Cervical-length measurement in mid-gestation to predict spontaneous preterm birth in asymptomatic triplet pregnancy.

OBJECTIVE: To assess the predictive value of sonographic cervical-length (CL) measurement in mid-gestation for spontaneous preterm birth (PTB) in asymptomatic triplet pregnancy. METHODS: This was a retrospective study of asymptomatic triplet pregnancies followed at five Italian tertiary referral centers, between 2002 and 2015. CL was measured transvaginally between 18 and 24 weeks' gestation. Pregnancies with medically indicated PTB were excluded. Demographic and pregnancy characteristics of pregnancies complicated by PTB were analyzed and the distributions of CL measurements in these patients were calculated. Logistic regression analysis was performed to assess the association between CL and PTB, adjusted for confounders. Performance of CL measurement in prediction of PTB < 28, < 30 and < 32 weeks of gestation was assessed. RESULTS: A total of 120 triplet pregnancies were included in the final analysis. Median CL was 35 (interquartile range (IQR), 29-40) mm measured at a median gestational age of 20 + 2 (IQR, 20 + 0 to 23 + 4) weeks. Overall, 23 (19.2%), 17 (14.2%) and eight (6.7%) patients had a CL < 25, < 20 and < 15 mm, respectively. Spontaneous PTB < 32 weeks occurred in 41 (34.2%) cases, < 30 weeks in 23 (19.2%) and < 28 weeks in 12 (10%) cases. CL < 15 mm was significantly more frequent in the group of patients who delivered < 28 (P = 0.03) and < 30 (P = 0.01) weeks' gestation, compared with those who delivered after 28 and after 30 weeks, respectively, while CL < 20 mm was more common in triplet pregnancies with delivery < 32 weeks compared with those delivered ≥ 32 weeks (P = 0.03). Logistic regression analysis was possible only for PTB < 32 weeks due to the small number of cases that delivered < 30 and < 28 weeks. After adjustment for confounders, CL was not significantly associated with PTB < 32 weeks (adjusted odds ratio, 0.97; 95% CI, 0.94-1.01). CL measurement had an area under the receiver-operating characteristics curve of 0.41 (95% CI, 0.20-0.62), 0.41 (95% CI, 0.26-0.56) and 0.42 (95% CI, 0.31-0.54) for the prediction of spontaneous PTB < 28, < 30 and < 32 weeks, respectively. CONCLUSION: CL assessed in mid-gestation is a poor predictor of PTB < 28, < 30 and < 32 weeks' gestation in asymptomatic triplet pregnancy. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Early prediction of twin-to-twin transfusion syndrome: systematic review and meta-analysis.

OBJECTIVE: To assess the role of first- and early second-trimester markers in the prediction of twin-to-twin transfusion syndrome (TTTS) in monochorionic twin pregnancies. METHODS: Electronic databases MEDLINE, EMBASE and ClinicalTrials.gov were searched from inception to April 2014, using the MeSH term 'fetofetal transfusion' in combination with phrases 'predictive value', 'sensitivity', 'specificity', 'false positive', 'false negative', 'screening', 'accuracy' and 'ROC'. Study quality was assessed using the PRISMA guidelines and QUADAS-2 tool. A meta-analysis was planned for the following predictive factors: intertwin nuchal translucency (NT) discrepancy; NT > 95th percentile in at least one twin; intertwin crown-rump length (CRL) discrepancy as a percentage of the larger CRL; abnormal ductus venosus (DV) flow in at least one twin. The outcome assessed was TTTS, defined according to the presence of a twin oligohydramnios-polyhydramnios sequence. The diagnostic performance of the predictive factors was evaluated for each included study. RESULTS: The electronic search identified 152 records, of which 23 were assessed in full for eligibility. We identified 13 eligible studies that reported the predictive accuracy of ultrasound parameters, measured before 16 weeks, for the development of TTTS, including a total of 1991 pregnancies, of which 323 developed TTTS. An increased risk of TTTS was associated with: intertwin NT discrepancy (positive likelihood ratio (LR+), 1.92 (95% CI, 1.25-2.96); negative likelihood ratio (LR-), 0.65 (95% CI, 0.50-0.84)); NT > 95th percentile (LR+, 2.63 (95% CI, 1.51-4.58); LR-, 0.85 (95% CI, 0.75-0.96)); CRL discrepancy > 10% (LR+, 1.80 (95% CI, 1.05-3.07); LR-, 0.92 (95% CI, 0.81-1.05)); abnormal DV flow (LR+, 4.77 (95% CI, 1.33-17.04; LR-, 0.49 (95% CI, 0.17-1.41)). The highest sensitivities were observed for intertwin NT discrepancy (52.8% (95% CI, 43.8-61.7%)) and abnormal DV flow (50.0% (95% CI, 33.4-66.6%)). CONCLUSION: Monochorionic twin pregnancies with intertwin NT discrepancy, NT > 95th percentile, intertwin CRL discrepancy > 10% or abnormal DV flow on first-trimester ultrasound examination are at significantly increased risk of developing TTTS. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Cervical length at mid-gestation in screening for preterm birth in twin pregnancy.

