Gastroenterology

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Gastroenterology

Features of gastrointestinal disorders in children are:

Vomiting

Posseting and regurgitation are terms used to describe the non-forceful return of milk, but differ in degree. Posseting describes the small amounts of milk which often accompany the return of swallowed air (‘wind’), whereas regurgitation describes larger, more frequent losses. Posseting occurs in nearly all babies from time to time, whereas regurgitation may indicate the presence of more significant gastro-oesophageal reflux.

Vomiting is the forceful ejection of gastric contents. It is a common problem in infancy and childhood (Fig. 13.1 and Box 13.1).

Box 13.1   ‘Red Flag’ clinical features in the vomiting child

Bile-stained vomit Intestinal obstruction
Haematemesis Oesophagitis, peptic ulceration, oral/nasal bleeding
Projectile vomiting, in first few weeks of life Pyloric stenosis
Vomiting at the end of paroxysmal coughing Whooping cough (pertussis)
Abdominal tenderness/abdominal pain on movement Surgical abdomen
Abdominal distension Intestinal obstruction, including strangulated inguinal hernia
Hepatosplenomegaly Chronic liver disease
Blood in the stool Intussusception, gastroenteritis – salmonella or campylobacter
Severe dehydration, shock Severe gastroenteritis, systemic infection (urinary tract infection, meningitis), diabetic ketoacidosis
Bulging fontanelle or seizures Raised intracranial pressure
Failure to thrive Gasto-oesophageal reflux, coeliac disease and other chronic gastrointestinal conditions

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Figure 13.1 Causes of regurgitation/vomiting.

It is usually benign and is often caused by feeding disorders or mild gastro-oesophageal reflux or gastroenteritis. Potentially serious disorders need to be excluded if the vomiting is bilious or prolonged, or if the child is systemically unwell or failing to thrive. In infants, vomiting may be associated with infection outside the gastrointestinal tract, especially in the urinary tract and central nervous system. In intestinal obstruction, the more proximal the obstruction, the more prominent the vomiting and the sooner it becomes bile-stained (unless the obstruction is proximal to the ampulla of Vater). Intestinal obstruction is associated with abdominal distension, more marked in distal obstruction. ‘Red Flag’ clinical features suggesting significant organic pathology are listed in Box 13.1.

Summary

Vomiting in infants

Gastro-oesophageal reflux

Gastro-oesophageal reflux is the involuntary passage of gastric contents into the oesophagus. It is extremely common in infancy. It is caused by inappropriate relaxation of the lower oesophageal sphincter as a result of functional immaturity. A predominantly fluid diet, a mainly horizontal posture and a short intra-abdominal length of oesophagus all contribute. While common in the first year of life, nearly all symptomatic reflux resolves spontaneously by 12 months of age. This is presumably due to a combination of maturation of the lower oesophageal sphincter, assumption of an upright posture and more solids in the diet.

Most infants with gastro-oesophageal reflux have recurrent regurgitation or vomiting but are putting on weight normally and are otherwise well, although the mess, smell and frequent changes of clothes is frustrating for carers.

Complications are listed in Box 13.2.

Box 13.2   Complications of gastro-oesophageal reflux

Severe reflux is more common in:

Investigation

Gastro-oesophageal reflux is usually diagnosed clinically and no investigations are required. However, they may be indicated if the history is atypical, complications are present or there is failure to respond to treatment. Investigations include:

Contrast studies of the upper gastrointestinal tract may support the diagnosis but are neither sensitive nor specific. They may be required to exclude underlying anatomical abnormalities in the oesophagus, stomach and duodenum, and to identify malrotation.

Case History

13.1 Severe gastro-oesophageal reflux

This infant (Fig. 13.2a) had a history of frequent regurgitation from the first few days of life. He developed two chest infections. Some of the vomits contained altered blood. A 24-hour oesophageal pH study showed severe gastro-oesophageal reflux (Fig. 13.2b,c). Endoscopy showed oesophagitis. He had probably had episodes of aspiration pneumonia. Symptoms resolved on treatment with feed thickeners and omeprazole. His parents also commented on how much better he slept at night. Treatment was reduced from 14 months of age and the symptoms did not recur.

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Figure 13.2a A pH sensor has been placed in the lower oesophagus.
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Figure 13.2b A section of the 24-hour oesophageal pH study showing severe reflux, with frequent drops in pH below 4.
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Figure 13.2c A section of a normal oesophageal pH study. The lower oesophageal pH is above 4 for most of the time.

Management

Uncomplicated gastro-oesophageal reflux has an excellent prognosis and can be managed by parental reassurance, adding inert thickening agents to feeds (e.g. Nestargel, Carobel) and positioning in a 30° head-up prone position after feeds.

More significant gastro-oesophageal reflux disease is managed with acid suppression with either H2 receptor antagonists (e.g. ranitidine) or proton pump inhibitors (e.g. omeprazole). These drugs reduce the volume of gastric contents and treat acid-related oesophagitis. Although the evidence for their use is poor, drugs which enhance gastric emptying (e.g. domperidone) may be tried. If the child fails to respond to these measures, other diagnoses such as cow’s milk protein allergy should be considered and further investigations performed.

Surgical management is reserved for children with complications unresponsive to intensive medical treatment or oesophageal stricture. A Nissen fundoplication, in which the fundus of the stomach is wrapped around the intra-abdominal oesophagus, is performed either as an abdominal or laparoscopic procedure.

