The Food and Drug Administration (FDA) has approved a Humanitarian Device Exemption (HDE) aimed at helping doctors provide treatment during pregnancy for fetuses affected by twin-to-twin transfusion syndrome. This syndrome sometimes occurs when women are pregnant with identical twins. It is a rare disease of the placenta.

As identical twin fetuses develop, there are often blood vessels in their shared placenta that connect the fetuses’ circulating blood. In most cases, the blood flows properly through these vessels. However, in TTS the blood flow is uneven, with one fetus receiving too much blood and one receiving too little.

This can cause heart failure in the twin receiving too much blood and life-threatening anemia in the one receiving too little. Many of these babies do not survive delivery or are born with severe handicaps.

HDEs are applications for approval of medical devices being developed for conditions that affect fewer than 4,000 Americans per year. Sponsoring companies must demonstrate the safety and probable benefit of such devices.

In this case, the device, known as Fetoscopy Instrument Sets, is intended to be used for the treatment of TTTS for fetuses between the 16th and 26th month of pregnancy. They are intended to help doctors identify the communicating blood vessels and normalize the blood flow. The devices are distributed by Karl Storz Endoscopy America, Inc., of Culver City, Calif.