Abdominal pain is a common reason for children to attend an emergency department (ED), occurring in up to 5% of all presentations in some institutions.¹ Most commonly the underlying cause is non-surgical and surgery is required in only 1–7% of children who present with abdominal pain.¹^,² It is not possible to make a definitive diagnosis in all children with abdominal pain. In one study, as many as 15% of children presenting to emergency with abdominal pain did not have a specific diagnosis at their discharge. Some children arrive at the ED soon after the onset of symptoms and it may take time, expectant management and review before a diagnosis becomes clearer or the symptoms of a self-limiting cause resolve. It is important, however, to exclude causes of abdominal pain that may require early surgical consultation, observation or investigations within the ED.

The priorities in managing children presenting with abdominal pain are:

• triage and early appropriate analgesia;

• resuscitation with attention to ABCs as required;

• diagnosis formulation using history, examination and investigation;

• consideration of surgical review and management according to the likely diagnosis.

If a clear diagnosis cannot be reached in the ED, then exclusion of serious/life-threatening diagnoses is the priority. Subsequent disposition and follow up is dependent on various factors including: likelihood of a serious diagnosis; severity of the pain; availability of review; and psychosocial factors that may be contributory.

Pathophysiology

The sensation of abdominal pain is transmitted by either somatic or visceral afferent fibres.³ Visceral pain from visceral peritoneum is poorly localised, whereas somatic pain arising from parietal peritoneum or the abdominal wall is more localised. Referred pain also occurs due to visceral and somatic pathways converging in the spinal column. Two examples of referred pain are diaphragmatic irritation leading to pain at the shoulder tip due to convergence of visceral and somatic pathways at C4, and somatic pain from pneumonia leading to T10–11 pain sensed in the lower abdomen.³ Abdominal pain may occasionally be found to be psychosomatic in origin after a thorough assessment of alternative causes.

Aetiology

There is a broad range of causes of abdominal pain in children and one needs to initially keep an open mind regarding the diagnosis (Table 7.1.1). The age and sex of the child need to be considered, as well as features of the abdominal pain and associated symptoms, and examination findings to determine the diagnostic possibilities.

Inflammatory gastrointestinal Appendicitis Meckel’s diverticulum Mesenteric adenitis Gastroenteritis Food poisoning Peritonitis Peptic ulcer, gastritis Hepatitis Pancreatitis Inflammatory bowel disease Non-gastrointestinal Tonsillitis, pharyngitis Pneumonia (especially basal) Pericarditis Serositis Pyelonephritis, cystitis Pelvic inflammatory disease Intra-abdominal abscess Epididymitis Generalised Infectious mononucleosis Acute rheumatic fever Herpes zoster Intestinal obstruction Intussusception Volvulus Adhesions Incarcerated hernia Abdominal trauma See Section 3 Gall bladder Cholecystitis, cholelithiasis Haematological Leukaemia, lymphoma Haemolytic crisis Sickle cell disease Neuroblastoma, Wilms’ tumour Endocrine Diabetic ketoacidosis, hypoglycaemia Adrenal insufficiency Hyperparathyroidism Vasculitic Henoch–Schönlein purpura Periarteritis nodosa Kawasaki disease Renal Renal colic Hydronephrosis Nephrotic syndrome Miscellaneous Constipation Colic Toxic ingestion, e.g. lead Torsion–testicular/ovarian Ectopic pregnancy Dysmenorrhea, Mittelschmerz pain Mesenteric artery occlusion Hypokalaemia Acute intermittant porphyria Familial Mediterranean fever Abdominal migraine Psychosomatic – including abuse

Source: Adapted from Rudolph 1996.

Assessment

Each child needs initial assessment and triage with attention to securing the ABCs and providing appropriate early analgesia. This will help achieve a more reliable examination. A detailed history and thorough, gentle, and age-appropriate examination need to be performed.

History

In considering a child who has presented with abdominal pain with no history of trauma, five important questions have to be addressed:

1 The age of the child

The age of the child helps narrow the diagnostic possibilities. The most common diagnoses to consider according to age are:

Neonates and infants

They usually present with a change in behaviour to signify pain.⁴ This may be persistent crying, irritability, inability to be consoled, fussiness, sleeplessness, and poor feeding.⁴ Serious or potentially life-threatening conditions not to miss in this age group are listed in Table 7.1.2.

