Acute abdominal pain in children: Viva

Branch 1: The single clinical question

The candidate must immediately state that the central task in acute abdominal pain in children is to decide whether the child needs a surgeon, because the surgical abdomen threatens bowel or organ viability and demands theatre or interventional reduction within hours. This infant's episodic drawing up of the legs with pallor, the vomiting that has turned bilious, and the drowsiness between episodes together signal a surgical emergency, and the priority is resuscitation in parallel with an urgent surgical opinion rather than prolonged diagnostic debate. [3]

The candidate should give the first actions in parallel: assess airway, breathing and circulation, keep the infant nil by mouth, place a nasogastric tube on free drainage to decompress the stomach, secure intravenous access, start fluid resuscitation, check a glucose, give analgesia, and call the surgical team immediately. The recognition that this is intussusception until proven otherwise, and the move to act rather than to investigate exhaustively first, is what the examiner is testing. [3]

Branch 2: Confirming the diagnosis and the reduction pathway

The examiner will ask how the candidate confirms intussusception. In a stable infant the investigation of choice is an abdominal ultrasound, which shows the target sign, the doughnut or pseudokidney appearance of the intussuscepted bowel. The classic triad of colicky pain, vomiting and redcurrant-jelly stool is present in only a minority of children at first presentation, so its absence never excludes the diagnosis, and the redcurrant-jelly stool is a late sign of ischaemia. [1]

The examiner will then ask about treatment. The stable child is reduced by pneumatic or hydrostatic enema under fluoroscopic or ultrasound guidance, and a meta-analysis found pneumatic and liquid enema reduction broadly comparable, with the choice guided by local expertise and resources. Surgery is required when the child is shocked, has signs of peritonitis, or has failed enema reduction, and the candidate should know the predictors of failed enema reduction, which include a longer symptom duration, the presence of a pathological lead point, and signs of bowel ischaemia. [2]

Branch 3: Broadening to the appendicitis presentation

The examiner will broaden the discussion to the older child. The candidate should describe the sequence of appendicitis: a dull central periumbilical ache that migrates over twelve to twenty-four hours to a constant right lower quadrant pain worse with movement, with anorexia the most consistent associated symptom and nausea and low-grade fever following the pain. The examiner will want the mechanism of the migration, which is the progression from visceral pain carried by midgut afferents at the tenth thoracic segment to somatic pain from the parietal peritoneum of the right iliac fossa. [3]

The candidate should then offer the Pediatric Appendicitis Score as a risk-stratification tool that rationalises the decision to observe, image or call a surgeon. The score combines eight variables into a maximum of ten points, with right lower quadrant tenderness and pain on coughing, hopping or percussion each scoring two, and migration, anorexia, nausea or vomiting, fever, leukocytosis and neutrophilia each scoring one. The strong candidate states that ultrasound is the first-line imaging modality and that computed tomography is avoided whenever possible to limit lifetime cancer risk from radiation. [3]

Branch 4: The analgesia question and the medical mimics

The examiner will test whether the candidate holds the outdated belief that analgesia masks the surgical abdomen. The correct answer is that early analgesia is a standard of care and must not be withheld, because a review of studies in children with undifferentiated abdominal pain found that opioid analgesia relieved pain without changing the accuracy of examination or the rate of correct diagnosis. The dose is titrated to comfort and the child is reassessed after each dose. [4]

The examiner may ask how the candidate separates appendicitis from its mimics. The useful rule is that pain which precedes vomiting suggests a surgical cause, whereas vomiting and diarrhoea that precede the pain point to gastroenteritis. Mesenteric adenitis is the closest mimic and is a diagnosis of exclusion reached once appendicitis is confidently excluded, while constipation causes cramping pain with a loaded rectum, urinary tract infection causes pain with dysuria and frequency, and lower-lobe pneumonia causes referred abdominal pain through the lower thoracic nerves. [3]

Branch 5: The adolescent torsions and safety-netting

The examiner will finish by asking what else must be excluded in the adolescent with acute abdominal pain. The candidate should name ovarian torsion and the gynaecological differential, and state that testicular torsion may present with abdominal or groin pain rather than scrotal pain, which is why the scrotum and testes are examined in every boy with acute abdominal pain. A pregnancy test is mandatory in any adolescent girl before imaging, because ectopic pregnancy is a must-not-miss diagnosis. [3]

The candidate should close with disposition and safety-netting. The child with a clear surgical diagnosis, peritonitis or shock is admitted for operation, while the child with an equivocal presentation is observed with serial examination. A child discharged with a medical diagnosis must receive a clear safety-net: return immediately if the pain worsens, localises or becomes constant, if the vomit turns green or bloody, if the child becomes drowsy, floppy or feverish, or if the child cannot keep fluids down or stops passing urine. Checking that the family can repeat the warning signs confirms understanding and closes the loop. [3]