Summary

Gastro-oesophageal reflux

Pyloric stenosis

In pyloric stenosis, there is hypertrophy of the pyloric muscle causing gastric outlet obstruction. It presents at between 2 and 7 weeks of age, irrespective of gestational age. It is more common in boys (4 : 1), particularly first-borns, and there may be a family history, especially on the maternal side.

Pyloric stenosis

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Figure 13.3 (a) Visible gastric peristalsis in an infant with pyloric stenosis. (b) Diagram showing a test feed being performed to diagnose pyloric stenosis. The pyloric mass feels like an ‘olive’ on gentle, deep palpation halfway between the midpoint of the anterior margin of the right ribcage and the umbilicus. (c) Ultrasound examination showing pyloric stenosis. (d) Pyloric stenosis at operation showing pale, thick pyloric muscle and pyloromyotomy incision.

Clinical features are:

A hypochloraemic metabolic alkalosis with a low plasma sodium and potassium occurs as a result of vomiting stomach contents.

Diagnosis

Unless immediate fluid resuscitation is required, a test feed is performed. The baby is given a milk feed, which will calm the hungry infant, allowing examination. Gastric peristalsis may be seen as a wave moving from left to right across the abdomen (Fig. 13.3a). The pyloric mass, which feels like an olive, is usually palpable in the right upper quadrant (Fig. 13.3b). If the stomach is overdistended with air, it will need to be emptied by a nasogastric tube to allow palpation. Ultrasound examination is helpful (Fig. 13.3c) if the diagnosis is in doubt.

Management

The initial priority is to correct any fluid and electrolyte disturbance with intravenous fluids (0.45% saline and 5% dextrose with potassium supplements). Once hydration and acid–base and electrolytes are normal, definitive treatment by pyloromyotomy can be performed. This involves division of the hypertrophied muscle down to, but not including, the mucosa (Fig. 13.3d). The operation can be performed either as an open procedure via a periumbilical incision or laparoscopically. Postoperatively, the child can usually be fed within 6 h and discharged within 2 days of surgery.

Summary

Pyloric stenosis

Crying

The time healthy babies cry for is highly variable. In most, it represents the baby’s response to hunger and discomfort. Reassurance and advice on appropriate feeding, wrapping and care will usually suffice.

Some babies cry for prolonged periods in spite of feeding and comforting and this is distressing for all concerned. It can engender a feeling of anxiety, helplessness and depression in the carer, particularly if they are inexperienced or poorly supported. It has also been suggested that the emotional climate within a home may be transmitted to a baby, and that in some instances, tense, anxious or irritable caregivers are more likely to have fretful babies. The complaint that a baby is ‘always crying’ may also be a pointer to potential or actual non-accidental injury.

A significant cause for the crying is identified in a minority of infants. If of sudden onset, it may be due to a urinary tract, middle ear or meningeal infection, to pain from an unrecognised fracture, oesophagitis or torsion of the testis. Severe nappy rash, constipation or coeliac disease may produce a miserable, crying infant. Preterm infants who have spent several weeks in hospital can be difficult to settle, as can infants with a chronic neurological disorder, e.g. cerebral palsy. On the basis of countless reports of parents, eruption of teeth is painful in some infants. However, teething does not cause vomiting, diarrhoea, high fever or seizures.

Infant ‘colic’

The term ‘colic’ is used to describe a common symptom complex which occurs during the first few months of life. Paroxysmal, inconsolable crying or screaming often accompanied by drawing up of the knees and passage of excessive flatus takes place several times a day, particularly in the evening. There is no firm evidence that the cause is gastrointestinal, but this is often suspected. The condition occurs in up to 40% of babies. It typically occurs in the first few weeks of life and resolves by 4 months of age. The condition is benign but it is very frustrating and worrying for parents and may precipitate non-accidental injury in infants already at risk. Support and reassurance should be given. Gripe water is often recommended but is of unproven benefit. If severe and persistent, it may be due to a cow’s milk protein allergy or gastro-oesophageal reflux and an empirical 2-week trial of a whey hydrolysate formula followed by a trial of anti-reflux treatment may be considered.

Acute abdominal pain

Assessment of the child with acute abdominal pain requires considerable skill. The differential diagnosis of acute abdominal pain in children is extremely wide, encompassing non-specific abdominal pain, surgical causes and medical conditions (Fig. 13.4). In nearly half of the children admitted to hospital, the pain resolves undiagnosed. In young children it is essential not to delay the diagnosis and treatment of acute appendicitis, as progression to perforation can be rapid. It is easy to belittle the clinical signs of abdominal tenderness in young children. Of the surgical causes, appendicitis is by far the most common. The testes, hernial orifices and hip joints must always be checked. It is noteworthy that:

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Figure 13.4 Causes of acute abdominal pain.

Acute appendicitis

Acute appendicitis is the commonest cause of abdominal pain in childhood requiring surgical intervention (Fig. 13.5). Although it may occur at any age, it is very uncommon in children <3 years old. The clinical features of acute uncomplicated appendicitis are:

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Figure 13.5 Appendicitis at operation showing a perforated acutely inflamed appendix covered in fibrin.

In preschool children:

With a retrocaecal appendix, localised guarding may be absent, and in a pelvic appendix there may be few abdominal signs.

Appendicitis is a progressive condition and so repeated observation and clinical review every few hours are key to making the correct diagnosis, avoiding delay on the one hand and unnecessary laparotomy on the other.

