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CHAPTER 133: Acute Abdominal Pain in Infants and Children 857 Acute Abdominal Pain in Infants and Children Ross J. Fleischman INTRODUCTION The diagnoses in this chapter are challenging, as emergent surgical conditions in children may present with symptoms other than pain, including vomiting, fever, irritability, or lethargy. Table 133-1 classifies conditions by age, although many conditions cross categories. The pathophysiology of abdominal pain is discussed in Chapter 71, “ Acute Abdominal Pain. ” Gynecologic causes are discussed in Chapter 97, “ Abdominal and Pelvic Pain in the Nonpregnant Female. ” Gastroenteritis is the most common cause of abdominal pain in children of all ages (see Chapter 131, “Vomiting, Diarrhea, and Dehydration in Infants and Children”). The largest single group of children will have no definite diagnosis and will receive the diagnosis of exclusion of nonspecific abdominal pain. Patients should not be given unsubstantiated diagnoses such as gastroenteritis, gastritis, or constipation without strong support for these diagnoses. Patients discharged without a clear diagnosis should have a planned reexamination. PHYSICAL EXAMINATION The assessment of young children depends on observation for subtle clues. Stillness suggests conditions that irritate the peritoneum, such as appendicitis. Writhing for a position of comfort suggests obstruction, such as intussusception or renal colic. Inspect, auscultate, and then palpate the abdomen, starting away from the expected area of maximal tenderness. Bringing the knees up relaxes the abdominal muscles. Move the hips to test for hip pathology or irritation caused by appendicitis or a psoas abscess. Thoroughly examine the diaper area to identify testicular torsion, paraphimosis, hair tourniquet, hernia, and imperforate hymen, as the young child may be unable to articulate problems in that area and the older child may be embarrassed to do so. Rectal exam may identify gross or occult blood, constipation, abnormalities of anogenital anatomy, and inflam matory processes. Evaluate for extra-abdominal causes of abdominal pain such as pharyngitis or pneumonia. LABORATORY STUDIES Bedside glucose measurement is a first step in the evaluation of any ill-appearing child or in cases of persistent vomiting or poor oral intake. Obtain a chemistry panel if there is suspicion for electrolyte or renal abnormalities in ill-appearing children and in the first 6 months of life, when sodium or metabolic abnormalities are more common. Urinalysis and urine human chorionic gonadotropin identify urinary tract infection, microscopic hematuria, and pregnancy. The WBC count and C-reactive protein are poor screening tests for undifferentiated abdominal pain. DIAGNOSTIC IMAGING US is the first-line test for appendicitis, pyloric stenosis, intussus ception, testicular torsion, urolithiasis, and biliary and gynecologic pathology. CT scan is the most sensitive study for appendicitis and intra-abdominal abscesses and may uncover a wide variety of pathology. Abdominal CT exposes children to a significant radiation dose to which young children are more sensitive than adults 1 and IV contrast carries a risk of serious allergic reactions and can cause nephropathy; therefore, reducing unnecessary CT use should be a goal of emergency physicians. Plain radiographs give a much lower radiation dose than CT (1/600th the dose for a chest radiograph compared with an abdominal CT) but are often nonspecific.

contrast carries a risk of serious allergic reactions and can cause nephropathy; therefore, reducing unnecessary CT use should be a goal of emergency physicians. Plain radiographs give a much lower radiation dose than CT (1/600th the dose for a chest radiograph compared with an abdominal CT) but are often nonspecific. 2 Use radiography selectively to exclude or support specific diagnoses (e.g., obstruction), rather than undirected screening. Free air from a perforation can be seen on upright or left lat eral decubitus views, although these are insensitive tests. Avoid barium oral or rectal contrast if perforation is suspected and use water-soluble contrast instead.  PAIN MANAGEMENT Contrary to fears that analgesics may mask surgical conditions, analgesia improves the physician’s ability to assess pain and does not worsen outcomes. See Chapter 115, “Pain Management and Procedural Sedation in Infants and Children. ”  SPECIAL CONSIDERATIONS BY AGE GROUP NEONATES AND YOUNG INFANTS (0 TO 3 MONTHS) The major life-threatening diagnoses in young infants are necrotiz ing enterocolitis, malrotation with midgut volvulus, incarcerated hernias, and nonaccidental trauma. Y oung infants typically eat every 2 hours, so inconsolability and lethargy with poor feeding are signs of serious disease. The maxim that bilious vomiting portends a surgical emergency is well supported, as between 27% and 51% of children with bilious vomiting require surgery. Intermittent, paroxysmal pain is often associated with intussusception (rare in this age group), colic, and gastroenteritis. Necrotizing enterocolitis and volvulus are more typically associated with constant pain. Pain after feeding may be caused by gastroesophageal reflux. Pyloric stenosis causes progressive painless projectile vomiting followed by renewed interest in feeding. Past medical history includes the complications of pregnancy and delivery. Constipation with a history of not passing meconium within the first 24 to 48 hours of life suggests Hirschsprung’s disease. Hirschsprung’s enterocolitis is a serious complication that presents with CHAPTER TABLE 133-1 Causes of Abdominal Pain by Age Group Age Emergent Nonemergent 0–3 months old Necrotizing enterocolitis Volvulus Incarcerated hernia Testicular torsion Nonaccidental trauma Hirschsprung’s enterocolitis Constipation Acute gastroenteritis Colic 3 months–3 years old Intussusception Volvulus Testicular torsion Appendicitis Vaso-occlusive crisis Urinary tract infections Constipation Henoch-Schönlein purpura Acute gastroenteritis 3 years old–adolescence Appendicitis Diabetic ketoacidosis Vaso-occlusive crisis Ectopic pregnancy Ovarian torsion Testicular torsion Cholecystitis Pancreatitis Urinary tract infections Tumor Pneumonia Streptococcus pharyngitis Inflammatory bowel disease Pregnancy Renal stones Peptic ulcer disease/gastritis Ovarian cysts Henoch-Schönlein purpura Constipation Acute gastroenteritis Nonspecific viral syndromes Tintinalli_Sec12_p0669-0996.indd 857 8/2/19 7:53 PM

