Ultrasound in the Evaluation and Management of Twin Pregnancies

The following article was written by Vickie Feldstein, M.D., Professor of Clinical Radiology in the Department of Radiology and Biomedical Imaging at UCSF.

The University of California, San Francisco has recently announced the plan to open a program at the UCSF Medical Center at Mission Bay dedicated to the care of twin pregnancies. The center, called EMBRACE (Evaluating Multiple Births through Research And CarE), will open in early 2013. This new program, which will provide patient-centered coordinated service over the course of pregnancy, will build on a history of excellence in clinical care and research of twins at UCSF. And, pivotal in this endeavor is the involvement of members of the UCSF Radiology and Biomedical Imaging Department who specialize in obstetric ultrasound.

The number of twin pregnancies is on the rise in the US, due, in part, to the increasing widespread use of assisted fertility techniques. Ultrasound is key in the detection of twins and in the evaluation and management of these pregnancies. In fact, ultrasound is the way in which twins are first recognized, so radiologists who perform these diagnostic imaging exams are often the first to share this news with expectant parents.

With this news comes the awareness of increased risk. Many potential complications, to the mother and to the developing fetuses, are increased in twin pregnancies compared to singleton pregnancies. And, among twin pregnancies, the relative risk of complications depends on whether each fetus is attached to its own placenta (dichorionic) or must share a placenta (monochorionic). Several unique and threatening conditions occur only in monochorionic (MC) gestations. The high risks of MC twin gestations are largely related to the vascular anatomy of the shared placenta and the presence of inter-twin vascular connections.

Careful assessment by ultrasound early in the pregnancy can help determine the likelihood of developing significant MC complications, including twin-twin transfusion syndrome (TTTS). This assessment is an area of interest and expertise among members of the Ultrasound section of the UCSF Department of Radiology. We have a long history of collaboration with the multi-disciplinary, highly regarded team of experts who comprise the UCSF Fetal Treatment Center. Together we are investigating new imaging and surgical techniques for in utero identification, assessment and intervention for these high-risk pregnancies.

Some twin pregnancies need careful obstetric and sonographic monitoring in order to optimize timing of delivery. For others, complications arise that threaten the health of both twins and that necessitate in utero intervention. Identifying and treating these cases is done in conjunction with colleagues from the obstetric, perinatology, genetics, neonatology, pediatric/fetal surgery and social work services. For those in whom a procedure is indicated to improve outcome, faculty members of the Ultrasound section are present in the operating room, guiding entry of a fetoscope or other device into the uterus and monitoring the twins during a potentially life-saving intervention.

Sonography has had a dramatic impact on the obstetric management of twin pregnancies. This is based, in part, on the ability, using prenatal ultrasound, to diagnose complications of monochorionic twinning. All twin pregnancies are at higher risk compared with singleton gestations, but complications compound the difficulties in management dramatically. These challenges are being met with promising solutions at UCSF resulting from collaborative investigations, advances in imaging assessment, including Doppler ultrasound and MR techniques, and in utero treatment options.

For more information on ultrasound at UCSF, please see here.