Abdominal Pain in Children

Jennifer R. Marin, MD, MSc ^a^,^*, Elizabeth R. Alpern, MD, MSCE ^b

^a Division of Emergency Medicine, Department of Pediatrics, Children’s Hospital of Pittsburgh, 4401 Penn Avenue, AOB 2nd floor, Suite 2400, Pittsburgh, PA 15224, USA

^b Division of Emergency Medicine, Department of Pediatrics, The Children’s Hospital of Philadelphia, 34th Street and Civic Center Boulevard, Philadelphia, PA 19104, USA

^* Corresponding author.

E-mail address: jennifer.marin@chp.edu

Abstract

Abdominal pain is one of the most common reasons pediatric patients seek emergency care. The emergency physician must be able to distinguish diagnoses requiring immediate attention from self-limiting processes. Pediatric patients can be challenging, particularly those who are preverbal, and therefore, the clinician must rely on a detailed history from a parent or caregiver as well as a careful physical examination in order to narrow the differential diagnosis. This article highlights several pediatric diagnoses presenting as abdominal pain, including surgical emergencies, nonsurgical diagnoses, and extraabdominal processes, and reviews the clinical presentation, diagnostic evaluation, and management of each.

Keywords

• Abdominal pain • Pediatric • Children

Abdominal pain is one of the most common reasons pediatric patients seek emergency medical care.¹^–³ In the emergency department (ED), physicians must distinguish between emergent diagnoses that require immediate intervention, such as appendicitis, intussusception, and ovarian torsion, and self-limiting processes that are amenable to outpatient management and parental/guardian education, such as viral gastroenteritis and constipation. Abdominal pain also may be a presentation of extraabdominal processes, such as pneumonia and asthma.

History

The diagnosis of a child with abdominal pain can often be determined, or the differential diagnosis can at least be honed, with the aid of a good history and physical examination. Before even entering the room, the clinician can gain a wealth of information simply by observing the child from the doorway. For example, it can be reassuring to see a young child running around the room or sitting playing with toys on the bed, versus the child lying flat on the stretcher crying from pain. For many young children, being in the hospital or in the presence of health care workers can be intimidating and frightening. Therefore, the physician should minimize the child’s anxiety. Some children fear even the sight of a white coat, and therefore its removal may provide some comfort. The physician should kneel or sit near the child as opposed to standing over the child, because being located near the child’s eye level can be less daunting for them.

It may be difficult to elicit a detailed or even accurate history from the parent/guardian secondary to the age of the child. For instance, a child may present with inconsolable crying and it may not be apparent to the caregiver that the source of the pain is abdominal. However, as long as the physician maintains a high index of suspicion for an abdominal condition in these patients, the diagnosis is unlikely to be missed.

The history should be tailored to the age of the child. For example, it is important to obtain the sexual past and present history of an adolescent patient presenting with abdominal pain. Furthermore, this history should be gathered with family members out of the room in order to respect confidentiality and evoke a more accurate history. Birth and neonatal history become more relevant to the infant presenting with possible abdominal pain, versus the older adolescent patient. The history should be elicited from both the patient and the caregiver in the verbal child, whereas in the preverbal child, the history is obtained from the parent/guardian exclusively.

Physical examination

The physical examination should begin with review of the vital signs. It is important to have knowledge of pediatric normal values for heart rate, respiratory rate, and blood pressure. Rather than memorizing ranges for each age group, it may be helpful to have a reference to which the clinician can refer when caring for a pediatric patient (Table 1).

