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Part A of 3 The 20 Skills Stations Chapter 19 of 35

Fluid Balance: OSCE Station Checklist

The NMC OSCE fluid balance station: completing the chart accurately, calculating the balance, spotting oliguria, escalation, and 5 questions.

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JobLabs Editorial
By JobLabs Editorial · UK healthcare reference editorial team
· · 2 min read

The fluid balance station takes the arithmetic from the CBT numeracy chapter and puts it at a bedside, where the marks stop being about addition and start being about completeness, timing and escalation.

The station’s usual shape: a scenario unfolds (drinks taken, an IV antibiotic given, a catheter emptied, a feed running) and you keep the chart, total it, and respond to what the numbers say.

Completeness is the real test

The intake side fails on clinical volumes: the 100 mL IV antibiotic bag, the running feed (rate × hours), the saline flushes. The output side fails on everything that isn’t urine: vomit, wound drains, stoma output. The examiner’s script includes these precisely because ward charts miss them; a chart that captures the drinks jug and nothing else is the fail state being tested.

Real-time recording is the second half of accuracy. Chart each event as it happens; a shift reconstructed from memory at handover produces confident, wrong totals, and the scenario will feed you events mid-station to see what you do with them.

The numbers that demand action

Two thresholds convert this station from clerical to clinical:

  • Urine output below 0.5 mL/kg/hour, sustained: oliguria. For 70 kg, under 35 mL/hour. Check the mechanical causes first (kinked tubing, blocked catheter), then escalate; falling urine output is among the earliest deterioration signals and the examiner wants to hear the escalation, not just see the low number circled.
  • A large or trending deficit alongside observations: a -1,200 mL balance with rising pulse and thirst is hypovolaemia in progress. Balance charts earn their labour when their trend is read with the obs chart, and saying that integration aloud (“deficit plus tachycardia, so I’m escalating for a fluid review”) is the station’s best sentence.

Positive balances have meanings too: expected in resuscitation, concerning in heart failure. The interpretation mark is for matching the number to this patient, not for preferring one sign over the other.

Documentation closes as always: totals accurate, balance calculated with its sign, abnormalities noted with the action taken. The chart is the document; keeping it well is the skill.

Five questions below, then the final skills-station chapter: MSSU collection.

Sources & further reading

  1. 1NMC — Test of competencenmc.org.uk
  2. 2NICE CG174 — Intravenous fluid therapy in adultsnice.org.uk
  3. 3RCP — National Early Warning Score resourcesrcp.ac.uk
Key takeaway from Fluid Balance: OSCE Station Checklist

Frequently asked questions

What goes on the intake side that candidates miss?
IV antibiotic volumes, drug infusions, flushes, and NG or PEG feed. The drinks jug is the easy half; the chart fails on the clinical inputs nobody logs.
What urine output triggers escalation?
Below 0.5 mL per kg per hour, sustained, in an adult: for a 70 kg patient that's under 35 mL/hour. Falling output is one of the earliest signs of deterioration and feeds directly into NEWS2-era escalation.
When is the chart totalled?
Running totals through the shift and a formal 24-hour total, but the recording itself happens at the time of each intake or output. Retrospective evening reconstruction is the habit the station is designed to expose.

Check your understanding

Quick quiz: Fluid Balance: OSCE Station Checklist

5questions. Click an answer to see the explanation. Your score is saved on this device only.

  1. 1

    Over your shift a patient drinks 900 mL, receives 500 mL IV fluid and a 100 mL IV antibiotic, and their catheter drains 600 mL with 150 mL from a wound drain. The balance is:

  2. 2

    A 70 kg patient's catheter has drained 20 mL in the last hour. You:

  3. 3

    The NG feed pump has run at 50 mL/hour for your whole 8-hour shift. The intake entry is:

  4. 4

    When should each drink or output be written on the chart?

  5. 5

    A post-operative patient's cumulative balance is -1,200 mL with a rising pulse and thirst. Your reading is:

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