Expulsions from the lower GI and GU tract

Context

• Normal neonatal stools
• Neonatal constipation and dyschezia
• Urinary urate crystals
• Vaginal bleeding and leukorrhoea

Basic science and pathophysiology

Normal neonatal stools

• In general there is no such thing as a normal bowel habit in a neonate!
• It is completely normal to produce stool multiple times a day or only once a week especially if breast-fed.
• However, knowledge of how these stools change over the first week of life can provide useful diagnostic information:
  • Meconium
  • Transitional stool
  • Yellow stool

a) Meconium

• Dark (almost black), sticky and odourless
• Present in both breast and bottle-fed infants
• Should first be passed within the first 48 hours of life
  • Otherwise consider Hirshsprungs disease or meconium plug (may be associated with cystic fibrosis)
• Should convert to transitional stools by day four of life
  • Otherwise inadequate feeding should be considered

b) Transitional stools

• Should appear from day four of life if adequate feeding
• Combination of dark coloured meconium with that of yellow stools characteristic of exclusive milk feeds

c) Yellow stools

• Appear by day five in established breast-fed infants
• Typically described as bright yellow and seedy
• The typical consistency has significant liquid stool within the nappy with solid material on top and is incorrectly reported as diarrhoea by parents.
• In bottle fed babies the colour of established stool can vary between yellow, brown or green and has a thicker consistency similar to peanut butter.

Neonatal constipation and dyschezia

• It is completely normal for breast-fed infants to defaecate only once a week.
• Difficulty in passing stools is a common problem in neonates but rarely is it constipation.
• Healthy infants (<6 months) can strain and become distressed but subsequently pass soft stool. This is a normal part of development as the child learns to coordinate increasing intra-abdominal pressure with relaxation of the pelvic floor. This is called dyschezia and will improve spontaneously overtime.
• Only if the stool is hard is it true constipation.
• True constipation in neonates is more suggestive of an underlying medical condition and these patients should be referred.
• The following should be considered:
  • Hirschsprungs disease
  • Congenital anorectal malformations
  • Spinal cord abnormalities
  • Meconium ileus (cystic fibrosis)
  • Metabolic causes: hypothyroidism, hypercalcaemia

Urinary urate crystals

• • Inability to concentrate and acidify urine within the neonatal period facilitates a large urinary uric acid load⁴¹.
  • The uric acid forms characteristic pink-orange deposits within the nappy of an otherwise well child.
  • It is especially common within the first week of life.

• However, they can appear anytime within the first year as renal tubular function gradually improves.
• No investigation or treatment is required.

Vaginal bleeding and leukorrhoea

• High levels of maternal oestrogens within the new-born can lead to a physiological white-yellow discharge called leukorrhoea.
• As these levels fall (typically around day three) it is not uncommon for small withdrawal bleeds to occur.
• Both phenomenon resolve spontaneously by the first week of life as maternal hormones are metabolised.
• Large amounts of blood and bleeding after one week of age is atypical and alternative diagnoses such as coagulopathy and non-accidental injury should be considered.

Image caption: Oestrogen withdrawal bleed