Table 1 Pediatric normal vital signs

It is important to focus not only on the abdominal portion of the physical examination of the child with abdominal pain, because extraabdominal causes may also present with abdominal pain. For example, the physician should perform a complete oropharyngeal, lung, back, skin, external genital, and possibly internal genital examination as part of the evaluation as well. When the physician is ready to examine the abdomen, the accuracy of the examination may be improved by using a toy as a distraction tool before auscultation or palpation.² If the child is already sitting in the lap of their caregiver, it may be useful to perform as much of the examination as possible with the child remaining there. The physician may initially palpate the caregiver’s or a stuffed animal’s abdomen in an effort to show the benign nature of the examination to the child. A school-age child may feel more comfortable if they are allowed to place their hand over or under the physician’s hand as the abdomen is being palpated. Asking the older child questions about school, friends, and activities that they enjoy may serve as a distraction tool and facilitate examination.

The abdominal examination should begin with visualization of obvious abnormalities, such as distension, bruising, or masses. If palpation is hindered by voluntary guarding from the child, it is useful to bend the child’s knees and attempt the distraction techniques mentioned earlier. When eliciting peritoneal signs, the child can be asked to jump up and down if they are able to stand. Otherwise, with the child sitting on a caregiver’s lap, the caregiver can be asked to bounce the child up and down and observe for signs of pain from the child. The rectal examination, evaluating for firm stool, blood, and a palpable mass, is not imperative in all children presenting with abdominal pain but may be useful in narrowing the differential diagnosis. In most children, it can be easily performed by partially introducing a small finger into the rectal vault.

Differential diagnosis

It is helpful to consider the differential diagnosis of the child with abdominal pain in terms of the age of the child, because many diagnoses are seen more commonly in children of certain age groups (Table 2).

Table 2 Pediatric diagnosis presenting with abdominal pain by age group^a

For purposes of this article, we consider select pediatric diagnoses in terms of surgical emergencies involving the abdomen and pelvis, nonsurgical gastrointestinal diseases, and extraabdominal diagnoses.

Diagnoses

Surgical

Appendicitis

Appendicitis is the most frequent surgical cause of abdominal pain in children presenting to EDs or outpatient clinics.^4,⁵ In one-third of children with appendicitis, the appendix ruptures before operative treatment.^6,⁷ This situation is particularly of concern in children less than 4 years of age. In this age group, despite not being a common diagnosis, the prevalence of perforation is high, with rates reported to be as high as 80% to 100%.⁸^–¹⁰ Moreover, because the omentum is less developed, perforations are less likely to be localized, leading to generalized peritonitis.²

The pathophysiology of appendicitis in children is different from that of adults because of the changing anatomic location and susceptibility of the appendix throughout childhood.¹¹ For example, neonatal appendicitis is infrequent because of their funnel-shaped appendix, soft diet, recumbent posture, and infrequent gastrointestinal and upper respiratory infections.^12,¹³ Around 1 to 2 years of age, the appendix becomes more susceptible to appendicitis as it assumes the adult shape. As the child ages, lymphoid follicle hyperplasia and size of the appendix gradually increase throughout childhood and peak in adolescence, which represents the highest incidence of appendicitis.^8,¹⁴

The classic presentation of appendicitis (periumbilical abdominal pain migrating to the right lower quadrant associated with nausea, vomiting, and fever) is seen less often in pediatric patients compared with adults,¹⁵ and its presence in children is not so strong a predictor for appendicitis as it is in adult patients.¹¹ Children often present earlier in the clinical process than adults, when only mild or nonspecific signs and symptoms are present. Furthermore, there are limited data indicating that signs such as rebound tenderness and Rovsing sign are accurate in children.¹⁶ More common findings of appendicitis in children are right lower quadrant pain, vomiting, abdominal tenderness, and guarding.¹⁶ In addition, the appendix may be located deep in the pelvis or rectocecally, which gives rise to back or pelvic pain, rather than the abdominal pain seen with the more common anterior appendix. Although difficult to elicit from caregivers, a history of abdominal pain preceding any emesis can be helpful to distinguish appendicitis from acute gastroenteritis (AGE).²

