What is the anatomy involved in endoscopy procedures, such as gastrointestinal (GI) endoscopy, respiratory endoscopy, and genitourinary (GU) endoscopy?

Anatomy of Endoscopy

Understanding the specific anatomical landmarks is essential for performing high-quality endoscopic procedures across gastrointestinal, respiratory, and genitourinary systems to ensure optimal patient outcomes and minimize complications.

Gastrointestinal Endoscopy Anatomy

Upper GI Endoscopy (Esophagogastroduodenoscopy/OGD)

• A complete upper GI endoscopy examination should assess all relevant anatomical landmarks starting at the upper esophageal sphincter and reaching the second part of the duodenum 1
• Key anatomical landmarks include:
  • Upper esophagus
  • Gastroesophageal junction/squamocolumnar junction
  • Fundus (requires J-maneuver for proper visualization)
  • Gastric body
  • Incisura
  • Antrum
  • Duodenal bulb
  • Distal duodenum (second part) 1
• The fundus should be inspected by a J-maneuver in all patients, and where there is a hiatus hernia, the diaphragmatic pinch should be inspected while in retroflexion 1

Standardized Documentation

• Photo-documentation should be made of relevant anatomical landmarks and any detected lesions to ensure complete examination 1
• At minimum, photodocumentation should include:
  • Lower esophagus/cardia with visualization of the squamocolumnar junction and gastroesophageal junction
  • Gastroesophageal junction/fundus in retroflexed view
  • Body and antrum in anterograde view
  • Incisura in retroflexed view
  • Distal extent of examination in the duodenum 1

Nasal and Sinus Endoscopy

• The standard three-pass technique for rigid nasal endoscopy examines specific anatomical structures 1:
  • First pass: Along the floor of the nose to the nasopharynx, examining the septum, inferior turbinates, and nasal mucosa
  • Second pass: Above the inferior turbinate to the middle meatus, then medial to the middle turbinate into the sphenoethmoidal recess
  • Third pass: During withdrawal, rolling laterally into the middle meatus 1
• Key anatomical structures include:
  • Nasal valves
  • Uncinate process
  • Infundibulum
  • Hiatus semilunaris
  • Ethmoid bulla
  • Frontal recess
  • Ostiomeatal unit (middle meatus, uncinate process, infundibulum, anterior ethmoid cells, and ostia of the maxillary, ethmoid, and frontal sinuses) 1

Neuroendoscopy/Skull Base Anatomy

• Neuroendoscopy provides visualization of anatomical structures from the crista galli to the jugular foramen and the ventral craniocervical junction 1
• Endoscopy can be used in preformed spaces (ventricles) or through natural corridors (endonasal approaches) 1
• Anatomic orientation requires exploration of:
  • Preformed cavities (intraventricular spaces)
  • Basal cisterns
  • Skull base structures and corridors (endonasal, transoral, or cranial vault routes) 1
• The "hard walls" of anatomic spaces should be identified during endoscopic inspection as they provide important landmarks 1

Technical Considerations for Anatomical Visualization

Equipment and Technique

• High-definition video endoscopy systems should be used to properly visualize anatomical structures 1
• Adequate mucosal visualization is essential for detecting pathology:
  • Mucosa should be free of bubbles and debris
  • Quality of views should be rated according to a validated scale 1
• For nasal endoscopy, a 4mm 30-degree endoscope is standard, but a 2.7mm endoscope and/or a zero-degree endoscope can be used 1
• Angled endoscopes (30-degree, 45-degree, and 70-degree) increase the view "around the corner" but may increase the risk of disorientation 1

Anatomical Challenges in Altered Anatomy

• Surgically altered anatomy (e.g., post-bariatric surgery) requires special consideration during endoscopy 2
• Understanding the altered anatomy is essential for successful navigation and procedure completion 2, 3
• Patient positioning can significantly affect anatomical exposure during endoscopic procedures:
  • Gravity can help move organs and facilitate exposure
  • Patient position can be changed by rotating along the head-toe axis or by tilting the surgical bed 4

Training Considerations for Anatomical Mastery

• Thorough theoretical and practical knowledge of surgical anatomy is required for endoscopic procedures 1
• Manual training should include:
  • Bimanual techniques (handling the endoscope in one hand and instruments in the other)
  • Developing spatial orientation when considering surgical anatomy 1
• Endoscopic training in an anatomic laboratory is valuable for learning anatomical landmarks and navigation 1
• Endoscopists should aim to perform a minimum of 100 OGDs per year to maintain high-quality examination standards 1

Common Pitfalls and Caveats

• Loss of three-dimensional perception is a limitation of endoscopy, though dynamic movements of the scope and tactile sensation help counter this 1
• Septal deviation can complicate nasal endoscopy but rarely prevents it, especially if a pediatric endoscope is used 1
• Inadequate decongestation or anesthesia can limit proper visualization of nasal anatomy 1
• In patients with complete obstruction of the ostiomeatal unit, tissue may look normal despite inflammation in the sinuses 1
• Endoscopists must be familiar with anatomical variations (e.g., persistent trigeminal artery in endoscopic transsphenoidal pituitary surgery) 1