Ultrasound of the temporal arteries may show vessel wall oedema in giant cell arteritis. This appears as a hypoechoic ring around the circumference of the artery lumen (halo sign). Meta-analysis has confirmed the sensitivity and specificity of this test to be 68% and 91% respectively. 31 The gold standard remains temporal artery biopsy and the results of further studies comparing the two procedures are awaited. In Takayasu’s arteritis ultrasound can localise areas of arteritis in extracranial vessels, but only a limited number are accessible. 32
Infertility affects both men and women. At least 97% of men with cystic fibrosis are infertile, but not sterile and can have children with assisted reproductive techniques.  The main cause of infertility in men with CF is congenital absence of the vas deferens (which normally connects the testes to the ejaculatory ducts of the penis ), but potentially also by other mechanisms such as causing no sperm , abnormally shaped sperm , and few sperm with poor motility .  Many men found to have congenital absence of the vas deferens during evaluation for infertility have a mild, previously undiagnosed form of CF.  Around 20% of women with CF have fertility difficulties due to thickened cervical mucus or malnutrition. In severe cases, malnutrition disrupts ovulation and causes a lack of menstruation .