Many practices have purchased endoscopy systems for diagnostic biopsy of the gastrointestinal (GI) and respiratory tracts. However, flexible endoscopes can also be used to retrieve ingested or inhaled foreign bodies (FBs). If successful, there is a sense of achievement in avoiding open surgery; however, success depends on having suitable equipment and selecting appropriate cases.
Introduction to selecting appropriate cases
Some gastric FBs, such as bones or potatoes, do not need removal as they will be digested, yet they will need to be removed if they are stuck in the oesophagus. Also, it may not be safe to try to remove sharp objects endoscopically. Ingested fishhooks often lie free in the GI lumen and are retrieved by gripping the curved part so that the hook is pointing backwards (Figure 1). If the barb is lightly embedded in the mucosa, it may be possible to rip it out, but if it is more deeply embedded, which is likely if someone has yanked on the fishing line exiting the mouth, it may be possible to force it forward, back into the lumen. However, surgical removal may be needed.
Other gastric FBs are simply too large to retrieve, either because they cannot be grasped or they are too large to pull back through the lower oesophageal sphincter (LOS) even though the patient managed to swallow them (Figure 2). Indeed, the availability and size of grasping instruments restrict the range of FBs that can be retrieved endoscopically. Unless the endoscope has a large channel (preferably 2.8mm), many instruments cannot be passed. However the large channel results in a larger endoscope tip diameter, precluding some attempts in small dogs and cats.
Biopsy forceps generally have cups that are too small to grasp most FBs, except for cloth or wool material, and are rarely used. Instead, there is a wide range of endoscopic retrieval devices (Figure 3), and practices should consider purchasing a minimum number just in case.
There is a wide range of endoscopic retrieval devices, and practices should consider purchasing a minimum number just in case
Grasping forceps are similar to biopsy forceps but have rat-tooth (Figure 3A) or alligator jaws that open wider. However, they rarely open wide enough to grasp rubber balls. The wires in basket forceps have a “memory”, so they spring open and can be steered over the FB by moving the endoscope tip before grasping it (Figure 3B). Very large baskets are available for large FBs, such as tennis balls, but again, these are often too large to pull out of the stomach via endoscopic removal.
Snares are wire loops that can be closed over soft FBs.
A Roth net is a wire loop with a mesh net, which is useful for securing small stones in the stomach.
Multiprong forceps are similar to tools used to clean drain blockages, having hooked tines that spring open around the FB. However, their grip is not very strong, and their utility is quite limited.
There are also many specialised instruments, such as magnetic probes for ferrous objects and “peanut forceps”, used for the endoscopic removal of the most common inhaled FB in people. However, a pair of rat‑tooth and basket forceps, and possibly a snare and a Roth net, should cover most eventualities. Challenging FBs, however, may require improvisation. For example, bronchoscopes often have a narrow working channel down which no grasping instrument will fit; however, it may be possible to retrieve inhaled FBs by taping forceps to the outside of the endoscope tip.
The approach to endoscopic FB retrieval depends on what the FB is and where it is lodged. It is essential to remember that some FBs will pass naturally and that others are too large or unsafe to retrieve endoscopically. Complications such as perforation can occur, but the risk to the patient is lower than in open surgery, and post-operative recovery is much quicker. Just before the procedure, radiographs should be taken to confirm where the FB is and that it has not moved after the initial diagnosis.
Complications such as perforation can occur, but the risk to the patient is lower than in open surgery, and post-operative recovery is much quicker
Oesophageal FBs are often the most challenging and can be true emergencies. There is a risk of perforation with pointed bones, and large objects such as indigestible chews can cause a complete obstruction (Figure 4A). Avoidance of surgical removal is preferred as it requires a thoracotomy, but surgery should be attempted sooner rather than later if endoscopic retrieval is unsuccessful. Because of the size of many oesophageal FBs, it is often easier to use long rigid alligator forceps alongside the flexible endoscope (Figure 4B). This allows visualisation of the procedure, but the endoscopist and the person manipulating the forceps must coordinate to avoid accidentally gripping the endoscope.
