Delayed passage of meconium

Meconium ileus and Hirschsprung disease (congenital aganglionic megacolon) should be considered in any neonate with delayed passage of meconium as 99% of healthy,  infants pass stool within 48 hours of birth. These 2 conditions have overlapping clinical features but can usually be differentiated by the level of intestinal obstruction and meconium consistency.

Meconium ileus is virtually diagnostic for CF. Although only 20% of patients with CF develop meconium ileus, almost all newborns with meconium ileus have CF. A mutation in the CF transmembrane conductance regulator gene results in abnormal chloride and sodium transport and thick, viscous secretions in multiple organs. Thick, inspissated meconium is difficult to propel, resulting in obstruction at the level of the ileum and a narrow, underdeveloped colon (microcolon).

Nearly all patients with CF develop sinopulmonary disease. Opacification of all sinuses can be seen as early as age 8 months, and  often require surgical debridement of  sinuses

Hirschsprung disease is associated with Down syndrome, which in turn is associated with an increased risk of Alzheimer disease and hypothyroidism. It typically presents with increased rectal tone, "squirt sign" (forceful expulsion of stool after rectal examination), and obstruction  at the rectosigmoid region with a transition zone between the aganglionic rectum and proximal dilated colon. Patients with CF are no more likely to develop Alzheimer disease or hypothyroidism than individuals in the general population.

Although men with CF are typically infertile due to congenital absence of the vas deferens, only 20% of women with CF have fertility problems. Infertility is due to the combination of secondary amenorrhea from malnutrition and thick cervical mucus obstructing sperm entry

Approximately 20% of patients with CF develop sensorineural hearing loss due to frequent treatment with aminoglycosides for gram-negative infections (eg, Pseudomonas aeruginosa)