Nasogastric Tube Depth Markings: What They Mean & Why They Matter

Centimeter markings on a nasogastric (NG) tube indicate distance from the tip to the naris.

Why It’s Critical

• Correct placement: Ensures tip sits in stomach (typically 50‑60 cm in adults).
• Prevents complications: Too deep → intestinal perforation, knotting. Too shallow → aspiration, tube dislodgement.
• Monitors migration: Daily marking checks detect tube movement.

Verification Methods

1. Aspirate gastric contents → pH ≤5.5.
2. Chest X‑ray (gold standard for initial placement).
3. Capnography / colorimetric CO₂ (emerging).

Best Practices

• Mark tube at naris with indelible tape at insertion.
• Document centimeter marking at naris each shift.
• Follow manufacturer’s instructions for specific tube type (weighted, Salem sump, Dobhoff).
• Reposition or replace if migration >2‑3 cm.

Accurate depth tracking = patient safety.