Patients rest in a courtyard in the General Hospital downtown of Port-au-Prince. (United Nations photo)In most of the world, if you're seriously injured in an accident, you will probably get enough care within a reasonable period of time. Most treatable injuries won't threaten your life.

But go to a country where medical supplies are in critically short supply at the best of times, and you could be in serious trouble if you're injured.

In Haiti, access to health care has been difficult for large parts of the population. The country has relied on foreign aid agencies to help deliver basic health services for decades. The 7.0 magnitude earthquake that hit on Jan. 12, 2010, meant even the most basic of health care was inaccessible to the vast majority of people.

Medecins sans Frontieres, known also by its English name Doctors Without Borders, reported that their four hospitals in the Port-au-Prince area were severely damaged and that people who suffered treatable injuries would die without a massive infusion of medical supplies.

The problem? Gangrene.

What is gangrene?

It's the decay and death of tissue caused by an interruption of the flow of blood to a part of the body. Gangrene usually affects the extremities — toes, feet, legs, fingers or hands, although it can also occur in organs and muscles.

Gangrene develops when the supply of blood is cut off to part of the body. Without the nutrients and oxygen that blood delivers, cells cannot survive. The body's ability to fight off infection is compromised.

People with diabetes or atherosclerosis are at higher risk than the general population of developing gangrene because their conditions damage blood vessels and impede blood flow.

Traumatic injuries can put you at risk as well - if you don't have access to treatment.

Are there different types of gangrene?

The five main types are:

• Dry gangrene, which is characterized by dry and shriveled skin ranging in colour from brown to purplish-blue to black. The condition normally develops slowly, most often in people with atherosclerosis.
• Wet gangrene, which is accompanied by a bacterial infection. The affected area will be swollen and blistered and look wet. It can develop after a severe burn, frostbite or an injury. Wet gangrene needs to be treated immediately because it can spread quickly and threaten your life.
• Gas gangrene, which normally affects deep muscle tissue. It is usually caused by an infection by the bacteria Clostridium perfringens, which develops in an injury or surgical wound that's depleted of blood supply. Your skin will look normal in the early stages, but as the condition progresses, the skin colour will change. The infection releases toxins and can become life-threatening if untreated.
• Internal gangrene occurs when blood flow to one of the organs is blocked. It causes fever and severe pain and can be fatal if untreated.
• Fournier's gangrene affects the genital organs, mainly in men. It is uncommon. It usually develops after an infection to the genitals or urinary tract. It causes pain, tenderness, redness and swelling.

How is gangrene treated?

Courtney Shores, member of the MA1 Disaster Medical Assistance Team, holds a child whose leg was amputated at a field hospital in Port-au-Prince. (Gerald Herbert/Associated Press)If gangrene has set in, the affected tissue cannot be saved. It is dead and must be removed. If it's caught early enough, the affected area could be quite limited.

There are steps that can be taken to prevent gangrene from spreading. They include:

• Surgery. The removal of dead tissue will allow healthy tissue to heal. Surgery may also allow damaged or diseased blood vessels to be repaired, increasing the flow of blood to the affected area. Skin grafts are possible for treating large areas that have been damaged - but only if adequate blood supply has been restored to the area.
• Antibiotics. Drugs can be administered intravenously to treat gangrene that's become infected - but only when diagnosed and treated quickly.
• Amputation. Surgically removing fingers, toes or limbs is unavoidable if the gangrene has spread to the point that your life is in danger. If cleaning away dead tissue and administering antibiotics cannot control the infection, amputation of the affected body part becomes necessary to prevent further deterioration.

Wet gangrene is very aggressive and spreads rapidly. You will die if you do not receive prompt treatment.

This was one of the major problems in the days after the quake struck Haiti. There were hundreds of thousands of injured people and a severe shortage of medical facilities and supplies.

"I have never seen anything like this," Loris de Filippi, emergency co-ordinator for MSF's Choscal Hospital in the Cité Soleil section of Port-au-Prince, said on Jan. 20, 2010. "We were forced to buy a saw in the market to continue amputations. We are running against time here."

The organization has estimated that as many as 200,000 people will have undergone amputations because the crushing injuries they suffered in the earthquake could not be treated in time. The vast majority of those amputations wouldn't be necessary if well-equipped, fully-staffed hospitals were available.

For the most part, medical care has been dispensed from hastily constructed field hospitals.