Fetal and Neonatal Circulatory Disorders in Twin to Twin Transfusion Syndrome (The Secondary Publication)

Abstract

Twin to twin transfusion syndrome (TTTS) is a major complication of monochorionic diamniotic (MD) twins, and its onset is known to be associated with placental vascular anastomoses and blood flow imbalance. In a typical case of TTTS, the recipient develops polyhydramnios, weight gain, cardiomegaly and hydrops fetalis in the uterus. In contrast, the donor develops oligohydramnios and intrauterine growth restriction. Recently, the significance of the renin-angiotensin-aldosterone system (RAAS) that transfers from the donor to the recipient has attracted interest in the fetal circulation of TTTS. The donor has decreased renal blood flow due to decreased circulating blood volume. For this reason, the secretion of RAAS hormones is augmented in the fetal kidneys of the donor. In TTTS, these RAAS hormones from the donor transfer to the recipient through the anastomosed vessels. In addition to excess preload, the recipient heart is exposed to excess afterload due to systemic vasoconstriction through RAAS hormones. Commonly occurring complications in the recipient include myocardial hypertrophy, atrioventricular valve regurgitation, and pulmonary valve stenosis or pulmonary atresia. Fetoscopic laser photocoagulation (FLP) has been introduced recently because neither mortality nor neurological morbidity have been satisfactorily improved with conventional treatment. FLP is a curative method that may improve the prognosis of TTTS. In Japan, this procedure has been performed frequently, and positive neurological outcomes have been achieved. (J Nippon Med Sch 2019; 86: 192 200)

Twin Pregnancies Labour Modus and Timing

“…Selective reduction at 12 weeks of gestation the abortion rate is 5% and the prematurity rate less than 33 weeks is 6%. Selective reduction at 20 weeks the abortion rate is 14% and the prematurity rate less than 33 weeks is 20% [31][32][33][34][35][36][37][38].…”

“…The diagnosis is ultrasound, usually between 16 and 26 weeks. 1 in 10 monochorionic twins will develop TTTS syndrome [34][35][36][37][38][39][40]. However, vascular anastomoses occur in>95% of monochorionic pregnancies.…”

“…In recent years, with the help of embryoscopy, laser anatomy of the anastomoses is performed. The procedure involves a risk of miscarriage/premature birth at a rate of 10-15% within the next 6 weeks of surgery [34][35][36][37][38]. However, after this operation, an increased incidence of congenital heart disease was reported in both recipient and donor twins.…”

“…Usually, under ultrasound control, a 2-3 mm fetoscope is inserted into the amniotic cavity (). An alternative but less common method is embryonic umbilical cord ligation [34][35][36][37][38][39][40]. Finally, there is a significant risk of structural abnormality in monochorionic twins, with 4% of cases the abnormality concerns only one of the two fetuses.…”

“…TTTS syndrome occurs in the early stages of pregnancy, when delivery is not an option because the fetuses are still very premature. Therefore, there is significant mortality and morbidity without therapeutic intervention, with possible miscarriage or fetal loss of one or both fetuses [34][35][36][37][38][39][40].…”