Pediatric Annals

Special Issue Article 

Imaging of Acute Abdominal Pain in the Pediatric Population

Erica L. Riedesel, MD; Susan D. John, MD; Leann E. Linam, MD

Abstract

Acute abdominal pain is a common complaint in pediatrics. Although age and location of pain can help focus differential diagnosis, imaging plays an essential role in clinical evaluation. In this review, we discuss the optimal imaging approach to pediatric patients with acute abdominal pain and important imaging findings in the most common causes of abdominal pain in the pediatric population. [Pediatr Ann. 2020;49(9):e380–e388.]

Abstract

Acute abdominal pain is a common complaint in pediatrics. Although age and location of pain can help focus differential diagnosis, imaging plays an essential role in clinical evaluation. In this review, we discuss the optimal imaging approach to pediatric patients with acute abdominal pain and important imaging findings in the most common causes of abdominal pain in the pediatric population. [Pediatr Ann. 2020;49(9):e380–e388.]

Acute abdominal pain is a common complaint in the pediatric population, accounting for 5% to 10% of emergency department visits in the United States for children younger than age 15 years and up to 2% of outpatient visits.1,2 Diagnosis based on history alone is challenging, as children may present with nonspecific symptoms and may be unable to characterize their pain. Differential diagnosis is driven by age and pain location (Table 1). Initial assessment should focus on identifying secondary signs and symptoms that raise concern for surgical causes of pain, including vomiting (bilious vs nonbilious, bloody vs nonbloody), bloody diarrhea, abdominal guarding, or rebound tenderness. Additional history including urinary symptoms and menstrual history may further target differential diagnosis.

Selected Differential Diagnosis of Nontraumatic Acute Abdominal Pain in Children By Age

Table 1.

Selected Differential Diagnosis of Nontraumatic Acute Abdominal Pain in Children By Age

Imaging plays an important role in evaluation of acute abdominal pain in pediatric patients.3-6 Radiographs may provide important information, but findings are seldom diagnostic. Ultrasound is generally considered the initial imaging modality of choice for detailed investigation of acute abdominal pain as it is widely available, inexpensive, does not require sedation, and uses no ionizing radiation. Computed tomography (CT) or magnetic resonance imaging (MRI) may be warranted in cases where ultrasound is indeterminate or incomplete. In this review, we discuss the optimal imaging approach to common causes of abdominal pain in pediatrics.

Right Upper Quadrant Pain

Right upper quadrant pain is classically associated with gallbladder disease, pancreatitis, or liver pathology. Ultrasound is the imaging modality of choice for evaluation of acute right upper quadrant pain in pediatric patients.3,4,7 Ultrasound may be performed with targeted imaging of the right upper quadrant structures only, or as a part of a complete abdominal ultrasound. Fasting is helpful for evaluation of the gallbladder and biliary tree; 2 hours is typically adequate for appropriate distension of the gallbladder.

Cholelithiasis, Cholecystitis, and Cholangitis

Gallstones are less common in children than adults, but incidence has increased in children in recent years.7,8 Associated symptoms of nausea and vomiting after meals, jaundice, acholic stools, and fever should increase suspicion.

Pediatric cholelithiasis is idiopathic in up to 40% of patients.8 In infants and young children, gallstones are sometimes incidentally found on ultrasound performed for other reasons, often related to prior administrations of diuretics or total parenteral nutrition. Patients with underlying medical conditions are predisposed to biliary stasis and gallstone formation.8 Childhood obesity and family history also contribute to biliary stone formation.

Ultrasound has a reported accuracy of 95% for detection of cholelithiasis in children.7 Gallstones appear as echogenic foci with posterior shadowing within the gallbladder lumen (Figure 1A). Occasionally, shadowing from numerous stones can make the gallbladder difficult to identify; nonshadowing stones can be mistaken for gallbladder sludge. Biliary sludge, seen as layering echogenic material in the gallbladder, may occur secondary to biliary stasis and predisposes to stone formation8 (Figure 1B).