titis Pancreatitis Urinary tract infections Tumor Pneumonia Streptococcus pharyngitis Inflammatory bowel disease Pregnancy Renal stones Peptic ulcer disease/gastritis Ovarian cysts Henoch-Schönlein purpura Constipation Acute gastroenteritis Nonspecific viral syndromes Tintinalli_Sec12_p0669-0996.indd 857 8/2/19 7:53 PM 858 SECTION 12: Pediatrics FIGURE 133-1. Plain abdominal film demonstrating air in the intestinal wall ( arrows), which is pathognomonic of necrotizing enterocolitis. [Reproduced with permission from Strange GR, Ahrens WR, Schafermeyer RW, Wiebe RA: Pediatric Emergency Medicine, 3rd ed. © 2009, The McGraw-Hill Companies, Inc. New York, Figure 9-12.] explosive diarrhea, fever, vomiting, abdominal pain, and distention. It is common in the first 2 years after resection of the aganglionic segment but also occurs in patients with undiagnosed disease. OLDER INFANTS AND TODDLERS (3 MONTHS TO 3 YEARS OLD) Intussusception, urinary tract infections, testicular torsion, and accidental and inflicted injury are serious causes of abdominal pain in older infants and toddlers. Malrotation with midgut volvulus and appendicitis are less common but remain considerations. Constipation is a common cause of abdominal pain that can be severe and often begins around the time of toilet training. Parents may not offer a stool ing history unless asked. Stranger anxiety is prevalent at this age. Take a few moments to gain the confidence of the child before any examination or procedures. It may be helpful to ask a parent to palpate the child’s abdomen while you observe, before palpating yourself or with the toddler’s assistance. Observe the child while coughing, walking, or jumping as a test for peritoneal irritation. Toddlers may not be able to differentiate pain from nausea. CHILDREN (3 TO 15 YEARS OF AGE) Diagnoses in this age group include problems that are common in adults. Appendicitis is the most common surgical emergency. Other important etiologies are diabetic ketoacidosis (Chapter 147, “Diabetes in Children”), urinary tract infection (Chapter 135, “Urinary Tract Infection in Infants and Children”), testicular torsion, ectopic pregnancy, pelvic inflammatory disease (Chapter 136, “Pediatric Urologic and Gynecologic Disorders”), pancreatitis, inflammatory bowel disease, cholelithiasis, sickle cell anemia (Chapter 143, “Sickle Cell Disease in Children”), Henoch-Schönlein purpura, and renal colic (Chapter 137, “Renal Emergencies in Children”). Upper respiratory symptoms may be associated with mesenteric adenitis, which may mimic appendicitis. An examination of the testicles is required. If two testicles cannot be identified, consider torsion of an undescended testis. Perform a pelvic examination in sexually active girls. Adolescents may offer additional history with parents out of the room.  SPECIFIC CONDITIONS NECROTIZING ENTEROCOLITIS Necrotizing enterocolitis is a neonatal disease thought to be caused by an immune overreaction to an insult to the intestine followed by inflammation, bacterial translocation, and coagulation necrosis of the intestine. Overall mortality is 15% to 30%, with many survivors left with short bowel syndrome and growth retardation. 4 While necrotizing enterocolitis is largely a disease of prematurity, 10% of cases occur in term infants. 5 Predisposing conditions include congenital heart disease, sepsis, neonatal asphyxia, polycythemia, and hypotension. 6 The mean age at onset is between 2 and 9 days. Therefore, although the disease rarely presents outside of the neonatal intensive care unit, its severity makes it an important consideration in near-term infants or those with comorbidities in the first 3 weeks of life.

neonatal asphyxia, polycythemia, and hypotension. 6 The mean age at onset is between 2 and 9 days. Therefore, although the disease rarely presents outside of the neonatal intensive care unit, its severity makes it an important consideration in near-term infants or those with comorbidities in the first 3 weeks of life.  CLINICAL FEATURES AND IMAGING Presenting signs and symptoms include poor feeding, lethargy, abdominal distention, bilious vomiting, temperature instability, apnea, and abdominal tenderness. Gross or occult blood in the stool increases the likelihood of necrotizing enterocolitis, but is neither sensitive nor specific. Obtain anteroposterior and left lateral decubitus abdominal radio graphs. Including the chest will screen for cardiopulmonary abnormalities. Early in the disease, abdominal radiographs may show signs of ileus or obstruction. Pneumatosis intestinalis (air in the bowel wall) and portal venous gas are both pathognomonic ( Figure 133-1),8 but normal abdominal radiographs do not exclude the disorder.  TREATMENT Evaluation must include a search for underlying causes, especially sepsis. Management includes nothing by mouth status, gastric tube decompression, aggressive IV hydration, broad-spectrum antibiotics, and surgical consultation. Consider ampicillin to cover gram-positive organisms, gentamicin or cefotaxime for gram-negative organisms, and metronidazole or clindamycin for anaerobes. 9 Although necrotizing enterocolitis is first managed medically, many cases require resection of necrotic bowel. Admit to intensive care. MALROTATION AND VOLVULUS Volvulus is a life-threatening complication of malrotation. Eighty percent of patients with malrotation present within the first month of life and 90% within the first year, but it can present at any age. 10 At approximately 10 weeks of gestation, the growing intestines return to the abdomen from the yolk sac, and the midgut undergoes a 270-degree counterclockwise turn around the superior mesenteric artery. Abnormal rotation can leave the cecum high in the abdomen, with its peritoneal attachments (Ladd’s bands) crossing the duodenum. Down syndrome, heterotaxy, and duodenal atresia are associated with malrotation.  CLINICAL FEATURES The child may be well until the malrotated gut twists (volvulus) or becomes obstructed by Ladd’s bands, causing obstruction and ischemia. Volvulus is a surgical emergency as it can result in gangrene of the entire midgut within hours. The infant with volvulus often has no significant past medical history and presents with the abrupt onset of constant abdominal pain, bilious vomiting, abdominal distention, and irritability. Patients with volvulus are typically ill appearing and may have signs of shock. The abdomen is diffusely tender and distended and may be rigid. Intermittent volvulus may present with stable vital signs and focal tenderness on abdominal examination. The absence of fever can help distinguish volvulus from sepsis. Tintinalli_Sec12_p0669-0996.indd 858 8/2/19 7:53 PM