Laboratory testing can aid in the diagnosis of appendicitis; however, no test is 100% sensitive and specific for the diagnosis. The white blood cell count (WBC),¹⁷^–¹⁹ C-reactive protein (CRP) test,^17,^18,²⁰^–²² and urinalysis (UA) may be useful; however, the WBC count and CRP level may be increased in other conditions and normal in appendicitis. Furthermore, if the inflamed appendix is located adjacent to the ureter, the UA may reveal sterile pyuria or hematuria.²³

Many scoring systems using a combination of signs, symptoms, and laboratory results to predict which patients have acute appendicitis have been developed and validated in children. These scoring systems have varying sensitivities (65%–98%) and specificities (32%–92%)²⁴^–²⁸ and are rarely used as definitive confirmation of the diagnosis.

Radiologic diagnosis of acute appendicitis before appendectomy has become increasingly more common as its availability in the ED has improved. Plain abdominal radiographs should not be routinely used in evaluating the patient with appendicitis, because only half of patients with surgically proved disease have abnormal findings, most of which are nonspecific.²⁹ Appendicoliths, which are believed to be the most specific finding of acute appendicitis, are visualized in only 5% to 15% of patients.^2,^30,³¹ If a radiograph is obtained in the evaluation of the child with abdominal pain, Box 1 lists findings that may be associated with acute appendicitis. Ultrasound has been increasingly used as the modality of choice in pediatric patients because of the lack of radiation exposure and need for contrast agents. As with ultrasound examinations for other indications, the test characteristics of ultrasound for diagnosing acute appendicitis depend on the experience and comfort level of the operator. In experienced hands, ultrasound can achieve sensitivities of 85% to 90% and specificities of 95% to 100%.³²^–⁴⁰ Using a graded compression technique, acute appendicitis is defined as an aperistaltic, noncompressible appendix larger than 6 mm in diameter. The presence of periappendiceal fluid may indicate inflammation or an early perforation. If present, an appendicolith may also be visualized by ultrasound. If ultrasound is unavailable, or is obtained and fails to visualize the appendix, a computed tomography (CT) scan becomes the test of choice. Sensitivity has been shown to be 88% to 97%, with specificities of 94% to 97% in pediatric studies,⁴¹^–⁴³ and it also offers the advantage of identifying complications of appendicitis as well as alternative diagnoses. However, it is slower, may require oral or rectal contrast, which may be difficult to administer to a young child, and carries the risk of significant radiation exposure.

Box 1 Abdominal radiograph findings in acute appendicitis

Sentinel loop

Air-fluid levels

Right-sided curvature of the spine

Fecolith

Mass in right lower quadrant

Loss of psoas sign

Children are at greater risk than adults from a given dose of radiation because they are inherently more radiosensitive and because they have more remaining years of life during which a radiation-induced cancer could develop.⁴⁴ Although no large-scale epidemiologic studies of the cancer risks associated with abdominal CT have been reported,⁴⁴ the cancer risks associated with the radiation exposure from CT scans have been estimated (Fig. 1). By adjusting for current CT usage, it can be estimated that about 1.5% to 2.0% of all cancers in the United States may be attributable to the radiation from CT studies.⁴⁴ If a CT is determined necessary, the question of which contrast agent or combination of agents to use (oral, intravenous, rectal) is a matter of debate in the radiology literature, is institutional-dependent, and should be decided on in concert with the radiologist or technician performing the study.

Fig. 1 Estimated lifetime cancer risk from single CT scan of the abdomen.

(From Brenner DJ, Hall EJ. Computed tomography–an increasing source of radiation exposure. N Engl J Med 2007;357(22):2281; with permission.)

