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Paediatrics

Mesenteric Adenitis

Mesenteric adenitis is reactive inflammation of mesenteric lymph nodes, often after a viral illness, causing abdominal pain that can mimic appendicitis; it is a diagnosis reached after safe clinical exclusion and observation rather than by enlarged nodes alone.

In a nutshell

Mesenteric adenitis is a self-limiting reactive lymph-node process, often after a viral illness, causing central or right iliac fossa pain in children. It is a diagnosis of exclusion: enlarged nodes on ultrasound are non-specific, and evolving appendicitis remains the key danger. Use serial examination, targeted tests or ultrasound when indicated, then supportive care and explicit return advice if the child improves.

Classic presentation

A well child has central/right-sided pain after a sore throat, low fever and mild anorexia, with diffuse tenderness that improves during observation and no guarding or progressive vomiting.

Key points

  • It commonly follows a viral upper-respiratory or gastrointestinal illness.
  • The key diagnostic task is to exclude appendicitis and other surgical emergencies.
  • Mesenteric nodes on ultrasound are non-specific and do not prove the diagnosis.
  • Worsening, localising pain, peritonism, persistent vomiting or toxicity needs urgent reassessment.
  • When the child improves after surgical causes are excluded, treatment is fluids, nutrition, simple analgesia and safety-netting.

First-line investigation

Clinical assessment with serial examination; use targeted bloods, urinalysis or ultrasound according to the differential and local paediatric pathway.

Management

Identify surgical red flags

  • Urgently assess progressive localised pain, guarding/peritonism, high fever, toxicity, persistent vomiting, obstruction or genital/pelvic symptoms for appendicitis or another emergency.2,1

Observe and investigate proportionately

  • Repeat abdominal examination in a stable child when the diagnosis is uncertain; use bloods, urine or ultrasound only when they address a specific differential.1,4
  • Do not treat enlarged mesenteric nodes on ultrasound as proof of adenitis or as a reason to stop reassessing the child.2,1

Support recovery

  • Once surgical disease is reasonably excluded and the child improves, give fluids, nutrition as tolerated and current BNF-based analgesia; antibiotics are not routine for uncomplicated reactive adenitis.3,5

Safety-net

  • Return urgently for worsening/localising pain, guarding, persistent vomiting, high fever, inability to drink, reduced urine, bloody stool or a child who looks more unwell.3,1

Exam traps

  • Enlarged mesenteric nodes do not confirm mesenteric adenitis.
  • A preceding sore throat supports but does not exclude appendicitis.
  • Normal inflammatory markers do not rule out early appendicitis.
  • Worsening or localising pain changes the diagnosis and needs reassessment.
  • Do not discharge without explicit return precautions and a clear clinical endpoint.

Illustrations

Mesenteric lymphadenopathy on ultrasoundAbdominal ultrasound showing several enlarged hypoechoic mesenteric lymph nodes; the image should be labelled as non-specific and not diagnostic of mesenteric adenitis alone.Rossana Helbling et al., Wikimedia Commons · CC-BY-4.0

Key sources

  1. Cambridge University Hospitals NHS, Appendicitis in children (UK paediatric surgical information on variable presentation, diagnosis, observation, treatment and discharge advice)
  2. NHS, Appendicitis (NHS symptom and urgent-assessment information, current page checked for appendicitis warning features)
  3. Cambridge University Hospitals NHS, Abdominal pain in children: discharge advice (UK paediatric emergency advice on red flags and returning when symptoms worsen or persist)
  4. NICE CG54, Urinary tract infection in under 16s (NICE targeted urinalysis and UTI assessment pathway when urinary symptoms or an alternative diagnosis is suspected)Updated 19 Oct 2022
  5. BNF for Children, current analgesic prescribing information (UK paediatric prescribing source; use current product monographs and local protocol for medicine choice and dose)

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.