Right upper quadrant. (A) Gallstones (>) appear brightly echogenic on ultrasound with posterior shadowing (arrow). (B) Layering biliary sludge (*) on ultrasound of the gallbladder. (C) Findings of cholecystitis on ultrasound and color Doppler images include gallbladder wall thickening and hyperemia. (D) Acute pancreatitis findings on ultrasound include enlargement of the pancreas, increased pancreatic echogenicity compared to the adjacent liver, and trace peripancreatic fluid (arrow). E) Acute pancreatitis on ultrasound with enlarged and echogenic pancreas; additional images of left upper quadrant demonstrate heterogeneous fluid collection (<) adjacent to pancreatic tail suggestive of pseudocyst. (F) Computed tomography of the abdomen/pelvis with intravenous contrast confirms pancreatic pseudocyst. c, pancreatic pseudocyst; Li, liver; p, pancreas; pt, pancreatic tail.

Figure 1.

Right upper quadrant. (A) Gallstones (>) appear brightly echogenic on ultrasound with posterior shadowing (arrow). (B) Layering biliary sludge (*) on ultrasound of the gallbladder. (C) Findings of cholecystitis on ultrasound and color Doppler images include gallbladder wall thickening and hyperemia. (D) Acute pancreatitis findings on ultrasound include enlargement of the pancreas, increased pancreatic echogenicity compared to the adjacent liver, and trace peripancreatic fluid (arrow). E) Acute pancreatitis on ultrasound with enlarged and echogenic pancreas; additional images of left upper quadrant demonstrate heterogeneous fluid collection (<) adjacent to pancreatic tail suggestive of pseudocyst. (F) Computed tomography of the abdomen/pelvis with intravenous contrast confirms pancreatic pseudocyst. c, pancreatic pseudocyst; Li, liver; p, pancreas; pt, pancreatic tail.

Biliary obstruction by stones lodged in the gallbladder neck, cystic duct, or common bile duct can lead to cholecystitis. Although obstructing stones are often visualized on ultrasound, dilation of the common bile duct may be the only sign of downstream calculi. Gallbladder wall thickening (>3 mm), gallbladder wall hyperemia, and pericholecystic fluid are important secondary findings of acute cholecystitis (Figure 1C). Acute acalculous cholecystitis in children has been associated with severe gram-negative bacterial infections, cytomegalovirus, and Epstein-Barr virus.

Cholangitis is most likely to occur in children with congenital malformations of the bile ducts that result in ductal obstruction or reflux of pancreatic secretions related to an abnormal pancreaticobiliary junction. Ascending cholangitis is a common complication of choledochal cysts. Ultrasound is the best initial imaging examination, usually demonstrating location of the cyst and degree of ductal dilatation.

Other imaging modalities to evaluate gallbladder and biliary duct disease in children include MRI and magnetic resonance cholangiopancreatography (MRCP). Both MRI and MRCP are highly sensitive for detection of stones not seen on ultrasound and for acute cholecystitis. MRCP can demonstrate bile duct anatomy more completely in the setting of ductal obstruction or suspected choledochal cyst.

Pancreatitis

The incidence of acute pancreatitis in children has increased in recent years to approach that seen in adults.7,9 Diagnosis may be made clinically in patients presenting with the classic combination of upper abdominal pain and elevated serum amylase or lipase. In a small percentage of cases, imaging provides important evidence for the diagnosis, determining the cause of pancreatitis, and identifying complications.9

Ultrasound is the recommended initial imaging modality for evaluation of acute pancreatitis. Findings include focally or diffusely enlarged gland with abnormal echogenicity7,9 (Figure 1D). Peripancreatic edema is a common finding in acute pancreatitis. Ultrasound is also useful in identification and characterization of localized peripancreatic fluid collections (Figure 1E, 1F). Findings on ultrasound that suggest biliary cause of acute pancreatitis include dilation of pancreatic or common bile ducts or obstructing biliary stones.

