Possible complications associated with cystic fibrosis include:

• Bronchiectasis. Lung disease in which the bronchial tubes become stretched out and form pockets where mucus collects. Bacteria grow in the mucus, causing repeated lung infections.
  
  
• Clubbing. Widening and rounding of the tips of the fingers and toes. It occurs when the lungs fail to move enough oxygen into the bloodstream.
  
  
• Collapsed lung (pneumothorax).
  
  
• Diabetes. Cystic fibrosis-related diabetes (CFRD) shares some features of type 1 diabetes and some features of type 2 diabetes. Between 10 and 20 percent of cystic fibrosis patients develop CFRD, according to the Cystic Fibrosis Foundation.
  
  
• Gallstones. Solid deposits formed in the gallbladder or nearby ducts that may cause ducts to become blocked.
  
  
• Intestinal blockage. This complication particularly affects newborns.
  
  
• Liver disease. Results from inflammation of or blocked bile ducts.
  
  
• Low bone density. Results from a lack of vitamin D, and can lead to osteoporosis.
  
  
• Nasal polyps. Growths that develop in the nose that may require surgery.
  
  
• Pancreatitis. Inflammation of the pancreas.
  
  
• Rectal prolapse. Chronic coughing and difficulty passing stool can force rectal tissue to move outside of the rectum.
  
  
• Sinusitis. Swelling of the air-filled spaces behind the eyes, forehead and nose. As the sinuses swell, they become blocked with mucus that creates a breeding ground for infection.
  
  
• Intussusception. Condition in which one part of the intestines displaces another part. This tends to occur in children older than 4 years of age.

Infertility also can be a complication for many adult patients with cystic fibrosis. Most men with cystic fibrosis are infertile because the gene that causes thick mucus also interferes with the action of the vas deferens, the tube that transports sperm away from the testicles. Women usually remain fertile but may have lowered fertility rates. However, both men and women with cystic fibrosis often can take advantage of new reproductive technologies to become a parent.