European association of perinatal medicine (EAPM) position statement: Screening, diagnosis and management of congenital anomalies of the umbilical cord.

Congenital anomalies of the umbilical cord are associated with an increased risk of pregnancy and perinatal complications. Some anomalies of the cord have a higher prevalence than other fetal structural anomalies. The most common anomalies are the absence of an umbilical artery and velamentous insertion of the cord (with or without vasa previa). These anomalies, even when not associated with fetal structural defects, increase the risk of adverse perinatal outcome including, fetal growth restriction and stillbirth. In the absence of prenatal diagnosis, vasa previa is associated with the highest perinatal morbidity and mortality of all congenital anomalies of the umbilical cord. Most cases can be detected by ultrasound from the beginning of the second trimester and should be included in the routine mid-pregnancy ultrasound examination. Documentation should include cord insertion site, number of vessels in the cord, and if other pathologies have been detected. Pregnancies at increased risk of velamentous cord insertion should be screened for vasa previa using transvaginal ultrasound and colour Doppler imaging. If a velamentous cord insertion or isolated single umbilical artery is detected, individualised follow-up during pregnancy and tailored obstetric management are indicated.

Clinical-sonographic scores for the screening of placenta accreta spectrum: A systematic review and meta-analysis.

OBJECTIVE: Clinical-sonographic scoring systems, combining clinical features and ultrasound imaging markers have been proposed for the screening of placenta accreta spectrum (PAS) but their usefulness in different set-ups remains limited. The aim of this study was to assess and compare different clinical-sonographic score systems performed from the midst of pregnancy for the prenatal evaluation of patients at risk of PAS at birth. DATA SOURCES: PubMed/MEDLINE, Google Scholar, and Embase were searched between October 1982 and October 2022 to identify eligible studies. STUDY ELIGIBILITY CRITERIA: Observational studies providing data on the use of a combined clinical-ultrasound score systems performed from the midst of pregnancy for the prenatal evaluation of PAS. METHODS: Study characteristics were evaluated by two independent reviewers using a predesigned protocol PROSPERO (CRD CRD42022332486). Heterogeneity between studies was analysed with Cochran's Q-test and the I2 statistics. Statistical heterogeneity was quantified by estimating the variance between the studies using I2 statistics. The area under the receiver operating characteristic curve AUC of ROC of each score and their summary (SROC) was calculated with sensitivity and specificity, and the integrated score of the SROC of all sonographic markers was calculated. Forest Plots were used to develop the meta-analysis of each sonographic marker and for the integrated sonographic score. RESULTS: Of 1028 articles reviewed, 12 cohorts and two case-control studies including 1630 patients screening for PAS by clinical-ultrasound scores met the eligibility criteria. A diagnosis of PAS was reported in 602 (36.9%) cases for which 547 (90.9%) intraoperative findings and/or histopathologic data were described. A wide variation in reported sensitivities and specificities was observed between studies and in thresholds used for the identification of patients with a high probability of PAS at birth. The SAUCs of the individual sonographic scores ranged between 0.85 (the lowest) for sub-placental hypervascularity to 0.91 for placental location in the lower uterine segment (LUS), myometrial thinning, and placental lacunae and 0.95 for the loss of clear zone. Only four studies included placental bulging in their sonographic score system and therefore no meta-analysis for this score was performed. The integrated SAUC was 0.83 [95% Confidence Interval (95% CI) 79 to 0.86). Forest Plot analysis revealed an integrated sensitivities and specificities of 0.68 [95% CI 0.53-0.80], and 0.88 [95% CI 0.68 to 0.96]), respectively. CONCLUSIONS: Clinical-sonographic score systems can contribute to the prenatal screening of patients at risk of PAS at birth. While we included multiple sonographic studies from the midst of pregnancy, standardized evaluation should be performed not only with strict ultrasound criteria for the placental position, mid third trimester gestational age at examination, and sonographic markers associated with PAS. Numeric sensitivities, specificities, NPVs, PPV, LR-, and LR+ should be recorded prospectively to assess their accuracy in different set-ups and PTP should be verified at delivery. The variables recommended for most predictive screening are: loss of clear zone underneath the placental bed, placentation in the LUS, and placenta lacunae.