Both CT with intravenous (IV) contrast and MRI have been shown to have high sensitivity in detecting acute pancreatitis and should be considered for imaging evaluation in patients whose body habitus or excessive bowel gas limits visualization of the pancreas on ultrasound.

Acute Hepatic Abnormalities

Acute right upper quadrant pain in children related to liver disease is most often caused by infection. Imaging findings in diffuse hepatic inflammation related to hepatitis are limited, but focal infections are well seen on imaging. Hepatitis may appear as hepatomegaly or subtle diffuse alterations of parenchymal echogenicity. Ultrasound is often successful in identifying hepatic abscesses, which appear as well-defined fluid collections with internal debris and septations.7

Left Upper Quadrant Pain

Left upper quadrant pain is rarely seen in clinical practice but can be associated with splenic infarct or splenic sequestration in sickle cell disease (SCD).

Sickle Cell Disease

SCD occurs in patients who are homozygous for sickle hemoglobin (HgbSS) and those with one sickle hemoglobin gene plus a gene for another abnormal hemoglobin type (eg, HbSβ±βthalassemia).10 In children, repeated sickling episodes can lead to splenic infarctions that progress over time to functional autosplenectomy. Acute splenic sequestration is a well-known complication in children with homozygous sickle cell disease resulting from sudden pooling of blood in an enlarged spleen, often associated with precipitous drop in serum Hgb level and hypovolemic shock. Both may present with acute left upper quadrant pain and should be suspected in the appropriate clinical setting in patients with HgbSS.10,11

Although diagnosis of splenic infarct or splenic sequestration does not require imaging, rapid identification allows for rapid treatment. If there is any clinical uncertainty, Ultrasound is recommended for initial evaluation of splenic pathology.

Splenic infarcts initially appear as ill-defined hypoechoic regions in the periphery of the spleen (Figure 2A). Color Doppler evaluation demonstrates lack of internal vascular flow. In acute splenic sequestration, the spleen is enlarged and often appears heterogeneous with areas of decreased echogenicity. Doppler evaluation demonstrates patent color flow in splenic vessels10,11 (Figure 2B).

Left upper quadrant. (A) Splenic infarct appears as a peripheral, wedge-shaped hypoechoic region (arrow) in the spleen on grayscale ultrasound with (B) lack of internal vascular flow (>) on color Doppler. (C) Findings of splenic sequestration include enlarged, heterogeneous spleen in the left upper quadrant with (D) normal color Doppler flow in the splenic vessels. sp, spleen.

Figure 2.

Left upper quadrant. (A) Splenic infarct appears as a peripheral, wedge-shaped hypoechoic region (arrow) in the spleen on grayscale ultrasound with (B) lack of internal vascular flow (>) on color Doppler. (C) Findings of splenic sequestration include enlarged, heterogeneous spleen in the left upper quadrant with (D) normal color Doppler flow in the splenic vessels. sp, spleen.

Right Lower Quadrant Pain

Epigastric pain and lower abdominal pain are typically signs of bowel pathology. Acute appendicitis occurs most commonly in older children and adolescents; however, up to 10% of cases occur in children age 2 to 5 years.12 Other bowel pathology that should be considered includes ileocolonic intussusception, inflammatory bowel disease, Henoch-Schonlein purpura (HSP), and infectious colitis.

Radiographs are often obtained early in evaluation of these patients. Bowel gas distribution may provide clues to bowel pathology; however, ultrasound can provide detailed evaluation of the bowel with characteristic diagnostic features.

Appendicitis

Acute appendicitis affects up to 90,000 children each year in the United States and is the most common surgical abdominal emergency in children.13 However, diagnosis may be challenging as the classic symptoms of periumbilical (pain migrating to right lower quadrant, nausea/vomiting, anorexia, and fever) are seen in less than 50% of patients. Clinical scoring systems such as the Alvarado score and the Pediatric Appendicitis score may be helpful in guiding clinicians.13,14 However, imaging plays an important role in prompt and accurate diagnosis of acute appendicitis in children.

