Your doctor will diagnose OC from blood tests called liver function tests (LFTs) and a serum bile acid test. They should also be keen to exclude all other possible causes of your itching, such as allergies or eczema.
Doctors may also take into consideration the following as evidence of OC:
- pale stools
- dark urine
- a family history of OC
Liver function tests are performed to gain an idea how the different parts of your liver are functioning. They are made up of a number of separate examinations, each looking at different properties of your blood.
In OC, doctors will be looking for abnormal levels of the liver enzymes alanine aminotransferease (ALT), aspartarte aminotransferase (AST) and gamma glutamyl transferase (GGT).
The most specific test involves measuring serum bile acids. Usually the level of bile acids in your blood is raised before the liver function tests can detect any changes. If the tests are within normal limits and you carry on itching, it is important that the tests are repeated.
Unfortunately the serum bile acid test is not available in all hospitals. Your doctor may need to send a sample to a specialist centre for diagnosis.
If LFTs are abnormal, doctors will carry out screening to eliminate other causes such as viral hepatitis and autoimmune disease before diagnosing OC.
This may involve an ultrasound scan to look for any sign of liver abnormality. Doctors may also use ultrasound to check for gallstones, as research suggests these occur more often with OC.
If measured levels return to normal or increase rapidly, doctors may consider that you do not have OC.
Research suggests that absorption of vitamin K is reduced in OC. A lack of vitamin K may affect your blood’s clotting mechanism and increase blood loss during birth. Following diagnosis it is important to have a blood test to check how your blood is clotting before the birth as you may need extra vitamin K.
Your pregnancy may involve having regular tests to monitor your baby’s heartbeat over a set period of time (cardiotocography).