Vasa previa in singleton pregnancies: diagnosis and clinical management based on an international expert consensus.

BACKGROUND: There are limited data to guide the diagnosis and management of vasa previa. Currently, what is known is largely based on case reports or series and cohort studies. OBJECTIVE: This study aimed to systematically collect and classify expert opinions and achieve consensus on the diagnosis and clinical management of vasa previa using focus group discussions and a Delphi technique. STUDY DESIGN: A 4-round focus group discussion and a 3-round Delphi survey of an international panel of experts on vasa previa were conducted. Experts were selected on the basis of their publication record on vasa previa. First, we convened a focus group discussion panel of 20 experts and agreed on which issues were unresolved in the diagnosis and management of vasa previa. A 3-round anonymous electronic survey was then sent to the full expert panel. Survey questions were presented on the diagnosis and management of vasa previa, which the experts were asked to rate on a 5-point Likert scale (from "strongly disagree"=1 to "strongly agree"=5). Consensus was defined as a median score of 5. Following responses to each round, any statements that had median scores of ≤3 were deemed to have had no consensus and were excluded. Statements with a median score of 4 were revised and re-presented to the experts in the next round. Consensus and nonconsensus statements were then aggregated. RESULTS: A total of 68 international experts were invited to participate in the study, of which 57 participated. Experts were from 13 countries on 5 continents and have contributed to >80% of published cohort studies on vasa previa, as well as national and international society guidelines. Completion rates were 84%, 93%, and 91% for the first, second, and third rounds, respectively, and 71% completed all 3 rounds. The panel reached a consensus on 26 statements regarding the diagnosis and key points of management of vasa previa, including the following: (1) although there is no agreement on the distance between the fetal vessels and the cervical internal os to define vasa previa, the definition should not be limited to a 2-cm distance; (2) all pregnancies should be screened for vasa previa with routine examination for placental cord insertion and a color Doppler sweep of the region over the cervix at the second-trimester anatomy scan; (3) when a low-lying placenta or placenta previa is found in the second trimester, a transvaginal ultrasound with Doppler should be performed at approximately 32 weeks to rule out vasa previa; (4) outpatient management of asymptomatic patients without risk factors for preterm birth is reasonable; (5) asymptomatic patients with vasa previa should be delivered by scheduled cesarean delivery between 35 and 37 weeks of gestation; and (6) there was no agreement on routine hospitalization, avoidance of intercourse, or use of 3-dimensional ultrasound for diagnosis of vasa previa. CONCLUSION: Through focus group discussion and a Delphi process, an international expert panel reached consensus on the definition, screening, clinical management, and timing of delivery in vasa previa, which could inform the development of new clinical guidelines.

Is telehealth useful in the management of placenta accreta spectrum in low-resource settings? Results of an exploratory survey.

OBJECTIVE: The optimal management of placenta accreta spectrum (PAS) requires the participation of multidisciplinary teams that are often not locally available in low-resource settings. Telehealth has been increasingly used to manage complex obstetric conditions. Few studies have explored the use of telehealth for PAS management, and we aimed evaluate the usage of telehealth in the management of PAS patients in low-resource settings. METHODS: Between March and April 2023, an observational, survey-based study was conducted, and obstetricians-gynecologists with expertise in PAS management in low- and middle-income countries were contacted to share their opinion on the potential use of telehealth for the diagnosis and management of patients at high-risk of PAS at birth. Participants were identified based on their authorship of at least one published clinical study on PAS in the last 5 years and contacted by email. This is a secondary analysis of the results of that survey. RESULTS: From 158 authors contacted we obtained 65 responses from participants in 27 middle-income countries. A third of the participants reported the use of telehealth during the management obstetric emergencies (38.5%, n = 25) and PAS (36.9%, n = 24). Over 70% of those surveyed indicated that they had used "informal" telemedicine (phone call, email, or text message) during PAS management. Fifty-nine participants (90.8%) reported that recommendations given remotely by expert colleagues were useful for management of patients with PAS in their setting. CONCLUSION: Telehealth has been successfully used for the management of PAS in middle-income countries, and our survey indicates that it could support the development of specialist care in other low resource settings.