No laboratory investigation or imaging is consistently helpful in making the diagnosis. A neutrophilia is not always present on a full blood count. White blood cells or organisms in the urine are not uncommon in appendicitis as the inflamed appendix may be adjacent to the ureter or bladder. Although ultrasound is no substitute for regular clinical review, it may support the clinical diagnosis (thickened, non-compressible appendix with increased blood flow); demonstrate associated complications such as abscess, perforation or appendix mass; and exclude other pathology causing the symptoms. In some centres, laparoscopy is available to see whether or not the appendix is inflamed.

Appendicectomy is straightforward in uncomplicated appendicitis. Complicated appendicitis includes the presence of an appendix mass, an abscess or perforation. If there is generalised guarding consistent with perforation, fluid resuscitation and intravenous antibiotics are given prior to laparotomy. If there is a palpable mass in the right iliac fossa and there are no signs of generalised peritonitis, it may be reasonable to elect for conservative management with intravenous antibiotics, with appendicectomy being performed after several weeks. If symptoms progress, laparotomy is indicated.

Non-specific abdominal pain and mesenteric adenitis

Non-specific abdominal pain (NSAP) is abdominal pain which resolves in 24–48 h. The pain is less severe than in appendicitis, and tenderness in the right iliac fossa is variable. It is often accompanied by an upper respiratory tract infection with cervical lymphadenopathy. In some of these children, the abdominal signs do not resolve and an appendicectomy is performed. The diagnosis of mesenteric adenitis can only be made definitively in those children in whom large mesenteric nodes are seen at laparotomy or laparoscopy and whose appendix is normal.

Summary

Acute abdominal pain in older children and adolescents

Intussusception

Intussusception describes the invagination of proximal bowel into a distal segment. It most commonly involves ileum passing into the caecum through the ileocaecal valve (Fig. 13.6a). Intussusception is the commonest cause of intestinal obstruction in infants after the neonatal period. Although it may occur at any age, the peak age of presentation is between 3 months and 2 years. The most serious complication is stretching and constriction of the mesentery resulting in venous obstruction, causing engorgement and bleeding from the bowel mucosa, fluid loss and subsequently bowel perforation, peritonitis and gut necrosis. Prompt diagnosis, immediate fluid resuscitation and urgent reduction of the intussusception are essential to avoid complications.

Intussusception

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Figure 13.6a Intussusception, showing why the blood supply to the gut rapidly becomes compromised, making relief of this form of obstruction urgent.

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Figure 13.6b A child with an intussusception. The mass can be seen in the upper abdomen. The child has become shocked.
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Figure 13.6c An abdominal X-ray demonstrating an intussusception (see arrowhead), taken during reduction by air insufflated per rectum.
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Figure 13.6d Intussusception at operation showing the ileum entering the caecum. The surgeon is squeezing the colon to reduce the intussusception.

Presentation is typically with:

Usually, no underlying intestinal cause for the intussusception is found, although there is some evidence that viral infection leading to enlargement of Peyer’s patches may form the lead point of the intussusception. An identifiable lead point such as a Meckel diverticulum or polyp is more likely to be present in children over 2 years old. Intravenous fluid resuscitation is likely to be required immediately, as there is often pooling of fluid in the gut, which may lead to hypovolaemic shock.

An X-ray of the abdomen may show distended small bowel and absence of gas in the distal colon or rectum. Sometimes the outline of the intussusception itself can be visualised. Abdominal ultrasound is helpful both to confirm the diagnosis and to check response to treatment. Unless there are signs of peritonitis, reduction of the intussusception by rectal air insufflation is usually attempted by a radiologist (Fig. 13.6c). This procedure should only be carried out once the child has been resuscitated and is under the supervision of a paediatric surgeon in case the procedure is unsuccessful or bowel perforation occurs. The success rate of this procedure is about 75%. The remaining 25% require operative reduction (Fig. 13.6d). Recurrence of the intussusception occurs in less than 5% but is more frequent after hydrostatic reduction.

Summary

Intussusception

Meckel diverticulum

Around 2% of individuals have an ileal remnant of the vitello-intestinal duct, a Meckel diverticulum, which contains ectopic gastric mucosa or pancreatic tissue. Most are asymptomatic but they may present with severe rectal bleeding, which is classically neither bright red nor true melaena. Other forms of presentation include intussusception, volvulus around a band, or diverticulitis which mimics appendicitis. A technetium scan will demonstrate increased uptake by ectopic gastric mucosa in 70% of cases (Fig. 13.7). Treatment is by surgical resection.

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Figure 13.7 Technetium scan showing uptake by ectopic gastric mucosa in a Meckel diverticulum in the right iliac fossa.

Summary

Meckel diverticulum

Malrotation

During rotation of the small bowel in fetal life, if the mesentery is not fixed at the duodenojejunal flexure or in the ileocaecal region, its base is shorter than normal, and is predisposed to volvulus. Ladd bands may cross the duodenum, contributing to bowel obstruction (Fig. 13.8).

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Figure 13.8 The commonest form of malrotation, with the caecum remaining high and fixed to the posterior abdominal wall. There are Ladd bands obstructing the duodenum. Dotted lines show normal anatomy.

There are two presentations:

Obstruction with bilious vomiting is the usual presentation in the first few days of life but can be seen at a later age. Any child with dark green vomiting needs an urgent upper gastrointestinal contrast study to assess intestinal rotation, unless signs of vascular compromise are present, when an urgent laparotomy is needed.

