Jan. 24, 2012 -- Rachel Schoger of Caldwell, Idaho, had been trying to have a baby for two years and eight months -- a grueling wait interrupted by three positive pregnancy tests and three unexplained miscarriages.

After a fourth positive test, she went to her doctor for answers. The news was devastating. "It's ectopic," Schoger recalled the doctor saying after a hormone test and an ultrasound. "I was so upset because we'd been trying for so long."

An ectopic pregnancy is one that occurs outside the womb, usually in one of the fallopian tubes. Because the fetus cannot survive and the mom could suffer life-threatening internal bleeding, ectopic pregnancies, which may account for as many as one in 40 pregnancies, are terminated at the earliest sign. Schoger's doctor recommended using methotrexate -- a chemotherapy drug that would save her and her fallopian tube, and kill the doomed fetus.

"I have three other kids at home," said Schoger, who was 29 at the time. "I couldn't take the risk."

Schoger was given two high-dose shots of methotrexate in the fatty tissue above her hips to abort her pregnancy, which was four weeks and five days along. Days later, she started having nightmares about a baby crying out in pain inside her. So when she returned to the doctor for a second round of shots a week later, she insisted on a follow-up ultrasound for peace of mind.

"I needed it to calm me down, to know I was doing the right thing," she said.

As the ultrasound technician rolled the probe over Schoger's pelvis, her jaw suddenly dropped. Schoger was still pregnant, and the fetus was in her uterus where it belonged.

Despite advances in medical imaging, roughly 40 percent of pregnancies diagnosed as ectopic are later revealed to be normal, intrauterine pregnancies, according to a 2002 study published in the journal Obstetrics and Gynecology.

And for women treated with methotrexate, the lapse can be catastrophic.

"Those fetuses that are misdiagnosed as ectopic and were actually in the uterus receive high doses of a teratogenic drug during early stage of development, and that causes malformations," said Dr. Yaron Finkelstein, an emergency physician at Sick Kids Hospital and associate professor of pharmacology and toxicology at the University of Toronto. "This is a serious problem, and one that's probably overlooked."

Finkelstein and colleagues described the effects of methotrexate on eight misdiagnosed ectopic pregnancies in a study published in the January issue of the American Journal of Obstetrics and Gynecology. Three of the pregnancies ended in miscarriage within two weeks after the injection; three were terminated surgically after the mothers were warned of the potential birth defects; and the remaining two were born -- one stillborn at 30 weeks, the other born with severe malformations at 37 weeks.

"We're not sure how many more cases like this are out there," said Finkelstein, adding that doctors have no incentive to report misdiagnosed ectopic pregnancies. "We wanted to highlight this phenomenon and bring it to awareness."

Schoger, who was not part of the study, decided to follow through on her pregnancy despite the risks. And in January 2006, she gave birth to Seraphine.

"She was beautiful," said Schoger. "She had 10 fingers, 10 toes. She just looked so good."

But relief quickly gave way to panic as nurses struggled to take Seraphine's temperature. The baby, who, against all odds, appeared to be normal, had no rectum. She also lacked a vagina and a uterus, and has a malformed spinal cord. These are all birth defects Schoger is convinced stemmed from methotrexate exposure in the womb. She filed a lawsuit against the doctor and a jury trial is set for January 2013.

Finkelstein stressed that diagnosing an ectopic pregnancy is tricky, and that failing to diagnose a pregnancy as ectopic can have a dire outcome, too. "If the woman is stable, one option is to admit her for 24 hours or send her home and ask her to come back for another [human chorionic gonadotropin] test and ultrasound." Another option is to come up with a safer drug -- "one that terminates ectopic pregnancies but is not teratogenic to normal, intrauterine pregnancies."

Misdiagnosed Ectopic: Heartache for Moms

After multiple surgeries, Seraphine is a surprisingly healthy 5-year-old, Schoger said. But her bulging and tethered spinal cord might one day limit her ability to walk, and she'll never be able to have children.

Schoger, now 35, said she spends hours on her computer scouring message boards. She hopes to catch women diagnosed with ectopic pregnancies and urge them to get a second opinion before they take methotrexate. She has yet to find one in time, though she said she has connected with nearly 200 other women with similar experiences. Most of them had already miscarried, though some aborted and a few others were raising babies with birth defects until they died from complications.

In 2008, Schoger was diagnosed with a true ectopic pregnancy -- a diagnosis she said saved her life.

"If you're too early, you have a baby that needlessly lost its life. If you're too late, the woman could rupture and die," she said. "They really need to focus in on the critical window."