Infantile Colic

Etiology

Infantile colic is a common condition causing abdominal discomfort in newborns during the first few weeks after birth. The etiology of colic is still unknown, as the studies conducted so far have been restricted due to inadequate blinding and conflicting or inconsistent results. Many proposed contributing factors, such as biological, gastrointestinal, and psychosocial elements, define colic causes. In addition, the signs and symptoms may indicate the culmination of various contributing factors.

People often attribute colic to incorrect feeding techniques, overfeeding, underfeeding, and insufficient burping. Maternal diets that include cow's milk may contribute to infant distress in breastfed infants with colic, suggesting a link to cow's milk protein intolerance. The connection to lactose intolerance presents more contradictory evidence.[5][6] Some studies support the presence of increased motilin in newborns and infants with colic, suggesting gut hypermotility as a result of autonomic imbalance.[7][8] Gut inflammation, as measured by fecal calprotectin, and alterations in the fecal microbiome may also contribute to infantile colic.[9][10]

Certain studies have suggested a link between colic and migraine, demonstrating an association between infantile colic and the later development of migraine headaches during adolescence.[11][6] Other proposed contributing factors include maternal smoking or nicotine replacement therapy, the immaturity of the nervous and gastrointestinal systems, sleep disruption, hypersensitivity to the environment, sensory overload, family stress, gastroesophageal reflux, and parental anxiety.

Epidemiology

Infantile colic affects an estimated 3% to 28% of infants worldwide.[12] The prevalence of infantile colic varies across studies, with some suggesting it to be as high as 40%. One study showed an incidence of 17% to 25% among newborns and infants under 6 weeks, 11% among those aged 8 to 9 weeks, and 0.6% among those aged 10 to 12 weeks.[13] Regardless of the variability in prevalence, there is no proven association between gender, formula-fed or breastfed infants, pre- or full-term birth, socioeconomic status, or birth order. Notably, White infants living in industrialized nations farther from the equator experience a higher prevalence of colic.

Although challenging to quantify, reports link caregiver stress, marital dissatisfaction, family stress, and parental lack of self-confidence during pregnancy with infantile colic.

Pathophysiology

Generally, the episodes associated with colic have a clear beginning and end, and they occur during the evening hours. The behavior of a newborn or infant can vary between being happy, sleeping, playing, or eating, and the specific triggers for these behaviors are not known. The cry associated with colic is typically louder and more urgent and is sometimes described as screaming. Less than 10% of infants with excessive and inconsolable crying have an organic cause, and standard soothing techniques are often ineffective. Most infants resolve colic spontaneously, with no lasting effects.

History and Physical

Although colic is benign and self-limiting, conducting a thorough history, physical examination, and review of the growth chart is essential to exclude organic conditions. The clinician should initiate a discussion regarding the caregiver's observations. Colic makes the infant cry loudly and suddenly in a high-pitched manner because of the abdominal pain associated with their signs of discomfort. The observable physical changes in an infant during colic pain include a red face, circumoral pallor, arching of the back, tensing of the abdomen, stiffening of the arms, and drawing up of the legs. 

Gathering history about the infant's feeding, stooling, voiding, and sleeping patterns is essential. Bloody stools of an infant indicate cow's milk protein allergy, soy-induced colitis, an anal fissure, or intussusception. Projectile vomiting may indicate pyloric stenosis or an intestinal obstruction. As infants become extremely fussy in cases of sepsis or meningitis, it is necessary to inquire about prenatal sepsis risk factors.

The physical examination begins by observing the infant's overall appearance and assessing the growth parameters. Infants who suffer from colic usually seem to be in good health and are gaining weight as they should.[14] Healthcare professionals should observe the baby during an episode of crying, if possible, and make a note of the caregiver's soothing techniques.

The abnormalities on physical examination that indicate an alternative cause are as follows:

• A bulging anterior fontanelle, indicating increased intracranial pressure or meningitis.
• Thrush or the presence of tongue tie, both of which are associated with feeding difficulties.
• A corneal abrasion or foreign body.
• Otitis media.
• Signs of heart failure or supraventricular tachycardia.
• Decreased bowel sounds or tenderness suggesting obstruction.
• Evidence of inguinal hernia or testicular torsion.
• Signs of bruising, trauma, or non-accidental injury.
• Hair tourniquet of fingers, toes, or genitalia.

Evaluation

Several sets of diagnostic criteria exist for diagnosing colic. In 1954, Wessel et al published an article titled "Paroxysmal Fussing in Infancy, Sometimes Called Colic," describing infantile colic.[14] Wessel proposed a diagnostic criteria for infantile colic known as the Wessels "Rule of 3," which are still helpful today. Infants affected by colic experience bouts of fussiness and crying that last at least 3 hours a day for 3 or more days a week for over 3 weeks. Contemporary clinicians have dropped the final requirement because only a few parents can wait 3 weeks to initiate evaluation or intervention when their baby is suffering.