Management of placenta accreta spectrum in low- and middle-income countries.

Placenta accreta spectrum (PAS) can be associated massive intra- and post-operative hemorrhage which when not controlled can lead to maternal death. Important advances have occurred in understanding the pathophysiology and therapeutic options for this condition. The prevalence of PAS at birth is direct association with the cesarean delivery (CD) rate in the corresponding population and is increasing worldwide. Limited health infrastructure in low- and middle-income countries increases the morbidity and mortality of patients with PAS at birth. In many cases, obstetricians working in limited resources settings cannot follow some of the international guideline's recommendations and have to opt for low-cost management procedures. In this review, we describe the particularities of managing PAS care in low- and middle-income countries from of prenatal evaluation of patients at risk of PAS at birth, therapeutic options, and inter-institutional collaboration. We also propose a management protocol based on training of the local obstetric teams rather than on sophisticated technological resources that are almost never available in low-resource scenarios.

Are international guideline recommendations for the management of placenta accreta spectrum applicable in low- and middle-income countries?

OBJECTIVE: The aim of this study was to explore how obstetricians-gynecologists in low- and middle-income countries (LMICs) can apply current international clinical practice guidelines (CPGs) for the management of placenta accreta spectrum (PAS) in limited resource settings. METHODS: This was an observational, survey-based study. Clinicians with expertise in managing patients with PAS in LMICs were contacted for their evaluation of the recommendations included in four PAS clinical practice guidelines. RESULTS: Out of the 158 clinicians contacted, we obtained responses from 65 (41.1%), representing 27 middle income countries (MICs). The results of this survey suggest that the care of PAS patients in middle income countries is very different from what is recommended by international CPGs. Participants in the survey identified that their practice was limited by insufficient availability of hospital infrastructure, low resources of local health systems and lack of trained multidisciplinary teams (MDTs) and this did not enable them to follow CPG recommendations. Two-thirds of the participants surveyed describe the absence of centers of excellence in their country. In over half of the referral hospitals with expertise in managing PAS, there are no MDTs. One-third of patients with intraoperative findings of PAS are managed by the team initially performing the surgery (without additional assistance). CONCLUSION: The care of patients with PAS in middle income countries frequently deviates from established CPG recommendations largely due to limitations in local resources and infrastructure. New practical guidelines and training programs designed for low resource settings are needed.

Surgical evacuation combined with Shirodkar cervical suture and selective uterine artery embolization: A fertility preserving treatment for 10-15 weeks' live cesarean scar ectopic pregnancies.

INTRODUCTION: Cesarean scar ectopic pregnancies (CSEPs) are associated with significant maternal morbidity and termination is often recommended in the early first trimester. Management of more advanced cases is challenging due to higher risks of major intraoperative hemorrhage. Hysterectomy is currently the intervention of choice for advanced cases. This study aimed to investigate if advanced live CSEPs could be managed effectively conservatively using suction curettage and interventional radiology. MATERIAL AND METHODS: A retrospective single-center cohort study was performed. A total of 371 women diagnosed with CSEP were identified between January 2008 and January 2023. A total of 6% (22/371) women had an advanced live CSEP with crown-rump length (CRL) of ≥40 mm (≥10 weeks' gestation). Of these, 77% (17/22) opted for surgical intervention, whilst the remaining five continued their pregnancies. A preoperative ultrasound was performed in each patient. All women underwent suction curettage under ultrasound guidance and insertion of Shirodkar cervical suture as a primary hemostatic measure combined with uterine artery embolization (UAE) if required. The primary outcome was rate of blood transfusion. Secondary outcomes were estimated intraoperative blood loss, UAE, intensive care unit admission, reintervention, hysterectomy, hospitalization duration and rate of retained products of conception. Descriptive statistics were used to describe these variables. RESULTS: Median CRL of the 17 patients included was 54.1 mm (range: 40.0-85.7) and median gestational age based on CRL was 12 + 3 weeks (range: 10 + 6-15 + 0). On preoperative ultrasound scan placental lacunae were recorded in 76% (13/17) of patients and color Doppler score was ≥3 in 67% (10/15) of patients. At surgery, Shirodkar cervical suture was used in all cases. It was successful in achieving hemostasis by tamponade in 76% (13/17) of patients. In the remaining 24% (4/17) patients tamponade failed to achieve complete hemostasis and UAE was performed to stop persistent arterial bleeding into the uterine cavity. Median intraoperative blood loss was 800 mL (range: 250-2500) and 41% (7/17) women lost >1000 mL. 35% (6/17) needed blood transfusion. No women required hysterectomy. CONCLUSIONS: Surgical evacuation with Shirodkar cervical suture and selective UAE is an effective treatment for advanced live CSEPs.

