Summary: Laser treatment aims to rectify TTTS by stopping the transfusion process within the placenta that causes this condition. A fetoscope is inserted into the fluid sac around the recipient twin providing direct visualisation of the placental blood vessels. The fetoscope is effectively a video camera that can be inserted into the uterus through a 4mm incision in the mother's abdomen. It also has a channel down which the laser fibre can be inserted. The laser is used to selectively close off the abnormal placental vessels connecting the twins. This is usually a single treatment procedure.

Detail: This technique, a form of fetal surgery, was originally described in 1995. This is currently the only form of treatment for twin-to-twin transfusion syndrome where the cause of the condition is addressed.

Fetal surgery is done under local or general anesthesia. A small incision is made on the mother's abdomen and, under ultrasound guidance, a long and thin fetoscope (less than 4mm in diameter) is introduced into the amniotic cavity. The fetoscope allows the surgeon to directly look into the uterus, and to insert a laser fiber to coagulate, or block, the blood vessels that are seen to cross from one twin to the other. All other blood vessels, that connect the fetus to its own side of the placenta, are left alone. The procedure has been performed thousands of times since it was first described.

The results of laser fetal surgery appear to be better than those of other techniques. Overall survival is has been reported to be 65-80%, and survival of at least one twin occurs in 75-90% of cases. Also, the complication rate appears to be much lower. In particular, there are fewer cases of heart and brain damage seen in surviving babies after laser treatment for TTTS compared to amnioreduction. The risk of major neurological disability among survivors treated with laser therapy is approximately 6-11%.

Preterm premature rupture of the membranes (PPROM) after laser for TTTS occurs within 7 days in 5-10% of cases, and by 37 weeks in 35% of cases. PPROM will usually leads to premature delivery. Sometimes a cervical stitch may be recommended to reduce the risk of preterm delivery following laser treatment for TTTS.