Infantile colic is a clinical diagnosis that relies on history and physical examination; therefore, laboratory studies and imaging are typically unnecessary. Clinicians and parents should be aware that healthy infants often cry. In the first 6 weeks, the average duration of crying ranges from 117 to 133 min/d, and by 8 to 9 weeks, the mean duration is reduced to 68 min/d.[13] 

In 1994, gastrointestinal experts gathered in Rome and formulated a classification system for diagnosing functional gastrointestinal disorders in adults based on symptom-based criteria. Subsequent revisions were extended to pediatric patients, leading to the development of the Rome IV criteria for evaluating infantile colic in 2016.[15] 

The Rome IV criteria include the following guidelines:

• The symptoms start and stop when the newborn or infant is younger than 5 months.

• Recurrent and prolonged periods of crying, fussing, or irritability without an apparent cause that caregivers cannot prevent or resolve.

• No evidence of poor weight gain, fever, or illness.

The criteria for clinical diagnosis excluded the 'Rule of 3' because clinicians considered them as 'too arbitrary.' For example, an infant who cries inconsolably for slightly less than 3 hours each day would not meet the criteria. However, the Rome IV committee did introduce 2 criteria for use in clinical research studies to standardize the diagnosis of infant colic. Parents or caregivers must inform a clinician or researcher that their infant cried for more than 3 hours per day on 3 or more days in the preceding week. They must also document the bouts of fussiness in a 24-hour behavior diary.[15] 

When the history aligns with the Rome IV criteria or the Wessel "Rule of 3," and there are no significant physical examination findings, clinicians can confidently diagnose infantile colic. Laboratory testing and imaging studies are unnecessary. However, if there is a fever, clinicians may need to evaluate for sepsis, which can involve conducting blood and urine cultures, radiographs, and possibly a lumbar puncture. Abdominal distension may prompt clinicians to consider the need for abdominal radiography or ultrasonography, and a positive fecal occult blood test suggests a diagnosis of cow's milk protein allergy. When suspecting traumatic injury in patients, clinicians should obtain skeletal surveys and perform computed tomography (CT) scanning of the head. In cases where an infant starts crying after the third month of life or continues beyond the fourth month, clinicians should conduct additional evaluation, as this falls outside the typical age range for infantile colic. 

Treatment / Management

The management of infantile colic focuses on interventions to provide caregiver support and reduce infant crying. However, currently, no universal evidence-based guidelines are available. The primary focus is to create a supportive environment for caregivers and assist them in coping with the symptoms to prevent long-term difficulties within the caregiver-child relationship. After completing the history and physical examinations on an infant, healthcare professionals should reassure caregivers that crying because of colic pain does not mean that the baby is ill, and the symptoms are not the result of anything they did wrong or failed to do correctly. Healthcare providers should also empathize that exhaustion, anger, guilt, and frustration are normal behavioral traits while caring for colic patients, acknowledge that the caregivers are doing their best, and reassure them that symptoms usually resolve in 3 to 4 months. Healthcare professionals should encourage parents to develop coping responses for fussiness, reducing the likelihood of becoming frustrated and unintentionally harming their infant. When parents feel frustrated, healthcare professionals should advise them to place the baby safely in a crib, take a brief break to avoid shaking the infant and causing harm, alternate caregiving responsibilities with other caregivers, or accept extra help from friends or family when offered.[16][17](A1)

Healthcare professionals can recommend a trial of feeding a bottle-fed baby vertically, using a curved bottle, burping the baby frequently, or using a bottle with a collapsible bag to diminish the amount of swallowed air. Healthcare professionals can also customize breastfeeding techniques for each individual and reassure the caregivers that soothing techniques may or may not always be helpful or work consistently. Notably, it is advisable to suggest that caregivers experiment with various soothing techniques if one fails to work after a few minutes. Some of the methods worth trying are taking a ride in the car or stroller, using a pacifier, gently rocking, using a swing or front carrier, doing a gentle abdominal massage, playing soft white noise in the background, reducing stimulation, having a warm bath, and swaddling.

Opting for swaddling to comfort an infant during colic pain is controversial, as swaddling may pose an increased risk of sudden infant death syndrome as the infant gets older and potentially cause an elevated risk of hip dysplasia.[18][19][20] Furthermore, reducing ambient lighting, lowering music volume, keeping siblings and pets in another room, avoiding strong-smelling odors or perfumes, and feeding the infant in a darkened room can facilitate infant sleep and reduce crying. Families usually benefit from regular follow-up visits to their infant's pediatrician to ensure they are growing well and meeting expected developmental milestones. (A1)

If these measures fail to improve colic symptoms, healthcare professionals should consider additional strategies on an individual basis. However, as limited data support these interventions, this approach can be inconvenient and costly for families. Healthcare professionals can consider dietary modifications as an initial option. In breastfed infants with colic, following a hypoallergenic diet that eliminates dairy, eggs, nuts, wheat, and soy may significantly reduce crying time. Notably, it is often easier for nursing mothers to initiate the process by eliminating dairy from their diet and assessing if it helps alleviate symptoms. An elimination diet is most likely helpful in patients with additional symptoms of a rash and wheezing or if the mother has a history of atopic conditions.

