Placental differences between uncomplicated and complicated monochorionic diamniotic pregnancies on diffusion and multicompartment Magnetic Resonance Imaging

INTRODUCTION

Twin-twin transfusion syndrome (TTTS) and selective fetal growth restriction (sFGR) are common complications in monochorionic diamniotic (MCDA) pregnancies. The Diffusion-rElaxation Combined Imaging for Detailed Placental Evaluation (DECIDE) model, a placental-specific model, separates the T2 values of the fetal and maternal blood from the background tissue and estimates the fetal blood oxygen saturation. This study investigates diffusion and relaxation differences in uncomplicated MCDA pregnancies and MCDA pregnancies complicated by TTTS and sFGR in mid-pregnancy.

METHODS

This prospective monocentric cohort study included uncomplicated MCDA pregnancies and pregnancies complicated by TTTS and sFGR. We performed MRI with conventional diffusion-weighted imaging (DWI) and combined relaxometry - DWI-intravoxel incoherent motion. DECIDE analysis was used to quantify different parameters within the placenta related to the fetal, placental, and maternal compartments.

RESULTS

We included 99 pregnancies, of which 46 were uncomplicated, 12 were complicated by sFGR and 41 by TTTS. Conventional DWI did not find differences between or within cohorts. On DECIDE imaging, fetoplacental oxygen saturation was significantly lower in the smaller member of sFGR (p = 0.07) and in both members of TTTS (p = 0.01 and p = 0.004) compared to the uncomplicated pairs. Additionally, average T2 relaxation time was significantly lower in the smaller twin of the sFGR (p = 0.004) compared to the uncomplicated twins (p = 0.03).

CONCLUSION

Multicompartment functional MRI showed significant differences in several MRI parameters between the placenta of uncomplicated MCDA pregnancies and those complicated by sFGR and TTTS in mid-pregnancy.

Comparison of crown-rump length discordance and abnormal cord insertions as first-trimester predictors of poor outcome in monochorionic diamniotic twin pregnancies

OBJECTIVES

This is a retrospective study to determine the predictive value and comparison of first trimester (1) crown-rump length discordance and (2) abnormal cord insertion as screening tests for poor outcome in monochorionic diamniotic twin pregnancies.

RESULTS

Retrospective data were collected over last 10 years from a single center (2009-2018). A total of 261 patients were a part of this study. CRL discordance or abnormal cord insertions are not accurate predictors of twin-to-twin transfusion syndrome, which corresponds to previously published data on the same subject. Both CRL discordance and abnormal cord insertions are strongly associated with selective fetal growth restriction (sFGR) as defined according to conventional criteria or the newer consensus criteria. A combination of these two markers substantially improves the screening rates, with a positive likelihood ratio of 10.33 for sFGR. However, this combination fails to distinguish the type 1 sFGR cases from the type 2/3, which typically have poorer outcomes.

CONCLUSION

CRL discordance and abnormal cord insertions are strongly associated with the development sFGR in monochorionic pregnancies. A combination of these two markers shows promising potential as a screening test to identify pregnancies at a high risk for development of sFGR. Earlier diagnosis can help plan timely fetal intervention and improve the overall outcomes of these pregnancies. These markers need to be validated in larger studies before being adopted for screening of monochorionic pregnancies.

Preoperative Ultrasound Prediction of Essential Landmarks for Successful Fetoscopic Laser Treatment of Twin-Twin Transfusion Syndrome

INTRODUCTION

The insertion site of the fetoscope for laser occlusion (FLOC) treatment of twin-twin transfusion syndrome (TTTS) determines the likelihood of treatment success. We assessed a standardized preoperative ultrasound approach for its ability to identify critical landmarks for successful FLOC.

METHODS

Three surgeons independently performed preoperative ultrasound and deduced the likely orientation of the intertwin membrane (ITM) and vascular equator (VE) based on the sites of the cord insertion, the lie of the donor, and the size discordance between twins. At FLOC, these landmarks were visually verified and compared to preoperative assessments.

RESULTS

Fifty consecutive FLOC surgeries had 127 preoperative assessments. Basic ITM and VE orientation were accurately predicted in 115 (90.6%), 109 (85.8%), and 105 (82.7%) assessments. Predictions were anatomically correct in 96 (75.6%), 70 (55.1%), and 58 (45.7%) assessments with no differences in accuracy between operators of different training level. The ITM/VE relationship was most poorly predicted in stage-3 TTTS (χ2, p = 0.016).