Ultrasound is the preferred imaging for initial evaluation of children with acute appendicitis, supported by the American College of Radiology (ACR) Appropriateness Criteria.14 Targeted right lower quadrant ultrasound is suggested using a linear transducer with graded compression technique. Ultrasound findings of a fluid-filled, distended (>6 mm diameter), noncompressible appendix suggest appendicitis (Figure 3A). Secondary findings that support diagnosis on ultrasound include hyperemia of the appendix wall, increased echogenicity of peri-appendiceal fat, and peri-appendiceal fluid collection.15

Right lower quadrant. (A, B) Acute appendicitis on ultrasound. with shadowing (>) appendicolith present. Appendix is enlarged with wall hyperemia on color Doppler, surrounding echogenic fat (*). (C, D) Computed tomography with intravenous and oral contrast demonstrates enlarged fluid filled appendix (arrow) with adjacent rim-enhancing abscess collection (>) consistent with perforated appendicitis. (E) Classic “target sign” (arrow) of ileocolonic intussusception on ultrasound. (F) Inflammatory bowel disease (Crohn's) demonstrates marked bowel wall thickening of the terminal ileum with loss of normal stratification and marked echogenicity of the mesenteric fat (*) on ultrasound. (G) Marked small bowel wall thickening (>3 mm) (+) on ultrasound in a patient with acute abdominal pain and bloody stool consistent with Henoch-Schonlein purpura.

Figure 3.

Right lower quadrant. (A, B) Acute appendicitis on ultrasound. with shadowing (>) appendicolith present. Appendix is enlarged with wall hyperemia on color Doppler, surrounding echogenic fat (*). (C, D) Computed tomography with intravenous and oral contrast demonstrates enlarged fluid filled appendix (arrow) with adjacent rim-enhancing abscess collection (>) consistent with perforated appendicitis. (E) Classic “target sign” (arrow) of ileocolonic intussusception on ultrasound. (F) Inflammatory bowel disease (Crohn's) demonstrates marked bowel wall thickening of the terminal ileum with loss of normal stratification and marked echogenicity of the mesenteric fat (*) on ultrasound. (G) Marked small bowel wall thickening (>3 mm) (+) on ultrasound in a patient with acute abdominal pain and bloody stool consistent with Henoch-Schonlein purpura.

Although multiple studies have reported high specificity (>95%) of appendix ultrasound, sensitivity remains low.15 Accuracy of appendix ultrasound also depends on operator skill and patient-specific factors including obesity. Several studies have demonstrated that lack of secondary findings has a high negative predictive value for acute appendicitis, even if the appendix is not visualized.16 However, negative ultrasound in the presence of ongoing clinical suspicion is not sufficient to exclude the presence of acute appendicitis.15,16

If ultrasound is equivocal or nondiagnostic, CT with IV contrast should be considered for further evaluation.14 On CT, identification of a normal appendix excludes acute appendicitis. When inflamed, the appendix appears dilated and thick-walled with increased contrast enhancement. Secondary findings such as appendicolith, mesenteric stranding, mesenteric adenopathy, cecal wall thickening, and free peritoneal fluid are commonly seen. CT has increased accuracy for perforation and abscess (Figure 3B). MRI has demonstrated similar accuracy for diagnosis of acute appendicitis and can be considered in centers familiar with its use.

Ileocolic Intussusception

Idiopathic ileocolic intussusception is most common between ages 3 months and 3 years and is thought to occur when hypertrophied lymphoid follicles in the distal ileum serve as a “lead point” for invagination of the small intestine (ie, intussusceptum) into an adjacent distal loop of colon (ie, intussuscipiens).12 Ileocolic intussusception leads to small bowel obstruction and if untreated to bowel ischemia and perforation. In older children, Meckel diverticulum, gastrointestinal duplication cyst, or bowel lymphoma may act as a pathologic lead point for ileocolic intussusception. The classic clinical presentation of ileocolonic intussusception includes intermittent abdominal pain, vomiting, and bloody stools described as “currant jelly” stools.

