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.

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.

Additional benefits of three-dimensional ultrasound for prenatal assessment of twins.

Three-dimensional ultrasound (3DUS) may provide additional information for prenatal assessment of twins. It may improve the diagnostic confidence of dating, nuchal translucency (NT) and chorionicity assignment in twin pregnancies. The "virtual 3DUS placentoscopy" can guide selective fetoscopic laser photocoagulation (SFLP) to treat twin-twin transfusion syndrome (TTTS). Volumetric assessment of the dysmorphic acardiac twin with the Virtual Organ Computer-aided Analysis (VOCAL) software is more accurate than the conventional ultrasound measurement. Twin anemia polycythemia (TAP) sequence and selective intrauterine growth restriction (sIUGR) may be clinically monitored with 3DUS placental volume (PV) and power Doppler vascular indices. Congenital anomalies are more common in twins. Evaluation of fetal anomalies with 3DUS could assist perinatal management. The 3DUS power Doppler can provide a better understanding of true and false umbilical cord knots, which are commonly found in monoamniotic (MA) twins. Single demise in monochorionic (MC) twin pregnancies can cause severe neurologic morbidity in the surviving co-twin. Prenatal prediction of brain injury in the surviving co-twin with unremarkable neurosonographic examination is difficult. The 3DUS power Doppler may aid in prenatal detection of subtle abnormal cerebral perfusion. Prenatal assessment of conjoined twins with 3DUS is important if emergency postnatal surgical separation is anticipated. There is no significant additional advantage in using real-time 3DUS to guide prenatal interventions. Assessment of the cervix and pelvic floor during twin pregnancies is enhanced with 3DUS. Due to lack of high-quality studies, routine prenatal 3DUS in twin pregnancies needs to be balanced with risks of excessive ultrasound exposure.

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.

Model Surgical Training: Skills Acquisition in Fetoscopic Laser Photocoagulation of Monochorionic Diamniotic Twin Placenta Using Realistic Simulators.

Fetoscopic laser coagulation of arterio-venous anastomoses (AVA) in a monochorionic placenta is the standard of care for twin-twin transfusion syndrome (TTTS), but is technically challenging and can lead to significant complications. Acquiring and maintaining the necessary surgical skills require consistent practice, a critical caseload, and time. Training on realistic surgical simulators can potentially shorten this steep learning curve and enables several proceduralists to acquire procedure-specific skills simultaneously. Here we describe realistic simulators designed to allow the user familiarity with the equipment and specific steps required in the surgical treatment of TTTS, including fetoscopic handling, approaches to anterior and posterior placenta, recognition of anastomoses, and efficient coagulation of vessels. We describe the skills that are especially important in conducting placental laser coagulation that the surgeon can practice on the model and apply in a clinical case. These models can be adapted easily depending on the availability of materials and require standard fetoscopy equipment. Such training systems are complementary to traditional surgical apprenticeships and can be useful aids for fetal medicine units that provide this clinical service.

Undiagnosed Uterine Sarcomas Identified During Surgery for Presumed Leiomyoma at a National Tertiary Hospital in Thailand: A 10-Year Review.

OBJECTIVES: The aim of this study was to evaluate the rate, clinical characteristics, and survival outcomes of an undiagnosed uterine malignancy in patients who underwent surgical treatment for presumed leiomyomas. METHODS: Medical records of patients who underwent surgical treatment for presumed leiomyomas, from January 2004 to September 2013, were retrospectively reviewed, and the data were followed until September 2016. Demographic data, tumor characteristics, oncologic treatment, and response rate were analyzed by descriptive statistics. Kaplan-Meier method was used for survival analysis. This study includes follow-up data through December 31, 2016. RESULTS: A total of 11,258 medical records of presumed leiomyoma patients undergoing hysterectomy during the studied period were reviewed. Pathology of uterine sarcoma was found in 22 patients (0.2%), all of whom were included. Nineteen patients had leiomyosarcoma, and 3 had endometrial stromal sarcoma. Mean age of patients was 48.3 ± 6.9 years. All patients underwent total abdominal hysterectomy, with 20 patients undergoing concurrent bilateral salpingo-oophorectomy. Uterine sarcoma was classified as stage IB in 21 patients and stage IIIC in 1 patient. Fifteen patients were prescribed the following adjuvant treatment: chemotherapy in 13 patients and megestrol acetate in 2 patients. Thirteen patients had recurrent disease, and 3 patients died of their disease. The mean progression-free survival was 50.1 ± 41.3 months, and overall survival was 59.3 ± 43.0 months. CONCLUSIONS: One in 512 patients who underwent hysterectomy because of presumed uterine leiomyomas had inadvertent uterine sarcomas. Even with adjuvant therapy, treatment outcome was rather poor, with almost 60% recurrence rate and median progression-free survival and overall survival of less than 5 years.

