Cystic Fibrosis
Key points
Genetics
Cystic fibrosis transmembrane conductance regulator (CFTR) mutation
Chromosome 7, autosomal recessive
5 classes of CFTR mutation
Commonest mutation is delta-F508 (a class 2 mutation - defective post translational modification of CFTR)
Inability of CFTR to transport chloride into mucus > sodium and water does not follow chloride > dehydrated, thick mucus
Systems affected
Lungs - chronic pseudomonas and staph aureus infection, mucus plugging, bronchiectasis, fibrosis, bleeding
GI - May present in neonatal period with meconium ileus, in childhood with constipation or distal intestinal obstruction (DIOS)
HPB - Pancreatic exocrine insufficiency, type 3c diabetes, pancreatitis, and gallstone disease
GU - Absent vas deferens, thick cervical mucus plugging
Diagnosis
Combination of clinical, genetics, sweat testing (>60 mmol/L sweat chloride is suggestive of CF - patient should be >2kg, >36 weeks corrected gestational age. >30mmol/L - borderline)
Can send meconium - Albumin is assessed using the tetrabromophenolethylester blue indicator <5 mg/g - normal, in CF >80 mg/g
CF - low meconium trypsin and chymotrypsin
Surgical considerations
Must always involve CF specialist team
Meconium ileus, Rectal prolapse - see Gastrointestinal section
Intussusception due to inspissated stool causing lead point - manage the same as non-CF patient
Pancreatitis - manage the same as non-CF patient
Gallstone disease - cholecystectomy if symptomatic
Constipation/DIOS - Manage with gastrografin follow through + enema, N-acetylcysteine, laxatives, hydration, ensure compliance with pancreatic enzyme supplements
Malnutrition/failure to thrive - feeding supplements may be needed, sometimes gastrostomy is beneficial if long term NG dependence
Vascular access - may require portacath
Gastro-oesophageal reflux - common, worsens lung function, consider fundoplication if present
Pneumothorax - manage the same as non-CF patient
Massive haemoptysis - Urgent CT angiogram + interventional radiology for embolisation
Other complications
Cirrhosis
Pancreatic endocrine + exocrine insufficiency
Infertility
Lung transplant criteria summary (Royal Brompton Lung Candidate Selection Criteria)
FEV1 <30% predicted
Pneumothorax in advanced disease
Haemoptysis not responding to IR embolisation
Progressive disease requiring multiple courses of antibiotics or 1 or more HDU/ICU admissions
Page edited by Mrs Charnjit Seehra BSc November 2024
References
https://www.cff.org/medical-professionals/sweat-test-clinical-care-guidelines
https://patient.info/doctor/cystic-fibrosis-pro
Escobar, Mauricio (Tony) A, et al. "Cystic Fibrosis." Pediatric Surgery NaT, American Pediatric Surgical Association, 2020. Pediatric Surgery Library, www.pedsurglibrary.com/apsa/view/Pediatric-Surgery-NaT/829674/all/Cystic_Fibrosis.
Royal Brompton & Harefield Hospitals POL231/1 Lung Candidate Selection Criteria