Infantile colic is one of the more distressing challenges for new parents and is a reason for 10% to 20% of pediatrician visits during the early weeks of an infant's life. Colic is estimated at affecting 5% to 40% of infants worldwide. The condition typically presents in the second or third week of life, peaks around 6 weeks, and usually resolves by the age of 12 weeks. Inconsolable crying, irritability, and screaming without an obvious cause characterize colic; during these episodes of fussiness, which occur more frequently in the evenings, the affected infant classically appears red-faced, draws up the legs and clenches the fists. The traditional methods of soothing the infant often fail to relieve the infant's distress. First described in 1954, the original "Rule of Three" diagnostic criteria (symptoms lasting for 3 hours per day, 3 or more days per week, for 3 or more weeks), has undergone a transition in recent years. The Rome IV criteria describe colic in infants from birth to 5 months of age to make the definition of infantile colic more consistent for research purposes. The criteria are as follows:
While benign and self-limiting, the condition is frustrating for parents and has been linked to maternal postpartum depression and shaken baby syndrome. Since treatments for colic are controversial and inconsistent, the role of the physician as a counselor and educator to parents is critical.
Despite its prevalence, a clear cause for infantile colic remains elusive. There have been many theories regarding the etiology, but a lack of uniformity in study definitions for colic have made it challenging to identify a common cause. It is likely that the etiology of the condition is multifactorial. Many of the theories regarding the cause focus on gastrointestinal (GI) dysfunction, including intolerance to formulas containing cow's milk protein, alterations in intestinal microflora or gut hormones, intestinal hypermotility, increased gas production, or colonic inflammation (indicated by elevated levels of fecal cal-protectin, a marker for inflammation). In breastfeeding infants with colic, maternal diets containing dairy, eggs, nuts, wheat, soy, or fish may contribute to infant distress. Others have suggested a link between colic and migraine physiology, as there are a growing number of studies showing an association between infantile colic and the later development of childhood migraines. Psychosocial issues have also been blamed, such as poor feeding techniques, maternal smoking, or nicotine replacement therapy, inadequate parental interaction, family tension, and parental anxiety. Unfortunately, this wide range of potential causes makes the treatment for colic challenging for both parents and physicians.
Colic affects 5% to 20% of infants worldwide, although some studies suggest the prevalence may be as high as 40%. A recent population-based survey in the United States suggested a prevalence rate of nearly 6%. These ranges in prevalence may reflect the previous lack of uniformity in defining colic. However, the recognition of colic also depends on the parental perception of crying intensity and duration. Parental wellbeing, as well as cultural differences in what is considered acceptable crying, may also affect these data. Regardless of the variability in prevalence, both genders are affected equally, and there seems to be no correlation between breastfeeding or bottle feeding, gestational age, or socioeconomic status.
Because a precise etiology for colic is unclear, the theories of pathophysiology are equally varied. An underlying organic disease is found in less than 5% of infants with inconsolable crying. Most pathways still focus on a GI process. More recent hypotheses point toward an immature hepatic synthesis with reduced intraluminal bile acids and impaired absorption of fats and other nutrients. Consequently, this alteration in the gut environment contributes to a change in the natural microflora. The normally protective Lactobacillus and Bifidobacterium are replaced by higher levels of Escherichia coli, Clostridium difficile, and Klebsiella, and these species contribute to increased nutrient fermentation and increased gas production as well as increased gut inflammation.
Although colic is a benign and self-limiting condition, a thorough history and examination are important to rule out more serious issues. After obtaining information regarding the frequency, circumstances, duration, and intensity of crying, the health care provider should take care to obtain information regarding fever, growth and weight gain, feeding patterns, the presence of bilious emesis, constipation or diarrhea, bloody stools, lethargy, cough, wheezing, rash, loss of willingness to move one or more extremities, or breasts not emptying with feeding. The physical exam should then focus on identifying signs of failure to thrive or serious illness. Findings such as poor weight gain or growth, abdominal distension and tenderness, scrotal or inguinal swelling, suspicious bruises or burns, and signs of dehydration should prompt further evaluation. Subtle findings such as a hair wrapped around a digit or penis should not be overlooked.
In the absence of significant physical findings and a history that is consistent with the Rome IV criteria or the "Rule of Three," the diagnosis of colic can be made confidently, and further evaluation is unnecessary. However, the presence of fever may necessitate a workup for sepsis and involve blood and urine cultures, imaging and even lumbar puncture. Abdominal distension may suggest the need for abdominal radiography or ultrasonography, while positive fecal occult blood testing may support suspected cow's milk allergy. Increased lethargy should prompt consideration for a septic workup and computed tomography (CT) of the brain. Suspicion for traumatic injury should be evaluated by skeletal surveys and CT of the head.
