Velamentous Umbilical Cord Insertion Research Articles

Prevalence, Risk Factors, and Perinatal Outcomes of Velamentous Umbilical Cord Insertion in Twin Pregnancies: A Single-Center Retrospective Study.

The effect of velamentous cord insertion (VCI) on perinatal outcomes in twin pregnancies is unclear due to conflicting findings. This retrospective study aimed to examine VCI prevalence and related risk factors in twin pregnancies and its association with adverse perinatal outcomes. Women with twin pregnancies who delivered between January 2012 and December 2021 in a single tertiary hospital were included. The participants were divided into dichorionic (DC) and monochorionic diamniotic (MCDA) groups, and their maternal and fetal characteristics and VCI rates were compared. Logistic regression models were used to identify risk factors for VCI and VCI-related perinatal outcomes. Among the 694 twin pregnancies included in this study, the VCI rate was significantly higher in MCDA than in DC twins. Body mass index and MCDA twins were significant risk factors for VCI, whereas assisted reproductive technology pregnancy was a significant protective factor against VCI. In DC twins, VCI did not affect perinatal outcomes. In MCDA twins, VCI was a significant risk factor for fetal growth restriction, twin-to-twin transfusion syndrome, and preterm birth at <36 weeks. VCI was a prominent risk factor for adverse perinatal outcomes only in MCDA twins. Antenatal sonographic assessment of the umbilical cord insertion site would be beneficial.

EP16.24: High‐definition three‐dimensional flow imaging in prenatal diagnosis of velamentous umbilical cord insertion

EP16.24: High‐definition three‐dimensional flow imaging in prenatal diagnosis of velamentous umbilical cord insertion

S3054 Interdisciplinary Management of a Complicated Pregnancy in a Patient With Cirrhosis

Introduction: We present a unique case of clotting disorder related cirrhosis leading to pregnancy complications. Case Description/Methods: A 29-year-old Caucasian female with a history of gastrointestinal bleeding, gastroesophageal reflux disease, epistaxis, and alcohol use disorder, goes for a routine gynecologic checkup when the physician notices a concerning enlargement of the caudate lobe on a computed tomography scan. Further evaluation reveals cirrhosis and Budd-Chiari syndrome. The patient starts enoxaparin and warfarin following this diagnosis. Eventually the patient is placed on the liver transplant list with a MELD (model of end-stage liver disease) score of 17 which improves to a score of 7 with sobriety. The patient attempts pregnancy and is unable to conceive. She is told she has early menopause at the age of 34. She undergoes reproductive endocrinology evaluation and achieves a successful in-vitro fertilization with a donor egg at age 36. This starts her high-risk pregnancy. The high-risk nature of this pregnancy revolves around the patient’s complicated past medical history of hemorrhagic stroke of unclear etiology, cirrhosis complicated by esophageal variceal bleeding, coagulopathy, Budd-Chiari syndrome, and thrombocytopenia. The patient has close variceal and hepatic vein thrombosis surveillance, labs, and routine checkup for vaginal bleeding with her increased risk of thrombosis during pregnancy. Endoscopy in the 1 st and 3rd trimesters shows small esophageal varices with no evidence of progression. Abdominal ultrasound displays vasa previa at approximately 28 weeks with velamentous umbilical cord insertion 2.3 cm from the internal os. After careful monitoring, the vasa previa is noted to resolve with umbilical cord insertion increasing to 4.8 cm from internal os in the following weeks. Repeated fetal echocardiograms present concern for the fetus being large for gestational age with estimated fetal weights ranging between the 95th-98th percentiles. The patient undergoes elective cesarean delivery and gives birth to a baby boy at 34 weeks with no labor complications. Discussion: We present a unique case of pregnancy during cirrhosis requiring management with multiple specialists. Although the physiologic changes in pregnancy are well understood, the way in which cirrhosis affects pregnancy and its outcomes are not yet well understood given paucity of published data. Certainly, there is complex interplay and physiology involved with increased potential for pregnancy complications.

Incidence and risk factors for velamentous umbilical cord insertion in singleton pregnancies after assisted reproductive technology.

