abdominal pain

• The major causes of acute abdominal pain in childhood are benign and self-limited. However, specific signs and symptoms and the clinical site of patient presentation can dramatically change the potential for severe disease.
• In most cases, history and physical examination findings can establish the diagnosis without further testing.
• Observation of indirect signs in small children, such as comfort in their parents’ laps, can be helpful in narrowing the differential diagnosis.
• The most helpful diagnostic tests for appendicitis are clinical scoring systems that incorporate a variety of signs and symptoms, although in the right clinical setting the presence of some individual signs, such as rebound tenderness, dramatically increase the likelihood of appendicitis.
• Laboratory tests and radiologic imaging should be ordered in limited cases, particularly when history and examination findings suggest causes of pain that need urgent surgical intervention. These tests should be directed at the likely diagnosis.

• Overview

  Abdominal pain is a common concern in the pediatric population in all clinical settings. Clinicians and research studies define acute abdominal pain as the onset of pain within 72 hours to one week of presentation. In this chapter, acute abdominal pain is differentiated from recurrent abdominal pain(repeated episodes of similar abdominal pain over a more prolonged period of time) and chronic abdominal pain (pain that is usually or always present over a prolonged period of time) (see Chapter 2). Both recurrent and chronic abdominal pain can originate from diagnoses that overlap with acute abdominal pain. However, once abdominal pain has recurred or persisted for a prolonged period, the most likely causes are different from the differential diagnoses associated with acute abdominal pain.
  Most cases of acute abdominal pain will prove to be from benign and self-limited conditions. Some patients, however, will present with urgent and occasionally life-threatening conditions causing their symptoms.
  Knowledge of the most common causes of abdominal pain in patients within certain age ranges can help focus preliminary diagnostic efforts (Table 1-1). A diagnostic challenge is that abdominal pain can be caused by a wide variety of sources within and outside of the abdominal cavity.
  Additionally, serial examination in many cases of diagnostic uncertainty is a reasonable and cost-effective approach.

• Clinical Features/Signs and Symptoms

  Fever will raise or lower the probability of a number of conditions. In infants, this should raise level of suspicion for urinary tract infection or gastroenteritis. In toddlers, fever will also raise suspicion of urinary tract infection, along with respiratory infections, including lower lobe pneumonia, even in the absence of obvious respiratory symptoms. School-aged children with fever have similar diagnostic considerations but should be considered for group A streptococcal pharyngitis too. Fever in female adolescents with abdominal pain should also raise the possibility of ascending sexually transmitted infections. In addition, fever can be associated with appendicitis and other conditions causing peritonitis. Absence of fever lowers the probability of appendicitis.
  Emesis is an extremely important symptom to assess. In infants, particular emphasis should be placed on presence or absence of bilious emesis, as bile-stained vomitus suggests an obstructive process in the proximal small bowel and is highly suggestive of a surgical and morbid cause of pain. Bilious emesis in the neonate should immediately prompt evaluation with an upper gastrointestinal tract series and discussion with a pediatric surgeon. In older children, emesis is less likely to be caused by intestinal obstruction and most frequently will be from acute gastroenteritis. Older children and adolescents can occasionally have bilious emesis after prolonged vomiting in the setting of a non-obstructive process. Classically, emesis will precede abdominal pain in gastroenteritis. This is in contrast to surgical causes of pain, which tend to have pain preceding emesis, though this pattern is not reliably consistent.

