When he was born about six weeks ago after a healthy, nine-month pregnancy, Nathaniel McQueen did everything he was supposed to do: He cried and cooed. He was robust and lively. But it quickly became apparent that something was seriously wrong. He could not keep any baby formula down.

The doctors diagnosed a bowel obstruction, which they said could be fixed with a relatively simple operation. His mother, Denise Robertson, expected him to make a routine recovery.

But when the pediatric surgeon opened the baby's abdomen the next morning, he found a deadly and rare medical condition that has banished the routine from Nathaniel's life forever. His body never developed a small intestine.

His only hope of survival--and it is a slim one--is to receive an intestine transplant, an operation that has been developed only in the last 10 years and now is performed fewer than 100 times a year. Until he grows large enough to withstand the surgery, Nathaniel will be sustained by intravenous food.

The birth defect apparently was the result of a mysterious accident that cut off the fetal blood flow to that developing organ around the third month of pregnancy, said Georgetown University Hospital neonatology chief K.N. Siva Subramanian. Whatever small-intestine tissue started to form stopped and then disappeared, he said.

"We're talking about a catastrophe," said Gregory Hoy, the Georgetown associate professor of surgery and pediatrics who discovered the birth defect in the operating room. "It was pretty depressing."

No one can survive without the small intestine, which extracts nutrients from food and conveys them to the bloodstream.

The only medical centers that attempt intestine transplants are in Miami, Nebraska and Pittsburgh, said Jorge Reyes, director of pediatric transplantation at Children's Hospital of Pittsburgh.

Robertson hopes her son will gain enough weight to become a transplant candidate in eight months to two years. Nathaniel will try to do that with a diet of liquid protein, fat, calories, vitamins and minerals that drips into his veins through a plastic tube. But nothing is simple for Nathaniel. Even the basic tube feeding has been complicated because his veins tend to collapse after they are used for a while.

It remains unclear whether Nathaniel will wait in a long-term facility or at his mother's apartment, with the help of visiting nurses.

But there is a limit to how long he can wait. Taking nutrition intravenously will eventually cause severe liver damage and could mean that he will need a new liver, a pancreas and even a stomach, doctors say.

Assuming that his liver holds up, Nathaniel also must overcome the risk of recurrent infections, bleeding episodes, blood clots and other complications, Subramanian said.

"I don't want my son to suffer any, but I want to make sure I'm giving the doctors a chance to do everything they can for him," said Robertson, 23, who lives in Southeast Washington. "It's just hard going up there, seeing him the way he is, not knowing if he's going to make it through this."

Many children are born with a defect known as severe short-bowel syndrome, but rarely do babies arrive with virtually no segment of the small intestine, a condition Subramanian calls total jejunal and ileal atresia.

So far, the bill at Georgetown has reached $50,000. Once Nathaniel is stable, it will cost up to $15,000 a month while he awaits surgery. The transplant could cost another $200,000. If everything is successful, the lifetime expenses of caring for Nathaniel could be enormous.

Nathaniel is covered by D.C. Chartered Health Plan, one of several health maintenance organizations that care for District Medicaid recipients. Company officials say they will pay for whatever he needs before and after admission to a transplant hospital.

"If he needs special services, such as transportation to the facility where he will have the transplant, we arrange that," said Carolyn Grandison, D.C. Chartered's utilization management director. "If he needs air transportation or whatever the physician feels is necessary, these things are all authorized."

The city would pay directly for transplant surgery and the baby's stay at a transplant center, said Donna Folkemer, the D.C. Medicaid program's chief of policy. She said her agency once before authorized a child for an intestine transplant, but he died before the surgery was attempted.

"Authorizing this is not going to be a problem," Folkemer said.

But some Medicaid and private health plans balk at the high cost of intestine transplants, Reyes said.

"It's really only in the last three years that we've been able to bend the insurance companies and the state Medicaid guidelines to include intestine transplantation as an accepted procedure," he said.

"More and more, the pediatric community are referring these patients. It would not be unusual five years ago for a case like this not even to be referred to a transplant center. The child would just die."

Robertson cares for her two other sons, 6-year-old Aaron and 1-year-old Bruce Jr., and subsists on welfare payments and help from the children's father.

She takes buses and subways for three hours round trip to see Nathaniel every other day. Her father, Carson Robertson, 50, of Winchester, spends even more time on the road. He drives four hours round trip to the hospital every other day.

The former truck driver, who lost a leg to diabetes this year and is on disability, is encouraged by Nathaniel's steady weight gain. As of Thursday, he tipped the scales at 6 pounds 7 ounces.

"If he takes after his grandfather," Carson Robertson said, "he's going to be a fighter."