Introduction

Infantile colic is characterised by paroxysms of persistent and uncontrollable crying in an otherwise healthy infant. It is extremely common, affecting approximately 15-20% of infants, being much more frequent in the first 6-weeks of life. It is a self-limiting and benign condition, usually resolving by 5 months of age, although is associated with significant caregiver anxiety and frustration due to the nature of the condition.

Epidemiology

  • Incidence: 180.00 cases per 100,000 person-years
  • Most commonly see in infants
  • Sex ratio: 1:1
Condition Relative
incidence
Infantile colic1
Gastro-oesophageal reflux in children0.28
Cow's milk protein intolerance/allergy0.18
Intussusception0.02
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Aetiology

Unfortunately, the aetiology of infantile colic is not entirely understood. Although the aetiology is likely multi-factorial in nature, a number of mechanisms have been proposed, including gastrointestinal, psychosocial, and biological aetiologies.

Gastrointestinal aetiologies
  • Infantile colic is frequently thought to be due to a disturbance in the gastrointestinal system, for example the Rome IV criteria classifies infantile colic as a functional gastrointestinal disorder in infants
  • In fact, the origin of the word 'colic' itself implies a gastrointestinal origin
  • Proposed mechanisms leading to infantile colic include:
    • Differences in gut microbiome, particularly alterations in Klebsiella species, anaerobic gram-negative bacteria, Escherichia coli and Lactobacillus species
    • Increased intra-luminal gas due to unabsorbed carbohydrate fermentation by colonic bacteria
    • Increased number of gastrointestinal and systemic inflammatory markers
    • Gastrointestinal dysmotility: notably intestinal hypermotility secondary to autonomic imbalance
    • Visceral hypersensitivity: increase in pain signals from hypersensitive gut visceral pathways
  • Faulty feeding techniques which lead to under/over feeding, or infrequent burping and inadequate gas expulsion leading to abdominal distention and intestinal spasm may lead to infantile colic

Psychosocial aetiologies
  • There is an association between certain psychosocial factors in the parents and infantile colic, including:
    • Stressful pregnancies and birth
    • Post-partum depression
    • Parental anxiety and depression, even paternal depression during pregnancy
    • Lower parental education and intelligence
  • It has been proposed that infantile colic is actually a psychosocial phenomenon, whereby it is the caregiver's perception of excessive and uncontrollable crying which defines whether it is considered 'normal crying' or infantile colic

Biological aetiologies
  • One of the theories that has been studied is that infantile colic may be the early manifestation of migraine, although studies have shown inconclusive results regarding this association
  • Tobacco smoke and nicotine exposure, particularly during pregnancy or the post-partum period, is associated with a greater risk of developing infantile colic (twice as common)
  • Elevated serotonin levels may play a role in infantile colic, where some studies have shown that urinary 5-OH IAA concentrations are greater in infants with colic compared to controls

Clinical features

Infantile colic is characteristically described as paroxysms of uncontrollable crying in an infant less than three months old. Paroxysms of crying indicate that these episodes tend to have a clear beginning and end, as in they seem to begin and end suddenly with no clear reason why. These episodes tend to occur early in the morning and in the evening within clusters. A key feature in infantile colic is that the infant is unable to be consoled, for example it is not possible to stop the crying by soothing, feeding or burping the infant.

The cry in colic tends to be more severe than that of normal crying, for example the cry may be:
  • Louder
  • Higher in frequency
  • Described as 'screaming' rather than crying
  • More piercing/grating in nature

Other clinical features which may occur during the episodes of colic include:
  • Facial flushing
  • Tense abdomen
  • Drawing up of legs to the abdomen
  • Clenched fists
  • Circumoral pallor
  • Stiffening and tightening of arms
  • Back arching

There is difficulty in distinguishing what is considered 'normal crying' to infantile colic. A useful tool, the Wessell criteria, defines infantile colic as:
  • Unexplained crying or fussiness
    • In an otherwise healthy infant
    • All red flags and organic causes of crying ruled out (see below in differential diagnosis)
  • Resolves by 3 months of age
  • Lasts for greater than 3 hours per day
  • Occurs on greater than 3 days per week
  • Persists for greater than 3 weeks

Another important factor in infantile colic is the absence of red flag symptoms and signs. Infantile colic is generally a diagnosis of exclusion, as it occurs in an otherwise healthy infant. Usually an organic cause of crying is only found in approximately 10% of patients who present with excessive crying. Red flag features which must be absent include:
  • Fever
  • Evidence of diarrhoea, vomiting, abdominal distention
  • Reduced conscious state e.g. lethargy, drowsiness, floppy
  • Signs of trauma e.g. bruising, bleeding, fractures
  • Poor feeding
  • Poor weight gain and growth
  • Signs of developmental delay

Differential diagnosis

It is important to remember that infantile colic is a diagnosis of exclusion, and signs of more serious disease or organic causes of crying must be ruled out first.

