The correct place to obtain a catheter urine specimen is:

The needle-free sampling port on the drainage tubing

Disconnecting the catheter from the tubing

Why is bag urine unsuitable for culture?

It's been standing at room temperature, so organisms have multiplied that don't reflect the bladder

The bag's plastic interferes with the lab analyser

It's fine, actually, if the bag is under half full

Before aspirating from the port, you should:

Clean the port with a 2% chlorhexidine in 70% alcohol wipe and let it dry

Nothing; ports are sterile inside

There's no urine in the tubing at the port. Per policy, you:

Clamp below the port briefly, let fresh urine collect, sample, then remove the clamp

Squeeze the bag to push urine back up the tubing

Take the sample from the bag instead, just this once

Abandon the specimen permanently

The specimen is in the container. The remaining marks come from:

Labelling at the bedside against the patient's wristband, documenting, and prompt dispatch to the lab

Labelling in the treatment room where the pens are

Storing the sample on the ward windowsill for the porter

Part A of 3 The 20 Skills Stations Chapter 11 of 35

Catheter Specimen (CSU): OSCE Station Checklist

The NMC OSCE catheter specimen station: sampling from the port, keeping the closed system intact, labelling rules, and 5 practice questions.

Start reading ← OSCE course outline ~5 min read

By JobLabs Editorial · UK healthcare reference editorial team

· July 18, 2026 · 2 min read

The CSU station tests one principle wearing a procedure: the closed drainage system stays closed. Every wrong answer available in this station is some way of opening it.

The sequence:

Confirm the indication (suspected infection, surveillance per policy) and gather: sampling syringe, port wipe, sterile specimen container, label and form.
Hand hygiene, identity, explanation, consent. Curtains; expose only the tubing.
Locate the needle-free sampling port on the drainage tubing. Not the bag, not the connection.
No urine at the port? Clamp the tubing below it briefly, per policy, and let fresh urine pool.
Clean the port: chlorhexidine/alcohol wipe, friction, air-dry.
Aspirate the required volume with the syringe (or vacuum system, per the equipment provided).
Transfer to the sterile container without touching its inside. Remove any clamp.
Gloves off, hand hygiene.
Label at the bedside against the wristband; document; dispatch promptly.

The two “why” questions

Examiners attach reasoning questions to this station more than most, because the procedure is easy and the understanding is the point.

Why not the bag: bag urine has been incubating at room temperature; culturing it grows the bag’s colony, not the bladder’s, and the patient ends up on antibiotics for organisms they don’t have.

Why the closed system matters: catheter-associated urinary tract infection is among the most common healthcare-associated infections, and every break in the circuit is an entry door. The sampling port is the engineered answer; using anything else defeats the engineering.

Small marks that add up

The clamp, if used, must come off, and saying so aloud is the safe way to prove you know. The port dries before access. The container’s interior is a key part in ANTT terms; fingers stay out. And the label goes on at the bedside, against the wristband, because mislabelled specimens are a national safety theme and the checklist mirrors it.

Documentation: what was collected, when, from where, the test requested, and anything the urine’s appearance told you on the way past (cloudy, blood-stained, offensive). Appearance observations are free marks lying on the ground.

Five questions below, then the other half of catheter care: catheter removal.

Sources & further reading

Key takeaway from Catheter Specimen (CSU): OSCE Station Checklist

Frequently asked questions

Why can't the sample come from the drainage bag?

Urine sits in the bag for hours at room temperature, growing organisms that were never in the bladder. A bag sample produces false culture results and wrong antibiotics. Fresh urine from the sampling port reflects what's actually in the patient.

What if there's no urine in the tubing at the port?

Clamp the tubing a few centimetres below the port for a short period per local policy, let fresh urine collect above the clamp, sample, then remove the clamp. Leaving a clamp on a catheter is its own incident; removing it is part of the procedure.

Why label at the bedside?

Specimen labelling errors are a recognised patient-safety theme: a tube labelled away from the patient can become someone else's result. Label against the wristband, at the point of collection, before anything leaves the room.

Check your understanding

Quick quiz: Catheter Specimen (CSU): OSCE Station Checklist

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

1
The correct place to obtain a catheter urine specimen is:
The sampling port exists so the closed system never opens. The bag options give stale, contaminated urine; disconnecting the circuit breaks the closed system and raises CAUTI risk. Port only, every time.
2
Why is bag urine unsuitable for culture?
Bag urine is an incubated specimen: whatever it grew in the bag drives the result, and the patient gets treated for the bag's flora. This is the 'why' question examiners attach to the station, and 'because policy says so' doesn't collect the mark.
3
Before aspirating from the port, you should:
Scrub the port, let it air-dry, then access: the same hub-hygiene rule as IV ports. Flushing saline into a urine specimen dilutes and contaminates it. The dry step matters; wet disinfectant entering the sample can suppress the culture.
4
There's no urine in the tubing at the port. Per policy, you:
A short clamp below the port pools fresh urine for sampling. Reflux from the bag reintroduces contaminated urine to the bladder side, the exact backwards-flow the drainage design prevents. And the clamp must come off; say that step aloud so the examiner hears the plan.
5
The specimen is in the container. The remaining marks come from:
Label at the point of care against the identity band, record the collection in the notes, and get the specimen to the lab promptly (or refrigerated per policy). Urine deteriorates fast at room temperature; a perfect collection with slow dispatch is a spoiled sample.

Catheter Specimen (CSU): OSCE Station Checklist

The two “why” questions

Small marks that add up

Sources & further reading

Frequently asked questions

Quick quiz: Catheter Specimen (CSU): OSCE Station Checklist

Keep reading

Urinary Catheter Care Questions

MSSU Collection: OSCE Station Checklist

Catheter Removal: OSCE Station Checklist