Imaging evaluation often begins with abdominal radiograph; however, ultrasound is considered the gold standard for diagnosis. Radiograph findings concerning for intussusception include lack of normal gas-filled bowel in the right lower quadrant or lateral displacement of small bowel loops in the low right abdomen.17,18 Additional left lateral decubitus radiographs are helpful to evaluate for small bowel obstruction.

Ultrasound for suspected intussusception should include evaluation of all four abdominal quadrants. The characteristic finding on ultrasound is a mass larger than 3 cm in the abdomen with a classic “target” sign formed by concentric rings of hypoechoic and hyperechoic layers of invaginating bowel wall (Figure 3C). When properly performed, a normal ultrasound can definitively exclude intussusception.17,18

Once the diagnosis of ileocolic intussusception has been made, the standard of care in most pediatric centers is air reduction under fluoroscopic guidance. Universally accepted contraindications to intussusception reduction include peritonitis or presence of bowel perforation. If not already performed, a two-view abdominal radiograph must be obtained prior to procedure to evaluate for free peritoneal air. It is also recommended that pediatric surgery be on standby for possible surgical reduction in the event of unsuccessful air enema.12,17,18

Inflammatory Bowel Disease

Pediatric inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is an important cause of abdominal pain in children, with 25% of patients presenting in childhood.19 As with adults, clinical presentation depends on site of GI tract involvement and extent of disease.

Recent improvements in ultrasound technology and technique have resulted in high correlation with MRI findings in pediatric Crohn's disease, and ultrasound is increasingly used for initial imaging evaluation.20,21 Ultrasound findings suggestive of IBD include circumferential bowel wall thickening (>3 mm) with loss of normal wall stratification, hyperemia, and decreased peristalsis (Figure 3D). Increased echogenicity of adjacent mesenteric fat is an important secondary finding of mesenteric inflammation.4,20 When IBD is identified on ultrasound, further imaging with magnetic resonance enterograph in conjunction with endoscopy is typically suggested to further assess disease location and extent.21

Henoch-Schonlein Purpura

HSP is a non-thrombocytopenic systemic vasculitis typically seen in children between ages 2 and 11 years.12 Patients classically present with a palpable purpuric rash associated with arthritis and abdominal pain. Bowel involvement occurs in 50% to 75% of patients and is often associated with gastrointestinal bleeding.12,22

Ultrasound is an effective initial imaging tool for evaluation of children suspected to have HSP, with a reported sensitivity of 83% and specificity of 100%.23 The jejunum and ileum are most commonly involved, and diagnostic findings on ultrasound include asymmetric small bowel wall thickening (>3 mm) with loss of normal wall stratification due to submucosal hemorrhage (Figure 3E). Small bowel and small bowel intussusception involving the jejunum or ileum are commonly seen and are usually self-limiting.

Flank Pain

Renal colic is an increasingly common complaint seen in pediatric emergency visits due to an exponential increase in incidence of pediatric renal stones over the past decade.24,25 Older children and adolescents typically report classic symptoms of localized flank pain and dysuria. However, younger children with renal stones may present with nonspecific pain localized to the abdomen, flank, or pelvis. Gross hematuria is reported at presentation in 30% to 55% of children with stone disease and should prompt further imaging evaluation.25

Imaging of the urinary system in patients with suspected renal stone disease is important for initial diagnosis. The ability to visualize renal stones on conventional radiographs depends on stone density, which is determined by mineral content. Calcium oxalate and calcium phosphate stones are extremely dense and may be easily seen on a radiograph. Struvite and cystine stones contain less mineral and may go undetected on a radiograph, but pure uric acid stones are radiolucent.25

Ultrasound can be useful in diagnosing kidney stones either via direct visualization or by evidence of obstruction. On ultrasound, kidney stones appear hyperechoic and may demonstrate posterior shadowing. “Twinkle artifact” on color Doppler evaluation can increase sensitivity for smaller stones (Figure 4A). Stones small enough to pass into the ureter may cause ureteral obstruction, resulting in hydronephrosis, hydroureter, and decreased or absent ureteral jets seen in the urinary bladder on the affected side. Noncontrast CT of the abdomen and pelvis may be used for further evaluation, as this study may better detect stones in the lower urinary tract and can provide information about the stone's composition by its density in Hounsfield units25 (Figure 4B).

