A pregnant Ghanaian teacher and her four-year-old son are on a flight back to Ghana after spending more than a week confined to a windowless room at Washington Dulles International Airport, following a federal judge's order on Friday that ended their attempt to seek asylum in the United States.

Anabella Gyasi, 38, a teacher from Ghana, arrived in the United States on a tourist visa with her son, who was born with physical abnormalities affecting his fingers on both hands.

She had secured an appointment at Akron Children's Hospital in Ohio for her son to be evaluated for possible surgery, after being told two years earlier that he was too young for the procedure. Their tourist visas were valid until 2028.

However, instead of boarding her connecting flight to Ohio, Gyasi and her son were taken into custody by US Customs and Border Protection officers and locked in a holding room at the airport.

According to the American Civil Liberties Union of Virginia, which represented her, they were denied adequate food and medical care during their detention.

CNN reports that the detention began after Gyasi, during customs questioning, disclosed her fear of returning to Ghana based on the persecution she and her son faced because of his disability. According to a government transcript of her statement to an immigration officer, Gyasi told authorities that her mother, a traditional priest, had urged her to kill her son when she saw his disability as a baby.

Her attorneys argued that she was being punished for her honesty.

"If she did not disclose the fear that she was having about persecution in her country, she could have still enter on the tourist visas," said Eden Heilman, Gyasi's lead attorney with the ACLU of Virginia. "Unfortunately, because she was honest and shared her concerns, that's what funneled her into this separate asylum-seeker category."

Crucially, a CBP officer wrote that when authorities examined Gyasi's phone, they found a history of searches on the topic of claiming asylum. In a sworn statement to immigration authorities, Gyasi admitted she had been researching the possibility of claiming asylum for the past two years and had also considered asylum in Canada and Australia.

The government argued that her tourist visa was not valid because Gyasi "admitted under oath... her intent was not to leave the United States to return to Ghana."

Gyasi received a credible fear interview from an asylum officer, which resulted in a negative determination. An immigration judge subsequently denied her asylum request on Wednesday, making it virtually impossible for her and her son to remain in the country.

During her detention, Gyasi, who is four and a half months pregnant, was hospitalised twice, initially for lightheadedness and then for vaginal bleeding, which doctors attributed to high stress and high blood pressure. Medical staff expressed concern that she was not eating enough and fed her, even giving her food to take back with her, her attorneys alleged.

Gyasi told officials that she and her son were not familiar with the food in the United States and that it was making her sick and weak. Her son spent much of the day crying because of his hunger pains, the court filing stated. When she requested to purchase food, CBP officers allegedly denied her request, saying she could only access the food they gave her.

On Friday, US District Judge Leonie Brinkema ordered that Gyasi and her son must be released from the hold room at the airport before the end of the day.

"She cannot spend tonight at Dulles. One way or another, we're going to get her out," Brinkema said at a hearing in Alexandria, Virginia.

The judge gave the Trump administration a 2pm deadline to arrange a nonstop flight back to Ghana. Hours later, the ACLU confirmed that Gyasi and her son were on a flight returning to their home country.

"We were very pleased that the judge recognised one fundamental principle, which is that human beings should not be detained under the conditions our client was being detained at Dulles Airport in a windowless room without access to appropriate food or medical care," said Mary Bauer, executive director of the ACLU of Virginia.

The Department of Homeland Security denied the allegations of mistreatment, stating that "everyone in CBP custody, including this individual, has access to appropriate care, including medical evaluation by a doctor, medication, and food."

Gyasi's attorneys noted that CBP agents seemed focused on the fact that she was pregnant when they first took her into custody.

They believe the scrutiny was in response to President Donald Trump's push to end birthright citizenship. An Immigration and Customs Enforcement policy dating back to the Obama administration stating that pregnant women should not be detained unless there are extraordinary circumstances was rescinded a year ago.

Although Gyasi's hopes that she and her son could remain in the United States were dashed, the judge insisted on one thing: no more nights in a windowless room at Dulles.