A healthy empty stomach is very acidic, with a normal pH range of 1.5 to 2.5. Immediately after consuming a meal, the pH of the stomach increases to a range of 4.0 to 6.0. The pH of stomach contents is often tested to help diagnose gastrointestinal illnesses, and after a nasogastric tube has been inserted into the stomach to verify that the tube has been properly placed. If the liquid obtained by aspirating the nasogastric tube of a patient who has not eaten in at least two hours has a pH of 1.5 to 2.5, placement in the stomach can be confirmed.
Don gloves and place paper towels on a flat surface, such as a table or counter top. Place a litmus strip on the paper towels in preparation for the procedure.
Turn off suction if the patient's stomach is being suctioned via the nasogastric tube.
Remove the cap from the syringe. Uncap the nasogastric tube if the patient's stomach was not suctioned. Remove the nasogastric tube from the suction port if his stomach was being suctioned.
Insert the syringe into the nasogastric tube and pull back on the plunger to retrieve stomach contents.
Remove the syringe from the nasogastric tube and place it on the paper towels. Return the nasogastric tube to the suction port if the patient's stomach was being suctioned or recap the nasogastric tube if not.
Expel a small amount of the stomach contents onto the litmus strip by pushing the plunger of the syringe.
Wait the amount of time specified on the litmus pH chart, which is typically one minute.
Compare the color of the litmus strip to the colors on the litmus pH chart. Match the color of the strip to the color it most closely matches on the chart to determine the pH of the stomach contents.