  TABLE 1-1. DIFFERENTIAL DIAGNOSIS OF ACUTE ABDOMINAL PAIN BASED ON AGE AND IMPORTANT SYMPTOMS

  	Infant	Toddler	School-aged Child	Adolescent
  Abbreviation: DKA, diabetic ketoacidosis.
  Specific symptoms	Fever Emesis: bilious or not Stool pattern: frequency and quality of stool Decreased feeding Peritoneal symptoms or signs	Fever Emesis Stool pattern: frequency and quality of stool Decreased appetite Dysuria Peritoneal symptoms or signs	Fever Emesis Stool pattern: frequency and quality of stool Decreased appetite Dysuria Pain character: colicky or dull Peritoneal symptoms or signs	Fever Emesis Stool pattern: frequency and quality of stool Decreased appetite Dysuria Menstrual history/pregnancy status Pain character: colicky or dull Peritoneal symptoms or signs
  Common nonsurgical abdominal diagnoses	Urinary tract infection Gastroenteritis Colic Infantile dyschezia Milk protein allergy	Nonspecific abdominal pain Gastroenteritis Constipation Mesenteric adenitis	Nonspecific abdominal pain Gastroenteritis Constipation Mesenteric adenitis	Nonspecific abdominal pain Gastroenteritis Constipation Ruptured ovarian cyst Pelvic inflammatory disease
  Common surgical diagnoses	Pyloric stenosis Volvulus Hernia Trauma Intussusception Hirschsprung disease	Intussusception Appendicitis Trauma Swallowed foreign body	Appendicitis Trauma	Appendicitis Trauma Ovarian/testicular torsion Ectopic pregnancy
  Nonabdominal or systemic causes	Upper respiratory tract infection	Upper respiratory tract infection Pneumonia Henoch-Schönlein purpura Discitis	Upper respiratory tract infection Pharyngitis, group A streptococcal pharyngitis Abdominal migraine DKA Pneumonia Henoch-Schönlein purpura	Upper respiratory tract infection DKA Pneumonia

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  The stooling pattern can also provide important history. A common history in young infants is straining with apparent discomfort during defecation, resultant soft stools, and normal appearance in between. This pattern is seen with infantile dyschezia, a benign condition in infants learning coordination of abdominal contractions with relaxation of rectal and pelvic floor musculature. Bloody stools in infants are most frequently from medical causes such as milk protein allergy, but if the infant is distressed or ill appearing, more serious causes, including intussusception, should be considered. Bloody stools in older children with abdominal pain should raise level of suspicion for bacterial enteritis, although bowel necrosis from an urgent surgical diagnosis needs to be considered as well. Intussusception is most commonly seen in children during the second year of life and will typically cause episodic severe pain, often associated with crying and drawing of legs up to the abdomen. Diarrhea in all age ranges is associated with gastroenteritis but can accompany other conditions causing abdominal pain. Lack of stool output can indicate constipation but may also reflect ileus or anatomic intestinal obstruction and can be a subtle symptom of developing peritonitis.
  Anorexia in older children is associated with appendicitis. It can also be associated with bacterial disease such as streptococcal pharyngitis and pneumonia, as well as any severe systemic disease.
  Peritoneal symptoms tend to be subtle in children, especially younger ones. They often manifest by the child being less active. A history of increased pain with movement, such as while driving in a car over rough roads, is important and may need to be asked specifically of parents to be elicited.
  Older children can have the same patterns as observed in infants and toddlers. In older children, painpreceding emesis is somewhat more suggestive of surgical pathology than the reverse.

TABLE 1-1. DIFFERENTIAL DIAGNOSIS OF ACUTE ABDOMINAL PAIN BASED ON AGE AND IMPORTANT SYMPTOMS

	Infant	Toddler	School-aged Child	Adolescent
Abbreviation: DKA, diabetic ketoacidosis.
Specific symptoms	Fever Emesis: bilious or not Stool pattern: frequency and quality of stool Decreased feeding Peritoneal symptoms or signs	Fever Emesis Stool pattern: frequency and quality of stool Decreased appetite Dysuria Peritoneal symptoms or signs	Fever Emesis Stool pattern: frequency and quality of stool Decreased appetite Dysuria Pain character: colicky or dull Peritoneal symptoms or signs	Fever Emesis Stool pattern: frequency and quality of stool Decreased appetite Dysuria Menstrual history/pregnancy status Pain character: colicky or dull Peritoneal symptoms or signs
Common nonsurgical abdominal diagnoses	Urinary tract infection Gastroenteritis Colic Infantile dyschezia Milk protein allergy	Nonspecific abdominal pain Gastroenteritis Constipation Mesenteric adenitis	Nonspecific abdominal pain Gastroenteritis Constipation Mesenteric adenitis	Nonspecific abdominal pain Gastroenteritis Constipation Ruptured ovarian cyst Pelvic inflammatory disease
Common surgical diagnoses	Pyloric stenosis Volvulus Hernia Trauma Intussusception Hirschsprung disease	Intussusception Appendicitis Trauma Swallowed foreign body	Appendicitis Trauma	Appendicitis Trauma Ovarian/testicular torsion Ectopic pregnancy
Nonabdominal or systemic causes	Upper respiratory tract infection	Upper respiratory tract infection Pneumonia Henoch-Schönlein purpura Discitis	Upper respiratory tract infection Pharyngitis, group A streptococcal pharyngitis Abdominal migraine DKA Pneumonia Henoch-Schönlein purpura	Upper respiratory tract infection DKA Pneumonia

