Dirty catch urine refers to a specific method of collecting a urine sample, often for diagnostic purposes. It's characterized by how the urine is collected and the part of the urine stream that's used. This method is different from a mid-stream catch.
Key Characteristics of Dirty Catch Urine
Here's a breakdown of what defines a dirty catch urine sample:
- Timing: The preferred collection time is after the individual has not urinated for at least one hour.
- Volume: The sample volume should be between 15 to 50 milliliters (mls).
- Collection Method: The "dirty catch" refers to collecting the first part of the urine stream, not the mid-stream, as is common with other collection methods.
- Container: The urine should be collected into a clean, polypropylene container.
- Preservatives: No preservatives are added to the container.
Why is it Called "Dirty Catch"?
The term "dirty catch" comes from the fact that the first part of the urine stream is believed to contain more bacteria, cellular debris, and other potentially contaminating substances from the urethra. This is in contrast to the mid-stream sample, which is considered cleaner.
Comparison with Other Collection Methods
| Feature | Dirty Catch Urine | Mid-Stream Catch Urine |
|---|---|---|
| Portion of Stream | First part of the stream | Middle part of the stream |
| Reason for Use | Typically for specific tests | Common for general analysis |
Practical Insights
- The dirty catch method may be used for tests that specifically require the analysis of these initial urinary elements.
- Always follow specific instructions from your healthcare provider when collecting a urine sample.
- Using a clean, sterile container is important to avoid contamination.
- If not specified, assume the midstream collection method should be used.