Surgical causes Medical causes Testicular torsion Diabetic ketoacidosis Appendicitis Toxic, e.g. iron ingestion Peritonitis Sepsis Necrotising enterocolitis Volvulus Haemolytic uraemic syndrome Intussusception Urinary tract infection Hirschsprung disease Incarcerated hernia

The diagnoses of acute gastroenteritis or ‘colic’ need to be made after excluding more serious causes.

2 Whether this is the first episode or recurrence of abdominal pain

3 Whether there are other associated symptoms

Generally children with abdominal pain have other associated symptoms. A full symptom review is required, with particular reference to gastrointestinal symptoms. This includes vomiting, and whether it is bilious or blood stained, and the timing and quality of stool, including the presence of blood or mucus. The child with fever, voluminous diarrhoea and vomiting is likely to have gastroenteritis. However, particularly in young children, one must keep an open mind to other possibilities that can mimic or complicate gastroenteritis (see Chapter 7.8 pp. 172–175 on Diarrhoea and vomiting).

More general questions should assess the child’s constitution – whether the child is febrile, lethargic, irritable, anorexic or has associated pallor. It is unusual for children with appendicitis to be hungry. The child with intussusception is often lethargic and pale. The presence of upper respiratory tract infection (URTI) or viral symptoms may suggest mesenteric adenitis. Dysuria or frequency may be reported in older children with a urinary tract infection. A typical rash or sore joints may indicate Henoch–Schönlein purpura as the cause of related vasculitic abdominal pain.

4 Whether there are any relevant pre-existing conditions

The child’s past medical and surgical history should be fully explored. In older females an adolescent approach (see Chapter 30.1) and a menstrual and sexual activity history may be important. Family history and racial background may be relevant, along with a psychosocial history that may contribute if there is a suggestion of somatisation.

5 What are the characteristics of the pain?

These include location (generalised or localised), radiation, severity, quality (constant, episodic or of a colic nature), what improves and worsens the pain, along with the timing of the pain – gradual or sudden onset and whether the pain wakes the child. Direct questioning of the verbal child often augments the description of the characteristics of the pain as reported by a parent.

Pain that has a sudden onset may occur with perforated viscus, intussusception or torsion. The pain from appendicitis has a more insidious onset and usually increases over a period of hours. In both intussusception and mesenteric adenitis, the pain may cause episodic distress. Constant pain over a number of hours in a child usually suggests a significant underlying cause.

Examination

The abdominal examination of the young child with abdominal pain needs to be performed in an unhurried and gentle fashion. Toddlers may be better examined on the parent’s lap. It is important to note the child’s general appearance and any features of toxicity. Children with colicky pain often writhe around, whereas the child with peritoneal irritation usually remains still as movement exacerbates the abdominal pain. Providing adequate analgesia improves the reliability of physical findings and does not mask the clinical detection of peritoneal findings. It is best to very gently approach the painful quadrant of the abdomen last in distressed children, after pain subsides post analgesia, the child has relaxed and become accustomed to the examination.

One of the keys to the assessment is to determine the presence of focal tenderness or true peritoneal irritation. In children this can sometimes be difficult, as many voluntarily guard the abdomen when examined, irrespective of the cause of the abdominal pain. This is expected when a previous examination may have been distressing. Differentiating the presence of true peritoneal signs may be helped by distraction techniques, or by serial gentle examination over a period of time to determine true reproducibility of findings.

Eliciting rebound should begin with gentle palpation to avoid distress and resultant voluntary guarding. Signs consistent with peritonitis include refusing or being unable to walk, slow or stooped walking, or increased pain on coughing or movement, or the child lying motionless on the bed. Likewise, peritoneal irritation may be detected by asking if the child can expand or contract their abdominal wall by asking them to ‘suck tummy in, then let it out’. The younger the child, the less likely they are to have reliable localising signs of appendicitis and the threshold for surgical review or observation needs to be adapted accordingly.

Important features of examination include the following:

• general appearance of the child;

• temperature and vital signs;

• jaundice;

• skin markings, e.g. abdominal bruising;

• abdominal distension;

• abdominal tenderness;

• guarding or rebound and/or rigidity;

• abdominal mass;

• bowel sounds;

• palpation of testes (in the male infant);

• presence of inguinal herniae;

• urinalysis.

