2) TTTS - A Viewpoint - by Dr. Joe Bruner, Fetal Diagnosis Unit, Vanderbilt University Medical Centre, USA. To begin, virtually all monochorionic placentas ("conjoined" placentas; single placentas) have blood vessels going back and forth between the twins (vascular anastomoses; intertwin shunts; etc). Normally, these vascular connections are clinically insignificant. If part of the placenta serving one twin has a poor blood supply itself, however, then resistance to blood flow within the substance of that portion of the placenta will increase. Once a threshold level of resistance is reached (which undoubtedly varies from one baby to the next; and probably also varies in the same baby from one time period to the next), the path of least resistance to blood flow becomes the intertwin anastomoses. When this occurs, TTTS is present. Management of TTTS is problematic. The important point is that there is no cure for TTTS--the fundamental problem is that one twin has a crummy placenta, and since no one has yet developed a plastic placenta, the underlying cause is insoluble. All proposed therapies, therefore, only treat SECONDARY symptoms of the underlying disorder. If no specific problems develop, then no specific treatment is required. No one really knows how often this happens, because most of these cases are never detected. If the only problem is polyhydramnios (too much fluid) of the larger twin, then decompression amniocentesis may be performed if the mother becomes uncomfortable, has difficulty breathing or sleeping, or if uterine contractions are frequent. In this case, drainage of the excess fluid may prolong the pregnancy and therefore benefit this twin. Of course, if the smaller twin is growth-restricted, then prolongation of the pregnancy may involve both risks and benefits for that baby, because it will continue in a hostile environment. The tendency, however, is usually for physicians to base most of their decisions on whatever will benefit the larger, "more normal" baby. This is inevitable, since the only thing that will really benefit the smaller baby is a new placenta. If the larger baby develops signs of fluid overload (large heart, umbilical venous pulsations, hydrops), then simply removing the excess amniotic fluid isn't going to help much. In this case, more drastic measures are indicated. If the babies are still too young to safely deliver, then interruption of the intertwin circulation may be recommended. This is usually performed by inserting an operating laparoscope into the sac of the larger twin, identifying each blood vessel on the surface of the placenta that crosses the boundary from the domain of one baby to the other, and coagulating that vessel with a laser beam. This is experimental surgery that should not be taken lightly; in the largest published study, 44% of the small twins died within 24 hours of this procedure, probably because of the loss of the "outlet valve" and the resultant increase in placental resistance to blood flow. Septostomy has recently been proposed as treatment for TTTS. The problem I have with septostomy is that I fail to see how equalization of amniotic fluid will benefit either baby--remember, the basic problem is that the smaller baby has a bum placenta. Secondly, one of the few worse things that can happen to twins besides TTTS is if both are in the same sac (monoamniotic), because then the cords can become entangled. Several deaths have been reported in babies when the membranes were disrupted by needles. Finally, an acceptable outcome with TTTS depends to a great extent on luck. I wish you all the best luck possible, and hope this has been helpful.