At operation, the volvulus is untwisted, the duodenum mobilised and the bowel placed in the non-rotated position with the duodenojejunal flexure on the right and the caecum and appendix on the left. The malrotation is not ‘corrected’, but the mesentery broadened. The appendix is generally removed to avoid diagnostic confusion in the event the child subsequently has symptoms suggestive of appendicitis.

Summary

Malrotation

Recurrent abdominal pain

Recurrent abdominal pain (RAP) is a common childhood problem. It is often defined as pain sufficient to interrupt normal activities and lasts for at least 3 months. It occurs in about 10% of school-age children. A cause (see Summary box) is identified in <10%.The pain is characteristically periumbilical and the children are otherwise entirely well. The widely held belief that they have psychogenic pain is without foundation, a number of studies having failed to show a difference between such children and their families and controls. In some children, it may however be a manifestation of stress (see Chapter 23) or it may become part of a vicious cycle of anxiety with escalating pain leading to family distress and demands for increasingly invasive investigations. There is evidence that anxiety may lead to altered bowel motility, which may be perceived by the child as pain.

It is increasingly recognised that many will have one of three distinct symptom constellations resulting from functional abnormalities of gut motility or enteral neurons – irritable bowel syndrome (most common), abdominal migraine or functional dyspepsia.

Management

The aim is to identify any serious cause without subjecting the child to unnecessary investigation, while providing reassurance to the child and parents. To do this, a full history and thorough examination is required, which includes inspection of the perineum for anal fissures. The child’s growth should be checked.

A urine microscopy and culture is mandatory as urinary tract infections may cause pain in the absence of other symptoms or signs. An abdominal ultrasound is particularly helpful in excluding gall stones and pelvi-ureteric junction (PUJ) obstruction.

Although there are many potential organic causes, most are rare and further investigations should be performed only if clinically indicated.

With irritable bowel syndrome and functional dyspepsia, it can be helpful to explain to both the child and parents that ‘sometimes the insides of the intestine become so sensitive that some children can feel the food going round the bends’. It is also necessary to make a distinction between ‘serious’ and ‘dangerous’. These disorders can be serious, if, for example, they lead to substantial loss of schooling, but they are not dangerous.

The long-term prognosis is that:

Irritable bowel syndrome

This disorder, also common in adults, is associated with altered gastrointestinal motility and an abnormal sensation of intra-abdominal events. Symptoms may occur following a gastrointestinal infection. Studies of pressure changes within the small intestine of children with irritable bowel syndrome suggest that abnormally forceful contractions occur. It has also been shown that affected adults experience pain on inflation of balloons in the intestine at substantially lower volumes than do controls. There is therefore an interplay between these two factors, both of which are modulated by psychosocial factors such as stress and anxiety.

There is often a positive family history and a characteristic set of symptoms, although not all patients experience every symptom:

Peptic ulceration, gastritis and functional dyspepsia

The greater use of endoscopy in children and the identification of the Gram-negative organism Helicobacter pylori (H. pylori) in association with antral gastritis have focused attention on it as a potential cause of abdominal pain in children. In adults, there is substantial evidence that H. pylori is a strong predisposing factor to duodenal ulcers. This association in children is much less clear. Duodenal ulcers are uncommon in children but should be considered in those with epigastric pain, particularly if it wakes them at night, or when there is a history of peptic ulceration in a first-degree relative.

H. pylori causes a nodular antral gastritis which may be associated with abdominal pain and nausea. It is usually identified in gastric antral biopsies. The organism produces urease, which forms the basis for a laboratory test on biopsies, and the 13C breath test following the administration of 13C-labelled urea by mouth. Stool antigen for H. pylori may be positive in infected children. Serological tests are unreliable in children.

Children in whom peptic ulceration is suspected should be treated with proton pump inhibitors, e.g. omeprazole, and if investigations suggest they have an H. pylori infection, eradication therapy should be given (amoxicillin and metronidazole or clarithromycin). Those that fail to respond to treatment or whose symptoms recur on stopping treatment should have an upper GI endoscopy and, if this is normal, functional dyspepsia is diagnosed.

As well as having symptoms of peptic ulceration, children with functional dyspepsia have rather more non-specific symptoms, including early satiety, bloating and postprandial vomiting and may have delayed gastric emptying as a result of gastric dysmotility. Treatment is difficult but some children respond to a hypoallergenic diet.

Summary

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Gastroenteritis

In developing countries, gastroenteritis remains a major cause of child mortality. In developed countries, it is a cause of significant morbidity, particularly in younger children. In the UK, approximately 10% of under 5 year olds annually present to health services with gastroenteritis and it remains a common reason for hospital admission in young children.

The most frequent cause of gastroenteritis in developed countries is rotavirus infection, which accounts for up to 60% of cases in children <2 years of age, particularly during the winter and early spring. An effective vaccine against rotavirus is now available, but has not been adopted into the national immunisation programme. Other viruses, particularly adenovirus, norovirus, calicivirus, coronavirus and astrovirus, may cause outbreaks.

Bacterial causes are less common in developed countries and are suggested by the presence of blood in the stools. Campylobacter jejuni infection, the commonest of the bacterial infections in developed countries, is often associated with severe abdominal pain. Shigella and some salmonellae produce a dysenteric type of infection, with blood and pus in the stool, pain and tenesmus. Shigella may be accompanied by high fever. Cholera and enterotoxigenic E. coli infection are associated with profuse, rapidly dehydrating diarrhoea. However, clinical features act as a poor guide to the pathogen.