OBJECTIVE: Short cervical length (CL) in mid-gestation is considered predictive of spontaneous preterm birth (PTB). The medical literature suggests 20 mm as the cut-off for high risk in twin pregnancies. Our objective was to assess the predictive value of CL for spontaneous PTB < 32 weeks' gestation in twin pregnancies and to calculate the cut-off point with the best sensitivity and specificity. METHODS: This was a single-center retrospective cohort study of women in whom CL had been measured by transvaginal ultrasound at 18-23 weeks' gestation. Pregnancies complicated by twin-to-twin transfusion syndrome, those requiring intrauterine therapy or those with indicated PTB were excluded. The predictive value of CL for PTB < 32 weeks was assessed. The distribution of CL measurements and the optimal cut-off in patients with PTB were calculated and logistic regression analysis was performed to assess the association between pregnancy characteristics and PTB. RESULTS: A total of 940 twin pregnancies were included. CL showed an area under the receiver-operating characteristics curve of 0.65 (95% CI, 0.58-0.71) for the prediction of PTB < 32 weeks. The optimal cut-off value for predicting PTB was 36 mm (sensitivity, 64.1%; specificity, 62.8%; positive predictive value, 13.5%; negative predictive value, 95.1%; accuracy, 62.9%). The relative risk of PTB with CL ≤ 36 mm was 2.35 (95% CI, 1.53-3.60; P < 0.001). After adjusting for confounders in logistic regression analysis, only CL (adjusted odds ratio (aOR), 0.94 (95% CI, 0.90-0.99); P = 0.03), and not monochorionicity (aOR 4.14 (95% CI, 0.89-19.25); P = 0.07), was independently associated with PTB. More than one-third (36%) of PTB cases delivering < 32 weeks had a normal CL in mid-gestation. This proportion rose to 85% when considering the 20-mm cut-off suggested by the medical literature. CONCLUSIONS: This study shows that, despite the weak independent association, CL assessed in mid-gestation is a poor predictor of PTB < 32 weeks' gestation in asymptomatic twin pregnancies. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Intertwin discrepancy in middle cerebral artery peak systolic velocity and third-trimester fetal growth restriction in monochorionic-diamniotic twin pregnancy.

OBJECTIVES: To assess the role of intertwin discrepancy in middle cerebral artery peak systolic velocity (MCA-PSV) for the prediction of late selective intrauterine growth restriction (sIUGR) at birth and birth weight discrepancy of > 25% (BW-25) in otherwise uncomplicated monochorionic-diamniotic (MCDA) twin pregnancies. METHODS: This was a cohort study including all MCDA pregnancies followed in a tertiary fetal medicine unit between 2008 and 2013. Exclusion criteria were referral after first trimester, abnormal karyotype, structural anomalies, twin-to-twin transfusion syndrome, twin anemia-polycythemia sequence and sIUGR detected before 28 weeks. MCA-PSV values of both twins measured in the second trimester (18-24 weeks) and early third trimester (26-32 weeks) were converted in multiples of the median (MoM). sIUGR was defined as birth weight < 5(th) centile. The relationship between MCA-PSV discrepancy, sIUGR and BW-25 was assessed by logistic regression analysis. Receiver-operating characteristics (ROC) curves were used to ascertain the predictive value of MCA-PSV discrepancy for such complications. RESULTS: In total, 136 MCDA twin pregnancies were included in the analysis. Thirty (22.1%) were complicated with sIUGR at birth and 12 (8.8%) were complicated with BW-25. Logistic regression analysis identified MCA-PSV discrepancy as an independent predictor for sIUGR. ROC curves identified third-trimester MCA-PSV discrepancy as the best predictor for both sIUGR (area under ROC curve (AUC), 0.73 (95% CI, 0.62-0.85)) and BW-25 (AUC, 0.79 (95% CI, 0.65-0.93)). The optimal cut-off point for MCA-PSV discrepancy was 0.30 MoM (sensitivity, 70% and specificity, 69% for sIUGR; sensitivity, 83% and specificity, 72% for BW-25). CONCLUSION: In MCDA twin pregnancies, MCA-PSV discrepancy is associated with both sIUGR at birth and BW discordance. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Pulmonary stenosis in complicated monochorionic twin pregnancies: prevalence, management and outcome.

OBJECTIVE: To review prevalence, management and prognostic factors of pulmonary stenosis (PS) in monochorionic diamniotic (MCDA) pregnancies complicated by twin-to-twin transfusion syndrome (TTTS). METHODS: Retrospective study over the last 10 years in a single referral center. We reviewed fetal echocardiography data of all MC twin cases with diagnosis of isolated PS. We assessed fetoscopy characteristics of those that underwent laser coagulation. We collected data regarding perinatal outcome, neonatal echocardiography and cardiac management. RESULTS: We found 24 cases of isolated PS among 2091 MCDA pregnancies. Among 1052 complicated MCDA that underwent fetal laser surgery, 22 (2.09%) developed PS of which 20 were diagnosed prenatally. Two cases were diagnosed in uncomplicated MCDA pregnancies (0.2%). Four of 22 (18.18%) cases with TTTS showed in utero regression after laser treatment. Thirteen newborns (65%) required valvular dilatation. Peak systolic velocities in the pulmonary artery trunk (PSV-PA) at diagnosis and the interval between the diagnosis of TTTS and that of PS were significantly different (p < 0.001 and p = 0.05 respectively) between PS requiring cardiac intervention and those who did not. CONCLUSION: An elevated PSV-PA at the time of PS diagnosis and a short time-interval between fetoscopic laser surgery and PS diagnosis are predictive of the need for interventional treatment after birth.