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Andrew Pollack-Gray

Nursing Notes

Measuring Intake and Output

4 min read

When & Why?

Intake and output (I&O) monitoring measures fluids entering and leaving the body.
It helps the healthcare team evaluate hydration and fluid balance.

Before You Start

  • Review the I&O order and care plan.
  • Identify what needs to be measured and how frequently.
  • Assemble graduated containers and documentation supplies.
  • Explain the procedure to the resident.
  • Perform hand hygiene and wear appropriate PPE when handling bodily fluids.

Steps

Measuring Intake

  1. Record the volume of drinks consumed.
  2. Include other items counted as fluids under the facility’s protocol.
  3. Measure fluids actually consumed, not just fluids served.
  4. Include enteral or IV intake only according to the assigned documentation process.
  5. Record measurements in milliliters (mL).
    Examples of oral intake:
  • Water.
  • Juice.
  • Milk.
  • Soup or broth.
  • Gelatin or frozen desserts when counted as fluids by facility policy.

Measuring Output

  1. Use the appropriate collection device.
  2. Avoid contamination with toilet paper.
  3. Transfer fluid into a graduated container if necessary.
  4. Read the volume at eye level on a stable surface.
  5. Record output in milliliters.
  6. Clean and store measuring equipment as directed.
  7. Report unusual volume, appearance, or symptoms.

Calculating Totals

Total Intake: Sum of all counted fluid intake.
Total Output: Sum of all measured fluid output.
Net Fluid Balance = Intake − Output
Example:

  • Intake = 1,500 mL.
  • Output = 1,200 mL.
  • Net = +300 mL.
    Important: Measured net balance does not capture every source of fluid loss, including unmeasured perspiration and breathing losses.

Safety & Observations

  • Document values accurately and promptly.
  • Don’t estimate when a measurement can be obtained.
  • Follow procedures for incontinent residents.
  • Report unexpectedly low urine output.
  • Observe for signs of dehydration or fluid overload.
  • Don’t independently change fluid restrictions or intake goals.

Unexpectedly Low or Absent Urine Output

Possible concerning observations include:

  • Urine output substantially below the resident’s usual pattern or prescribed reporting parameters.
  • No recorded urine output during an interval when output would normally be expected.
  • A resident reporting an inability to urinate despite feeling the need.
  • Lower abdominal discomfort or distention accompanying inability to urinate.
  • Decreased urine output accompanied by weakness, confusion, swelling, or breathing difficulty.

CNA Response:

  1. Verify that the recorded output is accurate and that no collection or documentation was missed.
  2. For a resident with a urinary catheter, observe for visible kinks, tension, or obvious drainage-system problems without disconnecting or manipulating the catheter.
  3. Notify the nurse promptly about unexpectedly low or absent output.
  4. Escalate immediately for sudden inability to urinate with significant pain or distention, or for severe accompanying symptoms.
  5. Report the time of the last known output, measured amounts, symptoms, and relevant changes from baseline.
  6. Follow instructions for continued observations and documentation.

Important: Do not independently diagnose urinary retention, alter prescribed fluid intake, irrigate a catheter, or initiate treatment.

Urine-output thresholds and monitoring intervals depend on the resident’s condition and care plan. Do not assume a single cutoff applies to every resident.

What Should I Remember?

  • 1 liter = 1,000 mL.
  • 1 US fluid ounce ≈ 30 mL for common bedside calculations.
  • The total is only as reliable as the individual measurements.

Practice

  • Studied
  • Observed
  • Practiced
  • Passed checkoff

Sources

Flashcards

What is the net fluid balance formula?01-foundations / clinical-skills
Answer

Measured intake minus measured output.

What is the approximate mL equivalent of one US fluid ounce?01-foundations / clinical-skills
Answer

30 mL.

Does measured output include every route of fluid loss?01-foundations / clinical-skills
Answer

No; breathing and sweating may be unmeasured.

What is urinary retention?01-foundations / clinical-skills
Answer

Inability to empty the bladder completely or at all.

What should a CNA do when urine output is unexpectedly low or absent?03-application / clinical-skills
Answer

Check recording accuracy, observe for problems, and promptly report to the nurse.

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