After initial radiographic confirmation of an nasogastric tube, a subsequent method to verify placement is to aspirate gastric contents and measure pH. What pH value indicates correct placement?

• A. Less than 4
• B. Greater than 6
• C. Equal to 7
• D. Greater than 7

Answer: (A)

Gastric contents are highly acidic because of stomach acid, so when you aspirate the tube and test the pH, a value under 4 indicates the material is from the stomach. This low pH confirms gastric placement more reliably than neutral or alkaline readings. Values above 6 or around 7 suggest non-gastric locations, such as the respiratory tract or the intestines, and would raise concern about tube placement. Keep in mind that medications like antacids or acid-suppressing drugs can raise gastric pH and potentially affect this test, so pH testing is best used in conjunction with radiographic confirmation and clinical assessment.