Rectal examination in children, when rarely indicated, should be performed once, and ideally by the surgeon who may require the information. The interpretation of localised rectal tenderness is often difficult in children, as it is uncomfortable in all children and therefore does not often add to the assessment. The inguinoscrotal regions should always be checked for an otherwise occult hernia or torsion referring pain upwards to the abdomen. A sensitively performed, private, and chaperoned pelvic examination may be indicated in pubertal females.

The cause of abdominal pain in children may be extra-abdominal. The child with ileus may have intra- or extra-abdominal pathology including sepsis, urinary tract infection, pneumonia, or meningitis.

Important features in the examination of other systems that may present with abdominal pain include:

• respiratory – signs of basal pneumonia;

• ENT – URTI, tonsillitis or adenopathy;

• neurological – meningitis;

• endocrine – blood glucose level in diabetic ketoacidosis;

• haematological – pallor, lymphadenopathy;

• dermatological – rash, particularly purpura/petechiae of Henoch–Schönlein purpura, zoster;

• renal – oliguria, haematuria, hypertension in haemolytic uraemic syndrome.

Investigations

Many children have the diagnosis clarified by a physical examination alone. The need for investigations should be tailored to the individual case, where the diagnosis is unclear and the result of the test is likely to ‘rule in or rule out’ significant pathology.

Pathology

A full blood count may demonstrate leucocytosis, anaemia or film changes of haemolysis. However, the white cell count/differential is not particularly useful to determine if a child has acute appendicitis. Electrolytes, urea and creatinine assess changes resulting from fluid losses and impaired renal function. This may be indicated in the child who has had significant losses from diarrhoea or vomiting. Liver function tests are indicated in children with potential hepatic and gall bladder pathology. The possibility of pancreatitis can be assessed by serum amylase or lipase levels. A blood glucose level excludes diabetic ketoacidosis in the child presenting with abdominal pain who appears acidotic or has glucose and ketones in the urine. Females of reproductive age should have a βhCG performed. Urinalysis, microscopy and culture are necessary to exclude renal pathology.

Imaging

The routine use of an abdominal X-ray is unhelpful to ‘screen’ children with abdominal pain. Specific situations where it may be helpful include: demonstrating the signs of bowel obstruction; free air, suggesting perforation; an ingested foreign body; calcification, including a faecolith in the appendix and Meckel’s diverticulum; ‘thumbprinting’, suggesting gut ischaemia or a sentinel loop adjacent to inflammation; or a soft tissue mass. Calcification may also represent renal stones, neuroblastoma or teratoma.

An erect chest X-ray may be indicated to demonstrate gas under the diaphragm or evidence of a basal pneumonia.³

An ultrasound study can help evaluate liver, gall bladder and kidneys, as well as detect intussusception, features of appendicitis (if able to be visualised) or evaluate a palpable mass. An abdominal computerised tomography (CT) scan may be indicated in selected cases.

Management

The initial management of the child with severe abdominal pain should include assessment and securing of ABCs and administration of appropriate analgesia to relieve the child’s distress. Children with similar pathophysiology can have markedly varied distress levels and analgesic requirements need to be individualised.⁴ Concurrent anxiety may increase painful stimuli and this can be lessened by involving parents in comforting their child and using a child-friendly environment to distract and help calm the child. Using a visual analogue scale to evaluate severity of pain may be helpful to assess response to analgesia.

There is no contraindication to providing adequate analgesia for any child presenting in pain. It is much easier to perform a reliable examination on a child who is made comfortable. For severe distress, intravenous morphine titrated in increments controls most children’s pain and will not mask the abdominal signs. Intra-nasal fentanyl is a useful alternative for rapid onset analgesia (2–3 minutes) with the advantage of not requiring venous access, but its short duration of action (30–60 minutes) means longer-acting analgesia will be required if pain is ongoing.⁶ Oral agents such as paracetamol, codeine or ibuprofen may be used in less severe pain. Serial examination of the child’s abdomen and observation of vital signs over a period may be important to exclude significant pathology. Children with a potential surgical cause should be given nil by mouth, until surgical review.

Disposition

Children with significant abdominal findings need to have a surgical consultation. Not all children who present with abdominal pain will have a clear definitive diagnosis after their assessment has excluded a serious cause or the need for a surgical review. Some children with severe pain, but negative physical examination findings, where the diagnosis is not clear, will warrant admission for ongoing observation. Children who are discharged home need to have clear instructions given to parents regarding returning, should they deteriorate, and have a planned timely follow up by the local doctor.

