Introduction
Your child is suspected to be suffering from urinary tract infection (UTI). This is a condition in which bacteria are actively growing in the urinary tract, causing inflammation and systemic illness in the child.
How to diagnose UTI?
UTI can be diagnosed by culture of a properly collected urine sample. A significantly positive culture tells us what bacteria is causing the UTI and what drugs can be used to treat it. This urine sample needs to be collected carefully so that it does not mix with any fluid or surface with contaminating bacteria. Otherwise the culture result will be misleading.
Collecting urine
Usually a mid-stream urine sample is collected to test for UTI. However in small children who do not void voluntarily, urine is usually obtained by one of the following methods:
1. Supra-pubic aspiration
Put a very fine needle through the lower abdomen into the bladder to aspirate a few millilitres of urine. It is usually done in young babies below one year of age. The good point is that it is the most definite method to diagnose or exclude UTI in infants, because the urine sample obtained should be sterile and any positive bacterial growth is abnormal. The limitation is that it is only successful when there is a full bladder (previous experience reported success rates varying from 36-60%). If it fails, we can repeat it at a later time or collect urine by bladder catheterization.
2. Bladder catheterization
Insert a soft plastic tube into the bladder through the urethra (that is, urinary passage through which urine passes out of the body). Then urine drained out into a sterile container. The good point is that urine can almost always be obtained by this method (unless the child has just emptied his/her bladder by voiding). Urine tests can thus be done quickly and treatment can be given to your child if needed. The bad point is that there is a chance of contamination of the urine sample, and the culture result can only tell us how likely the diagnosis of UTI is or is not.
3. Clean catch urine collection
Clean your child’s perineum and keep it exposed while waiting for him/her to void. The urine stream is then collected by a sterile container. This may take a long time if your child cannot void when asked to.
Any risk and complication?
1. Supra-pubic aspiration
Your child will feel the pain of a needle puncture. Rarely there may be transient blood stained urine after the procedure, and this will settle in 1-2 days.
2. Bladder catheterization
Your child will feel the discomfort of the tube going through the sensitive urethra. Rarely there may be minor trauma causing transient blood stained urine, or transient pain on voiding. Rarely bacteria may be introduced into the bladder and cause an infection, though the chance is small (1.9-6.1%).
3. Clean catch technique
There is no complication, but a delay in urine testing may delay the treatment that your child needs.
Preparing your child for the procedure
- Your doctor will discuss with you and let you know which method of collecting urine is best for your child.
- It is important for your child to have urine in their bladder before carrying out the procedure. Please give a good drink to your child shortly before the procedure, and examine the nappy to ensure that your child has not voided just before the procedure.
- Supra-pubic aspiration and bladder catheterization are relatively safe procedures. Your cooperation would very much facilitate such procedures.
Remarks
The list of complications is not exhaustive and other unforeseen complications may occasionally occur. In special patient groups, the actual risk may be different. For any queries or further information, please consult our medical staff.