earing and may have signs of shock. The abdomen is diffusely tender and distended and may be rigid. Intermittent volvulus may present with stable vital signs and focal tenderness on abdominal examination. The absence of fever can help distinguish volvulus from sepsis. Tintinalli_Sec12_p0669-0996.indd 858 8/2/19 7:53 PM CHAPTER 133: Acute Abdominal Pain in Infants and Children 859  IMAGING AND TREATMENT Imaging studies should not delay surgical consultation, as rapid detorsion of the volvulized bowel is necessary to prevent loss of the entire small intestine. Upper GI series with contrast remains the test of choice for diagnosing malrotation with sensitivities of 93% to 100% for malrotation and 54% to 79% for volvulus. 11 The normal location of the duodenojejunal junction is at the level of the duodenal bulb and to the left of the spine. In malrotation, the junction is commonly located low and to the right of the spine. If midgut volvulus is present at the time of the study, there may be an abruptly tapered cutoff of contrast in the duodenum (bird’s beak) or a corkscrew appearance of the bowel. If concern persists after a negative study and surgical consultation, options for additional evaluation include repeat upper GI series to exclude intermittent volvulus, abdominal CT, US, and contrast enema. Plain abdominal radiographs are neither sensitive nor specific for malrotation. The most common findings on plain abdominal radio graphs are an air-filled stomach with little distal gas, which may show a distal obstruction, nonspecific, or even normal gas pattern. Treatment consists of medical resuscitation and immediate surgical consultation. Obtain electrolytes, CBC, coagulation studies, and a type and cross-match for packed red blood cells. INTUSSUSCEPTION Intussusception is the most common cause of intestinal obstruction in children under 2 years of age. It is rare before 2 months. The maleto-female ratio is 2:1. 13,14 Intussusception occurs when one segment of the intestine telescopes into another, usually the ileum into the colon. Constriction of the mesentery results in engorgement of the intussusceptum and bowel ischemia. In infants, lymphoid hyperplasia from viral illness may cause a “lead point, ” which drags one portion of bowel into another. In older children, causes of intussusception include Meckel’s diverticulum, intestinal polyps, congenital duplications, lymphoma, and Henoch- Schönlein purpura.  CLINICAL FEATURES Intussusception is notoriously difficult to diagnose because of its two disparate presentations: intermittent pain and lethargy. The classic presentation of ideopathic intussusception is an infant aged 5 to 12 months who suddenly develops a few minutes of severe abdominal pain with the legs drawn to the chest and who then appears well until the next episode of pain. An alternative presentation is an infant with unexplained lethargy, which may divert the provider to an evaluation for altered mental status. Vomiting is not usually present at first but develops over 6 to 12 hours and may be bilious. The physical examination between attacks may be normal, although a sausage-shaped mass may be palpated in the right upper quadrant. Occult blood is found in 70% of stools and gross blood in about 50%, although it rarely resembles the classic “currant jelly. ”  DIAGNOSIS AND TREATMENT A history consistent with the intermittent symptoms of intussusception should prompt further evaluation or observation even if the patient is asymptomatic at the time. US should be the first study when the diagnosis is ambiguous. In research settings, the accuracy of US for intussusception is nearly 100% (Figure 133-2). Children with a high suspicion of intussusception should undergo immediate air-contrast enema, which is both diagnostic and therapeutic.

is asymptomatic at the time. US should be the first study when the diagnosis is ambiguous. In research settings, the accuracy of US for intussusception is nearly 100% (Figure 133-2). Children with a high suspicion of intussusception should undergo immediate air-contrast enema, which is both diagnostic and therapeutic. Prepare the child for reduction with boluses of normal saline if dehydrated, since volume loss due to intestinal edema, decreased intake, and vomiting is common. Notify a surgeon prior to air-contrast enema in case the reduction is unsuccessful or perforation occurs. Children with peritonitis, with free air on plain radiographs, or in shock should not undergo air-contrast enema and require emergent surgical reduction. Plain abdominal radiographs are not highly useful unless needed to rule out perforation, but they may show a mass or paucity of bowel gas in the right abdomen, a “crescent sign” where the curved edge of one segment of bowel intrudes into another, or an obstructive pattern (Figure 133-3). Approximately 10% of infants or children will have a recurrence after a successful reduction, usually within the first 24 to 48 hours.17 However, after a few hours of ED observation, discharge of patients who remain asymptomatic, are able to tolerate oral intake, and can easily return to the ED has been shown to be safe. 18,19 Recurrence should prompt a second enema reduction. Further recurrences may require surgery. APPENDICITIS Appendicitis is the most common surgical emergency in children. The peak ages for appendicitis are between 9 and 12 years, with a male predominance. The appendix is a diverticulum that arises from the cecum. Appen dicitis usually begins with obstruction of the appendiceal lumen by fecaliths, lymphoid hyperplasia, or less commonly parasites, tumors, or foreign bodies. Multiplying bacteria and mucus secretion increase pressure on the wall, leading to dilation, ischemia, and perforation. FIGURE 133-2. A and B. US image of intussusception showing the classic target appearance of bowel-within-bowel. [Reproduced with permission from Ma OJ, Mateer JR, Blaivas M: Emergency Ultrasound, 2nd ed. © 2008, McGraw-Hill, Inc., New York, Figure 9-15.] Tintinalli_Sec12_p0669-0996.indd 859 8/2/19 7:53 PM

