Peeking into the womb

Bill Snyder
Published: February, 2006

One of the most powerful applications of imaging science is the diagnosis of fetal abnormalities.

“Imaging provides an ability to depict things that previously were only able to be diagnosed by surgery,” says Marta Hernanz-Schulman, M.D., director of Pediatric Diagnostic Imaging at Vanderbilt University Medical Center.

Some conditions can be treated before birth.

For example, when the male urethra—the tube that carries urine from the bladder to the outside—is obstructed, the bladder can become massively dilated. Urine may back up the ureters, causing severe kidney damage. By inserting a needle through the uterine wall into the fetal bladder, under the guidance of ultrasound, the obstetrician can drain the bladder into the amniotic fluid surrounding the baby, thereby relieving pressure on the kidneys.

Usually pregnant women are referred for further imaging studies when a routine ultrasound indicates there may be a problem, says Sharon M. Stein, M.B., Ch.B., associate professor of Radiology and Radiological Sciences, and Pediatrics.

Computed tomography (CT) is not used because of the need to protect the fetus from exposure to X-rays. Instead, remarkably detailed pictures can be obtained using ultrasound and magnetic resonance imaging (MRI), which have no known harmful effects.

During a weekly fetal therapy conference, Vanderbilt specialists in radiology, neonatology, surgery, urology, genetics and medical ethics review the images, and use them to guide decisions about the management of the pregnancy, including the timing of delivery.

The aim, says Stein, is to ensure “that everything is well orchestrated and planned for optimum care” once the baby is born.

Fetal magnetic resonance images with structures noted with arrows
A) Normal brain and bladder
B) Hydrocephalus—abnormal accumulation of fluid in the brain
C) Congenital diaphragmatic hernia—hole in the diaphragm that allows the liver and bowel (marked) to enter the chest cavity
D) Myelomeningocele—open neural tube defect (spina bifida)
Courtesy of Sharon M. Stein, M.B., Ch.B.