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Evaluation

In most settings, physicians approach the diagnosis of abdominal pain by simultaneously approaching 2 goals. First, physicians look for a constellation of symptoms and signs to confirm that one of the common relatively benign syndromes is present, such as gastroenteritis or nonspecific, self-limiting abdominal pain. Second, physicians are also continuously assessing for severe or red-flag findings that could suggest serious illnesses, particularly illnesses that need urgent surgical intervention.

Physical examination should begin with the child in a position of comfort away from the examiner. Overall comfort and appearance should be noted as well as if the patient is walking or moving normally, moving frequently, or lying still. For most children, this should be followed by a complete examination, focusing on the abdomen toward the end of the physical examination but before other uncomfortable examination elements. It is particularly important to focus on the anatomic structures located near the abdomen, including the lung bases superior to the abdomen and the genitalia and hips inferior to the abdomen. Specific examination of the abdomen may start with auscultation of bowel sounds and be followed by palpation of the abdomen. A rectal examination is usually not needed to diagnose the cause of abdominal pain. Similarly, gynecologic examination is rarely needed, but if vaginal discharge or lower abdominal pain and fever in an adolescent are present, pelvic examination can be critical. The most common diagnosis of acute abdominal pain that requires surgical intervention for all ages except infancy is appendicitis. In some case series in emergency departments, up to 10% of children with abdominal pain are reported to have appendicitis, even higher if certain historical elements are present. However, in a large case series with more than 1,000 children presenting to either an urgent care setting or emergency department at a large children’s hospital, slightly less than 1% of children older than 2 years with a chief concern of abdominal pain had appendicitis. History and physical examination findings are most helpful when grouped in a clinical scoring system. The most commonly studied system is the Alvarado score (Box 1-1), which applies points for specific signs and symptoms as follows:

Box 1-1. Alvarado Score for Appendicitis (Note mnemonic of MANTRELS for criteria.)

		Value
From Alvarado A. A practical score for the early diagnosis of acute appendicitis. Ann Emerg Med. 1986;15(5):557–564. Reprinted with permission.
[a] Scores ≥7 points have a positive likelihood ratio that approximates 4.0 (confidence interval of 3.2 to 4.9) and scores ≤4 dramatically decrease the likelihood of appendicitis with a likelihood ratio of 0.05 (confidence interval of 0.0 to 0.85).
Symptoms	Migration	1
	Anorexia-acetone	1
	Nausea-vomiting	1
Signs	Tenderness in right lower quadrant	2
	Rebound pain	1
	Elevation of temperature	1
Laboratory	Leukocytosis	2
	Shift to the left	1
Total score[a]		10

In cases of diagnostic uncertainty, laboratory tests for complete blood count, erythrocyte sedimentation rate, and C-reactive protein concentration, and urinalysis, are usually the first tests ordered. Other laboratory tests evaluating for liver inflammation, pancreatic inflammation, genitourinary tract infections, or pregnancy should be used in appropriate clinical scenarios. Radiologic imaging should be focused on diagnosing or excluding specific conditions, rather than as a broad diagnostic tool in the undifferentiated patient.

Infant

Laboratory Tests

Catheterized urinalysis should be ordered for the febrile infant to exclude urinary tract infection. Stool antigen testing for rotavirus can be diagnostic in the setting of acute diarrheal illness, though management of disease is not altered by this result.

