Vomiting and watery diarrhoea in a 2-year-old: a paediatric case to work up

Why vomiting and watery diarrhoea in a young child matters

Acute diarrhoea is one of the commonest reasons a young child is brought to a doctor in India, and dehydration, not the infection itself, is what makes it dangerous. The skill is judging how dry the child is and spotting the few children whose vomiting is not coming from the gut at all.

What to ask in the history

• Onset, and how many episodes of vomiting and stools in the last 24 hours
• What the stool looks like: watery, blood or mucus in it
• What the vomit looks like: food, bile (green) or blood
• Oral intake: is the child keeping any fluid down?
• Urine output: wet nappies or trips to the toilet in the last 12 hours
• Fever, abdominal pain, rash, unusual drowsiness or irritability
• Contacts with similar illness, food, water source, recent travel
• Immunisations (including rotavirus), recent antibiotics, past illnesses

Red flags

• Lethargy, unusual drowsiness or difficulty waking the child
• Signs of shock: cold hands and feet, prolonged capillary refill, fast weak pulse
• Unable to drink, or vomiting everything
• Blood in the stool
• Green (bilious) vomiting, a distended or very tender abdomen
• Markedly reduced urine output
• High fever, a non-blanching rash or a stiff neck

What to examine

• General condition: alert, irritable, or lethargic
• Weight, to compare with a recent weight and to calculate fluids
• Heart rate, capillary refill time, temperature of hands and feet
• Eyes (sunken?), tears, mouth and tongue
• Skin pinch on the abdomen: how fast it goes back
• Abdomen: distension, tenderness, masses, bowel sounds
• A quick look for other sources of illness: ears, throat, chest, rash

First investigations

• Often none, if the child is only mildly unwell and drinking
• Serum electrolytes, urea, creatinine and blood glucose if dehydration is more than mild or fluids go into a vein
• Stool microscopy and culture if there is blood, or the diarrhoea is prolonged
• Urine dipstick and culture if the cause is unclear

Differential diagnosis of vomiting and watery diarrhoea in a young child

Grouped, not ranked. Which one fits this patient is for you to work out in the case.

Common mistakes

• Vomiting is not always gastroenteritis. Look for a surgical abdomen and for infection elsewhere before you settle.
• Underestimating dehydration. Use a structured scale (such as the WHO no / some / severe dehydration signs) rather than an impression.
• Ordering blood tests in a well, drinking child changes nothing and upsets everyone.