I. Description of the problem. There is no reliably objective definition of colic. It is often characterized as persistent, excessive, paroxysmal crying in an otherwise well, thriving infant; colic begins at about 3 weeks of age, peaks at 6-8 weeks of age, and dissipates by 4 months of age. However, the length of time spent crying to qualify as excessive crying continues to be debated and alters true estimates of the prevalence. Using the most restrictive definition, Wessel’s rule of threes (more than 3 hours per day, for 3 or more days per week for more than 3 weeks of excessive crying), colic is thought to affect 10% of all full-term infants, whereas using the least restrictive definition, problematic crying, colic is thought to affect up to 40% of all full-term infants. In addition, parental tolerance for infant crying is quite variable: some are stoic in the face of constant crying, whereas others come to the primary care clinician for the occasional whimper. The best definition of colic may be a purely clinical one: colic is any recurrent inconsolable crying in a healthy and well-fed infant that is experienced by the parents or caregivers as a problem.
A. Epidemiology.
Estimates range from 7%-40%, depending on the criteria for diagnosis
No differences by gender, breast- versus bottle-fed, full-term versus preterm, or birth order
Two times increased risk if maternal smoking during pregnancy
Whites > nonwhites
Parents older and more educated
Industrialized countries > nonindustrialized
More frequent the farther away from the equator
Increased incidence of physical abuse in colicky infants especially shaken baby syndrome
B. Clinical features.
1. Colic typically begins at 41-42 weeks of gestational age (including preterm infants).
2. Two patterns of colic have been noted.
a. Paroxysmal fussing typically occurs between 5-8 PM. The infant is contented and easily soothed at other times of the day. These infants do not cry more frequently over 24 hours; rather, they sporadically cry for a longer period of time.
b. The hyperirritable infant is one whose crying occurs at all hours of the day, often in response to ambiguous external or internal stimuli. They may also exhibit increased tone and other signs of hyperarousal.
3. Colic stops as mysteriously as it starts, by 3 months in 60% and by 4 months in 80%-90% of infants. Infants crying past the 4-month period are at higher risk for developmental delays.
4. There are no predictable long-term infant outcomes (behavioral, temperamental, or psychological) that emerge from a colicky infancy, although later sleep problems are often seen, and parents and caregivers with a colicky infant may have more depression, anxiety, and marital difficulties.
C. Etiology. Theories of causation abound (Table 37-1), but evidence for any one is scant. It appears likely that there is no single cause of colic and that it represents the final common pathway for a number of etiologic factors.
II. Making the diagnosis.
A. History: key clinical questions.
1. “When does the crying occur?” The timing of the cry provides useful information. For example, if it occurs directly after a feeding, aerophagia, or gastroesophageal reflux may be considered. If it occurs reliably 1 hour after feedings, a formula intolerance is possible. If the crying occurs only from 5-7 PM everyday, it is difficult to posit an organic problem that would cause pain at only one time of the day.
2. “What do you do when your baby cries?” It is important to determine how the parents have tried (successfully and unsuccessfully) to console the infant. In some cases, their
techniques may have inadvertently worsened the situation (e.g., anxiously overstimulating a hypersensitive infant); in other cases, the technique may be inappropriate (e.g., giving half-strength formula or dangerous/suspect home/folk remedies).
Table 37-1. Theories of the etiology of colic
Gastrointestinal
Cow’s milk protein intolerance (an equal number of studies have found an association of cow’s milk with colic as have not)
Gastroesophageal reflux
Lactose intolerance (higher breath H2 level in some colicky infants)
Immature gastrointestinal system (ineffective peristalsis; incomplete digestion; gas)
Faulty feeding techniques (e.g., under- or overfeeding, infrequent burping)
Hormones causing enterospasm
Increased motilin levels (one study showed higher levels of motilin, but not vasoactive intestinal peptide or gastrin, in colicky infants)
Decreased cholecystokinin levels (→ gallbladder contractions)
Hormonal
Increased circulating serotonin (hypothetical only but an attractive hypothesis because serotonin has a circadian rhythm in infancy, which could explain the curious timing of paroxysmal fussing)
Progesterone deficiency (one study in 1963, never repeated)
Neurological
Imbalance of autonomic nervous system (parasympathetic » sympathetic)
Immature neurotransmitters
Nonestablished circadian rhythm
Temperamental
Difficult temperament (but there is poor correlation of colic and later temperament)
Hypersensitivity (crying at end of day represents discharge after a long day of shutting out intrusive environmental stimuli, parents may be overstimulating)
Parental behaviors/handling
Most studies do not show a relationship between parental anxiety, psychopathology, and/or emotional difficulties and colic; at most, nonoptimal handling may exacerbate but not cause the symptoms
3. “What does the cry sound like?” Most parents can distinguish a cry of pain from that of hunger. In addition, the description of the cry provides insight into parental distress, empathy, or anger with the cry. Research suggests that colicky cries have a higher pitch and are described as “urgent” or “piercing.”
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Colic
Colic
Steven Parker
Tracy Magee