In gastroenteritis there is a sudden change to loose or watery stools often accompanied by vomiting. There may be contact with a person with diarrhoea and/or vomiting or recent travel abroad. A number of disorders may masquerade as gastroenteritis (Box 13.3) and, when in doubt, hospital referral is essential. Dehydration leading to shock is the most serious complication and its prevention or correction is the main aim of treatment.

Box 13.3   Conditions which can mimic gastroenteritis

Systemic infection Septicaemia, meningitis
Local infections Respiratory tract infection, otitis media, hepatitis A, urinary tract infection
Surgical disorders Pyloric stenosis, intussusception, acute appendicitis, necrotising enterocolitis, Hirschsprung disease
Metabolic disorder Diabetic ketoacidosis
Renal disorder Haemolytic uraemic syndrome
Other Coeliac disease, cow’s milk protein intolerance, adrenal insufficiency

The following children are at increased risk of dehydration:

Infants are at particular risk of dehydration because they have a greater surface area to weight ratio than older children, leading to greater insensible water losses (300 ml/m2 per day, equivalent in infants to 15–17 ml/kg per day). They have higher basal fluid requirements (100–120 ml/kg per day, i.e. 10–12% of bodyweight) and immature renal tubular reabsorption. In addition, they are unable to obtain fluids for themselves when thirsty.

Assessment

Clinical assessment of dehydration is important but difficult. The most accurate measure of dehydration is the degree of weight loss during the diarrhoeal illness. A recent weight measurement is useful but is often not available and may be misleading if the child had clothes on or the different measuring scales are not accurate. The history and examination are used to assess the degree of dehydration as:

• No clinically detectable dehydration (usually <5% loss of body weight)

• Clinical dehydration (usually 5–10%)

• Shock (usually >10%) (Fig. 13.9 and Table 13.1). Shock must be identified without delay.

Table 13.1

Clinical assessment of dehydration

  No clinical dehydration Clinical dehydration Shock
General appearance Appears well Appears unwell or deterioratingimage Appears unwell or deteriorating
Conscious level Alert and responsive Altered responsiveness, e.g. irritable, lethargicimage Decreased level of consciousness
Urine output Normal Decreased Decreased
Skin colour Normal Normal Pale or mottled
Extremities Warm Warm Cold
Eyes Normal Sunkenimage Grossly sunken
Mucous membranes Moist Dry Dry
Heart rate Normal Tachycardiaimage Tachycardia
Breathing Normal Tachypnoeaimage Tachypnoea
Peripheral pulses Normal Normal Weak
Capillary refill time Normal Normal Prolonged (>2 s)
Skin turgor Normal Reducedimage Reduced
Blood pressure Normal Normal Hypotension (indicates decompensated shock)

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image; ‘Red Flag’ sign – helps to identify children at risk of progression to shock.

The more numerous and more pronounced the symptoms and signs, the greater the severity of dehydration.

From NICE Guideline, Diarrhoea and vomiting in children, 2009.

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Figure 13.9 Clinical features of shock from dehydration in an infant.

Isonatraemic and hyponatraemic dehydration

In dehydration, there is a total body deficit of sodium and water. In most instances, the losses of sodium and water are proportional and plasma sodium remains within the normal range (isonatraemic dehydration). When children with diarrhoea drink large quantities of water or other hypotonic solutions, there is a greater net loss of sodium than water, leading to a fall in plasma sodium (hyponatraemic dehydration). This leads to a shift of water from extra- to intracellular compartments. The increase in intracellular volume leads to an increase in brain volume, which may result in convulsions, whereas the marked extracellular depletion leads to a greater degree of shock per unit of water loss. This form of dehydration is more common in poorly nourished infants in developing countries.

Hypernatraemic dehydration

Infrequently, water loss exceeds the relative sodium loss and plasma sodium concentration increases (hypernatraemic dehydration). This usually results from high insensible water losses (high fever or hot, dry environment) or from profuse, low-sodium diarrhoea. The extracellular fluid becomes hypertonic with respect to the intracellular fluid, which leads to a shift of water into the extracellular space from the intracellular compartment. Signs of extracellular fluid depletion are therefore less per unit of fluid loss, and depression of the fontanelle, reduced tissue elasticity and sunken eyes are less obvious. This makes this form of dehydration more difficult to recognise clinically, particularly in an obese infant. It is a particularly dangerous form of dehydration as water is drawn out of the brain and cerebral shrinkage within a rigid skull may lead to jittery movements, increased muscle tone with hyperreflexia, altered consciousness, seizures and multiple, small cerebral haemorrhages. Transient hyperglycaemia occurs in some patients with hypernatraemic dehydration; it is self-correcting and does not require insulin.

Management

This is shown in Figure 13.10.

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Figure 13.10 Fluid management of dehydration. (Adapted from Diarrhoea and vomiting in children, National Institute for Health and Clinical Excellence, 2009).

Post-gastroenteritis syndrome

Infrequently, following an episode of gastroenteritis, the introduction of a normal diet results in a return of watery diarrhoea. Temporary lactose intolerance may have developed, which can be confirmed by the presence of non-absorbed sugar in the stools giving a positive ‘Clinitest’ result. In such circumstances, a return to an oral rehydration solution for 24 h, followed by a further introduction of a normal diet, is usually successful.

