Laser treatment

Laser treatment for Twin–Twin Transfusion Syndrome

The fundamental principle behind the laser treatment of twin–twin transfusion syndrome (TTTS) consists of interrupting the vascular anastomoses that allow blood exchange between the fetuses and thus eliminating the intertwin transfusion process.

The surgical technique assumes that all placental vascular anastomoses can be identified and obliterated. Neodynium:YAG laser photocoagulation of placental vascular anastomoses was first proposed by De Lia in the late 1980s.1 The approach involved performing a limited laparotomy, placement of a purse string in the myometrium, and introduction of a trocar and endoscope to perform fetoscopy.


Unfortunately, a description of the actual technique to identify the placental vascular anastomoses was never provided. Instead, vessels that appeared ‘suspicious’ for being anastomoses were targeted.2 Thus, a reproducible surgical technique to obliterate all placental vascular anastomoses was lacking. In 1995, Ville et al reported their preliminary experience with laser treatment for TTTS. In their technique, all vessels crossing the dividing membrane were targeted.3 The technique assumed that all vessels crossing the dividing membrane were placental anastomoses, which is indeed the case in many patients.

However, many non-anastomotic vessels could cross the dividing membrane and thus be potentially targeted. Under normal circumstances, the anatomical location of the dividing membrane on the surface of placenta bears little relationship to the location of the vascular equator. In the case of TTTS, the dividing membrane could potentially be displaced even more towards the sac of the donor twin, thus exposing more normal vessels of this fetus.

Photocoagulation of all vessels crossing the membrane, while effectively interrupting the vascular communications between the two fetuses, could also increase the likelihood of injury or death of the donor twin (typically) or the recipient twin by targeting vessels not involved in the syndrome but critical to the survival of the fetuses. In 1998, I developed a surgical technique based on precise endoscopic identification of the vascular anastomoses between the fetuses.

I dubbed this technique ‘selective laser photocoagulation of communicating vessels, or SLPCV’, in contradistinction to the previous non-selective technique.4 Briefly, deep arteriovenous (AV) communications are identified on the surface of the placenta by noting that the terminal end of the artery from one of the fetuses does not have a corresponding returning vein to the same fetus. Instead, the returning vein travels to the other twin.

A systematic analysis at the vascular equator of the placenta discloses deep AV communications from donor to recipient. A deep AV communication from donor to recipient is identified if the artery originates in the donor twin (AVDRs), or from recipient to donor, if the artery originates in the recipient twin (AVRDs), regardless of the location of the dividing membrane.

Superficial arterioarterial or venovenous communications (AA, VV) are easily identified as vessels that do not have a terminal end in the placenta, but rather continue their course from one umbilical cord to the other. treated with SLPCV compared favorably with those treated with the non-selective technique.5 While some centers may still use a non-selective approach to photocoagulate all vascular anastomoses, SLPCV has essentially become the standard technique in most institutions.