Despite the increased usage of radiologic modalities to confirm the diagnosis of acute appendicitis, when the clinician has a high suspicion for appendicitis, a surgeon should be consulted early in the patient course. While the diagnostic evaluation is being pursued, it is important to medically manage the patient until the diagnosis is confirmed and surgical management can occur. Children with appendicitis usually have decreased oral intake throughout the day, may have significant insensible losses if they are febrile, and also have third spacing secondary to intestinal inflammation, all leading to fluid losses, which should be replenished intravenously. Normal saline or lactated Ringer boluses should be given in order to establish euvolemia, followed by maintenance fluids until the child is taken to the operating room. Antibiotic coverage for gram-negative and anaerobic bacteria (such as ampicillin/sulbactam, piperacillin/tazobactam, or ampicillin/gentamicin/flagyl) should be started in the ED once the diagnosis is confirmed.

It is not uncommon for the diagnosis to remain unconfirmed, particularly in those children with a low or moderate suspicion for appendicitis. These patients should either be admitted to the hospital for serial abdominal examinations or if the suspicion for appendicitis is low, the patient seems well and has adequate oral intake, and there is reliable follow-up within 8 to 12 hours, the patient may be sent home with strict anticipatory guidance for when to return to the ED.

Intussusception

Intussusception is second to appendicitis as the most common cause of an acute abdominal emergency in children.⁴⁵ It is the most common cause of intestinal obstruction in children between 3 months and 6 years of age.⁴⁵ Although intussusception can occur at any age, the peak incidence occurs between 5 and 9 months of age,⁴⁶ and about half of patients are less than 1 year of age.⁴⁷

Intussusception occurs when a segment of bowel (intussusceptum) invaginates into the distal bowel (intussuscipiens) (Fig. 2). This situation results in venous congestion and bowel wall edema initially; however, if unrecognized and untreated, this may lead to arterial obstruction with bowel necrosis and perforation.^48,⁴⁹ Most intussusceptions in children (90%) are ileocolic and idiopathic in nature.⁵⁰ Presumably, idiopathic intussusception is caused by lymphoid hyperplasia, which has been suggested as the lead point.⁵¹ Viral infections caused by adenovirus, rotavirus, and human herpesvirus 6 have been reported to be associated with intussusception.^52,⁵³

Fig. 2 The mechanism of intussusception.

(From Del Mar, C. Royal Australian College of General Practitioners Complete Home Medical Guide, 2nd ed. Dorling Kindersley Australia; 2006; with permission.)

The clinician should have a high index of suspicion for intussusception in a young child with paroxysmal, colicky abdominal pain and vomiting. The classic triad of intermittent abdominal pain, red currant jelly stool (caused by venous congestion from obstruction), and a palpable mass occurs in a minority of patients (up to 40% of children with intussusception).^54,⁵⁵ More common than grossly bloody stools is the presence of fecal occult blood, which is seen in approximately 50% of patients.⁴⁵ Therefore, the suspicion of intussusception should prompt the clinician to perform a rectal examination with testing for occult blood. Although it is an unusual presentation, some children with intussusception may present with lethargy or altered mental status, a feature that is postulated to be caused by the release of endogenous opioids secondary to the paroxysms of pain.^56,⁵⁷ In addition, many children present with nonspecific signs and symptoms, which may lead to a delay or missed diagnosis in up to 60% of cases.⁴⁵ Specifically, infants younger than 4 months have a higher incidence of painless intussusception.⁵⁵ Also, up to 30% of patients with intussusception have diarrhea,⁵⁸ and therefore viral gastroenteritis is frequently entertained as the initial diagnosis. Intermittent intussusception is another entity that may prove challenging for the clinician, because these children may have resolution of their symptoms between episodes of obstruction.

When evaluating a child with suspected intussusception, the first step in diagnosis is obtaining 2 or 3 radiographic views of the abdomen. Left lateral decubitus radiographs are particularly helpful for this diagnosis, because the presence of air in the right lower quadrant makes the diagnosis of intussusception less likely. This situation is because most idiopathic intussusceptions occur at the level of the right upper quadrant, resulting in a paucity or absence of gas in the right lower quadrant, which can be confirmed in the decubitus position. However, plain abdominal films are neither sensitive nor specific for intussusception and may be completely normal in 25% of patients.⁵⁹ Fig. 3 is an example of the plain radiographs in a patient with intussusception. Table 3 lists other characteristic signs on plain radiograph and ultrasound that may be seen in patients with intussusception.

