(RNS) Citing “confusion among the faithful” after a controversial abortion at a Catholic hospital in Phoenix, Catholic bishops issued a statement explaining when it is morally permissible to terminate a pregnancy.

In May, Bishop Thomas Olmsted of Phoenix declared Sister Margaret McBride, an ethicist at St. Joseph’s Hospital and Medical Center, automatically excommunicated because she condoned an abortion to save a woman’s life.

The case drew widespread media coverage and disagreement from some Catholics, who argued that abortions are permitted under church rules in such cases. Doctors determined that the gravely ill woman, a mother of four, would have died of heart failure if she continued the pregnancy.

While not explicitly supporting Olmsted, the U.S. bishops’ doctrine committee offered an analysis on Wednesday (June 23) that appears to sanction his decision.

It is sometimes permissible to perform a medical procedure on a seriously ill pregnant woman that has a secondary effect of killing the unborn child, the bishops said, offering a hysterectomy as an example. Such a procedure would be an “indirect” abortion, the bishops said.

But surgery that targets the life of the unborn child — even to protect the health of the woman — is a “direct” abortion, and forbidden, the bishops said.

“As the church has said many times, direct abortion is never permissible because a good end cannot justify an evil means,” the bishops said.