Assisted reproductive technology (ART) is gaining popularity worldwide. However, it is associated with increased incidence of velamentous umbilical cord insertion (VCI) in the placenta, resulting in adverse perinatal outcomes. This study aimed to identify the risk factors that might affect the incidence of VCI in pregnancies after ART treatment. We retrospectively analyzed the records of 906 singleton pregnancies via ART; all women delivered in our facility. Three ART-related variables and infant sex were examined: (1) fertilization method (conventional in vitro fertilization or intracytoplasmic sperm injection), (2) type of embryo at the time of transfer (fresh or frozen-thawed), (3) developmental stage of embryo at the time of transfer (cleavage stage or blastocyst), and (4) infant sex (male or female). Logistic regression analysis was used to assess the impact of these variables on the incidence of VCI. Of 906 cases, 55 had VCI (incidence rate, 6.1%). After adjusting for potential confounders, blastocyst stage of development (adjusted odds ratio [aOR]: 4.3, 95% confidence interval [CI]: 1.9-12.7) and female sex (aOR: 2.2, 95% CI: 1.2-3.9) emerged as independent risk factors for the development of VCI. The fertilization method and type of embryo at the time of transfer did not affect the incidence of VCI. Blastocyst stage of development and female sex pose a higher risk for developing VCI. Thus, more attention should be paid to pregnancies achieved by blastocyst and with a female fetus to detect VCI proactively and safeguard the health of both mother and fetus/neonate.

Clinical features of velamentous umbilical cord insertion and vasa previa: A retrospective analysis based on 501 cases.

To identify the risk factors associated with velamentous cord insertion (VCI) and investigate the association between adverse pregnancy outcomes and VCI in singleton pregnancies and those with vasa previa.A total of 59,976 single cases admitted from Qinhuangdao Maternal and Child Health Hospital and Qinhuangdao Beidaihe Hospital from January 2004 to January 2014 were included in this study. We retrospectively analyzed the perinatal complications, neonatal complications, and the clinical features, as well as the Color Doppler ultrasonography findings of the velamentous placenta and placenta previa.We reviewed the clinical data of 59,976 women with singleton pregnancies delivered in Qinhuangdao Maternal and Child Health Hospital and Qinhuangdao Beidaihe Hospital from January 2004 to January 2014. Risk factors and the risks of adverse pregnancy outcomes including admission to a neonatal unit, fetal death, preterm delivery, low birth weight of <2500 g, the infant being small for its gestation age, low Apgar scores (<7) at 1 and 5 minute were evaluated separately among women with and without VCI by means of logistic regression analyses.The prevalence of velamentous umbilical cord insertion was 0.84%, and the prevalence of vasa previa was 0.0017%. The independent risk factors for VCI were nulliparity, obesity, fertility problems, placenta previa, and maternal smoking. VCI was associated with a 1.83-, 2.58-, 3.62-, and 1.41-fold increase in the risk of retention in the neonatal unit, preterm delivery (<37 gestation weeks), low birth weight, and small-for-gestational age, compared to pregnancies involving normal cord insertion. Of the women with VCI, 16.1% underwent emergency cesarean section compared to 8.9% (P < .001) of women without VCI.The prevalence of VCI was 0.84% in singletons. The results suggest that VCI is a moderate risk condition resulted in increased risks of prematurity and impairment of fetal growth.

Comparison of placental characteristics of twin-twin transfusion syndrome with and without selective intrauterine growth restriction

