and Spencer W. Beasley2
(1)
Department of Urology, Royal Children’s Hospital, Melbourne, Australia
(2)
Paediatric Surgery Department Otago, University Christchurch Hospital, Christchurch, New Zealand
Abstract
This chapter addresses one of the commonest problems in children, abdominal pain. First, we discuss the general considerations about the physical characteristics of the child’s abdomen and the location of the pain. Then we describe the specific features in the history that help elucidate the cause. For the examination, we discuss preparing the patient and how to determine if there is peritonitis. Then we discuss the specific features of appendicitis and a mass in the right iliac fossa. Finally, we discuss the features of the other common pathologies in suspected appendicitis.
Abdominal pain is extremely common in children and may reflect a variety of conditions (Table 3.1). Often, the cause cannot be determined with certainty, or is caused by pathology unrelated to the abdomen. Pain which lasts for more than 4–6 h, which is becoming worse or is associated with persistent vomiting or prolonged diarrhoea, should be taken seriously and a surgical cause excluded. If appendicitis is the cause, it is best treated before peritonitis develops. Therefore, examination of the abdomen is directed at localizing the likely origin of the pain and detecting the presence of peritonitis. Peritonitis is a surgical emergency and should almost always be treated by operation within hours of diagnosis. When a child presents with persistent or worsening abdominal pain, every effort must be made to obtain a clinical diagnosis.
Table 3.1
Differential diagnosis for acute abdominal pain
Very common | Acute appendicitis |
Non-specific viral infection (mesenteric adenitis) | |
Gastroenteritis | |
Constipation | |
Urinary tract infection | |
Less common | Intussusception |
Lower lobe pneumonia | |
Intestinal obstruction | |
Congenital (1 %) | |
Adhesions (2 %) | |
Urinary tract obstruction | |
Strangulated inguinal hernia | |
Rare | Henoch-Schönlein purpura |
Primary peritonitis | |
Pancreatitis | |
Diabetic ketoacidosis | |
Lead poisoning | |
Acute porphyria | |
Herpes zoster | |
Sickle-cell anaemia | |
Haemophilia (retroperitoneal haematoma) |
Frequently, children with significant abdominal pain are anxious and scared. Their fear that palpation of the abdomen will cause further suffering may make them appear uncooperative. Patience and skill are needed to assess the abdomen accurately to avoid the disaster of not recognizing significant intra-abdominal pathology. Where children are old enough to understand, each stage of the examination must be explained before it is commenced so that they know what to expect. The clinician must appear understanding, sympathetic and gentle, and it is helpful to develop a rapport with the child before commencing palpation of the abdomen. Interesting toys, a torch or stethoscope may act as a distractor during examination in the smaller child. Most children are cooperative if they are comfortable with the situation and if they see that they are not going to be hurt unnecessarily.
In the vast majority of children with abdominal pain of unknown cause, the symptoms resolve spontaneously over several hours. At the other end of the spectrum, abdominal pain may reflect significant pathology and necessitate precise clinical assessment before the appropriate therapeutic measures can be undertaken. In young children, infection outside the abdomen (e.g. lung, hip) may be interpreted as abdominal pain. This pain must be distinguished from pain arising within the abdomen. As a general rule, conditions which cause peritonitis need surgery, and therefore one of the more important aspects of the examination of the abdomen is the ability to detect the presence of peritonitis.
The age of the patient is helpful in diagnosing acute abdominal disease because some disorders are confined largely to specific age ranges (Fig. 3.1).
Fig. 3.1
Influence of age on the incidence of acute abdominal disease
Intussusception occurs rarely in children over 3 years of age and, when it does, may signify the existence of a pathological lesion as the lead point.
Appendicitis is uncommon below the age of three, but in the older age groups becomes the predominant condition requiring surgery. Knowledge of the age of the patient, supplemented by a detailed history of the onset, duration, location and characteristics of the pain and related symptoms, provides substantial diagnostic evidence even before physical examination is commenced. This allows a physical examination directed at confirming or refuting the provisional diagnosis and obviates the need for many unnecessary laboratory and radiological investigations. For example, a history of lower abdominal pain lasting several days, with general malaise, recent diarrhoea and the passage of mucus rectally, suggests a diagnosis of untreated appendicitis causing a pelvic abscess, and so the clinician should perform a digital rectal examination to feel a tender swelling bulging from the anterior rectal wall. A 7-month-old child with episodes of screaming and pallor accompanied by vomiting should be subjected to a careful examination of the abdomen in search of an intussusception mass. Failure to make the appropriate provisional diagnosis after taking a history will usually result in failure to detect the key physical sign which will tend to confirm the diagnosis. The importance of a careful history cannot be over emphasized.
General Considerations
Physical Characteristics of the Abdomen in Children
The shape of the abdomen in an infant differs from that of an older child in three respects:
1.
