Nasogastric tube insertion: a guide for nursing students

Nasogastric (NG) tube insertion is one of the most commonly performed nursing procedures in acute care. NG tubes are used across nearly every inpatient unit — from the emergency department to the ICU, from surgical floors to medical wards. Whether a patient needs gastric decompression after abdominal surgery, enteral nutrition when oral intake is unsafe, or medication delivery when swallowing is impaired, the NG tube is a foundational clinical tool nurses must know how to place and manage safely.

This guide walks through everything a nursing student needs to know: tube types and sizes, indications and contraindications, the step-by-step insertion procedure, how to verify correct placement (including what NCLEX wants you to know), ongoing nursing care, and complications to watch for. NCLEX tips are highlighted throughout.

Types of NG tubes

Not all NG tubes are the same. Choosing the right tube depends on the clinical indication.

Salem sump: The most common NG tube in acute care. The double-lumen design is the key feature: the large lumen drains gastric contents, while the smaller blue pigtail serves as an air vent. The air vent prevents the suction from drawing gastric mucosa into the tube tip (a phenomenon called wall adherence). Keep the blue pigtail above the level of the patient’s stomach when on suction to prevent fluid backflow through the vent.

Levin tube: A simpler, single-lumen tube. Because it lacks an air vent, it has a higher risk of gastric wall adherence if placed on continuous low suction. Often used for short-term feeding or one-time medication delivery.

Dobhoff (nasoenteric feeding tube): A small-bore, flexible tube with a weighted tungsten tip designed to facilitate passage into the duodenum or jejunum for post-pyloric feeding. Because the small bore makes aspirate difficult to obtain for pH testing, X-ray confirmation is mandatory before initiating feeds through a Dobhoff.

French sizes: Tube size is measured in French (Fr) — 1 Fr = 0.33 mm outer diameter. Larger French numbers = wider tubes. Salem sumps typically range 14–18 Fr. Dobhoff feeding tubes are narrow at 8–12 Fr.

Indications and contraindications

Indications

• Gastric decompression: Postoperative ileus, bowel obstruction, gastroparesis, pancreatitis — removing accumulated gastric secretions reduces nausea, vomiting, and aspiration risk
• Enteral nutrition: When the GI tract is functional but oral intake is unsafe or impossible (altered consciousness, dysphagia, severe anorexia)
• Medication delivery: Patients who cannot swallow pills but have intact GI function
• Gastric lavage: Certain poisoning or overdose presentations (though clinical use is now more limited per AACT guidelines)
• Gastric sampling: Occult GI bleeding workup, pH monitoring

Contraindications

NCLEX alert: Basilar skull fracture is the highest-yield contraindication. If NCLEX presents a patient with a head injury and basilar skull fracture, the answer is do not insert NG tube — use orogastric if decompression is needed.

Equipment and patient preparation

Before gathering equipment, assess the patient’s nares by asking them to occlude each nostril and breathe. Use the patent side. Inspect for septal deviation, polyps, or prior nasal surgery.

Standard kit contents:

• Appropriate NG tube (size and type per order)
• Water-soluble lubricant (not petroleum-based — petroleum can cause lipoid pneumonia if tube is misplaced in airway)
• 60 mL catheter-tip syringe
• pH paper (range 0–7 or 0–14)
• Stethoscope
• Emesis basin and tissues
• Tape or commercial nasal bridle for securing
• Suction setup (if decompression ordered)
• Gloves, mask, and eye protection

Patient positioning: Elevate the head of bed (HOB) to 45–90 degrees (high Fowler’s). This position uses gravity to direct the tube toward the esophagus and reduces aspiration risk during insertion. If the patient cannot tolerate upright positioning, a minimum of 30 degrees is used, but 45–90 degrees is preferred.

Explain the procedure clearly. Reassure the patient that discomfort is brief and that their cooperation — particularly swallowing on cue — significantly improves success. Establish a hand signal the patient can use to indicate distress and request a brief pause.

Step-by-step insertion procedure

Step 1: Perform hand hygiene and don PPE

Wash hands thoroughly. Put on gloves, mask, and eye protection (insertion can trigger coughing or gagging that produces respiratory droplets).

Step 2: Measure tube length using the NEX method

The NEX (Nose-Earlobe-Xiphoid process) measurement determines insertion depth for initial gastric placement.

1. Place the tube tip at the patient’s nose
2. Extend the tube to the earlobe (not the ear canal)
3. Continue down to the xiphoid process (lower end of the sternum)
4. Mark or note this measurement — typically 45–55 cm in adults

This measurement, described by Metheny et al. and referenced in major nursing skills textbooks (including Perry, Potter & Ostendorf), provides an estimate of tube length needed to reach the stomach. It is a starting point, not a guarantee — placement must always be verified.

Step 3: Lubricate the tube

Apply water-soluble lubricant generously to the distal 3–4 inches of the tube. Do not use petroleum jelly or oil-based lubricants.