Objective To explore differences among placental anastomoses, territory discordance, and umbilical cord insertion of twin-to-twin transfusion syndrome (TTTS) with and without selective intrauterine growth restriction (sIUGR). Methods This study retrospectively analyzed 57 patients with TTTS who received conservative treatment and finally delivered at the Department of Obstetrics and Gynecology of Peking University Third Hospital from April 2014 to April 2019. Nine of the patient’s placentas were too broken to finish the perfusion, and 48 were kept for graph analysis after perfusion. Among the 48 placentas, there were 17 in the TTTS with sIUGR group and 31 in the TTTS without sIUGR group. Differences in the placentas were compared between groups. Results The birth weight discordance ratio in the sIUGR group was significantly higher than that in the non-sIUGR group (0.41 ± 0.20 vs 0.24 ± 0.15, p = .001). The prevalence of thick artery-artery (AA) anastomoses in the sIUGR group was significantly higher than that in the non-sIUGR group (35.3% vs 6.5%, p = .017). The placental territory discordance ratio in the sIUGR group was significantly higher than that in the non-sIUGR group (0.40 [0.05, 0.86] vs 0.25 [0.02, 0.67], p = .024). The prevalence of velamentous cord insertion in the sIUGR group was significantly higher than that in the non sIUGR group (35.3% and 6.5%, p = .017). Conclusions Placental territory discordance and velamentous umbilical cord insertion may be causes of TTTS with sIUGR. Compared with TTTS without sIUGR, TTTS with sIUGR had a higher prevalence of protective AA anastomoses in the placenta.

Risk factors for abnormal umbilical cord insertions among term singleton art pregnancies

The placenta with velamentous umbilical cord insertion (VCI) is a rare pathologic condition that is supposed to increase the risk of perinatal complications. The reported adverse outcomes include fetal growth restriction, non-reassuring fetal status requiring emergency Cesarean section, fetal exsanguination due to the rupture of vasa previa, and cerebral palsy. We reported on a study, emphasizing a higher incidence of the placenta accompanied by VCI in ART pregnancies when compared with non-ART cases, at the 70th ASRM Annual Meeting. In this research, we examined the ART-conceived cases closely for the purpose of identifying the ART-associated risk factors that might affect the incidence of the placenta with VCI. Retrospective cohort study and comparative analysis. We reviewed the records of 427 consecutive singleton, term labor and delivery ART-conceived cases from January 2011 to April 2016. Information about maternal age, obstetric history, details of ART treatment, mode of delivery, and insertion site of the umbilical cord was all collected from their medical records. Our study population was divided into two categories as follows: cases with VCI (Group A: n=23), and cases without VCI (Group B: n=404). Odds ratios for VCI, 95% confidence intervals (CI), and significance of the odds ratio were calculated according to ART-related variables (i.e., fertilization method (conventional-IVF vs. ICSI), type of embryo (fresh vs. frozen-thawed), embryo transfer timing (day 2-3 early-cleavage stage embryo vs. day 5-6 blastocyst), and fetal sex), using multivariate logistic regression. Maternal basal characteristics and odds ratios were shown in the table below. The incidence of VCI in our study population was 5.4% (23/427). The rate of delivery necessitating emergency C-section or operative vaginal delivery in Group A (14/23, 61%) was much higher than in Group B (138/404, 34%). Blastocyst transfer and female fetus significantly increased the likelihood of developing the placenta with VCI. Fertilization method and type of embryo did not affect the incidence of the placenta with VCI.Tabled 1Baseline characteristics and adjusted odds ratio(aOR) for velamentous umbilical cord insertionGroup A (cases with VCI: n=23)Group B (cases without VCI: n=404)aOR for VCI (95% CI, P value)Maternal age35.9±3.835.5±3.61.03 (0.91 - 1.16, 0.66)Parity (primipara / multipara)20 / 3302 / 1021.00 (reference) / 0.40 (0.09 - 1.23, 0.15)c-IVF / ICSI5 / 18143 / 2611.00 / 1.96 (0.76 - 6.05, 0.19)Fresh / Frozen-thawed7 / 16136 / 2681.00 / 1.25 (0.52 - 3.34, 0.63)Early cleavage / Blastocyst1 / 22117 / 2871.00 / 10.23 (2.09 - 184.78, 0.02*)Male / Female5 / 18200 / 2041.00 / 3.48 (1.35 - 10.71, 0.02*)[Note of the table above: Data are mean±SD or number of subjects. Odds ratios were all adjusted for maternal age and parity. *: P<0.05 was considered statistically significant.] Open table in a new tab [Note of the table above: Data are mean±SD or number of subjects. Odds ratios were all adjusted for maternal age and parity. *: P<0.05 was considered statistically significant.] As VCI often brings about serious obstetric complications, ART pregnancies achieved by blastocyst transfer and/or of female fetus are optimal candidates for checking up on and identifying the umbilical cord insertion site more proactively during routine obstetric ultrasound examinations.