It is more protuberant (Fig. 3.2).
Fig. 3.2
The different shape of the infant’s abdomen compared with that of a young adult; not only is it more protuberant but it is also much wider than it is long
2.
It is wider (Fig. 3.2). In the infant, the abdomen tends to bulge between the costal margin and the iliac crest. This is one reason most surgical incisions in children are horizontal rather than vertical.
3.
The pelvis is shallow. In infants, this means that the bladder is an abdominal organ which extends upwards as far as to the umbilicus when it is full. The shallow pelvis also allows extensive information to be gained by rectal digital examination. The fingertip is able to reach the pelvic inlet, to palpate the internal ring in the case of a strangulated hernia and to palpate the reproductive organs in the female.
The posterior abdominal wall is not flat but has a prominent midline ridge due to the vertebral bodies (Fig. 3.3). This makes the aorta and the transverse colon easy to feel compared with other organs, such as the adrenal glands, which lie to the side of the vertebral column. In infancy, the relatively horizontal direction of the ribs contributes to the normal liver edge being palpable below the right costal margin.
Fig. 3.3
A cross section of the abdominal cavity to show the anterior prevertebral organs compared with those situated laterally
The attachment of the membranous layer of the subcutaneous tissue (Scarpa’s fascia) to the fascia lata of the thigh produces the ‘inguinal’ skin crease (see Fig. 4.4 in Chap. 4). This crease is located below the inguinal ligament, which may be a trap in the localization of herniae in infants, especially between 6 and 18 months. The inguinal ligament is palpable through the subcutaneous tissue about 1 cm above this skin crease.
In infants, the processus vaginalis is often patent, and any fluid that collects in the peritoneal cavity (e.g. blood, pus or meconium) may track down through the processus and produce a discoloured scrotum (Fig. 3.4).
Fig. 3.4
The downward tracking of fluid (blood, pus or intestinal contents) to the most dependent parts of the peritoneal cavity
The muscles of the ventral abdominal wall contract during crying and make examination of the abdomen difficult. Therefore, the abdomen is best palpated with the child relaxed or between episodes of crying and can be done most easily lateral to the rectus muscle where the abdominal musculature is thinnest. In pneumonia, some degree of splinting of the abdominal muscles may occur but is overcome by examining the child leaning forwards in the sitting position (Fig. 3.5). This manoeuvre is useful also when there is difficulty evaluating the amount of tenderness in a child with suspected peritonitis.
Fig. 3.5
Overcoming the tight abdominal muscles by examination with the child sitting up and leaning forwards
The Location of Pain
Inflammation or distension of the bowel or its coverings causes pain which is transmitted through two separate pathways. Distension of the bowel and inflammation of the visceral peritoneum stimulate sympathetic pathways, and the perceived location is dependent on the level of bowel involved (Fig. 3.6). As a general rule, pain arising in the foregut projects to the epigastrium, in the midgut to the umbilicus and in the hindgut to the infra-umbilical or hypogastric region. As with most autonomic pathways, localization of pain is not precise and the distribution described serves as a rough guide only. Localized distension with peristalsis against obstruction causes colic, whereas inflammatory lesions produce constant pain, usually in association with anorexia and nausea. It is the visceral pain that so commonly causes the vomiting seen early in the development of appendicitis and other inflammatory lesions of the abdomen.
Fig. 3.6
Surface projection of referred pain from the gastrointestinal tract
In contrast, irritation of the parietal peritoneum supplied by segmental somatic nerves is localized, sharp, continuous and made worse by movement. Not all parts of the parietal peritoneum are subserved by the segmental nerves, which also supply the muscles of the ventral abdominal wall. Irritation of the pelvic peritoneum produces no abdominal wall guarding. Rectal examination may be the only way to diagnose pelvic peritonitis.
Referred pain is not recognized commonly in children, but when appreciated may provide valuable clues as to the underlying pathology. Irritation of the underside of the diaphragm by blood or pus may produce pain referred to the shoulder tip. The explanation for this is that the phrenic nerve which supplies the diaphragm is largely made up of fibres from the fourth cervical nerve root, of which other fibres are cutaneous to the shoulder region. Biliary colic is rare in children but may produce pain in the back, below the inferior angle of the right scapula. Uterine and rectal pain may be referred to the lumbosacral region of the back, while loin pain emanating from the kidney may radiate to the ipsilateral testis. The close proximity of the ovary to the obturator nerve as it courses on the lateral pelvic wall accounts for the pain radiating to the inner aspect of the thigh in ovarian disease.
Masses Palpable in the Normal Abdomen
Faeces may be palpable in the colon and can be distinguished from pathological masses in that they are indentable (see Chap. 15, Fig. 15.2). Their distribution follows the line of the colon, and it must be remembered that the sigmoid colon may lie in the right iliac fossa. The lower pole of the right kidney is often palpable with deep inspiration as the diaphragm pushes the kidney downwards. The liver causes the right kidney to assume a slightly lower position than the left. The liver in infancy is often palpable 2–3 finger breadths below the right costal margin. Further details are found in Chap. 15.