Step 4: Insert tube through the naris

With the patient in high Fowler’s, gently insert the tube into the selected naris. Initially angle the tube straight back (toward the occiput, not upward toward the forehead — this is a common student error). Advance slowly along the floor of the nasal cavity.

Step 5: Advance with swallowing

When the tube reaches the nasopharynx (approximately 7–10 cm), the patient will feel the tube in the back of the throat. This is the critical moment:

• Ask the patient to flex their chin toward their chest (neck flexion closes off the tracheal opening and opens the esophagus)
• Instruct the patient to swallow sips of water through a straw (if allowed) or perform dry swallows
• Advance the tube steadily with each swallow — advance approximately 3–5 cm per swallow
• Do not force the tube if significant resistance is met

Step 6: Watch for signs of airway misplacement

Stop advancing immediately if the patient develops:

• Respiratory distress — increased work of breathing, oxygen desaturation
• Coughing, choking, or gagging beyond normal discomfort
• Cyanosis or color change
• Inability to speak (tube in larynx)
• The patient signals distress

If any of these occur: withdraw the tube completely, allow the patient to recover, and reattempt.

Step 7: Advance to measured depth

Continue advancing until the tube reaches the premeasured NEX depth. Note the centimeter marking at the naris. Secure the tube temporarily with tape at the naris.

Step 8: Verify placement before any use

Do not instill anything into the tube until placement is confirmed. Proceed to verification (next section).

Verifying correct placement

This is the highest-yield NCLEX section of this entire guide.

Incorrect NG tube placement — particularly bronchial or pulmonary placement — is a never event that can cause fatal pneumonia, pneumothorax, or drowning from enteral feeds infused into the airway. The Joint Commission and ASPEN (American Society for Parenteral and Enteral Nutrition) have issued safety guidelines specifically about NG tube placement verification.

Method 1: X-ray — the gold standard

Radiographic confirmation (chest or abdominal X-ray) is the only method that definitively confirms NG tube tip location and is required:

• Before initiating tube feeding through any newly placed tube
• Before using a Dobhoff/small-bore feeding tube (aspirate is often unobtainable)
• Any time tube position is in doubt
• After any episode of vomiting or coughing that may have displaced the tube

On X-ray, the tube tip should appear in the gastric body, below the left hemidiaphragm, and to the left of midline. The tube should bisect the carina (not course to one side) as it descends through the thorax.

Method 2: pH testing of aspirate

Aspirating gastric contents and testing pH is the most reliable bedside method and is widely used to confirm ongoing tube position before each use (after the initial X-ray has been done for new tube placement).

How to perform:

1. Attach a 60 mL syringe to the tube
2. Aspirate 5–10 mL of fluid
3. Place a drop on pH paper
4. Read result

Interpreting results:

• pH ≤ 5.5 = gastric placement confirmed (gastric acid, normal fasting pH 1.5–3.5)
• pH 6–7 = ambiguous — may be intestinal fluid, diluted gastric fluid (patient on antacids/PPIs), or respiratory secretions → do not rely on this; obtain X-ray
• pH > 6 = do not proceed; obtain X-ray confirmation

Important caveats: Patients on proton pump inhibitors (omeprazole, pantoprazole) or H2 blockers (famotidine) may have gastric pH > 5.5 even with correct gastric placement. Document medication use and consult institutional policy. Do not assume misplacement solely based on pH > 5.5 in a patient on acid suppression — but do obtain X-ray confirmation before proceeding.

Aspirate color can provide supporting (not confirmatory) evidence: gastric aspirate is typically yellow-green, tan, or clear/white; respiratory secretions are typically pale yellow or mucoid; intestinal aspirate is golden yellow or bile-colored.

The auscultation method: do NOT rely on this

You will encounter the air bolus auscultation method in older textbooks and occasionally in clinical practice: injecting 10–20 mL of air into the tube while auscultating over the stomach for a “whooshing” sound.

NCLEX question trap: this method is NOT reliable for confirming NG tube placement.

The Joint Commission, the Infusion Nurses Society (INS), and ASPEN have all stated that the auscultation method cannot distinguish gastric placement from bronchial, esophageal, or pleural placement. Air injected into a misplaced tube will produce transmitted sounds that can be heard over the stomach. This method has been directly linked to patient harm from undetected airway placement.

Bottom line: If NCLEX asks how to confirm NG tube placement, the answer is X-ray (gold standard). For routine ongoing verification before feeds or medications, pH testing is acceptable. Auscultation alone is never acceptable for verification.

Ongoing nursing care

Once placement is confirmed and the tube is in use, ongoing nursing management focuses on maintaining tube patency, preventing complications, and monitoring position.

Securing the tube: Use a commercial nasal bridle or tape to secure the tube to the nose and cheek. Avoid pressure on the naris (naris necrosis is a real complication of poorly secured tubes). Change tape every 24–48 hours or when it loosens. Document the centimeter marking at the naris at each assessment and compare to original placement depth.

