It's usually clear from your symptoms whether you have stress incontinence. But your doctor will ask you questions and may do some tests to find out what's causing your symptoms.
Your may be referred to a doctor specialising in the treatment of stress incontinence. This might be a urologist (a doctor with specialist knowledge of the parts of your body that make, carry, and store urine) or a gynaecologist (a doctor with specialist knowledge of diseases and conditions that particularly affect women).
You may also be referred to a continence nurse or a physiotherapist who specialises in teaching pelvic floor exercises. You could go to a continence clinic to try simple treatments for stress incontinence that don't involve surgery.
Questions your doctor may ask
Your doctor may ask you about: 
Keeping a diary
You may be advised to keep a bladder diary for a week, or a frequency and volume chart.  You'll write down when you go to the toilet, if you leak any urine, and what you drink. Your doctor may also ask you to measure how much urine you pass in 24 hours. To do this, you can use a special pan that fits over the rim of your toilet. 
Your doctor may also ask you to write down how many pads you use each day or how wet they get over several hours. This tells your doctor how much urine you're leaking.  It's called a pad test.
Having an examination
Your doctor may examine the area around your vagina and back passage (rectum) for medical conditions that can cause incontinence. For example, bad constipation can cause incontinence. Also, if you have poor reflexes and feeling in this area, it can mean that your nerves are damaged. 
Tests on your urine
Your doctor may send a sample of your urine to be tested in a laboratory, or use a dipstick to test your urine straight away.  This checks for signs of infection or another problem.  This test is called a urinalysis. It should be done before you start any treatment. 
Tests on your bladderUrodynamic tests
These are tests to check how well your bladder is working. You need to have these tests before surgery for stress incontinence.  They can tell if you also have another type of incontinence (see Other types of incontinence) or if there are any other complications. This information will help you and your doctor choose the right treatment for you.Uroflowmetry test
A uroflowmetry test measures how much urine you pass and how fast it comes out. To do this, you pass urine into a toilet that has a pan to catch your urine, and a measuring device. You do this in private. A graph shows how fast your urine came out and helps your doctor tell if your bladder is working normally.Cystometry
This test measures how much liquid your bladder can hold and the pressure inside your bladder. A doctor or nurse will put a small tube called a catheter into your bladder to empty it. Then a smaller tube is used to fill your bladder with water. Another tube is usually put into your back passage (rectum) to measure the pressure there as well. You'll be asked how you feel as your bladder fills and when you get the urge to pass urine. And you may be asked to cough to see if you leak any urine. This test may be slightly uncomfortable, but it shouldn't hurt.