Paediatric Acute Abdomen
Acute abdominal pain is a common paediatric complaint with a vast differential, ranging from benign to life-threatening surgical emergencies. The UK’s current approach, guided by sources like the Royal College of Emergency Medicine and NICE, prioritises rapid identification of “red flags” and the distinction between medical and surgical causes.
Presentation and Assessment
A comprehensive history and focused physical examination are the most important diagnostic tools.
History:
Pain: Use a structured approach (e.g., SOCRATES). The location, onset (sudden or gradual), and character of the pain are key. Pain that localises to the right iliac fossa (RLQ) after migrating from the periumbilical region is classic for appendicitis. Colicky pain is typical of intussusception or bowel obstruction.
Associated Symptoms: Ask about vomiting (bilious vomiting is a red flag for bowel obstruction), diarrhoea, constipation, and fever.
Urinary and Gynaecological Symptoms: In all children, especially girls, enquire about dysuria, frequency, and haematuria, as these may point to a urinary tract infection (UTI). In teenage girls, a full gynaecological history, including last menstrual period (LMP) and sexual activity, is essential.
Examination:
Systemic: Assess the child’s overall well-being. Look for signs of sepsis (tachycardia, fever, prolonged capillary refill time) or dehydration.
Abdominal: A gentle, methodical approach is crucial. Look for distension, visible peristalsis, and hernial sites. Palpate for tenderness, guarding, and rebound tenderness (a sign of peritonitis). The presence of a palpable mass may indicate intussusception, a tumour, or an abscess.
Other Systems: Always check the ENT region (tonsillitis), auscultate the chest (basal pneumonia can cause referred abdominal pain), and examine the groin (incarcerated hernia or testicular torsion).
Common Medical Causes
Gastroenteritis: Often accompanied by vomiting and diarrhoea.
Mesenteric Adenitis: Inflammation of the lymph nodes in the mesentery, typically following a viral illness, presenting with pain similar to appendicitis.
Urinary Tract Infection (UTI): Can present with abdominal pain alone, especially in young children.
Constipation: A very common cause, often presenting with diffuse pain.
Referred Pain: From conditions like pneumonia (at the lung base), tonsillitis, or pyelonephritis.
Systemic Illnesses: Consider diabetic ketoacidosis (DKA), Henoch-Schönlein purpura (HSP), or a sickle cell crisis.
Common Surgical Causes
- Acute Appendicitis: The most common surgical emergency.
Intussusception: The most frequent cause of intestinal obstruction in infants and toddlers. The child presents with colicky abdominal pain, drawing their legs up to their chest. A palpable “sausage-shaped” mass may be felt.
Bowel Obstruction / Volvulus: Can be due to malrotation. Bilious vomiting is a critical sign.
Incarcerated Hernia: A tender, non-reducible lump in the groin.
Testicular Torsion: An acute surgical emergency. Can present with referred abdominal pain, but a tender, swollen testicle is the key finding.
Red Flags
These suggest a serious, likely surgical cause and warrant immediate senior review:
Peritonitis: Guarding, rebound tenderness, and rigidity.
Bilious Vomiting: Especially in a neonate or infant.
Sudden, severe, unremitting pain.
Haemodynamic instability (tachycardia, hypotension).
Bloody stools (e.g., “redcurrant jelly” stools in intussusception).
Testicular swelling or tenderness.
Palpable mass.
Investigations and Management
Initial Investigations:
Blood Tests: FBC (for white cell count), CRP (for inflammation), and blood gas with lactate (for signs of shock).
Urinalysis: A dipstick is essential to rule out UTI.
Urine Pregnancy Test: Mandatory for all post-menarche girls with abdominal pain.
Imaging:
Ultrasound Scan (USS): The primary imaging modality. It can diagnose appendicitis (thickened appendix), intussusception (a “target” or “doughnut” sign), ovarian torsion, or fluid collections.
Plain Abdominal X-ray: May be useful for suspected bowel obstruction (showing dilated bowel loops or a “double-bubble” sign in duodenal atresia).
Management:
Surgical Cause Suspected: The child must be kept nil by mouth, IV fluids should be started, and the paediatric surgical team must be informed immediately. Analgesia should be given as it does not obscure a surgical diagnosis.
Medical Cause: If a benign medical cause is suspected and the child is well, a trial of observation and symptom management may be appropriate.
Safety Netting: If the child is discharged home, the family must be given clear safety netting advice on when to return to hospital, including worsening pain, fever, or bilious vomiting.