At the Silver Spring Office of Right-to-Life of Maryland, volunteer Nancy Wells works nearly full-time juggling requests to see a movie that is the latest weapon in the war against abortion.

"We just can't keep our hands on it, people are so interested in seeing it," said Wells. "It's booked through March 6."

Called "The Silent Scream," the movie shows a suction abortion of a 12-week-old fetus as portrayed on a sonogram, which consists of computer-reconstructed images of echoes from high frequency sound waves aimed at the uterus. Abortion opponents compare the 28-minute film to television footage of starving children in Ethiopia and say they hope that it will have the same impact on the hearts -- and votes -- of American viewers.

"A picture's worth a thousand words, and this says it all . . . any child that's sucking its thumb is more than a blob of tissue," said Kathleen C. Sweet, executive director of the group, which is hosting a screening for Maryland politicians Feb. 19 in Annapolis.

Abortion rights activists, while grudgingly impressed by the publicity "The Silent Scream" has generated, complain that it is inaccurate and misleading, particularly the narration describing the fetus' actions during the abortion. Some medical experts also have charged that the description of the fetus experiencing pain and trying to escape the abortion instruments is not based on medical fact.

"We wanted to bring abortion home as reality, much as pictures of the mushroom cloud at Hiroshima," explained the film's narrator, Dr. Bernard Nathanson, a cofounder of the National Abortion Rights Action League who later became a fervent opponent of the procedure he estimates he performed 5,000 times.

Sen. Gordon J. Humphrey (R-N.H.) at a press screening last month called "The Silent Scream" the "'Uncle Tom's Cabin' of the right-to-life movement."

Since the movie's release in early December, its producer, American Portrait Films in Anaheim, Calif., has sold more than 800 copies, at $100 in VHS or Beta videocassette and $400 in 16-millimeter. The three major networks and Cable News Network have all shown excerpts on their news programs.

President Reagan, who provided the inspiration for the film with his assertion last year that fetuses suffer "long and agonizing pain" during abortions, praised the movie last month in his remarks to more than 71,500 protesters in Washington for the annual March for Life on the 12th anniversary of the Supreme Court decision legalizing abortion.

"It's been said that if every member of Congress could see that film, they would move quickly to end the tragedy of abortion, and I pray that they will," said Reagan, who will receive a commemorative copy of the film at a White House screening Tuesday.

"We heard that on the radio, and we immediately sent a telegram saying it would be available," said Don Tanner of American Portrait Films. The firm is busy duplicating copies to be donated to the White House and sent to members of Congress and the Supreme Court.

The sonogram depicts the abortion procedure in grainy black-and-white footage of the fetus, first floating in the womb, then churning violently when the suction tube for the vacuum abortion is inserted in the uterus. The fetus is clearly visible before the abortion begins, but the picture becomes less clear once it is under way.

At the start of the procedure, Nathanson says in the accompanying narration, "we can see the child moving rather serenely in the uterus . . . the mouth is receiving the thumb of the child, the child again is moving quietly in its sanctuary."

Then, as the doctor inserts the suction tube, "We can see the tip moving back and forth as the abortionist seeks the child's body," Nathanson says. "Once again we see the child's mouth wide open in a silent scream . . . the silent scream of a child threatened imminently with extinction . . . . It is moving away, one can see it moving to the left side of the uterus in an attempt, a pathetic attempt, to escape the inexorable instruments which the abortionist is using to extinguish its life."

Watching the sonogram at an editing session, the doctor who performed the abortion "was so appalled at what he had done that he left the room momentarily, came back to finish the editing, but never again did another abortion," Nathanson tells viewers. Nathanson will not reveal the doctor's name.

Some medical experts have challenged Nathanson's description of the procedure. At 12 weeks, the fetus' nervous system lacks the synapses that would transmit neurological impulses, and therefore cannot experience pain, said Dr. Pasko Rakic, a professor of neuroanatomy at the Yale University School of Medicine and an expert in fetal development.

As for the description of the fetus attempting to "escape" from the suction tube, he said, "This is like saying a ping pong ball moves when you put it in a bowl of water and stir it with a pencil."

But Dr. Ronan O'Rahilly, a fetal development specialist at the University of California at Davis, said of the narration, "It's a rather highly emotional account, of course, but I would not want to say it's incorrect . . . . I certainly think that the fetus could feel some pain. The nervous system is quite well developed by then."

Whether it is accurate, the movie has abortion rights advocates on the defensive.

"I think we definitely have to get our acts together as far as helping the American public remember what illegal abortion was like," said Barbara Radford, executive director of the National Abortion Federation, which also is beginning to assemble a panel of medical experts to respond to the film.

"He's hawking it as truth," Radford said of Nathanson. "We know it isn't truth and we will get as many people as we can who are better scientists than he is to say it isn't truth."

And the Planned Parenthood Federation of America is considering making its own film featuring shots of unwanted, abandoned children in Latin American countries where abortion is illegal, and carefully saved pictures of women who suffered injuries or died as the result of illegal abortions in this country.

"It's the most powerful thing the right-to-life movement has put out to date," Dr. Allan Rosenfield, chairman of the Board of Planned Parenthood Federation of America, said of the movie. "We need to come up with something that focuses on the woman . . . . That part of the story, from the perspective of the woman, needs to get the same type of visibility 'The Silent Scream' has received."