OSCE: Nasogastric (NG) Tube Insertion: A Step-by-Step
- Mayta
- Jan 17
- 5 min read
Step | Key Points |
1. Indications | - Enteral feeding/medication when oral route is unsafe - Gastric decompression (e.g. in bowel obstruction) - Diagnostic purposes (e.g. aspiration of gastric contents) |
2. Contraindications | - Suspected base of skull fracture - Severe coagulopathy (unaddressed) - Oesophageal stricture (relative contraindication) |
3. Preparation | - Introduce yourself (e.g. “นศพ [Your Name]”), confirm patient identity (name, DOB) - Explain the procedure in simple terms, gain consent - Gather equipment (NG tube, lubricant, syringe, pH strips, tape/dressing) - Position the patient upright, check for allergies |
4. Measurement | - Measure from bridge of the nose → earlobe (ติ่งหู) → 5 cm below xiphisternum aka. Xiphoid process - Mark or note the insertion length |
5. Insertion | - Lubricate tip of tube - Insert tube gently via nostril - Ask the patient to swallow (if safe) to facilitate passage - Check mouth to ensure no coiling - Advance to the measured length |
6. Secure & Confirm Placement | - Secure tube with tape/dressing on the nose - Attempt aspiration; check pH (ideally <4 or per local guidelines) - If there is no aspirate/abnormal pH, obtain a chest X-ray to confirm placement |
7. Completion | - Remove guidewire once confirmed safe - Dispose of equipment, perform hand hygiene - Document procedure details (time, length, pH/X-ray, complications) |
Nasogastric (NG) tube insertion is a fundamental clinical procedure that medical students and healthcare professionals must master. It involves passing a flexible tube through the patient’s nasal passage, down the esophagus, and into the stomach. The primary purpose is to facilitate feeding, administer medications, or decompress the stomach. This guide provides a clear step-by-step approach, ideal for an OSCE (Objective Structured Clinical Examination) setting.
1. Introduction
Hand hygiene and PPE
Perform hand hygiene before and after patient contact.
Wear disposable gloves and other personal protective equipment (PPE) if appropriate.
Introduction and patient identification
Introduce yourself (name and role).
Confirm the patient’s identity (name, date of birth).
Explain the procedure in simple terms: “We need to insert a fine tube through your nose into your stomach. It may be uncomfortable, but it shouldn’t be painful.”
Check for patient understanding and allow questions.
Consent and safety checks
Gain verbal consent.
Confirm no known allergies (e.g. latex).
Ask about any current pain or discomfort.
If there is suspicion of a base of skull fracture (e.g. following trauma), avoid NG tube insertion to prevent possible entry into the cranial vault.
2. Indications and Contraindications
Indications
Short-term enteral feeding (when oral intake is not possible or is unsafe).
Administration of medications directly into the stomach.
Gastric decompression (e.g. in bowel obstruction).
Contraindications
Suspected base of skull fracture.
Severe coagulopathy without correction.
Recent nasal, facial, or oesophageal surgery depending on local guidelines (risk assessment required).
3. Equipment Checklist
Prepare and gather all necessary equipment on a clean tray:
Nasogastric tube (fine bore)
Disposable gloves
Lubricant gel (to lubricate the tip of the tube)
Gauze (to wipe off excess lubricant)
Disposable bowl (for potential vomiting)
Paper towels (for patient to wipe around the mouth/nose)
Large syringe (to obtain an aspirate)
pH testing strips (to check aspirate acidity)
Dressing or tape (to secure the NG tube)
Glass of water (if the patient’s swallow is deemed safe)
Local anaesthetic spray (optional, to numb the oropharynx if available)
4. Patient Positioning and Measurement
Positioning
Sit the patient upright (ideally at a 45°–90° angle).
Ensure the head is in a neutral, slightly flexed position to align the pharynx and oesophagus.
Measurement of the NG Tube
Wear non-sterile gloves.
Estimate the insertion length by measuring from:
Bridge of the nose →
Earlobe →
5 cm below the xiphisternum (i.e., the tip of the sternum).
Note or mark this length on the tube (e.g., use a small piece of tape).
5. Insertion of the NG Tube
Preparation
Lubricate the first few centimeters of the NG tube with a water-based lubricant.
If available and safe, spray local anaesthetic to the back of the throat.
Insertion
Gently insert the NG tube into one nostril.
Angle the tube slightly towards the ear on the same side to follow the natural nasal passage.
If resistance is met or the patient is in significant distress, stop, withdraw slightly, and reassess the angle. Avoid forcing the tube.
Advancement and swallowing
Once past the nasopharynx, ask the patient to swallow sips of water if their swallow is safe. Swallowing helps guide the tube into the oesophagus.
Intermittently check the patient’s mouth to ensure the tube is not coiling in the oral cavity.
Advance the tube to the predetermined length.
Securing
Once at the correct depth, secure the tube to the nose using a dressing or specialist NG tube fixation device. This prevents accidental displacement.
6. Confirming NG Tube Placement
Aspiration and pH testing
Attach the syringe to the NG tube and attempt to aspirate gastric contents.
If you obtain aspirate, test the pH using the pH strip.
A pH <4 typically indicates correct gastric placement. However, local guidelines may vary (some use pH <5.5 or <6).
Chest X-ray
If no aspirate is obtained, or the pH is not in the safe range, a chest X-ray is required to confirm placement.
Some institutions mandate a chest X-ray in all cases for safety.
Removal of the guidewire
Once correct placement is confirmed (via pH or X-ray), remove the radiopaque guidewire if present.
Secure the tube again if needed and ensure it is comfortable for the patient.
7. Completion of the Procedure
Comfort and clean-up
Inform the patient that the procedure is complete.
Offer tissues or paper towels to clean the face and nose if necessary.
Dispose of equipment
Remove gloves and PPE carefully.
Dispose of all equipment and waste in appropriate clinical bins.
Hand hygiene
Perform thorough hand hygiene after removing PPE.
Documentation
Record the following details in the patient’s notes:
Date and time of procedure.
Your name, position, and (if applicable) registration number.
The reason for NG tube insertion.
The length of NG tube inserted.
Aspirate pH or chest X-ray findings (including interpretation).
Any complications or difficulties.
Whether the NG tube is safe to use for feeding or medication.
8. Common Pitfalls and Tips
Coiling in the mouth
Always check the oral cavity if you suspect coiling or the patient reports discomfort.
Excessive resistance
Do not force the tube. Withdraw slightly, change the angle, or attempt the other nostril if needed.
Patient distress
Reassure the patient, slow down, and allow breaks as necessary.
Swallowing
If the patient cannot safely swallow (e.g., dysphagia), consider alternative methods or additional caution to reduce the risk of aspiration.
pH variance
Gastric pH can vary with medications (e.g., proton pump inhibitors). Be aware of local guidelines for safe pH ranges.
9. Conclusion
Nasogastric tube insertion is an essential skill for Thai medical students and healthcare professionals. By following a systematic approach—preparing the patient, measuring accurately, inserting gently, confirming placement, and documenting thoroughly—you can perform this procedure safely and effectively. The key to success is ensuring patient comfort, strictly adhering to safety guidelines, and always confirming correct tube placement before use.
Key Takeaways
Proper preparation and explanation to the patient promote cooperation and reduce anxiety.
Accurate measurement helps avoid complications and ensures correct tube positioning.
Confirming tube placement via aspirate pH and/or chest X-ray is crucial for patient safety.
Thorough documentation and communication with nursing staff are vital for ongoing patient care.