Acute Appendicitis

Introduction

Appendicitis is the most common non-traumatic surgical emergency in children. It occurs slightly more commonly in males at any age, although it is uncommon in those under 2 years, and very rare in neonates. The peak incidence is at 9–12 years.

Clinical features

The clinical features of classic appendicitis are well known. Pain is felt initially in the periumbilical region due to visceral pain from obstruction of the appendix. There is often associated nausea, vomiting, anorexia and a low-grade fever. Later, there is migration of the pain to the region of the appendix. This more intense right lower quadrant pain results from irritation of the abdominal parietal lining. Up to 50% of adults have this progression of symptoms but it is less common in children.

Importantly, some children may have false localising diarrhoea or dysuria caused by irritation from an inflamed appendix. Fever is generally below 39.5°C, unless perforation has occurred. Asking the child to walk or hop to demonstrate pain with right leg movement may be useful in indeterminate cases to reveal the presence of true peritoneal irritation. Likewise, manoeuvres such as the iliopsoas, obturator or Rovsing’s signs may help confirm suspicion of appendicitis. In children with clear signs of appendicitis, the rectal examination adds little value, is distressing for a child and does not alter management.⁷

Under the age of 2 years, vomiting (85–90%) and pain (35–77%) are the most common symptoms, with diarrhoea (18–46%) and fever (40–60%) less common. Sometimes grunting respirations (8–23%), cough or rhinitis (40%) and right hip symptoms (3–23%) may be misleading. Right lower abdominal tenderness is present in less than 50% so the diagnosis of appendicitis in this age group is often delayed, leading to perforation rates of 82–92%.

As children become older, right lower abdominal tenderness becomes more common (age 2–5 years, 58–85%), up to nearly all children in the school-age group, with some (15%) having generalised tenderness without perforation. In children 6–12 years, vomiting occurs in 68–95% of children, anorexia in 47–75%, diarrhoea in 9–16%, constipation in 5–28% and dysuria in 4–20%.

Differential diagnoses

These include mesenteric adenitis (less severe pain without peritoneal signs is usual and it is rare under 3 years of age), bacterial enterocolitis, pelvic inflammatory disease, urinary tract infection, Meckel’s diverticulitis, intussusception and right lower lobe pneumonia.

Investigations

Children with a clear clinical diagnosis of acute appendicitis do not require investigations and delay of surgical consultation. In equivocal cases, imaging of the appendix may be helpful or demonstrate alternative causes of the pain.

No single test is diagnostic in appendicitis, with the white blood cell count insensitive and non-specific.⁸ C reactive protein (CRP) levels >10 mg dL^–1 have varying reported sensitivities (48–75%) and specificities (57–82%) in different studies on appendicitis. Normal CRP values do not exclude acute appendicitis in children.⁸ On urine microscopy more than five white blood cells per high power field or the presence of red blood cells is found in 7–25% of children with appendicitis. Abdominal X-rays may show other pathology (e.g. right lower lobe pneumonia) and occasionally an appendiceal faecolith, but are also insensitive and non-specific for diagnosing appendicitis. Note the rare presence of an appendolith can give a more colicky nature to the pain.

Ultrasound

Has reported sensitivity of 71–92% with specificity of 86–98% and is often used when there is initial diagnostic doubt. However, in one series patients undergoing sonography before appendicectomy had a longer delay before operation, a higher rate of misdiagnosis, and more postoperative complications. It is not uncommon for the appendix to be difficult to visualise (up to 10% of cases). High positive likelihood ratios and moderate negative likelihood ratios suggest that ultrasound can be used to confirm but not exclude a diagnosis of appendicitis.⁸

CT scan

Abdominal helical CT scan in diagnosing appendicitis shows sensitivities from 87–100% and specificities 83–97% with signs of distension of the appendix, faecolith, focal caecal wall thickening and fluid collections in ruptured appendicitis. Some institutions have used a protocol incorporating ultrasound and subsequent CT scan with patients whose diagnosis is equivocal. They have shown this to be an accurate and cost-effective approach when compared with a negative appendicectomy rate of 23%. The American College of Radiology in general advocates the use of ultrasound over CT scan.