perforation. FIGURE 133-2. A and B. US image of intussusception showing the classic target appearance of bowel-within-bowel. [Reproduced with permission from Ma OJ, Mateer JR, Blaivas M: Emergency Ultrasound, 2nd ed. © 2008, McGraw-Hill, Inc., New York, Figure 9-15.] Tintinalli_Sec12_p0669-0996.indd 859 8/2/19 7:53 PM 860 SECTION 12: Pediatrics  CLINICAL FEATURES The classic progression of periumbilical pain that migrates to the right lower quadrant followed by vomiting and fever is seen in less than 50% of children with appendicitis. 21 Many of the classic symp toms are seen with only moderate frequency: pain of <48 hours in duration (82%), nausea or emesis (71%), anorexia (60%), and migration of pain to the right lower quadrant (50%). Constipation is seen in 9% to 33% of cases and diarrhea in 10% to 33%. 22 Perforation rates approach 90% in children <4 years old, so younger children are more likely to present with vomiting, fever, peritonitis, or sepsis. Children with appendicitis may perforate early in the course of the disease. One study of children aged 3 to 18 found no perforation before 12 hours, but a 10% perforation rate at 18 hours and 44% by 36 hours. Perforation may cause a brief relief of pain prior to the development of peritonitis and worsening symptoms. Tenderness may be localized to the right lower quadrant (68% of cases) or McBurney’s point (two thirds of the way from the umbi licus to the anterior-superior iliac spine) or may involve the entire abdomen. Assessing pain when the child coughs, walks, and jumps is useful for detecting peritoneal inflammation. Rebound tenderness and guarding are more common with perforation and may be absent in early appendicitis. Assess for hernias and perform a testicular examination in boys. A pelvic examination may be needed in adolescent females to compare the tenderness of McBurney’s point to the adnexa. Rectal tenderness had a positive likelihood ratio of 2.3 and negative ratio of 0.7 in a summary of three studies.  DIAGNOSIS There is a high potential for missing the diagnosis of appendicitis in children. The Alvarado and Samuel scores have been widely cited, but have insufficient positive predictive values to safely identify the need for surgery for appendicitis in children, and other decision rules may or may not be generalizable (Table 133-2). Problems with interrater reliability make it difficult to apply decision rules in the clinical prediction of appendicitis (Table 133-3). WBC count has insufficient sensitivity or specificity to confirm the diagnosis of appendicitis; however, a normal WBC is strongly correlated with a decreased likelihood of appendicitis. 26 A WBC <10,000/mm 3 is a strong negative predictor for appendicitis (negative likelihood ratio = 0.26). C-reactive protein is a nonspecific later marker of inflammation and correlates with severity of appendicitis and may be helpful for dis tinguishing ruptured or gangrenous appendicitis from early disease. No single cut point for C-reactive protein has been established as a sensitive or specific marker of appendicitis; some studies suggest that C-reactive protein in conjunction with WBC and clinical signs and symptoms may add to the diagnostic evaluation of children with abdominal pain. 27-32 Sterile pyuria can be seen with acute appendicitis as the inflamed appendix irritates the nearby ureters.  IMAGING Patients with a history and examination compelling for appendicitis should have surgical consultation without imaging. When the diagnosis is uncertain, US is the preferred initial imaging exam. Appendiceal findings include a maximal diameter >6 mm, wall thickness ≥3 mm, lack of compressibility, hyperemia on color Doppler US, surrounding edema or fat stranding, and an appendicolith (Figure 133-4).

