From Amniocentesis to Selective Laser Coagulation
It is also important to inform neonatologists and referring obstetricians of the special circumstances of these babies, who behave very differently—both in the NICU and beyond—than do other babies of similar size or with other underlying conditions.
Babies who matured in utero as TTTS “recipients” are chronically hypervolemic and will not respond well, for instance, to dopamine given in the NICU as the primary agent to boost blood pressure. Careful attention to fluid balance is essential to prevent neonatal complications under these circumstances.
Fortunately, technologic advances in equipment are making intrauterine therapy much more minimally invasive. The development of fetoscopes with a 2-mm lens offers superior visual resolution and facilitates a minimally invasive approach. Digital camera technology also enhances the visualization of the smallest blood vessels. Steerable and angulated optical devices tackle the problems of anterior placenta. The smaller caliber of the entry site also decreases the risk for complications.
Today, laser surgery is typically performed under local anesthesia that requires minimal hospitalization with only perioperative tocolysis. The average length of patient stay is 1 day at the University of Maryland Medical Center.
The initiation of the North American Fetal Therapy Network (NAFTNet), a research consortium, is a significant development in the United States.
The membrane is seen folding around the donor who becomes a “stuck twin.” Courtesy Dr. Ahmet A. Baschat
When bladder filling of the donor can no longer be demonstrated, progression to stage 2 TTTS is diagnosed. (Left arrow, small bladder; right arrow, empty bladder.)
Critically abnormal waveforms in the umbilical artery (left) and ductus venosus (right) indicate stage 3 TTTS.
Ultrasound findings of hydrops (arrows point to fluid in fetal abdomen) indicate stage 4 TTTS. Photos courtesy Dr. Ahmet A. Baschat
Twin-to-Twin Transfusion Syndrome
Despite the advances that have occurred in obstetrics over the years, who would have imagined that fetal surgery would be a viable therapeutic approach today? Well, indeed, this is where we are in the history of obstetrics.
Fetal evaluation has been conducted over the years using a variety of noninvasive techniques, most notably electronic fetal monitoring. More invasive techniques, such as amniocentesis, have also been used with very good success and with relatively low risk to mother and fetus. Certain conditions, however, cannot be addressed with noninvasive or slightly invasive approaches, but rather require either open surgery or more involved surgery of a minimally invasive nature.
One of these conditions is twin-to-twin transfusion syndrome, in which one of the fetuses may succumb during intrauterine life. Over the years, amniocentesis has been used with limited success. However, newer techniques involving endoscopic laser therapy are being introduced with improved outcomes. In this Master Class, we review both modalities in the management of these patients, with careful attention to advances in fetal laser therapy.
We are pleased to introduce Dr. Ahmet A. Baschat, of the department of obstetrics, gynecology, and reproductive sciences at the University of Maryland School of Medicine, Baltimore, as our guest professor this month. Dr. Baschat is considered a national expert in fetal therapy, including laser and other intrauterine surgical procedures.
EMILY BRANNAN, ILLUSTRATION