Establishing Prenatal Surgery for Myelomeningocele in Asia: The Singapore Consensus.

OBJECTIVES: The Management of Myelomeningocele Study (MOMS Trial) has inspired many fetal therapy centers (FTCs) to offer open fetal surgery for myelomeningocele (MMC). This is an initial effort to create a candidate model that can be applicable to many parts of Asia. MATERIAL AND METHODS: A limited selection of specialists from 4 established FTCs in Thailand, Hong Kong, India, and Singapore met for a round table discussion. Experts from Children's Hospital of Philadelphia (CHOP) involved in the Trial moderated the session. The practice suggestions in this statement were from a targeted literature review and expert opinion. RESULTS: A high prevalence of MMC in Asia supports an effort to adopt the procedure, but only in established FTCs with good maternal and neonatal ancillary supports. The falling incidence of MMCs may affect case volume and maintenance of skill. A regional approach was recommended. Fetal benefits have to be weighed against maternal risks, with a consideration of recent outcome data from the endoscopic approach. Responsible FTCs need standardized diagnosis and management, with their long-term outcome data available for an audit. CONCLUSIONS: It is envisaged that the information presented by this multidisciplinary team would be useful for FTCs in Asia or elsewhere that plan to establish more advanced fetal care in the future.

Three-dimensional ultrasound for prenatal assessment of conjoined twins: additional advantages?

Conjoined twins are a rare, but serious, complication of monozygotic twins. Early prenatal diagnosis of conjoined twins is increasingly made with transvaginal ultrasound and color Doppler studies. Most prenatally diagnosed conjoined twins are terminated due to the high perinatal mortality, but advancement in pediatric surgery has allowed for successful postnatal separation in a small number of cases, and some parents may consider this option over termination of pregnancy. It is important to get a detailed prenatal ultrasound for the site and extent of fusion for an accurate categorization. Three-dimensional ultrasound (3DUS) provides images that can facilitate counselling for the parents. Additional information that impacts on diagnosis, prognostication, and perinatal management of conjoined twins could be obtained from selective use of 3DUS, particularly those with atypical fetal union. Most of the proposed additional benefits of 3DUS are based on case reports. Magnetic resonance imaging (MRI) has been increasingly used for the purpose of identifying intricate organ sharing. Because of the rarity of this condition, and the heterogeneity of fetal fusion, added benefits of either 3DUS or MRI for prenatal diagnosis and perinatal management of conjoined twins have not been demonstrated by well-conducted clinical trials. This article aims to review clinical application of various 3DUS display modes in prenatal assessment of conjoined twins, focusing on their potential additional benefits, risks and misuses. 3DUS may help detecting additional findings that are not possible with 2DUS, but, it has not been scientifically shown to improve the survival rate of the twins or reduce maternal morbidity.

Differential patterns of prenatal ipsilateral and contralateral lung growth in cases of isolated left-sided congenital diaphragmatic hernia.

