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.     

Do sibling and friend relationships share the same temperamental origins? A twin study

BACKGROUND: Friendship and sibling relationships differ in that there is an element of choice in friendships, whilst the latter represent a fixed and given relationship. The present study set out to investigate the temperamental correlates of friendships and sibling relationships, as well as to examine their genetic and environmental components. METHOD: Two hundred and twelve same-sex twin-pairs (102 MZ and 110 DZ; 104 male pairs and 108 female pairs) aged between 12 and 15, together with their parents, comprised the sample. The twins themselves reported on both negative and positive aspects of the two relationships, and all family members provided reports of the twins' temperament (mothers, fathers, and adolescent self-reports). RESULTS: Analyses revealed that negative aspects of both the sibling relationship and friendship were related to emotionality, while the positive aspects of these relationships were associated with sociability and activity. Genetic influences and the shared environment accounted for variance seen in the sibling relationship. In addition, nonshared environment accounted for a moderate amount of the sibling relationship variability and explained most of the variance for the friendship components. Finally, bivariate analyses of the covariance between temperament and close relationships highlighted the importance of nonshared environmental influences during adolescence. CONCLUSION: Three themes emerged. First, congruent temperamental expressions were seen across these two relationships' contexts. Second, friendship and the sibling relationship have distinct etiological profiles, indicating the child-specific character of adolescent friendships versus the reciprocal nature of the sibling relationship. Finally, the common influences to temperament and relationship quality provided evidence for the validity of adolescents' unique, nonshared experiences.     

Twin–twin transfusion syndrome: cerebral ischemia is not the only fetal MR imaging finding

Background Twin–twin transfusion syndrome (TTTS) is a complication of monochorionic/diamniotic twin pregnancies. An imbalance of blood flow occurs through placental anastomoses, causing potentially significant morbidity and mortality in both twins. Although the sonographic findings of TTTS are well documented, we believe that MR imaging is a valuable adjunct. Objective We describe the fetal MR imaging findings associated with TTTS. Materials and methods From 2003 to 2005, 37 consecutive MR imaging studies were performed on multiple-gestation pregnancies. Of the 37, 25 were consistent with TTTS, correlated and confirmed by sonographic criteria. MR fetal abnormalities were documented. Results Cerebral ischemia, which could not be demonstrated by sonography, was delineated well by MR imaging. New findings noted on fetal MR imaging were enlargement of cerebral venous sinuses in both twins, dilatation of the renal collecting system in the recipient, lung lesions in the recipient and cerebral malformations in the donor. Conclusion MR imaging is an important adjunct in TTTS imaging. Its benefit over sonography is its clear definition of cerebral pathology, which is important for intervention and counseling. The new findings, particularly in the urinary tract and cerebral venous sinuses, also help support the diagnosis of TTTS and might reveal additional consequences of the altered hemodynamics that occur in TTTS.     

Identical twin brothers concordant for Langerhans’ cell histiocytosis and discordant for Epstein-Barr virus-associated haemophagocytic syndrome

We report on identical twin brothers, one of whom presented at 14 months of age with fever and clinical, laboratory and histological evidence of Epstein-Barr virus-associated haemophagocytic syndrome (EBV-AHS) and 4 months later with typical signs and symptoms of Langerhans cell histiocytosis (LCH). The other twin, without previous symptoms, also displayed at that time LCH associated with signs of recent EBV infection, but without symptoms of haemophagocytic syndrome. No mutation in the SH2D1A gene, as observed in X-linked lymphoproliferative disease, or in the perforin gene as observed in some cases of hereditary haemophagocytic syndrome, was found. Conclusion:the occurrence of haemophagocytic syndrome and Langerhans cell histiocytosis, although genetically based, can be triggered by environmental agents and viruses, in particular Epstein-Barr virus.Abbreviations CAEBV chronic active Epstein-Barr virus infection - EBV Epstein-Barr virus - EBV-AHS EBV-associated haemophagocytic syndrome - HS haemophagocytic syndrome - HHS hereditary haemophagocytic syndrome - XLP X-linked lymphoproliferative disease     

Porcine dermal collagen (Permacol®) for chest and abdominal wall reconstruction in thoraco-omphalopagus conjoined twin separation

Each set of conjoined twins presents a unique challenge, which centers on the ability to separate and if necessary reconstruct shared organs and to achieve subsequent skin cover of the often very large residual defect after completion of the separation. This report describes the use of a bioprosthetic Permacol^® derived from porcine dermal collagen to reconstruct the chest and abdominal wall.     

Correlation between cord insertion type and chorionic villus vascularization of the co-twin in diamniotic–monochorionic twin pregnancies

Background

Recent evidence suggests that cord insertion type of one twin correlates with chorionic plate vascularization of the monochorionic co-twin. Specifically, for twins with paracentral cords, chorionic plate vascularization is significantly greater when the co-twin has a velamentous, rather than paracentral cord insertion.

Aims

To determine whether this correlation between cord insertion type and vascularization of the co-twin also extends to the deeper chorionic villus tree.

Study design

Morphometric analysis of chorionic villus vascularization in CD31-immunostained sections of a retrospective cohort of gestational age-matched third trimester monochorionic placentas with discordant paracentral/velamentous (PC/V) or concordant paracentral/paracentral (PC/PC) cord insertions.

Outcome measures

Vascular numerical density (number of vascular profiles per unit villus stromal area) of intermediate villi (> 80 μm diameter) and terminal villi (< 80 μm).

Results

For twins with paracentral cord insertion, the vascular numerical density of intermediate villi was significantly higher for twins in a discordant PC/V relationship than for those in a concordant PC/PC relationship (P < 0.05), thus replicating previous findings in superficial chorionic vessels. For terminal villi, in contrast, the vascular numerical density of twins with paracentral cords in a PC/V combination was significantly lower than of those in a PC/PC combination, and similar to that of their co-twins with velamentous cord insertion.

Conclusions

Early placental angiogenesis in monochorionic twin gestations may be influenced by implantation and cord localization of the co-twin. The regulation of terminal villus angiogenesis appears to be dissociated from more proximal villus angiogenesis and independent of cord insertion of the co-twin.