Dr. Julie Kanter, a hematologist at the University of Alabama at Birmingham and director of the university’s adult sickle cell clinic, reviewed the medical records of 5,347 children in 28 medical centers, large and small, including academic and minor medical centers. Depending on the center, only 30 to 75 percent of the children had received the recommended screening. On average, only 48.4 percent received the ultrasound. The prices were independent of the size of the medical center or the academic affiliation.

“The rate is terrible, actually worse than we thought,” said Dr. Canter.

The researchers interviewed parents and caregivers and found that some doctors did not inform parents about the checkups. Some parents, even when told, did not understand its critical meaning. (Dr. Kanter would like to rename the Stroke Screen test to Transcranial Doppler Ultrasound to make its purpose clearer.) Some medical centers with special sickle cell clinics have not been able to consistently track families who missed appointments.

There were also logistical obstacles. Sometimes medical centers that offered the test were far from the homes of children with the disease. Some parents struggled to take time off work to take their children to test. And the centers that ran the tests were sometimes not part of a family’s insurance network.

Ultrasound screens aren’t the only medical care that children with sickle cells receive inconsistently. Hydroxyurea, a low-cost generic drug that has been around since the 1980s, may reduce the risk of irreversible damage to organs and the brain. But unfortunately it is not being used enough. The National Institutes of Health guidelines published in 2014 state that all children and adolescents should attend, as well as adults with three or more pain crises per year or other serious complications.

A recent survey of 2,200 sickle cell patients in eight locations, funded by the National Institutes of Health, found that only 48 percent of patients were taking hydroxyurea regularly. Interviews with doctors who had not prescribed the drug revealed that many were unfamiliar with the drug, while others feared that hydroxyurea, which is also a cancer treatment in much higher doses, could cause cancer, although at the lower level of sickle cell disease it could cause cancer. Dose is not the case.

Another recent study of Medicaid patients in North Carolina found that only 32 percent of the 2,790 Medicaid patients with sickle cells even had a prescription for hydroxyurea, and only 31 percent of those patients were taking the drug regularly.