Flank pain. (A) Renal stones (arrow) appear brightly echogenic on grayscale ultrasound and (B) may demonstrate characteristic “twinkle artifact” on color Doppler. (C) Noncontrast computed tomography of the abdomen and pelvis may be useful to detect stones in the lower urinary tract (arrow).

Figure 4.

Flank pain. (A) Renal stones (arrow) appear brightly echogenic on grayscale ultrasound and (B) may demonstrate characteristic “twinkle artifact” on color Doppler. (C) Noncontrast computed tomography of the abdomen and pelvis may be useful to detect stones in the lower urinary tract (arrow).

Pelvic Pain

When a girl or woman presents with acute lower abdominal or pelvic pain, ovarian etiologies should be considered. Pelvic abnormalities that can cause pain include simple or hemorrhagic ovarian cyst, ovarian torsion, ovarian mass, pelvic inflammatory disease (PID), or pregnancy (intrauterine or ectopic). A detailed history and physical examination, including sexual history and pelvic speculum examination, can help narrow the differential diagnosis.3

Imaging of suspected pelvic abnormality should always begin with ultrasound. This is usually performed via transabdominal approach, but transvaginal ultrasound may be performed in older, sexually active adolescents.

Ovarian Cysts

Ovarian cysts are more common in infancy and adolescence due to increased hormonal activity during these periods. Neonatal ovarian cysts are commonly identified in-utero and develop from the influence of maternal human chorionic gonadotropin on ovarian follicles. Simple neonatal ovarian cysts are not commonly a source of pain and usually resolve spontaneously. Neonatal cysts larger than 2 cm should be observed with ultrasound every 4 to 6 months until they resolve.26

Ovarian cysts are infrequent in prepubertal girls. If a cyst is found on pelvic ultrasound, further evaluation for signs of precocious puberty should be performed. Most cysts in prepubertal girls are follicular in origin and can be followed if they are simple in appearance. If the cyst is persistent or symptomatic, it should be surgically resected.27

Ovarian cysts are common in adolescent girls and can be either follicular cysts or persistent corpus luteum. Corpus luteal cysts can grow to be large, are more likely to have hemorrhage into them, and more commonly present with pain than follicular cysts. Both types of cysts typically resolve after two to three menstrual cycles and can generally be followed with ultrasound.26 However, if the girl presents with acute pain and vomiting, and a cyst is seen on ultrasound, then ovarian torsion, which cannot be excluded by imaging, should be considered.

Ultrasound appearance of a simple cyst, regardless of patient age, is an anechoic structure in the pelvis; the ovary may or may not be identified separate from this structure (Figure 5A). Findings suggestive of complication such as hemorrhage or torsion include echoes within the cystic structure or enlarged adjacent ovary (Figure 5B).

Pelvic pain. (A) Simple ovarian cyst on ultrasound appears anechoic. (B) Complex ovarian cyst with thin internal septations (arrow) on ultrasound, likely hemorrhagic cyst. (C) Tubo-ovarian abscess on ultrasound appears as a complex cystic mass adjacent to the left ovary. (D) Asymmetric enlargement of the left ovary with peripheral displacement of multiple follicles (>) and increased echogenicity of the ovarian stroma in the setting of ovarian torsion. Note that color Doppler flow (arrow) in the ovary does not exclude torsion due to the ovary's dual blood supply. O, ovary.

Figure 5.