Velamentous cord insertion as a risk factor for obstetric outcome: a retrospective case-control study.

Velamentous umbilical cord insertion (VCI) is associated with adverse pregnancy outcomes. Literature lacks data on Doppler. We aimed to evaluate obstetric outcomes and results of uterine and umbilical artery Doppler flowmetry associated with VCI. In a retrospective case-control study, 108 singleton pregnancies with VCI were age- and body mass index-matched to 108 singleton pregnancies without VCI. The main outcome parameters were obstetric outcome, pregnancy-related complications, uterine artery flowmetry at the second-trimester screening, and umbilical artery flowmetry before delivery. Statistical analysis was accomplished using Pearson's Chi-square test or Fisher's exact test, and the Mann-Whitney U test, where appropriate. Pregnancies with VCI revealed a significantly higher PI in the umbilical artery during the last measurement before delivery (1.00 ± 0.25 vs. 0.90 ± 0.10; p = 0.001). Gestational age at this measurement did not differ between the groups. Fetal malformations and intrauterine fetal death were more common in pregnancies with VCI (12.7 vs. 0 %; p < 0.001, and 6.5 vs. 0 %; p = 0.014, respectively). Patients with VCI delivered significantly earlier (36.2 ± 4.5 vs. 38.4 ± 2.6; p < 0.001). Higher rates of (early) preterm delivery were found in pregnancies with VCI. Fetuses with VCI also suffered from malformations and IUFD more frequently. The last pulsatility index value in the umbilical artery, before delivery, was significantly higher in pregnancies with VCI, which is of uncertain clinical value.

Risk Factors and Perinatal Outcomes of Velamentous Umbilical Cord Insertion.

To explore the risk factors of velamentous umbilical cord insertion(VCI)and the impact of VCI on perinatal outcomes. The clinical data of 588 VCI patients who were treated in Beijing Gynecology and Obstetrics Hospital from January 2006 to January 2011 were retrospectively analyzed. In addition,61,143 non-VCI subjects were enrolled as the control group. The possible risk factors of VCI and the impact of VCI on perinatal outcomes were analyzed. In addition,the causes of perinatal deaths were analyzed. The gemellary pregnancy,multiple pregnancy,in vitro fitilization(IVF),placenta praevia,and placenta succenturiata/placenta bipartite were found to be the risk factors of VCI. The incidences of low birth weight,intrauterine growth restriction,asphyxia of newborns,deaths of fetuses or neonates,and single umbilical artery in the VCI group were significantly higher than those in the control group(all P<0.05). In 678 perineonates with VCI,the total death toll of perineonates was 7(1.0%),among whom the death causes included angiorrhexis of placenta praevia(n=1),preterm birth and low birth weight(n=3),torsion of cord(n=1),prolapse of cord(n=1),and placental abruption(n=1). The risk factors of VCI should be carefully monitored. A diagnosis of VCI,if any,should be correctly made by using modern ultrasound techniques before delivery,so as to lower the mortality of perineonates.

Hypoxic ischemic encephalopathy in newborns linked to placental and umbilical cord abnormalities

Objective: Birth asphyxia and hypoxic ischemic encephalopathy (HIE) of the newborn remain serious complications. We present a study investigating if placental or umbilical cord abnormalities in newborns at term are associated with HIE.Materials and methods: A prospective cohort study of the placenta and umbilical cord of infants treated with hypothermia (HT) due to hypoxic brain injury and follow-up at 12 months of age has been carried out. The study population included 41 infants treated for HT whose placentas were submitted for histopathological analysis. Main outcome measures were infant development at 12 months, classified as normal, cerebral palsy, or death. A healthy group of 100 infants without HIE and normal follow-up at 12 months of age were used as controls.Results: A velamentous or marginal umbilical cord insertion and histological abruption was associated with the risk of severe HIE, OR = 5.63, p = 0.006, respectively, OR = 20.3, p = 0.01 (multiple-logistic regression). Velamentous or marginal umbilical cord insertion was found in 39% among HIE cases compared to 7% in controls.Conclusions: Placental and umbilical cord abnormalities have a profound association with HIE. A prompt examination of the placentas of newborns suffering from asphyxia can provide important information on the pathogenesis behind the incident and contribute to make a better early prognosis.

