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 client 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.