CONCLUSION

In TTTS, preoperative ultrasound identification of placental cord insertion sites, lie of the donor twin, and size discordance enables preoperative prediction of key landmarks for successful FLOC.

Twin-twin transfusion syndrome - What we have learned from clinical trials

Monochorionic twin pregnancies are at increased risk for adverse outcome compared to dichorionic twin pregnancies and singletons. Monochorionic-specific complications include twin-twin transfusion syndrome (TTTS), twin anemia-polycythemia sequence, single intrauterine fetal demise and its consequences on the co-twin, and selective intrauterine growth restriction. Whereas the natural history of monochorionic-specific complications carries a high risk of fetal death or severe neurologic disability, a framework now exists, based on well-designed clinical trials, for optimal treatment of these entities. Fetoscopic selective laser coagulation of anastomotic vessels on the chorionic plate has been clearly demonstrated to improve survival and neurologic outcomes for Quintero stage ≥2 TTTS. However, many challenges remain unsolved, the most important of which is preterm premature rupture of membranes. Further improvement in the outcomes of monochorionic pregnancies will require improvements in the rate of premature delivery, and improved diagnosis and treatment strategies for early and late onset TTTS.

Doppler assessment of patients with twin-to-twin transfusion syndrome and survival following fetoscopic laser surgery

OBJECTIVE

To investigate fetal-survival rates following laser surgery for twin-to-twin transfusion syndrome (TTTS) and the impact of Doppler analysis.

METHODS

The present retrospective single-center study included data from patients with pregnancies exhibiting TTTS treated with fetoscopic laser surgery between January 1, 2007, and December 31, 2016. Perinatal outcomes were examined and variables were compared between the donor and recipient fetuses that survived and died, respectively.

RESULTS

There were 86 pregnancies exhibiting TTTS treated with fetoscopic laser surgery included in the study. The median length of pregnancy at the time of surgery was 21.1 weeks. Both twin fetuses and at least one fetus survived in 61 (71%) and 73 (85%) pregnancies, respectively. Among recipient fetuses, ductus venosus a-wave anomalies (P=0.026), shorter cervical length (P=0.044), and a greater than 25% discrepancy in the estimated weight of the twin fetuses (P=0.045) were associated with reduced survival.

CONCLUSION

Among pregnancies exhibiting TTTS, laser surgery was associated with significant dual-fetus survival. Preoperative ductus venosus anomalies were associated with lower survival among recipient fetuses, and 1-week postsurgical ultrasonography data demonstrated lower survival among recipient fetuses with persistent anomalous ductus venosus compared with normalized ductus venosus.

Umbilical Cord Occlusion via Laser Coagulation in Monochorionic Multifetal Gestations before and after 20 Weeks of Gestation

INTRODUCTION

Umbilical cord occlusion (UCO) utilizing laser photocoagulation is often not considered an option for selective termination after 20 weeks of gestation due to reported limitations of the procedure because of umbilical cord size. We compared outcomes after laser umbilical cord occlusion (L-UCO) before and after 20 weeks of gestation.

MATERIALS AND METHODS

We examined all patients with monochorionic- diamniotic twins and higher-order multiples (monoamniotic excluded) that underwent L-UCO at our facility between 2006 and 2014. Statistical analysis was performed using Fisher's exact and Kruskal-Wallis tests as appropriate.

RESULTS

Of 43 L-UCO cases, 11 cases (25.6%) had a discordant anomaly, and 32 cases (74.4%) had twin reversed arterial perfusion (TRAP) sequence. We achieved complete vascular occlusion in 100% (43/43) of cases of attempted L-UCO. There were 22 cases (51.2%) with gestational age ≤20 weeks, and 21 cases (48.8%) with gestational age >20 weeks. Perioperative patient characteristics and outcomes did not differ between the two groups. Survival rates were 90.9% (20/22) and 100% (21/21) at ≤20 weeks of gestation and >20 weeks of gestation, respectively.

DISCUSSION

The results of this study suggest that L-UCO is a reasonable surgical modality for patients prior to and beyond 20 weeks of gestation.

Fetal distress and circulatory disturbance in monochorionic twins: Possible risk factors for sialadenitis?

Neonatal sialadenitis is a rare condition. The vast majority of cases are caused by Staphylococcus aureus with predominant involvement of the parotid gland and need for long-term antimicrobial therapy. We reviewed three distinct cases of submandibular sialadenitis in preterm infants from monochorionic pregnancies. The association with neonatal sialadenitis is unproven. We speculate about the role of fetal distress and circulatory compromise in monochorionic twins as a risk factor in the development of this serious condition.