airways of the lower respiratory tract, proximal gastrointestinal tract (esophagus, stomach and proximal duodenum), caudal intestinal tract (rectum and distal small colon), lower urinary tract (urethra, bladder and occasionally ureters), and uterus are commonly examined using endoscopy. This chapter will review complications associated with endoscopic examination procedures, whereas surgical endoscopic procedures will be discussed separately. Similarly, complications associated with arthroscopy, tenoscopy, laparoscopy and thoracoscopy will be reviewed in their respective chapters. Complications can occur related to equipment damage, patient injury from the endoscope, and sequellae from insufflation.
List of Complications Associated with Endoscopy
Epistaxis/mucosal trauma
Equipment damage
Insufflation‐related complications
Air embolism
Epistaxis/Mucosal Trauma
Definition
Epistaxis is the presence of hemorrhage exiting the nares. Mucosal trauma includes bruising, abrasions, and lacerations which can occur during passage of the endoscopy into any hollow organ.
Risk factors
Small‐sized horses or foals
Insufficient restraint
Unsedated patients
Restriction of the passageway to be scoped by luminal masses or extraluminal swelling
Pathogenesis
Similar to passage of a nasogastric tube, there is the potential risk of epistaxis or other mucosal trauma. The severity of this injury is typically much less than for nasogastric intubation, because passage of the endoscope is visually guided and directed and the endoscopes are generally narrower in diameter and more pliable than most nasogastric tubes. Sources of epistaxis would most likely include the nasal mucosa during endoscope advancement, because visualization would reduce the risk of traumatizing the nasal turbintate and ethmoid turbinates. However, further advancement of the endoscope into a more restricted space (guttural pouches, esophagus) could result in inadvertent flexing of the scope into the turbinates. Advancement of the endoscope into the urethra, ureters, uterus, or caudal intestinal tract could cause direct mucosal trauma in some cases.
Prevention
Use of intranasal phenylephrine, which causes vasoconstriction of mucosal vessels, and application of carbomethylcellulose lubricant, which reduces friction between the endoscope and the passageways, may reduce mucosal trauma and irritation in small patients or patients with restricted nasal passages.
Treatment and expected outcome
Most epistaxis and mucosal trauma complications associated with endoscopy are self‐limiting and do not need specific treatment. If severe epistaxis occurred, treatment could be applied similar to that described for epistaxis associated with nasogastric intubation (see Chapter 5: Complications of Nasogastric Intubation).
Equipment Damage
Definition
Crushing damage to the endoscope by mastication
Risk factors
Upper airway endoscopy or gastroscopy without endoscope protector
Inexperience
Oral endoscopy without a mouth speculum
Pathogenesis
The most common damage is associated with endoscopy of the nasopharynx due to retroflexion of the endoscope into the oral cavity. Damage can occur at the end of the endoscope if the leading edge retroflexes into the oral cavity or it may occur in the body of the endoscope if the scope does not advance through the cranial esophageal sphincter and a loop of the endoscope retroflexes into the oral cavity (Figure 4.1). This would be most common when performing esophagoscopy and gastroscopy, because of the intentional induction of a swallowing reflex to enter the esophagus and the long length of the endoscope used for gastroscopy. Upper airway endoscopy is not immune to oral retroflexion, although the risk is much lower because the esophagus is not intentionally entered. Use of the endoscope to evaluate the oral cavity directly exposes the endoscopy to risk of damage by the teeth. The damage is caused by the horse chewing on the scope and the scope will be immediately non‐functional.
Prevention
This complication can be minimized by awareness of the risk of it occurring during gastroscopy and upper airway endoscopy. The person passing the endoscopy controls the forward motion. This person should be careful when advancing the endoscope until confident in its location. Once seated in the esophagus, the person advancing the scope should make sure that there is aboral advancement of the scope synchronous with advancement of the endoscope into the nasal cavity. Alternatively, a larger diameter hollow tube can be positioned through the nasal cavity and into the esophagus [1]. The gastroscope is then passed through this tube, which prevents any resistance to passage and retroflexion of the endoscope in the nasopharynx [1]. Oral speculums must be used for any oral endoscopy procedures and the scope should be protected by a rigid sheath when in the mouth, if possible.
Figure 4.1 Photograph showing large segment (spanning the 160 cm to 205 cm gradations) of crushing and damage to a 3‐meter gastroscope after a segment of the midbody of the endoscope retroflexed into the oral cavity, where it was chewed by the patient.
Source: Julie E. Dechant.
Insufflation‐related complications
Definition
Insufflation is the directed administration of air through the endoscope to provide distension and visualization of collapsible hollow organs and can result in small intestinal volvulus or rupture of a hollow viscus.
Risk factors
None identified
Inattention during procedure
Pathogenesis
These complications are