Clinical Significance of Pregnancies Complicated by Velamentous Umbilical Cord Insertion Associated With Other Umbilical Cord/Placental Abnormalities.

BackgroundWe examined the clinical significance of pregnancies complicated by velamentous cord insertion (VCI) associated with other umbilical cord/placental abnormalities.MethodsData were collected from 168 deliveries complicated by VCI and from 16,797 unaffected controls. All placentae were screened identically by trained staff. In this study, we examined the presence of excessively long umbilical cord (longer than 70 cm), vasa previa, single umbilical artery, circumvallate placenta, succenturiate placenta, lobed placenta, placenta previa, low lying placenta and placenta accrete as the other umbilical cord/placental abnormalities.ResultsUsing a multivariate analysis, the pregnancies complicated by VCI were independently associated with in vitro fertilization use (P < 0.01), maternal smoking (P = 0.03), preterm delivery (P = 0.03), fetal asphyxia (P = 0.01) and small-for-gestational-age infants (P = 0.02). It was also independently associated with vasa previa (P < 0.01), single umbilical artery (P = 0.04), lobed placenta (P = 0.01) and placenta previa (P = 0.03). However, these umbilical cord/placental abnormalities were not associated with the further adverse outcomes of the pregnancies complicated by VCI.ConclusionVCI is associated with an increased risk of adverse perinatal outcomes irrespective of the presence of other umbilical cord/placental abnormalities. Routine identification of the placental cord insertion site should be considered.

Risk factors and adverse pregnancy outcomes among births affected by velamentous umbilical cord insertion: a retrospective population-based register study

To identify risk factors associated with velamentous cord insertion (VCI) and to evaluate the association between adverse pregnancy outcomes and VCI in singleton pregnancies. The total population of women (n=26,849) with singleton pregnancies delivered in Kuopio University Hospital during the study period between 2000 and 2011 was reviewed. Risk factors and the risk of adverse pregnancy outcomes (admission to a neonatal unit, fetal death, preterm delivery, low birth weight (LBW< 2500 g), the infant being small for its gestation age (SGA), low Apgar scores (<7) at 1 and 5 min and fetal venous pH<7.15) were evaluated separately among women with and without VCI by means of logistic regression analyses. The incidence of VCI among women with singleton pregnancies was 2.4% (n=633 of 26,849). Independent risk factors for VCI were nulliparity, obesity, fertility problems, placenta previa and maternal smoking. VCI was associated with a 1.38-, 2.01-, 3.93- and 1.39-fold increased risk of admission to a neonatal unit, preterm delivery (<37 gestation weeks), LBW and SGA, respectively compared to pregnancies involving normal cord insertion. Of the women with VCI, 15.3% underwent non-elective cesarean section compared to 8.3% (p ≤ 0.001) of women without VCI. The results suggest that the incidence of VCI increases along with an increase in fertility problems and maternal obesity. VCI is a moderate risk condition increasing the risks of prematurity and impaired fetal growth.

Sex-specific basis of severe placental dysfunction leading to extreme preterm delivery

