If your cat is showing symptoms of bile duct inflammation, making a definitive diagnosis begins with you providing a detailed history of your cat's current symptoms along with any past symptoms or health problems. Prior episodes of bladder stones could indicate a recurrence and potential blockage. Previous abdominal surgery, especially any procedures involving the bladder, liver or small intestines might indicate fibrosis or adhesions. Exposure to other cats, especially those who are potentially not vaccinated against FeLV or FIP, should be disclosed.
Keeping in mind the history and list of symptoms, your veterinarian will perform a thorough physical exam that includes taking your cat's temperature, inspecting mucous membranes, palpation of the abdomen to check for swelling or lumps, and feeling lymph nodes. Based on the findings of the initial exam, your veterinarian will likely conduct other diagnostic tests including the following:
- Blood tests
- Urinalysis
- Stool sample
- Abdominal X-ray
- Ultrasound
The blood, urine, and stool samples will be examined for evidence of bilirubin. Bilirubin is one constituent of bile that is normally excreted via urine and stool, but it will become concentrated in the blood if the bile ducts are not functioning properly. High levels of bile in the blood paired with low levels in stool and urine indicate poor function of bile ducts. Excess bilirubin in the blood causes jaundice, hence the inspection of mucous membranes for the telltale yellow discoloration.
X-rays of the abdomen will sometimes help pinpoint the existence and location of bladder stones, but if nothing shows up on the radiographs your veterinarian might perform an ultrasound. The ultrasound will allow for the evaluation of your cat's organs, specifically swelling or thickening of the liver, pancreas or gall bladder.
If the diagnosis remains elusive, your vet may conduct the following additional tests:
- Ultrasound-guided fine needle aspiration
- Ultrasound-guided biopsy
These tests allow your veterinarian to take samples from the bile ducts and affected organs to look for infection or cancer.
One other procedure that is not uncommon if a blockage is suspected is exploratory surgery. Since blockages and tumors need to be removed surgically anyway, this procedure allows your vet to diagnose and treat the problem at the same time.