Fig. 3 (A–C) Upright (A unlabeled, B labeled) and left lateral decubitus (C) radiographs of a patient with intussusception. (B) Target sign (concentric circles), crescent sign (thin arrow with semicircle), paucity of gas in right lower quadrant (thick arrow). (C) Air-fluid levels and paucity of gas throughout abdomen.

Table 3 Radiologic findings of intussusception

Finding	Description	Radiograph or US
Soft-tissue mass in upper abdomen		Radiograph
Paucity/absence of air in right lower quadrant		Radiograph
Small bowel obstruction		Radiograph or US
Target sign	2 concentric, circular, radiolucent lines to the right of the spine superimposed on the kidney; caused by right upper quadrant mass with mesenteric fat of intussusceptum	Radiograph
Crescent/meniscus sign	Crescent of gas within the colonic lumen that outlines the apex of the intussusception	Radiograph
Pseudokidney sign	Hyperechoic tubular center with a hypoechoic rim on both sides, producing a kidneylike appearance in longitudinal plane	US
Donut sign	Hypoechoic outer rim of homogeneous thickness (intussuscipiens) with a central hyperechoic core (intussusceptum) representing layers of the intestine within the intestine in transverse plane	US

Abbreviation: US, ultrasound.

Data from Waseem M, Rosenberg HK. Intussusception. Pediatr Emerg Care 2008; 24(11):794.

Ultrasound (Fig. 4) has recently emerged as a sensitive (98%–100%) and specific (88%–100%) diagnostic tool for the evaluation of children with suspected intussusception.⁶⁰^–⁶³ However, because ultrasound is operator dependent, its test characteristics for this indication vary depending on the institution. Ultrasound is a noninvasive, rapid, and nonionizing modality, making it an attractive diagnostic option in children. In addition, a lack of perfusion in the intussusceptum detected with color duplex imaging may indicate the development of ischemia. Ultrasound also has the advantage of providing information regarding a pathologic lead point mass, the presence of a small bowel intussusception, information regarding reducibility based on bowel wall findings, and in the identification of alternative diagnoses.^60,^61,^64,⁶⁵ If ultrasound is unavailable or if an intussusception is identified by ultrasound, the patient should undergo a fluoroscopic barium or air enema, which is both diagnostic and therapeutic.

Fig. 4 Transverse ultrasonographic view of intussusception. Note the donut sign (yellow arrow).

Although capable of showing intussusception, CT is usually not indicated because the diagnosis is reliably made either by ultrasound or radiographic barium or air enema. However, an abdominal CT scan may be useful in older children in excluding other diagnosis and in assessing for a lead point.

Treatment of confirmed intussusception begins with fluid resuscitation and maintenance of intravenous fluids, because most patients are dehydrated secondary to vomiting, poor oral intake, and third spacing.⁴⁵ Because intussusception may become a surgical condition, if radiographic barium or air enema reduction is unsuccessful, it is important that a pediatric surgeon be available before attempted reduction with enema. Nonoperative reduction of intussusception includes air, barium, or aqueous enema, typically under fluoroscopic guidance (Fig. 5). The decision about which agent to use is typically based on the comfort and preference of the radiologist performing the procedure. Success ranges up to 70% for barium⁶⁶ and 84% for air,^67,⁶⁸ and is influenced by the duration of symptoms, with enema reduction being less successful the longer the delay in diagnosis.⁶⁹ Some pediatric radiologists have begun to incorporate the use of ultrasound-guided enema reduction as a treatment modality instead of traditional fluoroscopy-guided reduction, which carries the risk of ionizing radiation. This method has been used in other countries and has been shown to be safe and effective.⁷⁰^–⁷²