Ambient air pollution and adverse birth outcomes: A review of underlying mechanisms.

Epidemiological data provide varying degrees of evidence for associations between prenatal exposure to ambient air pollutants and adverse birth outcomes (suboptimal measures of fetal growth, preterm birth and stillbirth). To assess further certainty of effects, this review examines the experimental literature base to identify mechanisms by which air pollution (particulate matter, nitrogen dioxide and ozone) could cause adverse effects on the developing fetus. It likely that this environmental insult impacts multiple biological pathways important for sustaining a healthy pregnancy, depending upon the composition of the pollutant mixture and the exposure window owing to changes in physiologic maturity of the placenta, its circulations and the fetus as pregnancy ensues. The current body of evidence indicates that the placenta is a target tissue, impacted by a variety of critical processes including nitrosative/oxidative stress, inflammation, endocrine disruption, epigenetic changes, as well as vascular dysregulation of the maternal-fetal unit. All of the above can disturb placental function and, as a consequence, could contribute to compromised fetal growth as well increasing the risk of stillbirth. Furthermore, given that there is often an increased inflammatory response associated with preterm labour, inflammation is a plausible mechanism mediating the effects of air pollution on premature delivery. In the light of increased urbanisation and an ever-changing climate, both of which increase ambient air pollution and negatively affect vulnerable populations such as pregnant individuals, it is hoped that the collective evidence may contribute to decisions taken to strengthen air quality policies, reductions in exposure to air pollution and subsequent improvements in the health of those not yet born.

Antenatal fetal growth patterns in uncomplicated pregnancies according to mode of conception and placental location.

Newborns resulting from in-vitro fertilisation (IVF) had a significantly (P= 0.002) higher birthweight centile than those resulting from spontaneous conception (SC) but no significant changes were found in ultrasound estimated fetal weight (EFW) centile between 20-22 and 32-34 weeks between the IVF and SC groups. When stratified for the IVF methods used, significant (P = 0.02) fastest in-utero fetal growth (mean increase in centile of 5 between 2nd to 3rd trimester) was observed in the frozen embryo transfer (FET) subgroup compared to SC, and to IVF pregnancies resulting from fresh blastocyst transfer (FBT) or from oocyte donation (OD). Low placentation was significantly (P < 0.001) more common in the IVF group than in the SC group but was not associated with a change in growth pattern suggesting that fetal growth in-utero is independent of placental location but may be influenced by embryo freezing.

Use of super resolution reconstruction MRI for surgical planning in Placenta accreta spectrum disorder: Case series.

