Abdominal pain

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7.1 Abdominal pain

Introduction

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:

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.

Table 7.1.1 Causes of acute abdominal pain in children

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.

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.

Table 7.1.2 Serious conditions not to miss in neonates and infants

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.

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.

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:

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:

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.

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.

Acute Appendicitis

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%.

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.

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

Meckel’s diverticulum

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.

Table 7.1.3 Causes of chronic abdominal pain

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:

References

1 Scholer S.J., Pituch K., Orr D.P., Ditttus R.S. Clinical outcomes of children with acute abdominal pain. Paediatrics. 1996;98:680-685.

2 Simpson E.T., Smith A. The management of acute abdominal pain in children. J Paediatr Child Health. 1996;32(2):110-112.

3 Rudolph A. Rudolph’s Textbook of Paediatrics, 20th ed. USA: Appleton and Lange; 1996.

4 D’Agostino J. Common abdominal emergencies in children. Emerg Med Clin North Am. 2002;20:1.

5 Browne G.J., Choong R.K.C., Gaudry P.L., Wilkins B.H. Principles and practice of children’s emergency care. Sydney: Maclennan and Petty; 1997.

6 Borland M.L., Jacobs I., Geelhoed G. Intranasal fentanyl reduces acute pain in children in the emergency department: a safety and efficacy study. Emerg Med. 2002;14(3):275-280.

7 Dunning P.G., Goldman M.D. The incidence and value of rectal examination in children with suspected appendicitis. Ann R Coll Surg Engl. 1991;73:233-234.

8 Kwok M., Kim M., Gorelick M. Evidence-based Approach to the diagnosis of appendicitis in children. Pediatr Emerg Care. 2004;20(10):690-701.

9 Cobben L., Groot I., Kingma L., et al. A simple MRI protocol in patients with clinically suspected appendicitis: results in 138 patients and effect on outcome of appendectomy. Eur Radiol. 2009;19(5):1175-1183.

10 Banez G. Chronic abdominal pain in children: what to do following the medical evaluation. Curr Opin Pediatr. 2008;20:571-575.

11 Behrman R., Kliegman R., Jenson H. Nelson’s Textbook of Paediatrics, 16th ed. Philadelphia: WB Saunders; 2000.