The treatment of infantile colic is as varied (and often unproven) as the theoretical causes for colic. First-line treatment should be directed at the distressed parents, educating them about colic, and reassuring them that the condition is self-limiting and benign. Parents can be encouraged to develop coping responses when the child begins crying, minimizing the likelihood that they will become frustrated and injure the infant. In fact, parents who are frustrated by the infant's crying should place the infant safely in a crib and walk away briefly, to avoid shaking the infant and causing harm. Traditionally parents have resorted to methods such as swaddling, rocking, or driving the infant in a car to control the symptoms of colic. However, clear evidence for the effectiveness of these methods is lacking.
Studies examining the effectiveness of simethicone in treating colic have been inconsistent, but most of the studies demonstrate no effect. The anticholinergic dicyclomine has shown improvement in crying time, but its potential side effects of respiratory depression, apnea, seizures, pulse rate fluctuations and muscular hypotonia make its use undesirable in young infants; dicyclomine is not approved for use in children under the age of 6 months. Proton pump inhibitors such as omeprazole are no better than placebo at reducing crying time in infants with colic. Thus, pharmacological approaches to the treatment of colic are not recommended.
Dietary modifications in the treatment of colic have been explored in some detail. Breastfed infants with colic have significant reductions in crying time if the mother is placed on a hypoallergenic diet, in which dairy foods, eggs, nuts, wheat, soy, and fish are eliminated from the mother's diet. Bottle-fed infants who are switched from traditional cow's milk formulas to soy-based formulas show no improvement in colic symptoms; at the same time, soy-based formulas are not recommended for infants less than 6 months of age due to the high concentrations of phytates, aluminum, and phytoestrogens in those formulas. The American Academy of Pediatrics discourages the use of soy-based formulas in the treatment of colic due to their lack of benefit. In contrast, a number of studies confirm the usefulness of extensively hydrolyzed or completely hydrolyzed cow's milk protein formulas in the reduction of crying times for infants with colic. Unfortunately, these formulas are more expensive and may provide a financial challenge to the parents; if no improvement in symptoms occurs within two weeks, the infant may be switched back to traditional formulas.
Some treatment approaches are directed at correction of the infant's gut microflora. While several studies demonstrate a reduction in crying time among bottle-fed infants with colic who receive supplements of Lactobacillus reuteri, other studies have contradicted those findings. However, there seems to be more consistent evidence regarding the positive effects of L. reuteri supplementation among infants who are breastfed. Probiotic supplementation may be useful for colicky breastfed infants but less useful for bottle-fed infants.
Reducing stimulation may be effective for some infants with colic, much like its effectiveness in children with migraines. Techniques may include reducing the lighting in the room, turning down loud music and avoiding toys that make noise, keeping siblings and pets in another room, avoiding strong odors or perfumes, and rocking the baby gently may have beneficial effects. Feeding the infant in a darkened room may facilitate infant sleep.
Comparisons have been made between infants with colic who were treated with massage and those who were treated with rocking. While there are reductions in crying time for both treatment groups in one study, the greatest reduction was seen in infants undergoing regular massage by their mothers. However, other studies examining the effects of massage have been inconsistent in demonstrating effectiveness. While the effectiveness of massage may not be concrete, it is at least a safe intervention that may improve parental-infant bonding and can be used in any intervention for colic.
Infantile colic is a benign and self-limiting condition that typically resolves spontaneously by three months of age. However, there are some indications that infants with colic may be at more risk for developing migraines without aura by age 18. There is also evidence linking excessive crying early in life with preschool adaptive problems, attention deficit hyperactivity disorder, and other behavioral problems, as well as being associated with maternal anxiety and depression. Thus, counseling parents regarding colic and helping them to develop coping mechanisms, as well as offering suggestions on the management of colic symptoms, seems prudent.
In the absence of other obvious causes, infants who meet the Rome IV criteria can be confidently diagnosed with colic. These criteria, which are modifications of the original "Rule of Three," include inconsolable crying or fussiness for 3 or more hours per day, during 3 or more days for 1 or more weeks. Etiologies are likely multifactorial, and treatment recommendations vary based on those potential etiologies. However, the strongest evidence for effective treatment recommendations includes eliminating potential allergens (dairy, eggs, fish, nuts, fish, soy, and wheat) from the diets of mothers who are breastfeeding and switching bottle-fed infants to hydrolyzed formulas. Weaker levels of evidence also support supplementing breastfed infants with Lactobacillus reuteri but do not endorse supplementing formula-fed infants with those probiotics.