INTRODUCTION: Comprehensive imaging using ultrasound and MRI of placenta accreta spectrum (PAS) aims to prevent catastrophic haemorrhage and maternal death. Standard MRI of the placenta is limited by between-slice motion which can be mitigated by super-resolution reconstruction (SRR) MRI. We applied SRR in suspected PAS cases to determine its ability to enhance anatomical placental assessment and predict adverse maternal outcome. METHODS: Suspected PAS patients (n = 22) underwent MRI at a gestational age (weeks + days) of (32+3±3+2, range (27+1-38+6)). SRR of the placental-myometrial-bladder interface involving rigid motion correction of acquired MRI slices combined with robust outlier detection to reconstruct an isotropic high-resolution volume, was achieved in twelve. 2D MRI or SRR images alone, and paired data were assessed by four radiologists in three review rounds. All radiologists were blinded to results of the ultrasound, original MR image reports, case outcomes, and PAS diagnosis. A Random Forest Classification model was used to highlight the most predictive pathological MRI markers for major obstetric haemorrhage (MOH), bladder adherence (BA), and placental attachment depth (PAD). RESULTS: At delivery, four patients had placenta praevia with no abnormal attachment, two were clinically diagnosed with PAS, and six had histopathological PAS confirmation. Pathological MRI markers (T2-dark intraplacental bands, and loss of retroplacental T2-hypointense line) predicting MOH were more visible using SRR imaging (accuracy 0.73), in comparison to 2D MRI or paired imaging. Bladder wall interruption, predicting BA, was only easily detected by paired imaging (accuracy 0.72). Better detection of certain pathological markers predicting PAD was found using 2D MRI (placental bulge and myometrial thinning (accuracy 0.81)), and SRR (loss of retroplacental T2-hypointense line (accuracy 0.82)). DISCUSSION: The addition of SRR to 2D MRI potentially improved anatomical assessment of certain pathological MRI markers of abnormal placentation that predict maternal morbidity which may benefit surgical planning.

Surgical evacuation of cesarean scar ectopic pregnancies.

Cesarean scar ectopic pregnancy is associated with significant maternal morbidity, including severe hemorrhage, need for the blood transfusion and hysterectomy. Early diagnosis is therefore key in ensuring timely management, with consensus being that treatment before 9 weeks of gestation leads to reduced morbidity. There is no universally adopted management protocol for cesarean scar ectopic pregnancy, but surgical management generally has a higher success rate than medical management. The primary surgical treatment modalities are suction evacuation versus resection of the pregnancy via multiple routes. Adjuncts that have been shown to successfully minimize bleeding with surgical management include cervical cerclage, balloon catheter, and uterine artery embolization. However, there remains a lack of high-quality evidence regarding what is the best surgical treatment option for cesarean scar ectopic pregnancy, and therefore it is essential that clinicians provide tailored management to patients considering the presenting symptoms and local expertise with various surgical techniques.

Definition and diagnosis of cesarean scar ectopic pregnancies.

Cesarean scar ectopic pregnancy is a rare type of ectopic pregnancy, where the pregnancy implants into a myometrial defect caused by a cesarean scar. Its incidence is predicted to increase, given the global increase in cesarean deliveries. As most cesarean scar ectopic pregnancies present as failing pregnancies or patients choose termination of pregnancy, there are limited data on their natural history. However, early first trimester diagnosis is essential, given the associated significant maternal morbidity. Transvaginal sonography is generally considered to be the optimal method for diagnosing cesarean scar ectopic pregnancy. There is no evidence that MRI adds to the diagnostic accuracy, and it is therefore not recommended for routine evaluation of cesarean scar ectopic pregnancy. There is no agreed reference standard for the diagnosis of cesarean scar ectopic pregnancy; therefore, the validity of several proposed sonographic diagnostic criteria reported by different authors remains unknown. There are also various suggested classification systems for cesarean scar ectopic pregnancy, which divide them in differet types. However, the proposals are very heterogeneous, and superiority of one classification system over another is yet to be established.

The role of transvaginal ultrasound in the third-trimester evaluation of patients at high risk of placenta accreta spectrum at birth.