surgical consultation without imaging. When the diagnosis is uncertain, US is the preferred initial imaging exam. Appendiceal findings include a maximal diameter >6 mm, wall thickness ≥3 mm, lack of compressibility, hyperemia on color Doppler US, surrounding edema or fat stranding, and an appendicolith (Figure 133-4). 33 US is useful to exclude gynecologic processes such as ovarian torsion and ruptured cysts. If done by experienced technicians and the appendix is visualized, US is highly sensitive and specific (88% and 94%). 34 An US with findings of appendicitis in a patient with a consistent clinical picture is sufficiently specific to warrant surgery. When the appendix is visualized and normal, US is sufficiently sensitive to exclude appendicitis in many cases. If clinical suspicion for appendicitis is very high, visualization of a normal appendix should not exclude the diagnosis, and additional evaluation should be undertaken. This may include surgical consulta tion, CT scan, admission for observation, or repeat US. FIGURE 133-3. The crescent-shaped head of the intussusceptum is seen as an intralu minal mass in the gas-filled transverse colon ( asterisk). [Reproduced with permission from Schwartz: Emergency Radiology Cases Studies © 2008, The McGraw-Hill Companies, Inc. New York. Figure II-4-6 Part A.] TABLE 133-2 A Clinical Decision Rule to Identify Children at Low Risk of Appendicitis* (rule has poor positive predictive value) Criterion Points Absolute neutrophil count >6.75 × 103/µL 6 Rebound pain or pain with percussion 2 Unable to walk or walks with limp 1 Nausea 2 History of migration of pain to right lower quadrant 1 History of focal right lower quadrant pain 2 Note: A score of ≤5 indicates low risk for appendicitis (sensitivity, 96.3%; 99% confidence interval, 87.5%–99.0%). If appendicitis is still suspected, repeat examination during ED observation, repeat examination within 12 hours, or US examination should be considered. *Caution: Interrater reliability is only fair to moderate for some of these variables. TABLE 133-3 Interrater Reliability of Selected Historical and Clinical Variables Used in the Clinical Assessment of Appendicitis Sign or Symptom Agreement, % Kappa (95% CI) Focal RLQ pain 84.9 0.48 (0.39–0.58) Migration of pain to RLQ 68.4 0.37 (0.29–0.45) Nausea 72 0.44 (0.37–0.52) Rebound 68.4 0.32 (0.24–0.40) Abdominal pain with walking, jumping, or coughing 83.6 0.54 (0.45–0.63) Abbreviations: CI = confidence interval; RLQ = right lower quadrant. Tintinalli_Sec12_p0669-0996.indd 860 8/2/19 7:53 PM

n 84.9 0.48 (0.39–0.58) Migration of pain to RLQ 68.4 0.37 (0.29–0.45) Nausea 72 0.44 (0.37–0.52) Rebound 68.4 0.32 (0.24–0.40) Abdominal pain with walking, jumping, or coughing 83.6 0.54 (0.45–0.63) Abbreviations: CI = confidence interval; RLQ = right lower quadrant. Tintinalli_Sec12_p0669-0996.indd 860 8/2/19 7:53 PM CHAPTER 133: Acute Abdominal Pain in Infants and Children 861 FIGURE 133-4. US of acute appendicitis with a diameter of 8 mm in short-axis view. [Reproduced with permission from Ma OJ, Mateer JR, Blaivas M: Emergency Ultrasound, 2nd ed. © 2008, McGraw-Hill, Inc., New York, Figure 18-23.] FIGURE 133-5. Acute appendicitis. A. A non–contrast-enhanced axial CT scan through the pelvis reveals a calcific appendicolith ( arrow) in a pelvic appendix. Inspissated, sometimes calcified fecal material leads to obstruction followed by secondary bacterial invasion. Radiographic evidence of a fecalith is seen in 20% of cases. The presence of an appendicolith along with inflammation is indicative either of acute appendicitis or of impending appendicitis. B. Contrast-enhanced CT scan of the pelvis reveals the previously described appendicolith (arrow) in a dilated fluid-filled and thick-walled appendix. Enhancement of the appendiceal wall is also noted. [Reproduced with permission from Shah BR, Lucchesi M: Atlas of Pediatric Emergency Medicine . © 2006, McGraw-Hill, Inc., New York, Figure 10-8.] The challenge is that many US exams will not visualize the appendix, in which case the presence or absence of secondary signs, including free fluid or abnormal echogenicity of fat in the right lower quadrant, is important. One study demonstrated a high negative predictive value when US did not visualize the appendix but showed no secondary signs of appendicitis, and another did so among patients with a WBC <7500/mm 3.35,36 Therefore, in settings with skilled pediatric sonographers, nonvisualization of the appendix may be able to exclude appendicitis in lower-risk patients. Abdominal CT scanning has superior test characteristics compared with US, with a sensitivity and specificity of 94% and 95%, respectively (Figure 133-5). Abdominal CT is useful for identifying perforation and abscess formation, which may require percutaneous drainage and antibiotics rather than immediate appendectomy, and therefore, CT may be the preferred imaging modality in children with prolonged pain or diffuse peritoneal signs suggestive of rupture. CT may also identify alternative diagnoses such as mesenteric adenitis, epiploic appendagitis, inflammatory bowel disease, renal stones, and tumors. Disadvantages of CT include radiation exposure, the time required for oral and/or rectal contrast when requested, and the possibility of allergic reactions. Insti tutional protocols often determine whether oral contrast is preferred in addition to IV contrast.  TREATMENT Once the diagnosis of appendicitis is highly suspected or confirmed, obtain surgical consultation and administer antibiotics. 37 Antibiotics for nonperforated appendicitis include cefoxitin, ampicillin-sulbactam, and ceftriaxone plus metronidazole; for perforated appendicitis, monother apy with piperacillin-tazobactam is as effective as multidrug therapy. Percutaneous drainage may be considered for abscess, followed by delayed appendectomy to prevent recurrence. In ambiguous cases, admission for serial abdominal examination by a surgeon is reasonable. While the quality of current evidence is insufficient to recommend nonoperative management of uncomplicated appendicitis with antibiotics alone, future studies may prove it to be a safe alternative to surgery with a significant rate of recurrent appendicitis.