The History
The characteristics of the pain must be established (Table 3.2). Even in the small child who is unable to provide a history, useful information regarding the nature of the pain can be obtained from the parents. They are aware of the duration of the illness and, where the pain has been severe and colicky, will have observed the child cry out and perhaps draw up the legs. Refusal to feed, objection to movement or handling and the presence of associated symptoms (e.g. vomiting and diarrhoea) are useful observations. The large, watery stools of gastroenteritis must be distinguished from the small, mucous stools of pelvic appendicitis or intussusception.
Table 3.2
Characteristics of the pain
1. Time of onset | Duration |
2. Location | At onset |
At examination | |
‘Referred’ pain | |
3. Severity | Mild to severe |
Progression | |
Alleviating factors | |
Exacerbating factors | |
4. Type | Colicky |
Constant | |
5. Associated symptoms |
Duration of Pain
Knowledge of the duration of pain and the normal rate of progression of pathological processes is the key to assessment of physical signs. In malrotation with volvulus, infarction of the entire midgut can occur within several hours. In appendicitis, the inflammatory process may proceed to gangrene and localized perforation, but this is uncommon within 18 h. By contrast, pain which has been present for a week or more without evidence of peritoneal irritation is less likely to be appendicitis (as long as a pelvic appendix has been ruled out).
Shifting of Pain
Movement of pain away from a vague central location to one or other side is often indicative of the development of parietal peritoneal signs (see the section on appendicitis). The extension of pain from a lateral position to involve the whole abdomen suggests that the pathology has extended to other parts of the peritoneal cavity. For example, after a blow to the left upper abdomen that has caused splenic injury, pain may be first located in the left hypochondrium but with continued bleeding progresses to generalized abdominal tenderness. Pain commencing in the right iliac fossa which extends across the midline may indicate extension of peritonitis following rupture of an inflamed appendix.
Type of Pain
The difference between splanchnic and somatic pain has already been described. Obstruction of a hollow viscus causes sharp spasms of ‘colic’ between which the patient suffers a dull ache. The interval between episodes of colic becomes less pronounced as the obstruction progresses. Not all abdominal pains are caused by intra-abdominal disease: when the features do not seem typical of appendicitis, extra-abdominal causes should be considered (Fig. 3.7).
Fig. 3.7
Extra-abdominal illnesses causing abdominal pain
Exacerbating and Relieving Factors
The child with colic is restless and may writhe around unable to obtain a position of comfort. On the other hand, children with peritonitis will remain still and dislike being disturbed or handled. Anything that causes movement between adjacent surfaces of inflamed peritoneum will exacerbate the pain. If they walk, they will do so slowly, bent forwards with both hands holding their abdomen in an attempt to prevent movement of the peritoneal surfaces (Fig. 3.8).
Fig. 3.8
The ‘appendix shuffle’. Movement of adjacent inflamed peritoneal surfaces makes the pain worse. The pain can be minimized by adopting this posture whilst walking
It will hurt to cough, sneeze, vomit or to take a deep breath. Where the inflammation involves the pelvis (as in pelvic appendicitis), micturition and defecation will exacerbate the pain.
In toddlers, pneumonia may masquerade as abdominal pain which is made worse by deep inspiration and relieved by breathing quietly. It is caused by abdominal muscle contraction to splint the diaphragm.
Associated Features
Vomiting commonly accompanies abdominal pain in children because autonomic reflexes stimulate vomiting in response to any inflammation or severe pain. The significance of the symptom is determined by:
1.
The relationship of its onset to the development of pain
2.
Its frequency
3.
The nature of the vomitus
In appendicitis, vomiting generally commences several hours after the onset of pain. It is unusual for it to appear before the pain except in the very small child where the time of onset of the pain may be difficult to ascertain. In acute colic of the ureter, the onset of vomiting coincides with that of pain, both being sudden and dramatic. In obstruction of the intestinal tract, the onset of vomiting is dependent on the level of obstruction. Where the obstruction is high (e.g. duodenum or upper small bowel), vomiting commences early, but where the obstruction is low (e.g. distal small bowel or colon), it may be a day or longer before vomiting appears.
The frequency of vomiting correlates with the severity of the pathology. For example, in acute appendicitis, severe vomiting is often associated with rapid progression of abdominal signs and may indicate an obstructed appendix which is likely to perforate early. On the other hand, in distal intestinal lesions (e.g. intussusception), the frequency of vomiting may not be impressive and may belie the seriousness of the underlying pathology. Proximal obstruction of the bowel is associated with frequent and forceful vomiting.
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