Switching formula-fed infants from a cow's milk formula to an extensive hydrolysate infant formula for a short trial may assist some infants with a cow's milk protein intolerance or allergy.[21] Although these formulas are expensive and are not often covered by health insurance, switching to these formulas will help improve colic symptoms in infants within 48 hours. However, if symptoms do not improve within 2 weeks, healthcare professionals should recommend resuming the use of cow's milk formula for the infant. Healthcare professionals do not recommend soy-based infant formulas for infants younger than 6 months due to the high concentrations of phytates, aluminum, and phytoestrogens in these formulas.[22] Furthermore, switching from traditional cow milk formula to soy-based or fiber-enriched infant formula does not yield any improvement. The American Academy of Pediatrics discourages using soy-based infant formulas for treating colic due to the lack of proven benefits. However, several studies confirm the usefulness of hydrolyzed formulas in reducing crying times for a minority of infants with colic, especially when allergy caused by cow's milk is the underlying cause. 

Most studies on simethicone show no effect, with inconsistent results. Although using the anticholinergic medication dicyclomine decreases infantile colic crying time in infants, its potential adverse effects, including respiratory depression, apnea, seizures, and muscular hypotonia, make it unsafe for newborns and infants. The U.S. Food and Drug Administration (FDA) has approved dicyclomine for infants aged 6 months and older.[23] Omeprazole and other proton pump inhibitors are ineffective in reducing colic symptoms compared to a placebo.  (B3)

Other approaches aim to modify the infant's gut microflora. Several studies show a reduction in crying time among formula-fed infants with colic who receive Lactobacillus reuteri supplements, whereas other reports contradict those findings.[24][25] There is stronger evidence regarding the potential positive effects of L reuteri supplementation among breastfed infants. The FDA does not evaluate probiotics, which can be expensive for families. At this time, no evidence-based treatment recommendations with probiotics exist. (A1)

Other unproven treatments that are not found to be effective for colic pain in infants are as follows:

• Lactose-free infant formulas or lactase supplements
• Sucrose
• Full body massage, with risk of overstimulation
• Herbal remedies, such as gripe water or camomile tea 
• Homeopathic preparations, with the possibility of toxic ingredients
• Chiropractic manipulation
• Acupuncture

Caregivers of colicky infants often experience feelings of inadequacy and concern that something is seriously wrong, leading them to seek assistance from healthcare providers. Clinicians who listen to caregivers' concerns, reassure them that their baby is healthy, discuss coping mechanisms, and remind them that the symptoms will spontaneously resolve can assist families in managing this distressing but self-limited condition. 

Differential Diagnosis

The presumptive diagnosis of infantile colic is clinical and based on ruling out organic causes of unexplained and excessive crying. Confirmation comes with spontaneous symptom resolution. When evaluating a fussy, inconsolable newborn or infant, clinicians should consider the following conditions:

• Increased intracranial pressure, sepsis, or meningitis
• Foreign body in the eye
• Ankyloglossia or other oral feeding difficulties
• Otitis media
• Treatable gastrointestinal conditions, including pyloric stenosis, gastroesophageal reflux, or obstruction
• Cardiovascular conditions, such as supraventricular tachycardia
• Cow's milk protein allergy or formula intolerance—typically experienced by less than 5% of individuals
• Hair tourniquet of the penis, fingers, or toes
• Torsion of testes or inguinal hernia
• Non-accidental trauma
• Early symptoms of autism spectrum disorder—rare and only recognized in retrospect [26]
• Neonatal abstinence syndrome
• Hunger
• Glaucoma
• Anal fissure

Prognosis

Infantile colic typically resolves spontaneously between 3 and 4 months of age, thereby making it a benign and self-limiting condition. Counseling caregivers about colic, assisting them in developing coping mechanisms, and providing specific suggestions for managing excessive crying will support families as their infant outgrows this self-limited condition.

Complications

Although infantile colic is benign and self-limiting, caregivers find this condition challenging. Therefore, caregivers may experience a negative impact on the bond with the infant, and breastfeeding may be discontinued early. Recent evidence establishes a link between excessive crying early in life and preschool adaptive problems, attention-deficit hyperactivity disorder, and behavioral problems, but it has not proven a causal relationship.[27] In the long term, infants and newborns with colic may face an elevated risk of developing migraine headaches without aura by age 18. Infantile colic can contribute to maternal depression and family stress, with the most severe potential being shaken baby syndrome. Infants with colic are at significant risk of shaken baby syndrome when overwhelmed caregivers inadvertently harm them while trying to stop excessive crying.[28]