for serial abdominal examination by a surgeon is reasonable. While the quality of current evidence is insufficient to recommend nonoperative management of uncomplicated appendicitis with antibiotics alone, future studies may prove it to be a safe alternative to surgery with a significant rate of recurrent appendicitis. HENOCH-SCHÖNLEIN PURPURA Henoch-Schönlein purpura is a vasculitis of children between 2 and 11 years of age with slight peaks in the fall and winter months. The cause is unknown, although a viral pathogen or group A Streptococcus may trigger the condition. Immunoglobulin A deposits are seen in the glomeruli and vessel walls.  CLINICAL FEATURES The typical clinical presentation of Henoch-Schönlein purpura is a triad of palpable purpuric rash, acute abdominal pain, and arthritis. The rash occurs in all cases and is the presenting sign in 50% of cases (see Chapter 142, “Rashes in Infants and Children”). The rash may initially be urticarial or macular-papular. The lesions typically appear first on the extensor surfaces of the lower extremities and buttocks; they may involve the arms and ears. The face, palms, and soles are usually spared. GI symptoms including abdominal pain and GI bleeding occur in 50% to 75% of cases. 40 The pain is usually diffuse and colicky in nature and may be associated with vomiting. Abdominal pain usually presents after the rash, but can precede the rash in 30% to 43% of patients. Intussusception occurs in 3.5%. 41 Arthralgia or arthritis occurs in 80% of cases and is the presenting sign in 25%. Joint symptoms are migratory and usually involve the knees and ankles with periarticular swelling and tenderness. Renal involvement including hematuria, edema, and proteinuria is the most significant long-term consequence (see Chapter 137, “Renal Emergencies in Children”). Obtain a urinalysis on all patients to detect hematuria. When hematuria is present, obtain renal function tests. Although microscopic hematuria is relatively common in patients with Henoch-Schönlein purpura, proteinuria and gross hematuria represent more extensive renal involvement. Stool guaiac may be positive in nearly Tintinalli_Sec12_p0669-0996.indd 861 8/2/19 7:53 PM

a. When hematuria is present, obtain renal function tests. Although microscopic hematuria is relatively common in patients with Henoch-Schönlein purpura, proteinuria and gross hematuria represent more extensive renal involvement. Stool guaiac may be positive in nearly Tintinalli_Sec12_p0669-0996.indd 861 8/2/19 7:53 PM 862 SECTION 12: Pediatrics half of cases and, in the absence of intussusception symptoms, does not require further evaluation. Additional laboratory studies, including CBC and coagulation studies, are not routinely indicated in the patient with a characteristic presentation of Henoch-Schönlein purpura, as these studies are normal in this condition. If the patient has a history consistent with accompanying intussusception, obtain an abdominal US or aircontrast enema to assess for this.  TREATMENT Treatment is mainly supportive. If the child is ill appearing, unable to tolerate oral fluids, or dehydrated, begin IV fluid hydration and arrange for admission. NSAIDs, such as ibuprofen and ketorolac, are used for management of arthritis, painful edema, and abdominal pain if renal function is normal based on urinalysis. Oral corticosteroids reduce symptoms of severe abdominal and joint pain. Care of patients with gross hematuria, more than small proteinuria, abnormal renal function, hypertension, or nephritic syndrome should be discussed with a pediatric nephrologist. Patients without these findings do not need steroids for prophylaxis of renal disease. 42 Arrange for repeat urinalysis and blood pressure measurements within 7 days, continuing for 6 months.43 INGUINAL HERNIA Inguinal hernias occur in up to 45% of children and are more common in those born prematurely. 44 Incarceration refers to a hernia that cannot easily be reduced and is the presenting sign of the hernia in up to 65% of cases. 45 Incarceration is most common in the first year of life.  CLINICAL FEATURES A simple inguinal hernia is often asymptomatic and is noted as a scrotal or inguinal mass. Symptoms of incarcerated hernia may include irrita bility, poor feeding, and vomiting. The differential diagnosis includes torsion of the testicle or testicular appendage, hydrocele of the cord or the scrotum, undescended testicle, inguinal lymphadenopathy, inguinal node abscess, orchitis, and trauma. The incarcerated sac may contain omentum, bowel, or ovary. Because it can be difficult to differentiate an incarcerated hernia from testicular torsion, it may be necessary to proceed with consultation and evaluation for both of these time-dependent emergencies simultaneously.  TREATMENT An incarcerated hernia may progress to strangulation and is therefore a surgical emergency. Attempt reduction as soon as possible. Place the patient in the Trendelenburg position. Apply pressure to the hernia sac with one hand while the other guides the contents through the ingui nal ring. Reduction may take minutes of steady pressure. Sedation and analgesia can be quite helpful. One third of children redevelop incar ceration, so either patients should be admitted for repair or expedited outpatient care should be arranged within 24 hours. If manual reduction is unsuccessful, request immediate surgical consultation. Unlike adults, children require referral for early repair even of hernias that have not become incarcerated because of the high risk of subsequent incarceration. INFLAMMATORY BOWEL DISEASE Children account for 20% to 25% of new diagnoses of inflammatory bowel disease. 46 In one series, 95% of those <10 years old with Crohn’s disease initially presented with abdominal pain, 77% with diarrhea, and 60% with bloody stools. 47 The pain in Crohn’s disease is often colicky and either diffuse or in the right lower quadrant, mimicking appendicitis.

