DAMASCUS -- Bit by bit, the Assad regime is wiping out resistance in the western half of Syria. One of the last opposition holdouts near Damascus is Ghouta. While the area is just a few miles from the capital, conditions could not be more different.

There's a steady stream of patients at a state-run hospital in Damascus. We saw the victim of a mortar attack brought in for treatment. Dr. Ali Ghazi works in the emergency room, often treating civilians who have been caught in sniper attacks or explosions.

CBS News was in a hospital in Damascus CBS News

"It's affecting everything," Ghazi said. "It's a very big stress in the medical teams."

But he says, for the most part, the hospital in Damascus has what it needs.

It's a different story only a couple of miles away in the besieged suburb of Eastern Ghouta. There, the rebels are completely surrounded by Syrian government forces. Hundreds of thousands of civilians are trapped.

It's was impossible for us to cross the front line in government-held Damascus to rebel-held Ghouta -- so we reached a doctor there by phone.

"We are under siege," Dr. Sakhr said.

He said he's now operating underground since his hospital was bombed. We asked what's been the most difficult for him.

"My patients die and I cannot do anything to help," he said. "Sometimes when I don't have a medicine, when I don't have a ventilator, when I cannot evacuate the patients to ICU due to the continuous shelling and airstrikes. This is a very bad situation for me."

Again on Wednesday, no medical aid came through those humanitarian corridor, and Sakhr has little faith it will.

"They will not send doctors," he said. "They send rockets."