BACKGROUND: Transvaginal ultrasound imaging has become an essential tool in the prenatal evaluation of the lower uterine segment and anatomy of the cervix, but there are only limited data on the role of transvaginal ultrasound in the management of patients at high risk of placenta accreta spectrum at birth. OBJECTIVE: This study aimed to evaluate the role of transvaginal sonography in the third trimester of pregnancy in predicting outcomes in patients with a high probability of placenta accreta spectrum at birth. STUDY DESIGN: This was a retrospective analysis of prospectively collected data of patients presenting with a singleton pregnancy and a history of at least 1 previous cesarean delivery and patients diagnosed prenatally with an anterior low-lying placenta or placenta previa delivered electively after 32 weeks of gestation. All patients had a least 1 detailed ultrasound examination, including transabdominal and transvaginal scans, within 2 weeks before delivery. Of note, 2 experienced operators, blinded to the clinical data, were asked to make a judgment on the likelihood of placenta accreta spectrum as a binary, low or high-probability of placenta accreta spectrum, and to predict the main surgical outcome (conservative vs peripartum hysterectomy). The diagnosis of accreta placentation was confirmed when one or more placental cotyledons could not be digitally separated from the uterine wall at delivery or during the gross examination of the hysterectomy or partial myometrial resection specimens. RESULTS: A total of 111 patients were included in the study. Abnormal placental tissue attachment was found in 76 patients (68.5%) at birth, and histologic examination confirmed superficial villous attachment (creta) and deep villous attachment (increta) in 11 and 65 cases, respectively. Of note, 72 patients (64.9%) had a peripartum hysterectomy, including 13 cases with no evidence of placenta accreta spectrum at birth because of failure to reconstruct the lower uterine segment and/or excessive bleeding. There was a significant difference in the distribution of placental location (X2=12.66; P=.002) between transabdominal and transvaginal ultrasound examinations, but both ultrasound techniques had similar likelihood scores in identifying accreta placentation that was confirmed at birth. On transabdominal scan, only a high lacuna score was significantly associated (P=.02) with an increased chance of hysterectomy, whereas on transvaginal scan, significant associations were found between the need for hysterectomy and the thickness of the distal part of the lower uterine segment (P=.003), changes in the cervix structure (P=.01), cervix increased vascularity (P=.001), and the presence of placental lacunae (P=.005). The odds ratio for peripartum hysterectomy were 5.01 (95% confidence interval, 1.25-20.1) for a very thin (<1-mm) distal lower uterine segment and 5.62 (95% confidence interval, 1.41-22.5) for a lacuna score of 3+. CONCLUSION: Transvaginal ultrasound examination contributes to both prenatal management and the prediction of surgical outcomes in patients with a history of previous cesarean delivery with and without ultrasound signs suggestive of placenta accreta spectrum. Transvaginal ultrasound examination of the lower uterine segment and cervix should be included in clinical protocols for the preoperative evaluation of patients at risk of complex cesarean delivery.

The human placenta: new perspectives on its formation and function during early pregnancy.

The placenta has evolved to support the development of the embryo and fetus during the different intrauterine periods of life. By necessity, its development must precede that of the embryo. There is now evidence that during embryogenesis and organogenesis, the development of the human placenta is supported by histotrophic nutrition secreted from endometrial glands rather than maternal blood. These secretions provide a plentiful supply of glucose, lipids, glycoproteins and growth factors that stimulate rapid proliferation and differentiation of the villous trophoblast. Furthermore, evidence from endometrial gland organoids indicates that expression and secretion of these products are upregulated following sequential exposure to oestrogen, progesterone and trophoblastic and decidual hormones, in particular prolactin. Hence, a feed-forward signalling dialogue is proposed among the trophoblast, decidua and glands that enables the placenta to stimulate its own development, independent of that of the embryo. Many common complications of pregnancy represent a spectrum of disorders associated with deficient trophoblast proliferation. Increasing evidence suggests that this spectrum is mirrored by one of impaired decidualization, potentially compromising histotroph secretion through diminished prolactin secretion and reduced gland function. Optimizing endometrial wellbeing prior to conception may therefore help to prevent common pregnancy complications, such as miscarriage, growth restriction and pre-eclampsia.

Perinatal assessment of complex cesarean delivery: beyond placenta accreta spectrum.

