Depending on the diagnosis, therapeutic treatments–known as fetal therapy–can be performed, with the objective of achieving fetal well-being. These treatments include medical and surgical procedures, such as fetoscopic selective laser photocoagulation, cordocentesis, and radiofrequency ablation.
Fetoscopic Selective Laser Photocoagulation
Fetoscopic selective laser photocoagulation (SLP) is used for the treatment of early-onset, advanced-stage twin-twin transfusion syndrome (TTTS). With this procedure, a fetoscope (an elongated surgical camera) is inserted into the uterus under anesthesia, enabling visualization of the placenta and twin circulations. Fetoscopy allows for the identification of disease-causing blood vessel communications between twin blood supplies. Using laser energy, blood flow within these anastomoses can be stopped, thereby interrupting the exchange of blood that is involved in TTTS.
Fetal shunts provide continuous drainage of abnormal fluid accumulations within certain fetal body spaces. They consist of flexible plastic catheters that are guided through the mother’s skin into an in utero fetal location under continuous ultrasound guidance. The two most commonly placed shunt types include vesicoamniotic shunts for lower urinary tract obstruction (LUTO), or fetal bladder obstruction, and thoracoamniotic shunts for severe fetal hydrothorax (fluid in chest) or certain forms of congenital pulmonary airway malformation (CPAM).
Cordocentesis refers to the ultrasound-based guidance of an amniocentesis needle into the umbilical vein, which is a main blood vessel within the umbilical cord of a pregnancy. Cordocentesis can be performed for diagnostic and therapeutic purposes. Common diagnostic uses include assessing for fetal anemia, evaluating for fetal thrombocytopenia (low platelet count), and occasionally for genetic testing. The most common therapeutic use for cordocentesis involves the transfusion of red blood cells as treatment for severe fetal anemia.
Radiofrequency ablation (RFA) causes thermal (heat-related) injury to tissues using high-frequency radio waves. When applied to the umbilical cord of an abnormal twin, RFA can be used to immediately stop blood flow within it. This leads to an intentional demise (loss) of the abnormal twin, while also decreasing risk of permanent neurological (brain) injury or death for a co-twin.
Complicated monochorionic (single-placenta) twin pregnancies can pose particular challenges due to the implications of a shared twin placental circulation; problems affecting one twin can directly risk the health of the other. In monochorionic twin pregnancies, where an abnormality is detected that places one or both twins at increased risk of death in utero or severe morbidity, selective fetal reduction (termination) by RFA can be considered in an attempt to maximize the outcome for the surviving twin.