Rarely, multiple dietary intolerances may result, such that specialist dietary management is required in the implementation of a diet which excludes cow’s milk, disaccharides and gluten. In very severe cases, a period of parenteral nutrition is required to enable the injured small intestinal mucosa to recover sufficiently to absorb luminal nutrients.

Summary

Gastroenteritis

Malabsorption

Disorders affecting the digestion or absorption of nutrients manifest as:

In general, parents know when their children’s stools have become abnormal. The true malabsorption stool is difficult to flush down the toilet and has an odour which pervades the whole house. In general, colour is a poor guide to abnormality. Reliable dietetic assessment is important. It is inappropriate to investigate children for malabsorption as a cause of their failure to thrive when dietary energy intake is demonstrably low and other symptoms are absent. Some disorders affecting the small intestinal mucosa or pancreas may lead to the malabsorption of many nutrients (pan-malabsorption), whereas others are highly specific, e.g. zinc malabsorption in acrodermatitis enteropathica.

Coeliac disease

Coeliac disease is an enteropathy in which the gliadin fraction of gluten provokes a damaging immunological response in the proximal small intestinal mucosa. As a result, the rate of migration of absorptive cells moving up the villi (enterocytes) from the crypts is massively increased but is insufficient to compensate for increased cell loss from the villous tips. Villi become progressively shorter and then absent, leaving a flat mucosa.

The incidence of ‘classical’ coeliac disease, diagnosed in childhood on the basis of characteristic clinical symptoms, has been about 1 in 3000 in Europe, including the UK. The age at presentation is partly influenced by the age of introduction of gluten into the diet.

The classical presentation is of a profound malabsorptive syndrome at 8–24 months of age after the introduction of wheat-containing weaning foods. There is failure to thrive, abdominal distension and buttock wasting abnormal stools and general irritability (see Case History 13.2). However, this is no longer the most common presentation and children are now more likely to present less acutely in later childhood. The clinical features of coeliac disease can be highly variable and include mild, non-specific gastrointestinal symptoms, anaemia (iron and/or folate deficiency) and growth failure. Alternatively, it is identified on screening of children at increased risk (type 1 diabetes mellitus, autoimmune thyroid disease, Down syndrome) and first-degree relatives of individuals with known coeliac disease.

The introduction of highly sensitive and specific serological screening tests (IgA tissue transglutaminase antibodies and endomysial antibodies) has provided evidence that coeliac disease is much more common than previously thought and as many as 1 in 100 UK school-age children may be antibody positive.

Diagnosis

Although the diagnosis is strongly suggested by positive serology, confirmation depends upon the demonstration of mucosal changes (increased intraepithelial lymphocytes and a variable degree of villous atrophy and crypt hypertrophy) on small intestinal biopsy performed endoscopically followed by the resolution of symptoms and catch-up growth upon gluten withdrawal.

There is no place for the empirical use of a gluten-free diet as a diagnostic test for coeliac disease in the absence of a small intestinal biopsy. Serological tests such as IgA tissue transglutaminase antibodies and endomysial antibodies are not currently considered sufficiently sensitive and specific to replace biopsy, particularly as the diet is lifelong.

Case History

13.2 ‘Classical’ coeliac disease

This 2-year-old boy (Fig. 13.11a) had a history of poor growth from 12 months of age (Fig. 13.11b). His parents had noticed that he tended to be crotchety and had three or four foul-smelling stools a day. A jejunal biopsy at 2 years of age showed subtotal villous atrophy (Fig. 13.11c,d) and he was started on a gluten-free diet. Within a few days, his parents commented that his mood had improved and within a month he was a ‘different child’. He subsequently exhibited good catch-up growth.

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Figure 13.11a Coeliac disease causing wasting of the buttocks and distended abdomen.
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Figure 13.11b Growth chart showing failure to thrive and response to a gluten-free diet. (Adapted from Chart© RCPCH/WHO/Department of Health.)
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Figure 13.11c Histology of a jejunal biopsy showing lymphocytic infiltration and villous atrophy confirming coeliac disease. (Courtesy of Dr Marie-Anne Brundler.)
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Figure 13.11d Normal jejunal histology is shown for comparison. (Courtesy of Dr Marie-Anne Brundler.)

Management

All products containing wheat, rye and barley are removed from the diet and this results in resolution of symptoms. Supervision by a dietician is essential. In children in whom the initial biopsy or the response to gluten withdrawal is doubtful, or when the disease presents before the age of 2 years, a gluten challenge is required in later childhood to demonstrate continuing susceptibility of the small intestinal mucosa to damage by gluten. This is done by either giving food containing gluten or gluten powder. At the start of the challenge, the serological markers should be negative. The gluten challenge is positive if the serology becomes positive again. Repeat small intestinal biopsy is not required. The gluten-free diet should be adhered to for life. The incidence of small bowel malignancy in adulthood is increased in coeliac disease, although a gluten-free diet probably reduces the risk to normal.

Summary

Coeliac disease

Toddler diarrhoea

This condition, also called chronic non-specific diarrhoea, is the commonest cause of persistent loose stools in preschool children. Characteristically, the stools are of varying consistency, sometimes well formed, sometimes explosive and loose. The presence of undigested vegetables in the stools is common, giving rise to the alternative title ‘peas and carrots diarrhoea’. Affected children are well and thriving and there are no precipitating dietary factors.

