How Do We Treat TTTS?
The proper treatment of the TTTS depends on the stage of disease. In most cases of TTTS (stages I-IV) that develop before 28 weeks, we recommend laser surgery as this approach directly treats the cause of the disease – the abnormal connections in the placenta. Sometimes, in the earliest stage I cases, a trial of observation with follow-up ultrasounds may be an option if heart strain has not yet developed or the TTTS has developed slowly after 26 weeks. The heart strain is evaluated by a specialized ultrasound of the fetal heart called a fetal echocardiogram, which is often referred to as a “fetal echo”. The fetal echo helps us to determine which of the patients with stage I TTTS are likely to progress to advanced stages of the disease during a possible observation period. In these cases, observation is not recommended.
At The Chicago Institute for Fetal Health (CIFH), laser surgery for TTTS is called “selective fetoscopic laser photocoagulation (SFLP)”. The goals of the SFLP procedure are:
- To directly visualize the abnormal vascular connections on the surface of the placenta through a small operating telescope.
- To coagulate these connections with a laser fiber.
- To remove the excess fluid from the recipient twin’s sac thereby relieving the tension on the mother’s abdomen.
In most cases, the SFLP procedure is done in a sterile operating room with the mother awake but lightly sedated with IV medication. Occasionally an epidural analgesia is preferred and rarely a general anesthesia is required. The specialized fetal anesthesiologist will tailor the anesthetic approach to the needs and preference of each mother. After the skin is cleaned and sterilized, a local anesthetic is administered to a single point on the skin of the mother’s abdomen, similar to the anesthetic for a dental procedure.
Next, a tiny incision is made through which we will pass a needle-like operating sheath into the amniotic sac of the recipient twin. The entire operation is done within the confines of that sac, because it is a large space filled with extra amniotic fluid due to the TTTS. In addition, all of the vascular connections can typically be seen from this space, as well.
Once it is in place, the hollow sheath permits the internal passage of the operating telescope and the laser fiber so that the operation can be done inside the uterus under the direct vision of the surgeon. Each of the abnormal vascular connections is identified and catalogued providing a “road map” for the surgery. Then, with a high degree of precision, the vascular connections are efficiently coagulated with the laser fiber along this road map, taking great care to avoid injury to the normal vascular networks.
After the laser portion of the SFLP procedure, the placental circulation is functionally separated so that there is no longer any significant sharing of the placental blood supply between the babies. Finally, the excess fluid is removed from the recipient twin’s amniotic sac bringing the level into the normal range, which helps with the early recovery after the procedure and relieves the tension on the mother’s abdomen. The operating sheath is then removed and the skin incision closed with a single absorbable stitch covered with surgical glue.