Pelvic pain. (A) Simple ovarian cyst on ultrasound appears anechoic. (B) Complex ovarian cyst with thin internal septations (arrow) on ultrasound, likely hemorrhagic cyst. (C) Tubo-ovarian abscess on ultrasound appears as a complex cystic mass adjacent to the left ovary. (D) Asymmetric enlargement of the left ovary with peripheral displacement of multiple follicles (>) and increased echogenicity of the ovarian stroma in the setting of ovarian torsion. Note that color Doppler flow (arrow) in the ovary does not exclude torsion due to the ovary's dual blood supply. O, ovary.

Ovarian Torsion

Adnexal torsion occurs when the ovary and/or fallopian tube twists on the vascular pedicle, causing compromise of blood flow to adnexal structures. Torsion can occur at any age but is more common prenatally and in adolescence. Adolescent girls with ovarian torsion most commonly present with acute pelvic pain, but pain may have been intermittent for 2 to 3 days prior to the acute episode. The acute episode often includes vomiting in addition to pain. Clinical findings are not specific enough to diagnosis, so imaging can be helpful.

The ultrasound appearance of ovarian torsion is most commonly an asymmetrically enlarged ovary28 (Figure 5D). The ovary is frequently heterogeneous, and follicles may be displaced peripherally. Doppler flow may be absent; however, presence of Doppler flow does not exclude ovarian torsion.16 Torsion can be difficult to distinguish from hemorrhagic cyst or PID on imaging alone; however, the presence of an enlarged ovary in the setting of acute pain should raise the suspicion of ovarian torsion, and surgical consult should be considered.28,29

Torsion can also be associated with benign ovarian masses such as ovarian cyst or ovarian teratoma. Intralesional fat and calcifications indicate teratoma.

Pelvic Inflammatory Disease

PID is infection and inflammation of the upper genital tract, usually involving ovaries and fallopian tubes. PID occurs most frequently as an ascending infection from a sexually transmitted infection but can be associated with adjacent infection such as perforated appendicitis.

PID has a widely variable appearance on ultrasound depending on timing of imaging and extent of disease. Early in the process, ultrasound may be normal. Other findings include prominent ovaries adherent to the uterus (salpingo-oophoritis), thick-walled, fluid-filled tubular structure with low-level echoes (pyosalpinx), or enlarged, echogenic ovary containing tiny abscesses. As infection progresses, tubo-ovarian abscess may develop (Figure 5C).

Conclusion

Children with acute abdominal pain can cause a diagnostic dilemma. History and physical examination with attention to location of pain and associated signs and symptoms can help guide further imaging evaluation. Ultrasound is usually the initial imaging evaluation of choice in the pediatric population, with abdominal radiographs providing supplemental information. CT or MRI can be considered in certain diagnoses for more in-depth information.

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Selected Differential Diagnosis of Nontraumatic Acute Abdominal Pain in Children By Age

All ages Infants/toddlers (0–4 years) School age (5–11 years) Adolescents (12–20 years)
Appendicitis Gastroenteritis Constipation Gallbladder disease Pancreatitis Sickle cell crisis Urinary tract infection Intussusception Meckel diverticulum Midgut volvulus Bowel obstruction Functional pain Intussusception Henoch-Schonlein purpura Functional pain Inflammatory bowel disease Ovarian or testicular torsion Pelvic inflammatory disease Ectopic pregnancy
Authors

Erica L. Riedesel, MD, is an Assistant Professor, Department of Radiology, Division of Pediatric Radiology, Emory University School of Medicine, Children's Healthcare of Atlanta. Susan D. John, MD, is a Professor, Department of Diagnostic and Interventional Imaging, Division of Pediatric Radiology, University of Texas McGovern Medical School. Leann E. Linam, MD, is an Associate Professor, Department of Radiology, Division of Pediatric Radiology, Emory University School of Medicine, Children's Healthcare of Atlanta.

Address correspondence to Erica L. Riedesel, MD, Department of Radiology, Children's Healthcare of Atlanta, 1405 Clifton Road NE, Atlanta, GA 30322; email: erica.riedesel@choa.org.

Disclosure: The authors have no relevant financial relationships to disclose.

10.3928/19382359-20200820-01

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