Toddler diarrhoea probably results from an underlying maturational delay in intestinal motility which leads to intestinal hurry. The loose stools are not due to malabsorption. Most children have grown out of their symptoms by 5 years of age but achieving faecal continence may be significantly delayed. Some relief of symptoms can be achieved by ensuring that the child’s diet contains adequate fat (which slows gut transit) and fibre. Excessive consumption of fresh fruit juice, particularly those high in non-absorbable sorbitol, can exacerbate symptoms.

Summary

Chronic diarrhoea

Inflammatory bowel disease

The incidence of inflammatory bowel disease (IBD) in children has increased markedly in the last two decades. The reason for this is unclear. Approximately a quarter of patients present in childhood or adolescence. Crohn disease can affect any part of the gastrointestinal tract from mouth to anus, whereas in ulcerative colitis the inflammation is confined to the colon. Inflammatory bowel disease results from environmental triggers in a genetically predisposed individual. It may cause poor general health, restrict growth and have an adverse effect on psychological well-being. Management requires a specialist multidisciplinary team.

Crohn disease

The clinical features of Crohn disease are summarised in Figure 13.13. Lethargy and general ill health without gastrointestinal symptoms can be the presenting features, particularly in older children. There may be considerable delay in diagnosis as it may be mistaken for psychological problems. It may also mimic anorexia nervosa. The presence of raised inflammatory markers (platelet count, ESR and CRP), iron deficiency anaemia and low serum albumin are helpful in both making a diagnosis and confirming a relapse.

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Figure 13.13 Presentation of Crohn disease in children and adolescents.

Crohn disease is a transmural, focal, subacute or chronic inflammatory disease, most commonly affecting the distal ileum and proximal colon. Initially there are areas of acutely inflamed, thickened bowel. Subsequently, strictures of the bowel and fistulae may develop between adjacent loops of bowel, between bowel and skin or to other organs (e.g. vagina, bladder).

Diagnosis is based on endoscopic and histological findings on biopsy. Upper gastrointestinal endoscopy, ileocolonoscopy and small bowel imaging are required. The histological hallmark is the presence of non-caseating epithelioid cell granulomata, although this is not identified in up to 30% at presentation. Small bowel imaging may reveal narrowing, fissuring, mucosal irregularities and bowel wall thickening.

Remission is induced with nutritional therapy, when the normal diet is replaced by whole protein modular feeds (polymeric diet) for 6–8 weeks. This is effective in 75% of cases. Systemic steroids are required if ineffective.

Relapse is common and immunosuppressant medication (azathioprine, mercaptopurine or methotrexate) may be required to maintain remission. Anti-tumour necrosis factor agents (infliximab or adalimumab) may be needed when conventional treatments have failed. Long-term supplemental enteral nutrition (often with overnight nasogastric or gastrostomy feeds) may be helpful in correcting growth failure. Surgery is necessary for complications of Crohn disease – obstruction, fistulae, abscess formation or severe localised disease unresponsive to medical treatment, often manifesting as growth failure. In general, the long-term prognosis for Crohn disease beginning in childhood is good and most patients lead normal lives, despite occasional relapsing disease.

image Growth failure and delayed puberty are features of Crohn disease in children.

Ulcerative colitis

Ulcerative colitis is a recurrent, inflammatory and ulcerating disease involving the mucosa of the colon. Characteristically, the disease presents with rectal bleeding, diarrhoea and colicky pain. Weight loss and growth failure may occur, although this is less frequent than in Crohn disease. Extraintestinal complications include erythema nodosum and arthritis.

The diagnosis is made on endoscopy (upper and ileocolonoscopy) and on the histological features, after exclusion of infective causes of colitis. There is a confluent colitis extending from the rectum proximally for a variable length. In contrast to adults, in whom the colitis is usually confined to the distal colon, 90% of children have a pancolitis. Histology reveals mucosal inflammation, crypt damage (cryptitis, architectural distortion, abscesses and crypt loss) and ulceration. Small bowel imaging is required to check that extra-colonic inflammation suggestive of Crohn disease is not present.

In mild disease, aminosalicylates (balsalazide and mesalazine) are used for induction and maintenance therapy. Disease confined to the rectum and sigmoid colon may be managed with topical steroids. More aggressive or extensive disease requires systemic steroids for acute exacerbations and immunomodulatory therapy, e.g. azathioprine to maintain remission alone or in combination with low-dose corticosteroid therapy.

Severe fulminating disease is a medical emergency and requires treatment with intravenous fluids and steroids. If this fails to induce remission, ciclosporin may be used.

Colectomy with an ileostomy or ileorectal pouch is undertaken for severe fulminating disease which may be complicated by a toxic megacolon, or for chronic poorly controlled disease. There is an increased incidence of adenocarcinoma of the colon in adults (1 in 200 risk for each year of disease between 10 and 20 years from diagnosis). Regular colonoscopic screening is performed after 10 years from diagnosis.

Constipation

Constipation is an extremely common reason for consultation in children. Parents may use the term to describe decreased frequency of defecation; the degree of hardness of the stool and painful defecation. The ‘normal’ frequency of defecation is highly variable and varies with age. Infants have an average of four stools per day in the first week of life, but this falls to an average of two per day by 1 year of age. Breast-fed infants may not pass stools for several days and be entirely healthy. By 4 years of age, children usually have a stool pattern similar to adults, in whom the normal range varies from three stools per day to three stools per week. A pragmatic definition of constipation is the infrequent passage of dry, hardened faeces often accompanied by straining or pain. There may be abdominal pain which waxes and wanes with passage of stool or overflow soiling (see Chapter 23, Emotions and behaviour).

