Hidden in a rebel-held location in Syria's rural north, the hospital is struggling to treat the most confronting of injuries, including those to a five-year-old boy. Phil Sands met Sultan Ibn Subhi at the hospital
Secret Syrian field hospital where a boy called Sultan defied a line on a wall
It had been a month and a half since Sultan, 5, was wounded after an aircraft bombed the building he was in. His mother and six-year-old sister were killed in the attack.
Sultan survived but lost his left leg and most of the soft tissue around his groin. His father, Nouri ibn Subhi, was out at the time and rushed home to find his family torn apart.
"I can only thank God that my son is alive but we are alone now," Mr ibn Subhi said.
Sultan gestured and his father scooped him out of the wheelchair, sitting him in his lap and fixing in place the nappy that had come unfastened. Sultan smiled.
"We had done nothing wrong and the regime did this. It's not acceptable that it will stay in power," Mr ibn Subhi said.
He spoke softly, cigarette in hand, still in shock at the disaster that had befallen those he loves.
Sultan is being treated at the hospital, run by the Arab Medical Union, in a secret location in Syria's rural north.
The hospital's whereabouts are not advertised for fear that regime forces will try to destroy it as they have other medical centres outside of their control.
Although deep in rebel territory, it is an easy flight for the MiG jets that killed Sultan's mother and sister, and that still menace the area.
The hospital is one of the best-equipped and staffed units in rebel-held areas of Syria.
About 10 volunteer doctors from Egypt work with little pause their during stints in the country, assisted by Syrian nurses and support staff.
They say they have an average of 50 patients each day, sometimes too many to deal with. They perform about 200 operations a month in two small, basic operating theatres.
There is a triage area where the grim equations are laid bare.
Drawn on the wall is a line that separates those who have a chance of living from those who do not.
Above their heads, written in black marker pen, it says simply: "Expected to die".
To the left of the line are written time codes, indicating those who need treatment immediately and who ought to be able to survive for an hour or two longer.
The hospital also has a simple intensive-care unit, an X-ray machine and a modest laboratory for tests. It is small, not much more than a dozen rooms and outbuildings, but it is clean and well organised, a professionally administered hospital in a war zone.
As one of the better medical centres in northern Syria, it takes cases referred to it by other, more rudimentary field hospitals in the surrounding area, particularly those closer to the front lines.
"Many casualties come in with trauma to their limbs and we have to amputate," said Hassan Shatori, an Egyptian neurosurgeon.
In his normal life Dr Shatori works at Suez Canal University but for the past month he has been in Syria, using his skills to help plug a huge gap in the provision of medical services. There are not many brain surgeons here - a specialisation much in demand.
Dr Shatori reeled off some statistics. In the past month he had done 30 operations on damaged brains and spines: one patient died on the operating table; at least 10 of those who survived will be disabled for the rest of their lives, some bedridden, others unable to walk, some unable to talk.
"We receive a lot of people with nerve injuries, bleeding, blasts to the head, many also have gunshots to the spine or spinal damage from explosions," he said. "Most of them recover somewhat, but not completely."
Struggling to cope with the daily flood of emergency cases, senior doctors also expressed concern about their ability to sustain the hospital over the long term.
None of them believe the conflict is near its end, or that demand for life-saving health care is going to go away.
"None of us expects this war to end soon, it will take months, maybe years," Dr Shatori said. "The people here are really poor, there is no healthcare system even for regular patients with their everyday needs, they have almost no service."
When battlefield casualties and wounded civilians are not being brought in, the doctors see ordinary patients with more banal problems: victims of car crashes, falls off ladders, and other domestic accidents.
There is also a shortage of follow-up care for patients who do survive. Many of them will need medical support for the rest of their lives. Amidst the chaos of war there is little prospect of them getting that.
Doctors were not sure that Sultan would survive. Close medical attention and the boy's stubborn will to live had seen him through the immediate dangers, hospital staff said.
"Sultan lost his leg and his genitalia," Dr Shatori said. "He is really in need of proper rehabilitation and maybe one day he could have an artificial limb or something."
For now, Sultan's father stays with him, pushing him around the hospital's courtyard in a wheelchair. They sit outside with other recovering patients.
One of them, wearing tracksuit bottoms and a vest, had a torso marked with small red shrapnel scars, and his arm and shoulder bandaged up. Two weeks ago he had been wounded in Aleppo city, caught in the street when there was an explosion nearby. His friend, waiting with him in the hospital, was unhurt.
"I don't know who fired the shell, all I see is that the city is being destroyed, our homes are being destroyed," the uninjured man said. Neither wanted to give their names.
"It was okay before the war, we could live at least, now it is impossible, now we have nowhere to go," he said.
He blamed international politics for the collapse of his country. "Everyone is working against the Syrian people, everyone has an agenda and no one is helping us," he said. "Syrians are alone."
Sultan's father demurred, saying the blame for the carnage lay with the regime, which had chosen war not peace in the face of a popular uprising. The only hope for a better future was to overthrow president Bashar Al Assad, he said.
Sitting with his wounded son, he said: "We are all fighters now".