ObjectivesSince pregnancies with a male fetus have higher perinatal complications attributed to placental dysfunction, including severe pre-eclampsia and intrauterine growth restriction, the objective of our study was to formally evaluate placental pathology for a placental origin of these sex-specific differences. DesignRetrospective study at Mount Sinai Hospital in Toronto, Canada. Identification of 262 singleton pregnancies affected by severe pre-eclampsia and/or intrauterine growth restriction who delivered between 22 and 32 weeks' gestation from 2000 to 2010. Detailed placental pathology was reviewed, and data from 140 pregnancies with male fetuses were compared with 122 pregnancies with female fetuses. A comparison group of 40 unaffected pregnancies who delivered in the same gestational range was used to determine baseline rates of placental pathology. Main outcome measuredDetailed placental pathology, including placental development/differentiation, velamentous umbilical cord insertion, maternal-fetal interface pathology, villous infarction, hemorrhagic lesions, villous development, and fetal vascular under-perfusion. ResultsImpaired placental development and differentiation was equally common amongst males (73/140, 52.1%) and females (69/122, 56.6%). Male placentas exhibited significantly higher rates of chronic deciduitis (17.9% vs. 9.0%; relative risk [RR] 1.98, 95% confidence interval [CI] 1.02–3.86) and velamentous umbilical cord insertion (9.5% vs. 1.7%; RR 5.66, 95% CI 1.30–24.6), and a significantly lower frequency of villous infarction (55.4% vs. 73.7%; RR 0.75, 95% CI 0.62–0.90) than female placentas. No significant differences were noted for other lesions. ConclusionsFetal sex exerts a differential effect on the placental pathology that mediates severe pre-eclampsia and/or IUGR. Placental pathology at birth may provide insight into the mechanisms linking adverse in utero events with long-term adult disease since, for example, a male tendency to an inflammatory pathology at the maternal-fetal interface may be linked to the excess risk of coronary artery disease.

Placental vasa previa

In April, 2010, a 25-year-old woman at 33 weeks’ gestation in her fi rst pregnancy presented to us for examination of a previously identifi ed velamentous umbilical cord insertion into the placenta. Ultrasonography showed a fundal placenta, and the cord insertion site was not visible inserting into the placental surface. Transvaginal ultrasonography was performed because of our patient’s reports of vaginal spotting. Doppler ultrasonography showed fetal blood vessels coursing over the internal cervical os, consistent with a diagnosis of vasa previa (fi gure A). Uterine tocometry demonstrated frequent contractions. After administration of betamethasone for enhancement of fetal lung maturity, a caesarean section was done because of the risk of impingement or laceration of the vulnerable cord vasculature. She delivered a vigorous male neonate weighing 2115 g. Examination of the placenta was consistent with our diagnosis of a velamentous cord insertion site, with fetal blood vessels present over the cervix indicating vasa previa (fi gure B). At last follow-up in June, 2010, our patient and her infant were doing well.

Inserción velamentosa de cordón umbilical y rotura de un vaso previo con evolución neonatal favorable

Vasa previa is an unusual anatomical variant. Rupture of a vasa previa is associated with a high rate of fetal mortality oscillating between 58% and 100% of cases. We report a recent case of fetal exsanguinations that occurred in our hospital due to vasa previa laceration of an undiagnosed velamentous umbilical cord insertion. Although neonatal outcome was favorable, we stress the need for early diagnosis and cesarian section to avoid this dramatic event.

Placental Ratio and Risk of Velamentous Umbilical Cord Insertion Are Increased in Women with Placenta Previa

The purpose of this study was to explore the maternal risk profile and obstetric outcome in pregnancies affected by placenta previa. Retrospective case-control study involved all women (93 [0.37%] women with diagnosed placenta previa and 24,857 unaffected controls) who gave birth to singleton infants at Kuopio University Hospital between the years 1989 and 2000. Grand multiparity, infertility problems, and advanced maternal age were independent risk factors of placenta previa, with adjusted relative risks of 5.8, 3.7, and 2.4, respectively. Most women with placenta previa (88.2%) underwent cesarean delivery before term. They also more often had velamentous umbilical cord insertion (7.5%) and higher placental-to-birthweight ratios than the controls. Placenta previa was associated with risks of preterm delivery, low birthweight infants, and need for neonatal intensive care, at odds ratios of 27.7, 7.4, and 3.4, respectively. In conclusion, placenta previa is an infrequent pregnancy complication associated with multiparity, advanced maternal age, infertility problems, elevated placental ratio, and velamentous umbilical cord insertion.

Inserción velamentosa de cordón umbilical y rotura de un vaso previo con evolución neonatal favorable

Vasa previa is an unusual anatomical variant. Rupture of a vasa previa is associated with a high rate of fetal mortality oscillating between 58 and 100% of cases. We report a recent case of fetal exsanguination that occurred in our hospital due to vasa previa laceration of an undiagnosed velamentous umbilical cord insertion. Although neonatal outcome was favorable, we stress the need for early diagnosis and cesarian section to avoid this dramatic event.