The cause of constipation is often unclear and multifactorial. In babies, Hirschsprung disease, anorectal abnormalities, hypothyroidism and hypercalcaemia need to be considered. Constipation may be precipitated by dehydration or reduced fluid intake or an anal fissure causing pain. In older children, it may relate to problems with toilet training, unpleasant toilets or stress.

Examination often reveals a palpable abdominal mass in a well-looking child. Digital rectal examination should only be performed by a paediatric specialist and only if a pathological cause is suspected. ‘Red Flag’ symptoms and signs indicative of more significant pathology are detailed in Box 13.4. Investigations are not usually required to diagnose idiopathic constipation, but are carried out as indicated by history or clinical findings.

Box 13.4   ‘Red Flag’ symptoms or signs in the child with constipation

‘Red Flag’ symptom/signs Diagnostic concern
Failure to pass meconium within 24 h of life Hirschsprung disease
Failure to thrive/growth failure Hypothyroidism, coeliac disease, other causes
Gross abdominal distension Hirschsprung disease or other gastrointestinal dysmotility
Abnormal lower limb neurology or deformity, e.g. talipes or secondary urinary incontinence Lumbosacral pathology
Sacral dimple above natal cleft, over the spine – naevus, hairy patch, central pit, or discoloured skin Spina bifida occulta
Abnormal appearance/position/patency of anus Abnormal anorectal anatomy
Perianal bruising or multiple fissures Sexual abuse
Perianal fistulae, abscesses or fissures Perianal Crohn disease

Constipation arising acutely in young children, for example after an acute febrile illness, usually resolves spontaneously or with the use of mild laxatives and extra fluids.

In more long-standing constipation, the rectum becomes overdistended, with a subsequent loss of feeling the need to defecate. Involuntary soiling may occur as contractions of the full rectum inhibit the internal sphincter, leading to overflow. Management of these children is likely to be more difficult and protracted (Fig. 13.14). Children of school age are frequently teased as a result and secondary behavioural problems are common.

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Figure 13.14 Summary of the management of constipation.

It should be explained to the child and the parents that the soiling is involuntary and that recovery of normal rectal size and sensation can be achieved but may take a long time. The initial aim is to evacuate the overloaded rectum completely. This can generally be achieved using a disimpaction regimen of stool softeners, initially with a macrogol laxative, e.g. polyethylene glycol + electrolytes (Movicol Paediatric Plain). An escalating dose regimen is administered over 1–2 weeks or until impaction resolves. If this proves unsuccessful, a stimulant laxative, e.g. senna, or sodium picosulphate, may also be required. If the polyethylene glycol + electrolytes is not tolerated, an osmotic laxative can be substituted.

Disimpaction must be followed by maintenance treatment to ensure ongoing regular, pain-free defecation. Polyethylene glycol (with or without a stimulant laxative) is generally the treatment of choice. The dose should be gradually reduced over a period of months in response to improvement in stool consistency and frequency.

Dietary interventions alone are unlikely to be successful in managing constipation in this situation, although the child should receive sufficient fluid and a balanced diet including adequate fibre. The child should be encouraged to sit on the toilet after mealtimes to utilise the physiological gastrocolic reflex and improve the likelihood of success.

The outcome is more likely to be successful if the child is engaged in the treatment process. This requires exploring the child’s concerns and motivation to change. Sometimes use of a star chart is helpful to record and reward progress, as well as motivating the child.

Encouragement by family and health professionals is essential, as relapse is common and psychological support is sometimes required. Occasionally, the faecal retention is so severe that evacuation is only possible using enemas or by manual evacuation under an anaesthetic. They should only be performed under specialist supervision, paying particular attention to avoiding distress and embarrassment for the child.

Hirschsprung disease

The absence of ganglion cells from the myenteric and submucosal plexuses of part of the large bowel results in a narrow, contracted segment. The abnormal bowel extends from the rectum for a variable distance proximally, ending in a normally innervated, dilated colon. In 75% of cases, the lesion is confined to the rectosigmoid, but in 10% the entire colon is involved. Presentation is usually in the neonatal period with intestinal obstruction heralded by failure to pass meconium within the first 24 h of life. Abdominal distension and later bile-stained vomiting develop (Fig. 13.15). Rectal examination may reveal a narrowed segment and withdrawal of the examining finger often releases a gush of liquid stool and flatus. Temporary improvement in the obstruction following the dilatation caused by the rectal examination can lead to a delay in diagnosis.

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Figure 13.15 Abdominal distension from Hirschsprung disease.

Occasionally, infants present with severe, life-threatening Hirschsprung enterocolitis during the first few weeks of life, sometimes due to Clostridium difficile infection. In later childhood, presentation is with chronic constipation, usually profound, and associated with abdominal distension but usually without soiling. Growth failure may also be present.

Diagnosis is made by demonstrating the absence of ganglion cells, together with the presence of large, acetylcholinesterase-positive nerve trunks on a suction rectal biopsy. Anorectal manometry or barium studies may be useful in giving the surgeon an idea of the length of the aganglionic segment but are unreliable for diagnostic purposes. Management is surgical and usually involves an initial colostomy followed by anastomosing normally innervated bowel to the anus.

Summary

Hirschsprung disease

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