OBJECTIVE: The aim of this research was to compare the impact of varying degrees of visceral herniation on the growth rates of the contralateral and ipsilateral fetal lungs in cases of isolated left-sided congenital diaphragmatic hernia (CDH). METHODS: Data were retrieved from 58 fetuses with isolated left-sided CDH undergoing magnetic resonance imaging studies at both mid-gestation (20-30 weeks) and late-gestation (>30 weeks) time points. The growth of the right and left lungs (ΔLV-R and ΔLV-L) was calculated. The impact of the degree of visceral herniation on the growth disparity between the right and left lungs was then compared. RESULTS: Measurable growth occurred in both lungs between the mid-gestation and late-gestation time points in each group. The ΔLV-R exhibited a strong correlation with ΔLV-L. However, the right lung grew significantly faster than the left lung (ΔLV-R = 1.36 vs ΔLV-L = 0.17 mL/week, P < 0.001). A higher degree of visceral herniation appeared to decrease the growth rate disparity by progressive limitation of the growth of the right lung. CONCLUSION: The contralateral lung retains the potential to grow faster than the ipsilateral lung during the third trimester. A higher degree of visceral herniation places progressive limitations on contralateral lung growth thereby diminishing the growth rate disparity between the right and left lungs.

8-year analysis of the prevalence of lymph nodes metastasis, oncologic and pregnancy outcomes in apparent early-stage malignant ovarian germ cell tumors.

PURPOSE: To determine the rate of lymph node metastasis, oncologic and pregnancy outcomes in apparent early-stage malignant ovarian germ cell tumor (MOGCT). MATERIALS AND METHODS: Medical records of apparent early-stage MOGCT patients undergoing primary surgical treatment at Siriraj Hospital, Bangkok, Thailand, between January 2006 and December 2013, were retrospectively reviewed. RESULTS: Thirty-eight patients had apparent stage I-II MOGCT. The mean age was 22.1±7.7 years (median, 20.8 years; range, 7.7-35.6 years). The mean tumor size was 17.8±6.5 cm with a median of 20 (range 4-30) cm. Three most common histopathologies were dysgerminoma (12 patients, 31.6%), immature teratoma (12 patients, 31.6%), and endodermal sinus tumor (6 patients, 15.8%). Twenty-seven of 38 patients underwent lymphadenectomy; 13 patients (48.2%) were stage IA and 8 patients (29.6%) were stage IC. The rate of retroperitoneal nodes metastasis was 7.4% (2/27 patients). At 26.1 months of median follow-up time (range 1.9-88.5 months), 9 patients retained fertility functions, with uneventful pregnancies in 3 of these. Only one patient (2.6%) had progression of disease at 4.9 months after surgery. The 5-year survival rate was 97.4%. CONCLUSION: As the rate of pelvic or para-aortic node metastasis in MOGCT is considerable, lymphadenectomy should be incorporated in surgical staging procedures.

Expanded intrathoracic space in fetal cases of isolated congenital diaphragmatic hernia contributes to disparity between percent predicted lung volume and observed to expected total lung volume.

OBJECTIVE: The aim of this study was to determine whether fetal lung volume and visceral herniation are associated with changes in intrathoracic space in congenital diaphragmatic hernia(CDH). METHODS: We retrospectively examined the relationship between magnetic resonance imaging-derived measurements of intrathoracic space [predicted lung volume (PLV)] and residual lung volume or visceral herniation among isolated left-sided CDH fetuses. RESULTS: Data from fetal magnetic resonance imaging studies of 60 isolated left-sided CDH cases were analyzed. The median PLV of the CDH fetuses was found to be much greater than the expected total lung volume (eTLV) of a normal fetus at the same gestational age. Surprisingly, liver herniation and observed TLV(oTLV) were positively correlated with the PLV. Although the PPLV was consistently less than the o/eTLV, both indices were greater in survivors than in non-survivors, whereas no significant difference was seen in the PLV/eTLV ratio in regard to survivorship. CONCLUSION: The intrathoracic domain available for lungs and viscera is expanded in CDH fetuses and positively affected by the lung volume and the presence of liver herniation, leading to the difference in the PPLV and o/eTLV. Future study of intrathoracic space as it relates to the growth of the lung and herniated viscera is needed to better characterize the relationship between these parameters.

Fetal lung growth represented by longitudinal changes in MRI-derived fetal lung volume parameters predicts survival in isolated left-sided congenital diaphragmatic hernia.

