A lack of sterile facilities and antibiotics mean amputees may struggle to survive
Doctors treating seriously injured survivors of last week's 7.0-magnitude earthquake in Haiti say they are having to perform amputations on hundreds of people whose limbs have been crushed or become badly infected.
They say the total could eventually run into the thousands as more badly wounded survivors are rescued and those from isolated areas arrive at the emergency medical centres which have been set up in the capital, Port-au-Prince.
"There are so many people to treat and so many people needing amputations," said Dr Jacques Lorblanches, a surgeon who is part of a team sent by Medecins du Monde (MDM). "We expect to perform around 400 amputations over the coming days."
The story is the same elsewhere in the city, with other medical organisations reporting that the majority of operations are ending with amputations.
"There is gangrene everywhere and you amputate on the go," said Hans Van Dillen of Medecins Sans Frontieres (MSF).
"You conduct radical surgery. There's nothing more you can do."
In the immediate aftermath of an earthquake, it may be necessary for doctors to carry out a field amputation to extricate a victim from the rubble of a collapsed building or to remove a hopelessly mangled limb.
The procedure is considered one of last resort, however, and the vast majority of amputations are carried out later in medical facilities after all attempts to spare a severely injured limb have failed, and to prevent loss of blood and infection.
But in areas where destruction is severe, infrastructure is poor, or there is a widespread lack of available medical care - such as Haiti - even minor injuries to limbs can become life-threatening within days and require amputations.
"You always have a big wave of amputations from around the third day, for about a week afterwards. Then the demand for such surgery becomes less intense," Susan Wright, the director of Medecins du Monde UK, told the BBC.
"There is a hope that it will shift in the coming week."
Ms Wright says the longer a person is trapped under rubble or does not receive treatment for their injuries, the more likely it is that they will suffer from crush syndrome - a serious condition resulting from damage to large areas of muscle - or shock, blood loss, dehydration, hypothermia and a weakened immune system.
Doctors frequently amputate infected limbs to prevent the onset of sepsis
All of these will reduce the body's ability to cope with injuries to limbs and to maintain the blood supply. If starved of blood and oxygen, cells and tissues will die, become more vulnerable to infection and may require amputation.
As time passes, the risk of developing a serious infection in a limb directly from even minor injuries such as cuts and grazes also becomes more acute.
Without antibiotics, a person can develop gangrene or blood poisoning, which if untreated can eventually lead to sepsis, the body's inflammatory response to an infection, and death.
Doctors frequently amputate seriously infected limbs in a last-ditch effort to prevent the onset of sepsis - an all too frequent occurrence in Haiti at present.
"We have had to perform dozens of amputations, including many double amputations. The problem is people haven't gotten medical care soon enough, so wounds are very infected. Some of them are coming in with bones just sticking out from the rest of the leg," said Dr Diana Lardy of the International Medical Corps.
'Full of larvae'
Under normal circumstances, a patient undergoing an amputation would be anaesthetised, and the bone would be sawn through with an oscillating saw. The procedure would be carried out in a sterile theatre to prevent infection.
But surgeons in Haiti say they have had to carry out dozens of amputations in unsterile conditions, without electricity or even the correct equipment.
Dr Lorblanches, who worked in Iran after a massive earthquake struck the city of Bam in late 2003, said Haiti was the worst disaster he had ever seen.
"I have never seen anything like this - infected wounds full of larvae," he said.
"I did my first amputation with three forceps, five scissors and a scalpel, without water, and just a flashlight to illuminate the injury."
Cuban medic Dr Olga Maria Delgado said she and her colleagues had performed more than 40 amputations on a tiled counter inside a tin-roofed building within the grounds of the Renaissance Hospital in Port-au-Prince. Sterility was less of an issue than normal, because most of the wounds were already infected, she added.
"There is an avalanche of patients and almost all of them come in with traumatic injuries," Dr Delgado said.
Ms Wright said MDM's clinics were also being inundated as more people were rescued and others found out where treatment was available, with more than a hundred people waiting for surgery.
"Every time we look out of the window, there's a queue around the block," she said.
But even once they have lost a limb, the lack of sterile equipment and antibiotics mean the new amputees face a struggle to stay alive.