Flushing protocol: Flush the tube with 15–30 mL of water before and after each medication administration, before and after each feeding (or every 4–8 hours during continuous feeds), and per institutional protocol. Flushing prevents tube occlusion and maintains tube patency.

Position during enteral feeds: Keep HOB elevated to at least 30–45 degrees during tube feeding and for 30–60 minutes after bolus feeds. This significantly reduces aspiration risk, particularly important for patients with altered gag reflex, decreased consciousness, or known aspiration risk.

Monitoring gastric residual volume (GRV): For patients receiving enteral nutrition, check GRV per protocol (commonly every 4–6 hours). GRV > 500 mL for two consecutive checks may indicate feeding intolerance — hold feeds and notify provider. GRVs < 500 mL should not automatically trigger feed holds (per ASPEN/SCCM guidelines — routine GRV monitoring for all patients is no longer universally recommended, but institutional policies vary).

Verify position before each use: Before administering medications or starting/resuming a tube feeding, confirm tube position using pH testing or per institutional protocol. Document the centimeter marking at the naris at each check.

Patient education: Teach the patient not to pull or tug on the tube, to report any coughing, choking, or shortness of breath, and to avoid lying flat during feeding.

Complications and troubleshooting

Removal procedure

NG tube removal is a brief, low-risk procedure:

1. Explain procedure to the patient
2. Perform hand hygiene; don gloves
3. Disconnect tube from suction (if applicable)
4. Remove tape or bridle securing the tube
5. Ask the patient to take a deep breath and hold it (or exhale slowly)
6. Pinch the tube (to prevent residual fluid dripping) and withdraw in one smooth, continuous motion
7. Discard tube in appropriate waste container
8. Provide oral and nasal hygiene — clean the naris and offer mouth rinse
9. Assess patient tolerance and document

NCLEX tips: high-yield NG tube facts

• X-ray is the gold standard for confirming NG tube placement — especially before initiating tube feeding through a newly placed tube. No other method definitively confirms tip location.
• Auscultation of air bolus is NOT reliable. If NCLEX lists this as an option for verifying placement, it is a distractor. The air “whoosh” can be heard over the stomach even when the tube is in the bronchus or esophagus.
• pH ≤ 5.5 confirms gastric placement at bedside. pH > 6 is ambiguous — obtain X-ray.
• Patients on PPIs or H2 blockers may have gastric pH > 5.5 despite correct placement. Proceed to X-ray confirmation if pH is ambiguous.
• NEX measurement (Nose → Earlobe → Xiphoid process) estimates insertion depth. Mark or note measurement before insertion.
• Basilar skull fracture is an absolute contraindication to NG tube insertion — risk of intracranial placement. Use orogastric route.
• HOB elevation 45–90 degrees during insertion and at least 30–45 degrees during enteral feeding prevents aspiration.
• Salem sump has two lumens: the large lumen drains gastric contents; the blue pigtail is the air vent. Keep the air vent above stomach level on suction to prevent fluid backflow.
• Dobhoff/small-bore feeding tubes require X-ray confirmation before use — aspirate is often unobtainable due to the small bore and flexible tip.
• Levin tube is single-lumen — higher risk of gastric wall adherence on continuous suction compared to Salem sump.
• Never advance against significant resistance — may indicate coiling in the pharynx, esophageal obstruction, or nasopharyngeal structure. Withdraw and reassess.
• Tube displacement monitoring: document the centimeter marking at the naris at every assessment. A change in external tube length indicates possible migration.
• A patient with a nasogastric tube receiving tube feeds must have HOB elevated — NCLEX will test this in aspiration risk scenarios.
• If a patient receiving tube feeds develops sudden onset coughing or respiratory distress, stop the feed immediately and verify tube position.
• Flush before and after medications to prevent tube occlusion and avoid drug interactions from residual medication in the lumen.

Putting it together: the clinical picture

NG tube management touches many conditions you will see throughout nursing school and clinical practice. Patients with increased intracranial pressure may have NG tubes placed for medication delivery when they cannot swallow safely. Patients with hepatic encephalopathy often require enteral nutrition via NG tube when oral intake is inadequate. The decompression role of NG tubes appears in postoperative care, bowel obstruction, and acute conditions requiring gastric rest.

The verification principles you learn here — X-ray gold standard, pH testing, the failure of auscultation — apply whether you are inserting a standard Salem sump on a general medical floor or checking a Dobhoff in the ICU.

For your broader clinical skill development, the procedural approach here — patient preparation, stepwise technique, verification, complication monitoring — mirrors what you will apply in urinary catheterization, wound assessment, and other hands-on skills covered in your head-to-toe assessment coursework.

Author: Lindsay Smith, AGPCNP

Clinical sources: Metheny NA et al. (2019) on NEX measurement and gastric pH verification; ASPEN/SCCM enteral nutrition guidelines; Joint Commission Sentinel Event data on tube misplacement; Infusion Nurses Society (INS) standards of practice on NG tube verification; Perry AG, Potter PA & Ostendorf W, Clinical Nursing Skills and Techniques (Elsevier); AACT position statement on gastric lavage.