OBJECTIVE: The aim of this study was to evaluate fetal lung growth rate for isolated left-sided congenital diaphragmatic hernia (CDH) using serial magnetic resonance imaging (MRI)-based volumetric measures. METHODS: Early and late gestational (22-30 and >30 weeks' gestation) lung volumetry was obtained by fetal MRI in 47 cases of isolated left-sided CDH. At both of these time points, lung volume indices, including total lung volume (TLV), observed to expected TLV (o/e TLV), and percentage of predicted lung volume (PPLV) as well as their change rates (Δ) and relative Δ during gestation were calculated and analyzed in regard to their capacity to predict neonatal survival. RESULTS: TLV, o/e TLV, and PPLV had various changes during gestation. Late TLV, early and late o/e TLV, and late PPLV were predictive of neonatal survival. Non-survivors had lower ΔTLV and more negative relative ΔPPLV than survivors (1.18 vs 1.85 mL/week, P = 0.004 and -4.15%/week vs -1.95%/week, P = 0.002, respectively). CONCLUSIONS: The severity of pulmonary hypoplasia is dynamic and can worsen in the third trimester. MRI lung volumetry repeated in late gestation can provide additional information on individual lung growth that may facilitate prenatal counseling and focus perinatal management.

Functional three-dimensional sonographic study of the postpartum uterus.

OBJECTIVE: To demonstrate sequential changes of the postpartum uterus using two- and three-dimensional (2D and 3D) ultrasounds and Doppler studies. METHODS: Eighty-one women who delivered a singleton at term were recruited for this prospective longitudinal study. Manual and ultrasound examinations of the uterus were performed for seven consecutive weeks. Sequential changes in size of the uterus, endometrial thickness and appearances and Doppler indices of the uterine and arcuate arteries were analyzed. RESULTS: Complete follow ups were achieved in 71 women who had an uncomplicated postpartum course. 2D and 3D ultrasound estimations of uterine volume are highly correlated with each other (r > 0.7), but not manual estimations (r < 0.3). Data generated from 497 3D observations demonstrated rapid involution of the uterus in the first two weeks after delivery. Breastfeeding and parity did not affect uterine involution (r < 0.2). Resistance index (RI) of the uterine artery started to elevate at four weeks after delivery (r > 0.7). RI of the arcuate artery was not significantly changed during the study period (r < 0.2). Uterine involution was independent from progressive thinning of the endometrium and elevation of uterine artery RI. (r < 0.1 and 0.2, respectively). CONCLUSION: Longitudinal sonographic study showed independent physiologic reversals of uterine volume, endometrium and vascular supply in the first seven weeks following vaginal delivery. Standardization of measurement techniques is essential to apply this information for an early detection of postpartum uterine complications.

Reference values for fetal aortic isthmus blood flow parameters at 24 to 38 weeks' gestation.

OBJECTIVE: The goal of this study is to establish population-specific nomograms of fetal aortic isthmus (AoI) Doppler indices in the period of 24-38 weeks' gestation. METHODS: This was a cross-sectional study of 240 Asian singleton pregnant women at 24-38 completed weeks' gestation. Fetal AoI blood flow was evaluated by Doppler study with automatic calculation of pulsatility index, resistance index, peak systolic velocity, end-diastolic velocity, and time-averaged maximum velocity. The relationship of these indices and gestational age was estimated by using regression analysis, and the best predictive models were determined to define mean, 5th, and 95th centile of each gestational age. The reproducibility was expressed by intraclass correlation coefficients and limits of agreement. RESULTS: The mean maternal age was 28 ± 5.7 years. A total of 97% of all attempts to obtain AoI Doppler waveforms were successful with high interobserver and intraobserver reproducibility. Pulsatility index and peak systolic velocity significantly correlated with gestational age (P = 0.03 and 0.001, respectively), whereas no significant change of resistance index, end-diastolic velocity, and time-averaged maximum velocity with advancing gestation was observed. CONCLUSION: This study offers normative values of fetal AoI Doppler indices, which may be useful in the difficult task of fetal surveillance in growth-restricted fetuses among our population.