An Illinois woman is suing her doctor for "wrongful pregnancy,” claiming a botched tubal ligation led to the birth of a daughter with sickle cell disease.

Cynthia Williams, a 40-year-old mother of three, only had one ovary and believed she couldn't get pregnant because the tube tethering it to her womb had been tied –- or so she thought.

“I was livid,” Williams said, recalling the “impossible” blue line on the pregnancy test, quickly confirmed by the flutter of a heartbeat on a sonogram. “I just lost it.”

Williams was 12 years old when she lost her right ovary to a cyst. On the same day, she discovered that she carried the sickle cell trait -– a genetic abnormality that could cause a dangerous blood disorder in her kids.

The man Williams later married found out that he, too, carried the trait after the couple’s second son was born with sickle cell disease.

“That’s when we decided not to have more children,” said Williams, who four years later became pregnant while using the rhythm method of birth control. There was a 25 percent chance that the baby would have sickle cell disease, so the Williams’ were relieved when she was born a carrier instead.

Williams started taking the birth control pill, but high blood pressure pushed her to find a more permanent option.

“At that point, I just wanted to get my tubes tied,” Williams said. She had the sterilization surgery in December 2008. Six months later, she was staring at the sonogram in disbelief.

Her fourth child, Kennadi, was born in February 2010 with sickle cell disease.

Learn more about sickle cell disease.

Now, Williams and her husband, Kenneth, are suing Dr. Byron Rosner of Reproductive Health Associates for “wrongful pregnancy,” claiming that he “failed to perform an adequate or appropriate tubal ligation,” resulting in an unplanned pregnancy and the birth of a sick child, according to the lawsuit.

Without a right ovary, Williams only needed her left Fallopian tube tied. But Rosner "tied," "excised" and "cauterized" Williams' right tube, according medical records obtained by ABCNews.com.

Williams’ left tube was intact and “normal in appearance” at the time of Kennadi’s birth, according to medical records from her C-section.

Williams is seeking damages for “personal injury to her, emotional distress, and for lost wages” as well as “the extraordinary expenses” she expects to incur raising Kennadi, according to court documents.

“I love Kennadi with all my heart, and that’s the honest-to-God truth,” said Williams. “But it’s been a life change for everybody –- my whole family.”

The whole family helped raise Kennadi, since Williams went into congestive heart failure shortly after the caesarean delivery.

“This is right after I have a baby that I still can’t believe I had,” she said, recalling her two-week stay in intensive care and her nine-month leave of absence from work. “I couldn’t be with my baby because I was too sick.”

Williams recovered, but Kennadi, now 4, faces a lifetime of health problems. Sickle cell disease makes her normally round and squishy red blood cells C-shaped and hard. Instead of flowing smoothly through her blood vessels, her misshaped cells become stuck, causing pain and raising the risk of infections and stroke.

Though tubal ligation is considered a “permanent method of birth control,” as many as 37 per 1,000 women become pregnant within 10 years after the procedure, according to the American College of Obstetrics and Gynecology. As a result, Williams struggled to find a lawyer that was willing to take her case.

“Having a baby after a sterilization procedure is something that happens,” said Williams’ attorney, Beverly Spearman, who initially rejected the case but reconsidered when she learned that one of Williams’ ovaries was missing. “When I found out more about the whole story, I said, ‘OK, let’s move forward. Let’s see where this goes.'"

Spearman soon discovered that the wrongful pregnancy suit, filed in November 2010, was the first of its kind in Illinois. Rosner’s attorney moved to dismiss the suit, arguing that Illinois law does not allow parents to recover costs associated with raising a child born with a genetic defect after an unsuccessful sterilization procedure. But an appellate court ruled February 26, 2014, that the case could move forward.

Rosner’s attorney, Todd Stalmack, said that he and his client are analyzing their options.

“We respectfully disagree with [the appellate court’s] decision,” Stalmack told ABCNews.com, raising the possibility of an appeal to the Supreme Court of Illinois.

Rosner maintains that he “complied with the standard of care” in performing Williams’ tubal ligation, according to Stalmack.

Williams, now 44, said she’s “tired all the time” raising her rambunctious and medically-needy 4-year-old.

“Everybody’s had to pitch in,” said Williams, whose other children are 25, 21 and 17. “It’s been hard to wrap my mind around having this child when my other children are grown.”

“It’s not fair,” she added. “She is the absolute love of my life, but it’s hard. Sometimes people think I’m her grandmother.”