Magnetic resonance imaging (MRI)

Recent studies suggest high sensitivity and specificity in adult patients with appendicitis.⁹ However, several disadvantages including high cost, long duration of study, and limited availability mean MRI has a limited role at the moment. It appears potentially useful in pregnant patients with suspected appendicitis in whom ultrasound is inconclusive.⁸

Active observation

Has also been used without investigation, with a positive predictive value of 97.9% in one series and a normal appendicectomy rate of 2.6%.

Management

The management of acute appendicitis is appendicectomy. Some children require intravenous rehydration, ongoing analgesia and antibiotics, if perforation is suspected.

The management of the child in whom the diagnosis is not clear, but may be possible early appendicitis, is more difficult and one needs to have a clear approach.

In some children it may be useful to perform imaging of the appendix such as ultrasound, particularly in older females who may have ovarian pathology as a cause of their pain. An expectant approach is appropriate in some children with a short history, with a clear plan of organised review over the next 6–12 hours. This may be achieved by actively observing the child in hospital or, if discharged, by arranging a definite early clinical review. Parents need clear instructions to return should their child’s symptoms progress.

Meckel’s diverticulum

Introduction

Meckel’s diverticulum is a vestige of the omphalomesenteric duct, occurring in 2% of the population, with 2% of those with Meckel’s diverticulum manifesting symptoms. The diverticulum is usually 60 cm proximal to the terminal ileum. Of symptomatic patients, 45% are under the age of 2, but it can present at any age. These findings are known as Meckel’s rule of twos. The majority of Meckel’s diverticuli contain gastric mucosa and may secrete acid.

Clinical features

The presenting features of a Meckel’s diverticulum vary and may include abdominal pain, bowel obstruction, gastrointestinal haemorrhage, or perforation.

Meckel’s diverticuli are the most common cause of significant lower gastrointestinal bleeding in children, usually from peptic ulceration within the diverticulum or adjacent ileum. It is classically painless bleeding, with stools either bright red or tarry, depending on the site and briskness of bleeding.

Diverticulitis causing crampy lower quadrant pain can occur in older children. A Meckel’s diverticulum can be a lead point in intussusception, as well as causing intestinal obstruction by the formation of intraperitoneal bands, which can lead to the possibility of a volvulus or internal herniation.

Differential diagnoses

These include intestinal polyps, intussusception, anal fissures, midgut volvulus and bacterial enteritis.

Investigations

A Meckel’s scan using ^99mtechnetium can be used, which is 75–85% sensitive and 95% specific ¹¹ at demonstrating the ectopic gastric tissue, when bleeding is present.

Management

Management is intravenous fluid support with blood transfusion for massive bleeding. A Meckel’s scan can be done in stable bleeding patients, but if unstable or with peritoneal signs, urgent surgical consultation must be obtained with a view to operative intervention. Definitive treatment is surgical excision, which may be done laparoscopically.

Chronic abdominal pain

Introduction

Chronic abdominal pain is defined as the presence of at least three discrete episodes of pain occurring over a period of 3 months or longer.³ The reported prevalence of abdominal pain interfering with activities is 10–15% in children between 5 and 14 years. Causes of chronic abdominal pain are diverse and are listed in Table 7.1.3.

Gastrointestinal causes Chronic recurrent functional abdominal pain Peptic ulcer disease Irritable bowel syndrome Inflammatory bowel disease Chronic or recurrent pancreatitis Biliary colic Appendiceal colic Constipation Partial bowel obstruction Parasitic infection Endocrine disease Hyperparathyroidism Addison’s disease Diabetes mellitus Cardiovascular disease Superior mesenteric artery syndrome Coarctation of aorta Neurological disease Abdominal migraine Migraine headaches Familial dysautonomia Haematological disease Sickle cell disease Porphyrias Gynaecological disorders Cystic teratoma of ovary Endometriosis Haematocolpos Mittelschmerz Musculoskeletal disorders Discitis Linea alba hernia Painful rib syndrome Muscle wall sprain Other Uteropelvic junction obstruction Familial Mediterranean fever Hereditary angioneurotic oedema

Source: Adapted from Rudolph 1996.³

Signs and symptoms suggesting organic disease causing chronic abdominal pain in school-aged children include:

• persistent fever;

• poor weight gain or weight loss;

• child awakened from sleep;

• pain away from the umbilicus;

• radiation of pain to back, shoulder or lower extremities;

• persistent regurgitation, vomiting or dysphagia;

• bloody emesis or stools;

• associated altered bowel pattern;

• perianal disease;

• sleepiness following pain attacks;