Nutrition · Topic 6 of 12
NG Tube Insertion & Verification
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NG Tube Insertion & Verification
A nasogastric (NG) tube passes through the nose into the stomach. The danger is a tube in the airway — confirm placement before anything goes down it.
Before insertion
Measure nose → earlobe → xiphoid (NEX) and mark the tube
The NEX estimate often underestimates the length needed to reach the stomach; some guidance adds 5–10 cm. On average about 55 cm of tube is inserted to reach the stomach in an adult.
During insertion
Chin tucked at the oropharynx, then swallow as it advances
Swallowing helps the tube pass into the esophagus and reduces gagging. End-tidal CO₂ (capnography) during insertion can detect airway placement where the facility uses it.
After insertion: confirm placement
X-ray is the gold standard — before the first feeding or medication
UK NPSA/BAPEN and some US sources (Open RN, PA Patient Safety Authority) use pH 5.5 or lower. pH testing cannot detect a tip sitting in the esophagus — esophageal pH can read 4–5.5.
When the pH test misleads
A high pH cannot tell intestine from lung — both usually read 6 or higher
After: every use
Re-verify before every feeding and medication, and per protocol
A long-term NG tube can cause nasal pressure injury, epistaxis (nosebleed) and sinusitis: re-secure the tape and inspect the naris regularly.
Red flags
The danger is a tube in the airway
Patients with a weak cough or gag (sedated, intubated, low consciousness) can have the tube in the airway without any coughing.
Nursing priorities
Teach your patient
On removal, the nurse kinks the tube and withdraws it in one steady motion.
X-ray before the first use, pH 5 or lower before every use — never the "whoosh." A high pH could be lung: hold the tube and get an X-ray.
Sources · Nasogastric Tube Insertion (StatPearls) · Confirming Feeding Tube Placement (Pennsylvania Patient Safety Authority) · Position Paper on Nasogastric Tube Safety (BAPEN) · Selecting pH Cut-offs for NG Tube Verification (PMC) · NG Tube Insertion Length and Tip Verification in Adults (PMC) · Clinical Nursing Skills 17.3 Specialized Diets (OpenStax) · Nursing Advanced Skills 5.4 Insert a Nasogastric Tube (Open RN) · Nursing Advanced Skills 5.5 Remove an NG Tube (Open RN) · Verification of Feeding Tube Placement in Adults (AACN Practice Alert) · Follow your facility's protocol for NG tube placement checks.
NG Tube Insertion & Verification
An NG tube that looks correctly placed can still be sitting in a lung. The verification method you choose — and the one you skip — can mean the difference between feeding and aspiration pneumonia.
Nasogastric tube placement verification begins before insertion with measurement: from the tip of the nose to the earlobe to the xiphoid process (NEX measurement), typically 55–65 cm in adults. After insertion, the gold standard for confirming correct placement is an abdominal X-ray — this is required before the first feeding or medication administration. Once initial radiographic confirmation is obtained, ongoing verification between feedings relies on pH testing of aspirated contents. Gastric aspirate pH should be 5.5 or less (typically 1–4). Intestinal aspirate tends to be 6.0 or above, and respiratory aspirate is usually 7.0 or higher. Auscultation — the old method of injecting air and listening for a "whoosh" over the epigastric area — is no longer considered a reliable verification method because air insufflated into a tube in the lung or esophagus can transmit sounds that mimic gastric placement. You also monitor external tube markings at the naris between checks; migration outward or inward signals displacement. If at any point the patient develops coughing, choking, cyanosis, or oxygen desaturation during insertion, stop immediately and withdraw the tube.
Key Distinctions
Don't rely on auscultation alone — it has been abandoned as a primary verification method because it cannot reliably distinguish gastric from pulmonary placement. Students confuse gastric pH (≤5.5) with intestinal pH (≥6.0); both are "in the GI tract" but feeding into the small bowel unintentionally changes absorption dynamics. X-ray is required before FIRST use only — not before every feeding. Note: medications such as PPIs or H2 blockers can raise gastric pH above 5.5, making pH testing unreliable in those patients — obtain an X-ray if results are equivocal.
Clinical Pearl
If you can't get aspirate OR the pH is above 5.5, don't feed — get an X-ray. When in doubt, image it out.
Knowledge Check
3 quick questions on the must-knows for this topic.
What confirms NG placement before the first feeding?
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