Antepartum rupture of the intertwin-dividing membrane in monochorionic diamniotic twins: a case report and review of the literature

We report a case of monochorionic diamniotic twin gestation confirmed by ultrasound visualization of the thin intertwin-dividing membrane at 32 weeks' gestation. Ultrasound at 36 weeks failed to demonstrate the thin dividing membrane. The pregnancy ended a few days later with spontaneous vaginal delivery of the first twin. The second twin was in transverse lie with no membranes that could be felt around. Severe fetal heart rate deceleration developed, prompting delivery by emergency caesarean section. Cord entanglement was noted at the time of delivery, which resulted in severe perinatal morbidity of the second twin. The antepartum rupture of the dividing membrane must have happened some time between 32 and 36 weeks. The etiology for this intrauterine disruption is unknown. A review of the literature about the antepartum rupture of the intertwin-dividing membrane is described, along with its possible causes and complications. In addition, we discuss possible causes of incorrect amnionicity determination, and thus how to minimize these pitfalls. We conclude that antepartum disruption of the intertwin-dividing membrane is more common than previously thought. Moreover, prenatal ultrasonographic visualization of a dividing membrane in a diamniotic twin pregnancy does not rule out future change in this environment to a monoamniotic one, with all its perinatal morbidity and mortality complications, which result mainly from cord entanglement. This suggests a modification in the method and frequency of the prenatal fetal well-being follow-up, as well as the time and mode of delivery. Copyright © 2005 John Wiley & Sons, Ltd.     

Intermittent absent and reversed umbilical artery flows in appropriately grown monochorionic diamniotic twins in relation to proximate cord insertion: A harmful combination?

Objective

To compare the prevalence of intermittent absent or reversed end-diastolic flow (iAREDF) in the umbilical artery in appropriately grown monochorionic diamniotic (MCDA) pregnancies with and without proximate cord insertion (PCI), and to evaluate pregnancy outcome.

Methods

The prevalence of iAREDF in MCDA pregnancies with PCI (n = 11) was compared with a control group without PCI (n = 33). PCI was defined as a distance between the cord insertions below the fifth percentile. Placental sharing, number, and diameter of anastomoses were assessed by placental examination. Pregnancy outcome was evaluated.

Results

iAREDF was present in 7/11 PCI pregnancies, compared with 0/33 in the control group (P ≤ .01). All PCI pregnancies and 94% of controls had arterioarterial (AA)-anastomoses (P = .56), the diameter was larger in the PCI group, respectively 3.3 vs 2.1 mm (P = .03). Three cases with iAREDF had adverse outcome, two resulted in fetal death of which one with brain damage in the co-twin, another underwent early premature emergency section for fetal distress.

Conclusion

iAREDF occurs in a large proportion of MCDA pregnancies with PCI and is related to the diameter of the AA anastomosis. We hypothesize that iAREDF in appropriately grown MCDA twin pregnancies reflects an unstable hemodynamic balance with an increased risk for fetal deterioration. Whether outcome in these pregnancies can be improved by altered management requires further investigation.

     

Twin–twin transfusion syndrome: mathematical modelling

Twin–twin transfusion syndrome (TTTS) represents a pregnancy complication with a high risk for perinatal mortality and postnatal morbidity. Mathematical models have been utilized to examine the mechanisms of disease and potential treatment modalities. We developed four consecutive models based on pathophysiology mechanisms. Conceptually, these models remained simple, but with increased complexity in details. We present our models tutorially with the necessary equations expressed in words. The aetiology of TTTS was related to AV anastomoses from donor to recipient and their growth commensurate with placental growth. We assessed that natural growth of placenta and foetuses causes the diameter and length of the AV, as well as the AV's pressure gradient, to increase proportional to gestational age. The AV transfusion then increases faster than natural foetal growth. A progressively increasing discordance subsequently develops, not compensated for by foetal growth. A simulation is performed to show how this discordance in blood volumetric development causes successive discordances in other functions, particularly renal, circulatory, and cardio-vascular, resulting in disease progression to the various stages of TTTS. In conclusion, mathematical modelling of TTTS has provided an understanding of the sequence of events that leads to the various presentations of TTTS stages as well as the efficacy of therapies. Copyright © 2008 John Wiley & Sons, Ltd.     

Long-term outcome after intrauterine laser treatment for twin–twin transfusion syndrome

Twin–twin transfusion syndrome (TTTS) is a severe complication occurring in about 10% of monochorionic twin pregnancies. The chronic unbalanced transfusion of blood across placental vascular communications from the donor to the recipient twin may lead to impairment of various organ systems in the affected twins. In Hamburg, Germany, since 1995 patients with TTTS were treated with fetoscopic laser coagulation as the first causal therapeutic strategy. All survivors after laser surgery were followed up in the University Children's Hospital in Bonn, Germany. In this article, we summarize long-term follow-up studies from our German study population and compare our results with data from the literature. Copyright © 2011 John Wiley & Sons, Ltd.     

Insights into the pathophysiology of twin–twin transfusion syndrome

Twin–twin transfusion syndrome (TTTS) is attributed to trans-anastomotic transfusion between twins. Anastomoses are ubiquitous in monochorionic (MC) placentae, yet TTTS develops in only 15%. Although ex vivo and in vivo studies fail to identify a unique anastomotic signature, TTTS placentae are typically associated with an imbalance in unidirectional arteriovenous anastomoses with absent bidirectional anastomoses. Doppler detection of an artery-artery anastomosis reduces the chance of TTTS, whereas, in those that develop the disease, it improves stage-independent survival. Selective laser is often curative, but an increasingly recognized risk of persistent or reverse TTTS may be attributable to atypical arteriovenous anastomoses not identifiable from the chorionic plate. Simple dysvolaemia fails to explain several phenotypic features, including haematological concordancy, recipient hypertension, and reversibly absent end diastolic flow in the donor. The renin-angiotensin system is upregulated in the donor and downregulated in the recipient's kidneys, while paradoxically raised renin levels in the recipient may contribute to raised afterload along with endothelin. Although research is limited in humans by therapy and the lack of a suitable experimental model, further studies of placental and vascular pathophysiology may not only refine current treatment modalities but may also, in addition, suggest further avenues for downstream management such as genetic predisposition testing or pharmacological intervention. Copyright © 2005 John Wiley & Sons, Ltd.