Radiologic Imaging

A plain abdominal radiograph, particularly with a supine and also an upright or lateral view, is helpful to evaluate for suspected obstructive processes or if signs of peritonitis are present to exclude a perforated viscus. It can suggest an intussusception but is generally not diagnostic. Ultrasound in experienced centers can diagnose intussusception; however, air or contrast (preferably water-soluble) enema will be both diagnostic and therapeutic. Upper gastrointestinal tract contrast study should be ordered when malrotation with volvulus or other proximal intestinal obstruction is suspected, usually in the presence of bilious emesis. Contrast enema is the test of choice when Hirschsprung is suspected in the acute setting. Guidelines suggest that anorectal manometry is a preferred diagnostic method for Hirschsprung disease in non-acute situations but cannot be immediately obtained in most centers. An abnormal contrast enema will reveal a transition point from a normal-sized rectum to a dilated sigmoid colon. This test should be done with no rectal manipulation in the preceding 24 hours to avoid temporarily dilating the transition point.

One to 5 Years

Laboratory Tests

Urinalysis should still be considered for the febrile patient. Group A streptococcal pharyngitis testing should also be considered. Rotavirus testing is a consideration in patients with diarrheal illness. Blood tests can be useful as an adjunct in diagnosis of acute appendicitis. A peripheral white blood cell count of less than 10,000/μL lowers posttest odds of appendicitis by 80% (likelihood ratio of 0.22), whereas one greater than 10,000/μL doubles posttest odds (likelihood ratio of 2.0).

Radiologic Imaging

Plain radiographs of the abdomen may be helpful to evaluate for constipation or when history or physical examination findings suggest obstruction or peritonitis. A plain radiograph of the chest should be considered for febrile patients, with or without respiratory symptoms, to exclude lower lobe pneumonia if no other cause of fever is apparent. Ultrasound may be utilized in experienced centers to look for intussusception. Additionally, ultrasound performs well with experienced operators in evaluation for appendicitis. Upper gastrointestinal tract contrast study should be performed when malrotation with volvulus or other proximal intestinal obstruction is suspected. Air or contrast enema will diagnose and treat cases of intussusception. Computed tomography can diagnose acute appendicitis reliably but is time-consuming and expensive and involves significant radiation exposure to the patient.

School-aged Child

Considerations are very similar to those for preschool-aged children, except that volvulus and intussusception are much less common, and patients can generally provide more detailed history and are more tolerant of physical examination.

Adolescent

Additional considerations include pregnancy and its complications, sexually transmitted infections, menstrual- and ovulation-related pain, and gonadal torsion.

Laboratory Tests

Urinalysis should be considered with symptoms of urinary frequency, dysuria, or hematuria. A urine pregnancy test should be considered for girls who are post-menarche. Urine can be sent for testing for sexually transmitted infections, and purulent urethral or vaginal discharge should be sent for gonorrheal and chlamydial disease testing.

Radiologic Imaging

Ultrasound with views of vascular structures when appropriate is often critical to diagnoses of genitourinary tract issues, including ovarian torsion, ectopic pregnancy, and testicular torsion.

Management

Treatment will depend on the underlying diagnosis. A firm diagnosis may not be obvious even after careful history, physical examination, and directed ancillary testing. In this case, serial abdominal examinations may be the best course. Several indications call for pediatric surgical consultation. These include signs or symptoms of peritonitis; intestinal obstruction, especially bilious or feculent emesis; incarcerated inguinal hernia; and any suggestion of surgical cause of abdominal pain on radiologic imaging, such as free air in the peritoneum. Suspected appendicitis is a frequent referral reason for surgical consultation.

Withholding pain medications in children with severe acute abdominal pain for fear of “masking” is not supported by medical evidence, and, in fact, adequate pain control may enhance diagnostic accuracy by allowing a more thorough physical examination. Acetaminophen is a reasonable choice in patients who can take oral medications and have mild to moderate pain, while weight-based intravenous morphine or fentanyl(not to exceed an adult dose) is safe and effective for patients who are unable to tolerate oral dosing or those who have more severe pain.