Aforeign body (FB) is any object originating outside the body of anorganism. In machinery, it can mean any unwanted intruding object.

Foreign body
Anendoscopy image of the stomach, showing a foreign body in the form of atoothbrush.
Specialty	Emergency medicine

Most references to foreign bodies involve propulsion through naturalorifices into hollow organs.

Foreign bodies can be inert or irritating. If they irritate they will causeinflammation andscarring. They can bringinfection into the body or acquire infectious agents and protect them from the body'simmune defenses. They can obstruct passageways either by their size or by the scarring they cause. Some can betoxic or generate toxic chemicals from reactions with chemicals produced by the body, as is the case with many examples of ingested metal objects.

With sufficient force (as in firing ofbullets), a foreign body can become lodged into nearly any tissue.

One of the most common locations for a foreign body is thealimentary tract.

It is possible for foreign bodies to enter the tract from the mouth orrectum.

Both children and adults experience problems caused by foreign objects becoming lodged within their bodies. Young children, in particular, are naturally curious and may intentionally put shiny objects, such as coins or button batteries, into their mouths. They also like to insert objects into theirear canals andnostrils.^[1] The severity of a foreign body can range from unconcerning to a life-threatening emergency. For example, a coin causes local pressure on the tissue but generally is not a medical emergency to remove. Abutton battery, which can be a very similar size to a coin, generateshydroxide ions at theanode and causes achemical burn in two hours.^[2] An ingested button battery that is stuck in theesophagus is a medical emergency. In 2009, Avolio Luigi and Martucciello Giuseppe showed that although ingested nonmagnetic foreign bodies are likely to be passed spontaneously without consequence, ingested magnets (magnetic toys) may attract each other through children'sintestinal walls and cause severe damage, such as pressurenecrosis,perforation, intestinalfistulas,volvulus, and obstruction.^[3]

•  
  A coin seen on AP CXR in the esophagus
•  
  A coin seen on lateral CXR in the esophagus
•  
  AP X ray showing a 9mmbattery in the intestines
•  
  Lateral X ray showing a 9mm battery in the intestines
•  
  Multiplebutton batteries in the stomach
•  
  Button battery in the stomach

Sometimes foreign bodies can pass spontaneously through the gastrointestinal tract and perforate or penetrate the wall of stomach andduodenum and migrate into thepancreas. Thelaparoscopic approach beforeopen surgery could be performed safely for the removal of foreign bodies embedded in the pancreas.^[4]

It is possible for a foreign body to enter the airways and causechoking.^[5] A choking case can require the fast usage of basicanti-choking techniques to clear the airway.

In one study,peanuts were the most common obstruction.^[6] In addition to peanuts, hot dogs, grapes, and latex balloons are also serious choking hazards in children that can result in death. A latex balloon will conform to the shape of the trachea, blocking the airway and making it difficult to expel with basicanti-choking techniques.^[7]

Airborne particles can lodge in the eyes of people at any age. These foreign bodies often result inallergies which are either temporary or even turn into a chronic allergy. This is especially evident in the case ofdust particles.

It is also possible for larger objects to lodge in the eye. The most common cause of intraocular foreign bodies ishammering.^[8] Corneal foreign bodies are often encountered due to occupational exposure and can be prevented by instituting safety eye-wear at work place.^[9]

Foreign bodies in the eye affect about 2 per 1,000 people per year.^[10]

Splinters are common foreign bodies in skin.Staphylococcus aureus infection often causesboils to form around them.^[11]

Tetanus prophylaxis may be appropriate.^[12]

Foreign bodies in theperitoneum can includeretained surgical instruments afterabdominal surgery. Rarely, anintrauterine device can perforate the uterine wall and enter the peritoneum.

Foreign bodies in the peritoneum eventually become contained in aforeign body granuloma. In the extremely rare case of retainedectopic pregnancy, this forms alithopedion, which involves the fetus being too large to be reabsorbed, and iscalcified^[13] as a means of shielding the surrounding tissue from infection.

Foreign bodies can also become lodged in other locations:

• anus or rectum^[14]
• blood vessels or thoracic system^[15]
• ears^[16]
• nose^[17]
• teeth andperiodontium^[18][19]
• urethra^[20]
• vagina^[21]

Foreign bodies are common in animals, especially youngdogs andcats. Dogs will readily eat toys, bones, and any object that either has food on it or retains the odor of food. Unlike humans, dogs are susceptible to gastrointestinal obstruction due to their ability to swallow relatively large objects and pass them through theesophagus. Foreign bodies most commonly become lodged in thestomach because of the inability to pass through thepyloric sphincter into thejejunum. Symptoms of gastrointestinal obstruction include vomiting, abdominal pain often characterized by aggression, acute infection, and depression due todehydration.^[22] Treatment of a foreign body is determined by its severity. The amount of time a foreign body is present, location of the object, degree of obstruction, previous health status of the animal and the type of material from which the foreign body is made can all determine the severity of the condition.Peritonitis results if either the stomach or intestine has ruptured. Foreign bodies in the stomach can sometimes be removed byendoscopic retrieval or if necessary bygastrotomy.^[22] Very often, a simple instrument to remove foreign bodies without operation endoscopy is theHartmann alligator forceps. The instrument is manufactured from 8 cm to 1 m length. Foreign bodies in the jejunum are removed byenterotomy.

Certain foreign bodies in animals are especially problematic. Bones or objects with sharp edges may cause tearing of the wall of the esophagus, stomach, or small intestine and lead to peritonitis.Pennies swallowed in large numbers may causezinc poisoning, which in dogs leads to severegastroenteritis andhemolytic anemia. Linear foreign bodies can especially be dangerous. A linear foreign body is usually a length of string or yarn with a larger object or clump of material at either end. One end is usually lodged in the stomach or proximal small intestine and the other end continues to travel through the intestines. The material becomes tightly stretched and the intestines may "accordion up" on themselves or be lacerated by it. This is especially common in cats who may enjoy playing with a ball of string or yarn. Sometimes the linear foreign body anchors in the mouth by catching under the tongue.^[23] Pantyhose is a common linear foreign body in dogs.

•  
  Bottle top swallowed by a dog
•  
  Needle swallowed by a cat

• Nanomaterials
• Particulates
• Xenobiotic

• Ingested Magnets. The New England Journal of Medicine.
• The Susy Safe Project. A Surveillance System on Suffocation Injuries due to Foreign Bodies in European Children.