more useful for trainees with limited clinical experience.

Simulation-based fetal shunting training.

OBJECTIVES: To develop a simulation model and assess the learning curve of fetal shunting. METHODS: Three staff and three trainees performed fetal shunting on a model using the fetal bladder stent. The model was evaluated according to various sources of validity evidence. The number of procedures to reach competency was determined by the learning curve-cumulative summation (LC-CUSUM) and CUSUM analysis. The learning and control phases were defined as the periods before and after passing the level of competency, respectively. RESULTS: The model was validated to be constructive in the educational process. A total of 600 procedures were carried out with an overall success rate of 94.2% and no significant difference between staff and trainees. The average number of procedures to reach competency was 47. Total procedural time decreased after passing the level of competency. Although the trainees required a longer procedural time in the learning phase than the staff did, there was no significant between-group difference in the control phase. CONCLUSIONS: Using this model, the estimated number of procedures to achieve competency was 47, as substantiated by the increased procedural success and reduced procedural time in the control phase. Training on this simulation model may improve technical performance.

Advanced ultrasound for prenatal interventions.

Ultrasound is an integral part of prenatal interventions. Doppler studies and 3-dimensional ultrasound (3DUS) are frequently used to determine whether fetal surgery is required. The operator's experience remains crucial for reducing procedure-related morbidity. Real-time 3DUS (or 4DUS) can simultaneously display the needle tip in three orthogonal planes, providing reassurance that no fetal parts are in the path. In experienced hands, 4DUS guidance may not be more effective than B-mode, but its value for less-experienced operators remains to be determined. Recent developments in needle, shunt, and video endoscopic technologies may compliment the use of image-guided in utero procedures. Future developments of higher-dimensional transducers and image software may improve the utility of ultrasound for invasive obstetric interventions.

Time and temperature dependence of radiofrequency ablation in the human placenta.

OBJECTIVE: The objective of the study is to compare radiofrequency (RF) effects on fresh placentae with varying levels of sustained time (Ts) and degrees of target temperature (°t). METHOD: A total of 108 pieces of fresh placentae were coagulated with a 2-cm RF needle at 60 W in an organ bath. The vertical and horizontal diameters (Vd, Hd) of tissue coagulation visualized by ultrasound were measured. The impacts of 12 different Ts-°t combinations on the ablation size ascertained on pathological examination (Vdp , Hdp ) were compared using 2-way ANOVA. The agreement between sonographic and pathological findings was assessed using Bland-Altman analysis. RESULTS: Considerable changes in the Vdp and Hdp were associated with increasing the Ts and °t. The impact of RF on tissue coagulation was greatest when the °t was set at 100°C, with further destruction as the Ts progressed to 7 minutes of exposure. The ablation size estimated by ultrasound exhibited an overestimation by an average of 5.65% and 21.02% for Vd and Hd, respectively. CONCLUSION: A prolonged Ts at a higher °t contributes to progressive placental tissue destruction by RF, with maximum destruction at 100°C for 7 minutes in an ex vivo nonperfused placenta. Tissue injury that is apparent on ultrasound may extend beyond pathological damage.

Effect of halogen light in fetal stimulation for fetal well-being assessment.

OBJECTIVE: To evaluate the shortening of the time of nonstress test (NST) by using transabdominal fetal stimulation with halogen light. STUDY DESIGN: Experimental research. MATERIAL AND METHOD: The authors enrolled 176 pregnant women between 32 and 42 weeks of gestation indicated for NST at the Division of Maternal Fetal Medicine, Siriraj Hospital, Mahidol University. They were randomly assigned to receive either NST (control) or halogen light stimulation test (LST). The stimulation was performed at the beginning of the test and repeated every 10 minutes until reassuring fetal heart rate (FHR) acceleration was achieved, or up to 3 times. All tracings were interpreted blindly by one investigator at the end of the tests. RESULTS: The mean (+/- SD) duration from starting the test to the first FHR acceleration was not significantly different between the control group and the LST group (5.6 +/- 7.2 and 5.4 +/- 5.2 minutes, respectively). The average testing time (+/- SD) to achieved reactivity was 10.5 +/- 8.8 minutes in the controls and 9.6 +/- 6.7 minutes in the LST group. This was not statistically different. The incidence of nonreactive tests was not significantly different between the LST and the controls (15.9% and 11.4%, respectively). Among the LST subjects, term fetuses and women with BMI < 27 kg/m2 required less time to reach reactivity, 2.4 and 2.3 minutes respectively. CONCLUSION: Transabdominal halogen light stimulation did not shorten the duration of NST in the presented population. However, the presented data suggests that the fetus at term could respond to visual stimulation, especially when the gestational age is more advanced.

Noninvasive diagnosis of fetal anemia and fetal intravascular transfusion therapy: experiences at Siriraj Hospital.

Traditionally, when fetal hydrops are found along with certain markers indicating fetal anemia, fetal blood sampling would be performed through cordocentesis to confirm the diagnosis. This procedure, however comes with an inherent risk of losing the whole pregnancy. When anemia was verified, treatment options were limited and the prognosis was grim. In this article, the authors described their experiences of using prenatal Doppler studies as a noninvasive venue in the diagnosis and treatment of fetal anemia. Once the diagnosis of fetal anemia is made, the patient will be asked to undergo an algorithm to investigate the definite cause of anemia, along with simultaneous ultrasound-guided intravascular fetal transfusion in selected cases. The authors selected two cases of fetal anemia of different etiologies and treatment outcomes to demonstrate the significance of early diagnosis and intervention. Review of the relevant medical literatures and the proposed algorithms were also provided.