ew diagnoses of inflammatory bowel disease. 46 In one series, 95% of those <10 years old with Crohn’s disease initially presented with abdominal pain, 77% with diarrhea, and 60% with bloody stools. 47 The pain in Crohn’s disease is often colicky and either diffuse or in the right lower quadrant, mimicking appendicitis. Weight loss is seen in 80% of patients with Crohn’s disease. Growth failure may be the only symptom in 5%. Up to 25% of children with inflammatory bowel disease have a positive family history. Tachycardia and hypotension may be present secondary to dehydration or anemia from chronic blood loss. Inspect the anal area for fistulas, fissures, and skin tags suggestive of Crohn’s disease. Extraintestinal signs, including arthritis, ankylosing spondylitis, and erythema nodosum, occur in 20%. Most children with moderate to severe disease will have anemia and an elevated erythrocyte sedimentation rate. Measure electrolytes in cases of severe diarrhea. If a new diagnosis is being considered, obtain stool culture, ova and parasite examination, and Clostridium difficile toxin to assess for infectious causes. An abdominal CT can be useful to evaluate for thickening of the terminal ileum and complications of Crohn’s dis ease such as intra-abdominal abscesses and fistula. Definitive diagnosis requires endoscopy and biopsy. A pediatric GI specialist should be consulted for further management, which may include oral or IV cortico steroids. Toxic megacolon is a complication of severe ulcerative colitis in which large bowel dilation is present on abdominal radiograph or CT in the setting of fever, abdominal pain, and laboratory markers of systemic inflammation. 48 Treatment requires hospital admission for steroids.49 RENAL STONES Calcium-containing renal stones are the most common type in children. Predisposing factors include immobilization, hyperparathyroidism, corticosteroids, diuretics, and neoplasms. Both ketogenic diets and antiepileptic drugs can predispose to stone formation.  CLINICAL FEATURES AND DIAGNOSIS Children with renal stones present with abdominal pain only 50% of the time. Microscopic or gross hematuria is present in 85% of chil dren with urolithiasis. 50,51 The ED workup should include imaging to exclude severe obstruction (US or CT) and urinalysis to exclude infection, as both of these potentially require immediate interven tion. If the patient has never had imaging to confirm the presence of two normal kidneys and labs to confirm baseline normal renal func tion, these should be obtained. If these studies are abnormal, contact a pediatric nephrologist or urologist. Because of the risk associated with radiation from CT, US is recom mended by the American Urological Association as the first imaging test for urolithiasis in children. 52 US is highly specific for stones but has limited sensitivity (76% in one study compared to CT). 53 If the US is nondiagnostic and the clinician feels the need to confirm the diagnosis, noncontrast CT should be the next test. A negative US alone is sufficient if the goal of testing is not to confirm urolithiasis but to rule out obstruction. Plain radiographs have poor sensitivity for stones. Because of the high rate of underlying metabolic abnormalities in children with urolithiasis (38% to 90%), all children with a new diagnosis require a metabolic evaluation, although this need not be done in the ED. 54 Workup may include a basic metabolic panel, serum calcium, phosphorus, parathyroid hormone, and 24-hour urine collection. 55 Anatomic abnormalities including vesicoureteral reflux, ureteropelvic and ureterovesicular junction obstruction, and neurogenic bladder are found in 11% of children with urolithiasis, so plans should be made for subsequent imaging.

panel, serum calcium, phosphorus, parathyroid hormone, and 24-hour urine collection. 55 Anatomic abnormalities including vesicoureteral reflux, ureteropelvic and ureterovesicular junction obstruction, and neurogenic bladder are found in 11% of children with urolithiasis, so plans should be made for subsequent imaging. 56 Parents should be instructed to strain the urine so the stone can be analyzed.  TREATMENT ED management is centered on pain and nausea control. If IV place ment is indicated for dehydration, pain control, or blood draws, pro vide aggressive rehydration. Indications for admission include urinary tract infection with obstruction, abnormal renal anatomy or function, uncontrolled pain or nausea, and dehydration. Most stones in the distal ureters smaller than 3 mm will pass spontaneously, while those larger than 4 mm will likely require intervention. 57 Discuss patients with larger stones or mild to moderate obstruction with a urologist to plan follow-up. One meta-analysis showed a benefit to tamsulosin or doxazosin for distal ureteral stones in children, but the quality of evidence is not sufficient to conclusively recommend for or against this. 58 Interventional therapy includes extracorporeal shock wave lithotripsy and urethral or transcutaneous endoscopy to extract the stone. Dehydration contributes to stone formation, so encourage oral fluids for all children discharged. Those with known metabolic causes for their stones may benefit from dietary modification, diuretics, or other medi cations specific to their condition. Tintinalli_Sec12_p0669-0996.indd 862 8/2/19 7:53 PM

extract the stone. Dehydration contributes to stone formation, so encourage oral fluids for all children discharged. Those with known metabolic causes for their stones may benefit from dietary modification, diuretics, or other medi cations specific to their condition. Tintinalli_Sec12_p0669-0996.indd 862 8/2/19 7:53 PM CHAPTER 133: Acute Abdominal Pain in Infants and Children 863 PANCREATITIS Pancreatitis is extremely rare in infants and is most commonly a secondary process in children and adolescents. See Chapter 79, “Pancreatitis and Cholecystitis, ” for a discussion of its pathophysiology. Table 133-4 lists causes of acute pancreatitis in children.59  CLINICAL FEATURES The typical history is an acute onset of epigastric or periumbili cal abdominal pain associated with anorexia, nausea, and vomiting. Although 62% to 89% of children with pancreatitis complain of epigas tric pain, <10% describe back pain or radiation of the pain to the back; nausea and vomiting are present in 40% to 80% of older children, but only 28% of children <2 years of age. 60 Older children may be able to describe dull, constant epigastric pain that is made worse by eating or lying supine. Physical examination reveals guarding or distention in fewer than half of children with pancreatitis, and Grey Turner sign is present in 2%. 61 The child may be lying quietly on his or her side with knees flexed.  DIAGNOSIS AND TREATMENT Acute pancreatitis is defined by an elevation of either lipase or amylase of three times the upper limit of normal, or imaging con sistent with pancreatitis. Lipase is between 82% and 100% sensitive in children. 60,62 Lipase rises within hours and remains elevated for up to 14 days. Also testing for amylase will identify some cases of pan creatitis with normal lipase values. 60 The level of enzyme elevation does not correlate with the severity of the disease. Obtain electrolytes, including calcium, and liver enzymes, which may suggest hepatic disease or biliary obstruction. Obtain an US or CT scan to assess for biliary causes (gallstones or sludge) or anatomic abnormalities of the pancreas. US has greater sensitivity for gallstones and gives no ionizing radiation. CT is better at identifying complications of severe pancreatitis including necrosis, fluid collections, and hemorrhage, although these complications are more likely to present a few days into the disease. CT should be ordered if trauma is suspected. Because intra-abdominal third spacing, shock, and multiorgan system failure are potential complications of acute pancreatitis, aggressively administer normal saline or lactated Ringer’s solution. Treat pain and admit the patient to the hospital. CHOLECYSTITIS Cholecystitis is rare in children compared to adults but rising sig nificantly coincident with the increase in childhood obesity. Whereas gallstones related to hemolytic disease, such as sickle cell disease, and total parenteral nutrition have historically been the most common causes, biliary disease in children without these risk factors has risen and is now just as common a cause. 63 Acute or chronic illness with dehydration, fasting, or mechanical ventilation can cause gallbladder sludge and obstruction in the absence of stones (acalculous cholecysti tis). When complicated by bacterial infection of the common bile duct, cholangitis results and is associated with a high risk of sepsis and shock. Children who have undergone surgical Roux-en-Y procedures (e.g., Kasai procedure for biliary atresia) are at risk for ascending cholangitis.  CLINICAL FEATURES AND DIAGNOSIS Children with biliary pain are typically restless and unable to lie still. Jaundice is more common in children than adults and may occur in the absence of common bile duct obstruction.