As long as grasping instruments are large enough, all except the largest and/or smoothest gastric FBs can be removed endoscopically. However, sometimes it can be frustrating chasing an object around the stomach or dropping it as one tries to pull it through the lower oesophageal sphincter. It is sensible to set a time limit on attempts at endoscopic removal of gastric FBs before opting for surgery, as a simple gastrotomy is often quicker! FBs with an edge or prominence are easier to catch with grasping forceps, whereas basket forceps or a Roth net is better for smooth/round objects.
It is sensible to set a time limit on attempts at endoscopic removal of gastric FBs before opting for surgery, as a simple gastrotomy is often quicker
If the patient has just eaten, visualising the FB can be difficult. Unless one has the luxury of a peristaltic flushing pump to wash the gastric surface endoscopically, it may be better to wait a few hours until the food has passed. However, this assumes there is no risk of the FB passing into the duodenum or perforating.
The biggest frustration with the endoscopic removal of gastric FBs is that the FB often falls out of the antrum and down to the cardia. This occurs when the patient is in the standard left lateral recumbency position as the stomach is insufflated (Figure 5). Having to retroflex the endoscope to grab the FB can then be difficult. Turning the patient into right lateral recumbency will roll the FB down to where it can be retrieved more easily.
Nasal FBs may be visualised and retrieved by rigid endoscopes and forceps placed anterograde, but retroflexion of a flexible endoscope may be necessary to retrieve FBs lodged above the soft palate; blades of grass and other plant material are most common (Figure 6A). However, the limited space in the pharynx makes retroflexion difficult. It is always worth first retracting the soft palate with a spay hook and looking with a dental mirror. It may then be possible to grab the FB with curved/angled artery forceps.
When trying to find inhaled FBs endoscopically, there is often a concern that the FB has been missed in the myriad of dividing airways. This is because an endoscope can typically only reach the first five to six bronchial divisions in the over 20 airway divisions that occur in the pathways to the alveoli. It is usually quite easy to find most bronchial FBs as they will likely be directly visible in the larger airways (Figure 6B). If the FB is small enough to have gone further into a lung lobe, it will never be retrieved endoscopically. Nevertheless, a systematic approach to searching every mainstem bronchus and their major divisions is good practice and having a map of the airways for reference is helpful. Fortunately, there is often a trail of blood or pus leading to the airway containing the FB.
One of the main challenges when retrieving inhaled FBs via endoscopy is keeping the patient oxygenated during the procedure, as the endoscope and/or FB may occupy most of the trachea. Being able to pass the endoscope via a gasket in a swivel connector and down the ET tube (Figure 7) makes the procedure easier. This is because ventilation can be continued while the endoscope is inserted, but this is only feasible in larger patients. Otherwise, it may be necessary to repeatedly intubate and extubate during the procedure with short windows of opportunity to attempt FB retrieval whenever the patient is extubated.
Common bronchial FBs in companion animals
Both dogs and cats with severe dental disease sometimes inhale loose teeth, but cats most commonly inhale blades of grass, twigs and pieces of grit or cat litter. Dogs more frequently inhale whole grass foxtails or cereal awns. A classic history is a dog running in a field at harvest time and emerging coughing. If not detected early, the foxtail or awn will putrefy, and the dog may then be presented with halitosis.
Cats most commonly inhale blades of grass, twigs and pieces of grit or cat litter. Dogs more frequently inhale whole grass foxtails or cereal awns
It can be difficult to remove a cereal awn soon after inhalation as the barbs wedge it in place. If it cannot be removed initially, the dog should be recovered and given antibacterial cover and anti-inflammatory doses of steroids to reduce oedema for a few days. Removal at repeat bronchoscopy is then usually successful as the material has softened. Some debris may remain but will likely be coughed out. Lung lobectomy is rarely indicated unless a small FB has passed beyond the reach of the endoscope when it is only likely to be found by CT examination.