Velamentous Insertion of the Umbilical Cord

The purpose of this study was to determine the feasibility of prenatal sonography for detecting velamentous insertion of the umbilical cord in singleton pregnancies at the 11- to 14-week scan. The placental umbilical cord insertion site was prospectively examined at the time of the routine first-trimester scan between 11 and 14 weeks as part of ongoing first-trimester sonographic screening for chromosomal abnormalities. Over a 1-year period, 533 consecutive singleton pregnancies were examined by a fetal medicine specialist at a median gestational age of 12 weeks. In 5 cases, a velamentous umbilical cord insertion was diagnosed, with a prevalence rate of 1 (0.9%) per 107. The diagnosis was further confirmed at the second-trimester scan and at the time of delivery in all cases. The placental umbilical cord insertion site can be readily determined by sonography at the time of the 11- to 14-week scan. Sonographic examination at this early gestational age provides the opportunity for screening for velamentous insertion of the umbilical cord in the first trimester, allowing close surveillance of the pregnancy for potential complications associated with this condition.

Increased Prevalence of Fetal Thrombi in Monochorionic-Twin Placentas

Fetal vessel thrombosis has been related to pregnancy complications and adverse neonatal outcomes in singleton pregnancies, but the clinical and pathologic characteristics of fetal thrombosis in twin pregnancy are still ill defined. To clarify the characteristics of fetal thrombosis in twins, we reviewed the histology slides and medical records of live-born infants of twin pregnancies involving the live birth of at least 1 fetus (monochorionic: 389 cases; dichorionic: 780 cases) and singleton pregnancies (1162 cases). The incidence of fetal thrombosis in monochorionic-twin pregnancies was significantly higher than that of dichorionic-twin and singleton pregnancies (5.1% vs 3.0% and 2.8%, respectively). The incidence of velamentous umbilical cord insertion in monochorionic- and dichorionic-twin placentas was also higher than in singleton placentas (12% and 7% vs 2%, respectively). Fetal thrombosis in twin placentas was associated with intrauterine growth restriction. In monochorionic twins, fetal thrombosis was associated with co-twin fetal death, but in dichorionic twins no correlation was identified. Microscopically, fetal vessel thrombosis in twin placentas was associated with vascular cushions (fibrous hyperplasia of fetal vessel), as is the case occasionally in singletons. The incidence of fetal vessel thrombosis in monochorionic placentas was higher than that seen in dichorionic-twin placentas and singleton gestations. Fetal vessel thrombosis in twin pregnancies showed a correlation with intrauterine growth restriction, peripheral cord insertions, and major vascular cushions.

Antenatal diagnosis of velamentous umbilical cord insertion and vasa previa with color Doppler imaging.

To determine whether cord insertion can be consistently visualized and whether velamentous cord insertion and vasa previa can be consistently identified with color Doppler imaging during routine sonography in the mid-trimester. A prospective study. A total of 587 fetuses at 18-20 weeks' gestation. During routine ultrasound examinations, the sonographer was instructed to take additional time and to image the placental cord insertion with color Doppler imaging and classify this as normal, velamentous or 'not seen'. When the insertion was velamentous, the sonographer was instructed to indicate whether or not it was vasa previa. The sonogram obtained at 18-20 weeks' gestation was used for comparison with outcome data. Cord insertion was visualized by color Doppler imaging in 99.8% (586/587) of the fetuses in our study. The mean time required for examination was 20 s and, in 95% of the cases, cord insertion was visualized within 1 min. The sonographic identification of velamentous cord insertion had a sensitivity of 100% (5/5), a specificity of 99.8% (580/581), a positive predictive value of 83% (5/6) and a negative predictive value of 100% (580/580). In our study, vasa previa was diagnosed at 18 gestational weeks in two cases and, in one of the cases, vasa previa was confirmed at delivery. We could consistently identify cord insertion and velamentous cord insertion with color Doppler imaging during routine sonography in the mid-trimester. Transvaginal color Doppler imaging and serial scans were needed to identify vasa previa.