Sue DiMatteo and her husband Pat, of Wallingford, Connecticut, began trying to get pregnant in May 2004, not long after their wedding.
The very next month, Sue, then 33, was pregnant. Everything was fine until her 20th week, when a technician performing an ultrasound suddenly left the room and returned with a doctor. Sue was told that she had no amniotic fluid. Her water had broken, and the obstetrician held out little hope that the baby would survive. Rather than terminate the pregnancy, Sue chose to be induced. “My daughter passed away during labor,” she says. “It was an experience I don’t wish on my worst enemy.”
Without answers about what caused the loss of the DiMatteos’ baby, Sue’s doctor referred her to specialist Beth W. Rackow, M.D., assistant professor in reproductive endocrinology and infertility at Yale University School of Medicine. Dr. Rackow scheduled a sonohysterogram, a type of ultrasound that uses saline, sent through a catheter, to examine the uterine cavity. The test showed what Sue’s routine pregnancy ultrasound hadn’t: that Sue had a septate uterus, in which tissue that’s normally absorbed by the body during fetal development remained, separating her uterus in two. Because the uterine cavity was so much smaller and the tissue didn’t have a good blood supply, the DiMatteos’ baby couldn’t grow. “I’d never heard of a septate uterus until it happened to me,” says Sue.
Luckily, the defect can be surgically corrected by removing the extra tissue from the uterus. Sue had the surgery in early 2005, and in February 2007 she gave birth to healthy twins, a boy and a girl.
An Unlikely Problem
Like Sue, most women are unaware that different kinds of uteruses exist—and for good reason: Uterine abnormalities are rare, affecting only about 3 to 4 percent of all women and up to 10 percent of women who have lost three or more consecutive pregnancies. No one knows what causes them. They don’t appear to be hereditary, but if you have one, you were born with it, and there’s nothing you could have done to prevent it. “They all occur during fetal development,” says Dr. Rackow.
Technically, an abnormal uterus is the result of defects of the Mullerian ducts, two tubes of tissue extending from each side of the pelvis that, if development continues normally, will eventually fuse to form the uterus, cervix, upper vagina, and fallopian tubes. If a woman is carrying a girl, by the 10th week of her pregnancy those tubes of tissue in her baby’s body will normally fuse, forming a cylindrical structure that will become her daughter’s uterus. Over the next few weeks of the baby’s development, the top of the cylinder widens. Eventually, the dividing tissue (or septum) degenerates, forming the uterine cavity.
When all those steps play out like they should, the result is a normal uterus, shaped like an upside-down pear. But when the Mullerian ducts don’t form, don’t fuse as they should, or don’t dissolve, the result is an abnormality. The uterus may be divided down the middle by tissue; it could develop on one side only; or it might become a double uterus with two cervixes. A woman could end up with a T-shaped uterine cavity, or her uterus could separate into two horn-shaped structures. In extremely rare cases, she can be born with no uterus at all.
Good Odds
The reassuring news is that most uterine abnormalities don’t affect a woman’s chances of conceiving. They can, though, make it harder for her to carry a pregnancy for the full 40 weeks. Approximately one-third of women with a uterine defect suffer miscarriages, compared to 15 percent of all pregnancies. Approximately one-quarter of women with a uterine defect have preterm deliveries, in which a baby is born before 37 weeks’ gestation, as compared to 10 to 12.5 percent in other women. Nonetheless, more than half of women with an abnormality will be able to bring home healthy babies.
An uncommon uterus isn’t likely to be the first thing that comes to your gynecologist’s mind as a reason for a miscarriage. Doctors don’t routinely screen for these anatomic problems, mostly because “a lot of women with these abnormalities are totally normal otherwise,” says Dr. Rackow. “They don’t have trouble conceiving, and they don’t have symptoms. As a result, they often go completely undiagnosed.” But if you’ve lost three pregnancies in a row and your doctor can’t find an obvious cause, your next stop should be screening, probably by a reproductive endocrinologist since these specialists are more likely to see women with this problem, says John K. Park, M.D., a reproductive endocrinologist at Carolina Conceptions, in Raleigh, North Carolina. “We can evaluate not only the overall shape of the uterus but the shape of the cavity of the uterus. That’s important in coming to a correct diagnosis.”
Sometimes there are symptoms that can tip you off to a uterine problem. If you don’t menstruate, or you’ve got chronic pelvic or back pain, for instance, it may be due to an obstruction in the uterus that’s causing menstrual blood to build up in the pelvis. Women with a uterine abnormality are more likely to have endometriosis, according to a 2007 paper by Dr. Rackow that appeared in the journal Obstetrics & Gynecology.
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