Normal crying
  • For many new parents, it may be difficult to cope with a crying child. It is possible that a new parent may be unable to identify what is considered 'normal crying' compared to infantile colic
  • Similarities
    • On average, infants normally cry for over 2-3 hours per day (cumulative)
    • May be present in discrete episodes
    • In both, it tends to increase in the earliest weeks of life, and peak around 6 weeks of age. It tends to improve by 3-4 months of age
  • Differences
    • Normal crying is usually consolable by soothing, feeding, burping, or changing nappies (there is usually a discernible cause of crying)
    • The crying in infantile colic tends to be louder, more 'screaming' in nature, of a higher pitch

Intussusception
  • Similarities
    • Both tend to present with colicky episodes of irritability
    • Both may draw legs up to the abdomen during episodes
    • Infants may appear very well or normal in between episodes
  • Differences
    • Vomiting may be present
    • Infants with intussusception may have diarrhoea, 'red-currant jelly' like stools or rectal bleeding
    • The pathognomonic sign is an elongated mass in the right upper quadrant

Cow's milk protein allergy
  • Similarities
    • Infants will be irritable
    • Colicky episodes may be present in both
  • Differences
    • Usually will have other symptoms such as vomiting, diarrhoea with blood/mucous, eczema
    • May have poor weight gain and growth
    • May have family history of milk protein allergy also

Gastro-oesophageal reflux disease
  • Similarities
    • Colicky episodes of irritability present
    • May be otherwise entirely well between episodes
  • Differences
    • May present with recurrent regurgitation of feeds after meals, often effortless and is worse when the infant lying down
    • May have poor weight gain and growth
    • In severe cases, may have haematemesis

Lactose overload/intolerance
  • Similarities
    • Significant crying, may be in distinct episodes
    • Irritable child
  • Differences
    • May have watery, frothy, and/or explosive diarrhoea
    • May have poor growth and weight gain
    • Anal excoriations and/or ulcerations may be present

Urinary tract infection
  • Similarities
    • Infants may both be more irritable
    • Acute onset of crying
  • Differences
    • UTI more common in females than males
    • Presence of malodorous urine
    • Fever may be present

Management

As infantile colic is a self-limiting and benign condition, it will usually self resolve by 3-5 months of age. Therefore, thorough education to the caregivers is absolutely key to allay anxiety and parental concern, as well as address any false beliefs regarding the condition.

Caregiver education and support
  • According to both BMJ best practice and UptoDate, the first-line technique to manage infantile colic is parental education and support, as the condition can result in significant distress and anxiety for the caregivers
  • It is important to educate the caregiver on the benign and self-limiting nature of the condition, providing reassurance that the infant is not unwell and that it will spontaneously resolve by 3-5 months of age
  • It is also essential to remind the parent that it is not their fault and that it is not something they are causing, to prevent feelings of guilt and failure which can further negatively impact the parent-infant relationship

Appropriate feeding techniques
  • Appropriate feeding techniques may be useful to address some of the potential causes of infantile colic, although the evidence is limited to prove a definite benefit (given the unclear aetiology of the condition)
  • The theory is that feeding techniques may be useful to assist in infant soothing, as well as reduce swallowed air which can cause pain
  • Proper feeding techniques include:
    • If bottle-feeding, do so in a vertical position to reduce swallowed air
    • Frequent burping post-feed to release trapped air
    • Consider consultation with a lactation specialist
    • Curved bottles, or bottles with a collapsible air bag may be useful to reduce air consumption

Dietary changes
  • Dietary changes should only be considered if first-line techniques fail, or if cow protein milk allergy is strongly suspected
  • If there is a strong suspicion for cows protein milk allergy, this should be eliminated from the infants diet
  • BMJ best practice suggest a trial of also eliminating cows milk from the mothers diet, if breastfeeding
  • BMJ best practice and UptoDate recommend a trial of a hypo-allergenic extensive hydrolysate infant formula (if formula-feeding) after failure to respond to other interventions
    • If there is a response, usually within 48 hours, this should be continued