ux-en-Y procedures (e.g., Kasai procedure for biliary atresia) are at risk for ascending cholangitis.  CLINICAL FEATURES AND DIAGNOSIS Children with biliary pain are typically restless and unable to lie still. Jaundice is more common in children than adults and may occur in the absence of common bile duct obstruction. Right upper quadrant tenderness and a positive Murphy sign may be elicited in older children and adolescents. Obtain liver function tests and lipase, which may be normal even in cases of acute cholecystitis. US is the first-line test for evaluation of biliary disease. CT scan may demonstrate acute cholecystitis but misses 20% of gallstones.  TREATMENT A child with biliary colic (cholelithiasis without acute cholecystitis, whose pain has resolved) may be discharged with outpatient follow-up. Children with cholecystitis or cholangitis should be admitted. Administer antibiotics for findings of gallbladder infection including fever and elevated WBC count: one common regimen is ampicillin, gentamicin, and clindamycin. Cholangitis, with Charcot’s triad of right upper quadrant pain, fever, and jaundice, is a medical emergency and requires immediate intervention. PNEUMONIA Although a child with pneumonia will often present with respiratory signs and symptoms and fever, the predominant complaint may be abdominal pain. The diagnosis and management of pneumonia in children are discussed in Chapter 128, “Pneumonia in Infants and Children. ” STREPTOCOCCUS PHARYNGITIS Streptococcus pharyngitis can cause abdominal pain with or without vomiting and without sore throat. Examine the oropharynx of any child ≥3 years of age with abdominal pain. If signs of pharyngitis are present, test for group A Streptococcus. If the rapid strep test is negative, send a throat culture because of the rapid antigen test’s good specificity but poor sensitivity. 65 See Chapter 124, “Mouth and Throat Disorders in Infants and Children. ” COLIC Colic is excessive, unexplained paroxysms of crying in a healthy infant from 2 weeks to 4 months of age, peaking at 6 weeks. Wessel’s “rule of threes” is a mnemonic for colic: crying >3 hours per day for >3 days per week for >3 weeks . Sufferers will flex their legs, turn red, and pass large amounts of gas. Colic is a diagnosis of exclusion made by the chronicity of episodes and exclusion of dangerous alternative diagnoses. See Chapter 116, “Neonatal Emergencies and Common Neonatal Problems. ” CONSTIPATION Constipation is defined as stools that are hard, infrequent, or painful to pass. Constipation may cause significant abdominal pain, prompting extensive evaluation. Normal infants may occasionally go up to 7 days without a bowel movement. As long as the child is not symptomatic and the stool is not hard, no evaluation is necessary. Hirschsprung’s disease is a pathologic cause of constipation in infants. Hirschsprung’s disease is caused by a failure of colonic ganglion cells to migrate during gestation and is more common in trisomy 21. A history of failing to pass meconium in the first 24 to 48 hours of life suggests Hirschsprung’s disease or cystic fibrosis. Symptoms include infrequent, explosive bowel movements, poor growth and feeding, and progressive abdominal distention. Constipation may be seen in older children with chronic medical conditions such as anorexia nervosa, cerebral palsy, neuromuscular disease, depression, or hypothyroidism and is common in children with autism.

s include infrequent, explosive bowel movements, poor growth and feeding, and progressive abdominal distention. Constipation may be seen in older children with chronic medical conditions such as anorexia nervosa, cerebral palsy, neuromuscular disease, depression, or hypothyroidism and is common in children with autism. TABLE 133-4 Causes of Acute Pancreatitis in Children Biliary: gallstones and sludge, pancreas divisum 10%–30% Medications: valproic acid, l-asparaginase, 6-mercaptopurine <25% Idiopathic 13%–34% Multisystem disease: sepsis, shock, systemic lupus erythematosus 33% Trauma 10%–40% Infectious: mumps, hepatitis, other viral infection, Mycoplasma <10% Metabolic: diabetic ketoacidosis, hypertriglyceridemia, hypercalcemia 2%–7% Hereditary: cystic fibrosis 5%–8% Tintinalli_Sec12_p0669-0996.indd 863 8/2/19 7:53 PM