Multiple cesarean deliveries are known to be associated with long-term postoperative consequences because of a permanent defect of the lower uterine segment wall and the development of thick pelvic adhesions. Patients with a history of multiple cesarean deliveries often present with large cesarean scar defects and are at heightened risk in subsequent pregnancies of cesarean scar ectopic pregnancy, uterine rupture, low-lying placenta or placenta previa, and placenta previa accreta. Moreover, large cesarean scar defects will lead to progressive dehiscence of the lower uterine segment with the inability to effectively reapproximate hysterotomy edge and repair at birth. Major remodeling of the lower uterine segment associated with true placenta accreta spectrum at birth, whereby the placenta becomes inseparable from the uterine wall, increases the rates of perinatal morbidity and mortality, especially when undiagnosed before delivery. Ultrasound imaging is currently not routinely used to evaluate the surgical risks of patients with a history of multiple cesarean deliveries, beyond the risk assessment of placenta accreta spectrum. Independent of accreta placentation, a placenta previa under a scarred, thinned partially disrupted lower uterine segment, covered by thick adhesions with the posterior wall of the bladder, poses a surgical risk and requires fine dissection and surgical expertise; however, data on the use of ultrasound to evaluate uterine remodeling and adhesions between the uterus and other pelvic organs are scarce. In particular, transvaginal sonography has been underused, including in patients with a high probability of placenta accreta spectrum at birth. Based on the best available knowledge, we discuss the role of ultrasound imaging in identifying the signs suggestive of major remodeling of the lower uterine segment and in mapping the changes in the uterine wall and pelvis, to enable the surgical team to prepare for all different types of complex cesarean deliveries. The need for postnatal confirmation of the prenatal ultrasound findings for all patients with a history of multiple cesarean deliveries, regardless of the diagnosis of placenta previa and placenta accreta spectrum, is discussed. We propose an ultrasound imaging protocol and a classification of the level of surgical difficulty at elective cesarean delivery to stimulate further research toward the validation of ultrasound signs by which these signs may be applied to improve surgical outcomes.

Changes in Artery Diameters and Fetal Growth in Cases of Isolated Single Umbilical Artery.

Background-There are conflicting data in the international literature on the risks of abnormal fetal growth in fetuses presenting an isolated single umbilical artery (SUA), and the pathophysiology of this complication is poorly understood. Objective-To evaluate if changes in diameter of the remaining umbilical artery in fetuses presenting an isolated SUA are associated with different fetal growth patterns. Study design-This was a two-center prospective longitudinal observational study including 164 fetuses diagnosed with a SUA at the 20-22-week detailed ultrasound examination and 200 control fetuses with a three-vessel cord. In all cases, the diameters of the cord vessels were measured in a transverse view of the central portion of the umbilical cord, and the number of cord vessels was confirmed at delivery. Logistic regression and nonparametric receiver operating characteristic (ROC) analysis were carried out to evaluate the association of the umbilical artery diameter in a single artery with small for-gestational age (SGA) and with fetal growth restriction (FGR). The impact of artery dimension was adjusted for maternal BMI, parity, ethnicity, side of the remaining umbilical artery and umbilical resistance index (RI) in the regression model. Results-A significantly (p < 0.001) larger mean diameter was found for the remaining artery in fetuses with SUA compared with controls (3.0 ± 0.9 vs. 2.5 ± 0.6 mm). After controlling for BMI and parity, we found no difference in umbilical resistance and side of the remaining umbilical artery between the SUA and control groups. A remaining umbilical artery diameter of >3.1 mm was found to be associated with a lower risk of FGR, but this association failed to be statistical significant (OR = 0.60, 95% CI = 0.33-1.09, p value = 0.089). We also found that the mean vein-to-artery area ratio was significantly (p < 0.001) increased in the SUA group as compared with the controls (2.4 ± 1.8 vs. 1.8 ± 0.9; mean difference = 0.6; Cohen's d = 0.46). Conclusion-In most fetuses with isolate SUA, the remaining artery diameter at 20-22 weeks is significantly larger than in controls. When there are no changes in the diameter and, in particular, if it remains <3.1 mm, the risk of abnormal fetal growth is higher, and measurements of the diameter of the remaining artery could be used to identify fetuses at risk of FGR later in pregnancy.