The diagnosis of colic is made only when the physical examination reveals no organic cause for the infant’s excessive crying. The examination begins with vital signs, weight, length, and head circumference, looking for effects of systemic illness on growth. A thorough inspection of the infant is important to identify possible sources of pain, including skin lesions, corneal abrasions, hair tourniquets, skeletal infections, or signs of child abuse such as fractures (see Chapters 22 and 199). Infants with common conditions such as otitis media, urinary tract infections, mouth ulcerations, and insect bites may present with crying. A neurologic examination may reveal previously undiagnosed neurologic conditions, such as perinatal brain injuries, as the cause of irritability and crying. Observation of the infant during a crying episode is invaluable to assess the infant’s potential for calming and the parents’ skills in soothing the infant.
Laboratory and imaging studies are reserved for infants in whom there are history or physical examination findings suggesting an organic cause for excessive crying. An algorithm for the medical evaluation of an infant with excessive crying inconsistent with colic is presented in Figure 11-2.
The differential diagnosis for colic is broad and includes any condition that can cause pain or discomfort in the infant and conditions associated with nonpainful distress, such as fatigue or sensory overload. Cow’s milk protein intolerance, maternal drug effects (including fluoxetine hydrochloride via breastfeeding), and anomalous left coronary artery all have been reported as causes of persistent crying. In addition, situations associated with poor infant regulation, including fatigue, hunger, parental anxiety, and chaotic environmental conditions, may increase the risk of excessive crying. In most cases, the cause of crying in infants is unexplained. If the condition began before 3 weeks’ corrected age, the crying has a diurnal pattern consistent with colic (afternoon and evening clustering), the infant is otherwise developing and thriving, and no organic cause is found, a diagnosis of colic is indicated.
Figure 11-2 Algorithm for medi-cal evaluation of infants with acute excessive crying. (From Barr RG, Hopkins B, Green JA, editors: Cry-ing complaints in the emergency department. In Crying as a Sign, a Symptom, and a Signal, London, 2000, MacKeith Press, p. 99.) INFANT WITH ACUTE EXCESSIVE CRYING History and physical examination Urinalysis and urine culture Assess pattern, observe 1–2 hours Crying ceases spontaneously Follow 24 hours in hospital or at home Consider idiopathic crying episode Crying persists Consider: Radiologic studies   Chemistry tests   Pulse oximetry Toxicology tests Lumbar puncture Continue observation, in hospital, until crying stops or diagnosis made History of recurrent episodes consistent with colic Treat for infantile colic Identify cause and treat Ensure appropriate follow-up Urinary tract infection
The management of colic begins with education and demystification. When the family and the physician are reassured that the infant is healthy, without infection, trauma, or underlying disease, education about the normal pattern of infant crying is appropriate. Learning about the temporal pattern of colic can be reassuring; the mean crying duration begins to decrease at 6 weeks of age and decreases by half by 12 weeks of age. Colic does not always resolve by 3 months of age. Approximately 15% of infants with colic continue to have excessive crying after 3 months of age.