1. Sonography of the Acute Abdomen in the Pediatric Patient
J Ultrasound Med 21:887–899, 2002
Diane S. Babcock, MD

2. Object
To review the causes and sonographic appearance of pathologic processes that result in abdominal pain in the pediatric patient and to understand the use and limitations of abdominal sonography in the acute pediatric abdomen

3. Acute Abdomen in Premature Neonate
Necrotizing enterocolitis(NEC) -- a serious abdominal disorder of premature neonates
Most often affects the terminal ilium and ascending colon
Symptoms: abdominal distention, hematochezia, apnea, acidosis, temperature instability, and lethargy
Plain film: pneumatosis coli, a thick walled bowel, free air, and portal venous air

4. Acute Abdomen in Premature Neonate
NEC
Sonography: useful when perforation and abscess formation are suspected
Mural thickening of the terminal ilium and ascending colon
Free intraabdominal fluid containing echogenic debris or a loculated right lower quadrant mass suggests perforation and abscess formation
Portal venous gas

5. Acute Abdomen in Premature Neonate

6. Acute Abdomen in Full-Term Neonate
Congenital intestinal obstruction is the most common condition producing a distended and tender abdomen in an irritable neonate
Paralytic ileus caused by septicemia must also be considered
Diagnosis of obstruction is usually made by plain radiographs and contrast studies

7. Acute Abdomen in Full-Term Neonate
Sonography: particularly helpful in the gasless abdomen
Confirming the presence and location of distended, fluid-filled bowel loops
Malrotation can be suggested when the positions of the superior mesenteric artery and vein are reversed

8. Acute Abdomen in Full-Term Neonate

9. Acute Abdomen in Full-Term Neonate

10. Acute Abdomen in Infant
After the neonatal period, a different set of diseases produces the acute abdomen
Intussusception: particularly common in the 1-month to 2-year age group
Strangulated inguinal hernia
Complicated Meckel diverticulum
Malrotation with volvulus
Appendicitis: less common in this age group
Non–surgically treated causes:
Primary peritonitis, colic, and gastroenteritis

11. Acute Abdomen in Infant
Ileocolic intussusception
Predominately in the first 2 years of life
Pathologic lead points such as lymphoma and GI duplication should be considered in children older than 3 years
Air, barium, or water-soluble contrast material under fluoroscopic guidance
Sonographically guided hydrostatic reduction has been described and recommended because of a substantial reduction in radiation exposure

12. Acute Abdomen in Infant
Ileocolic intussusception
Sonography:
Mass with a typical “target” appearance
Pseudokidney appearance on longitudinal scans
Negative findings can exclude intussusception with near 100% accuracy
Doppler sonography:
To evaluate bowel ischemia and risk of perforation
Ischemic bowel, entrapped fluid, and interloop lymphadenopathy make successful reduction less likely

13. Acute Abdomen in Infant

14. Acute Abdomen in Infant
Inguinal hernia:
May incarcerate and appear as an acute abdomen
Sonography:
Presence of bowel loops may be evident
May contain omentum and may be difficult to diagnose
Other abdominal structures such as the ovary may herniate into the inguinal area and become entrapped

15. Acute Abdomen in Infant

16. Acute Abdomen in Child and Adolescent
Causes of abdominal pain in the child differ from those in the infant
Acute appendicitis is the most common surgically treated condition
Able to localize of the pain, and thereby narrowing the differential diagnosis

17. Acute Abdomen in Child and Adolescent -- RUQ
Gallbladder disease
Hepatitis
Pyelonephritis
Renal colic
Acute hydronephrosis

18. Acute Abdomen in Child and Adolescent -- RUQ
Gallbladder dilatation
Can occur with sepsis or lack of enteral feeding
May or may not be associated with pain
Suggested when the length is greater than the normal right kidney and when the diameter is greater than 4 cm

19. Acute Abdomen in Child and Adolescent -- RUQ
Acute acalculous cholecystitis
Association with septicemia, dehydration, streptococcal infections, and Kawasaki disease
Sonography:
Gallbladder wall thickening
Tenderness when scanning over the gallbladder
Murphy sign

20. Acute Abdomen in Child and Adolescent -- RUQ

21. Acute Abdomen in Child and Adolescent -- RUQ
Cholelithiasis
Predisposing diseases include hemolytic anemia, cystic fibrosis, metabolic disease, liver disease, malabsorption before orthopedic surgery, and others
Gallbladder sludge may be shown with lack of enteral feeding or diuretic therapy and often clears when the patient returns to a normal diet

22. Acute Abdomen in Child and Adolescent -- RUQ
Hepatitis and pyelonephritis are diagnosed on the basis of clinical symptoms, blood tests, and urinalysis
Acute hydronephrosis can cause an acute abdomen, and sonographic examination shows dilatation of the collecting system

23. Acute Abdomen in Child and Adolescent -- RUQ

24. Acute Abdomen in Child and Adolescent -- LUQ
Spleen
Splenomegaly:
Lower pole extends below the ribs
Splenic torsion
Abnormal location of the spleen in the mid or lower abdomen
Decreased flow on Doppler imaging
Splenic infarction
Abnormal echogenicity or areas of abnormal perfusion on Doppler imaging

25. Acute Abdomen in Child and Adolescent -- LUQ

26. Acute Abdomen in Child and Adolescent -- LUQ

27. Acute Abdomen in Child and Adolescent -- LUQ
Acute pancreatitis
Cause: blunt abdominal trauma, infection, drug toxicity, biliary-pancreatic tract anomalies, and others
Sonography:
Child’s pancreas is normally relatively larger and less echogenic
May be enlarged and abnormally hypoechoic
Pancreatic duct may be dilated
Fluid collection (pseudocysts) can form around the pancreas, particularly adjacent to the tail

28. Acute Abdomen in Child and Adolescent -- LUQ

29. Acute Abdomen in Child and Adolescent -- LUQ

30. Acute Abdomen in Child and Adolescent -- LUQ

31. Acute Abdomen in Child and Adolescent -- RLQ
Acute appendicitis:
The most common acute surgically treated ailment in children and adolescent
Diagnosis: on the basis of a physical examination and elevated WBC count
Imaging is used in atypical or uncertain cases
Plain film is useful if an appendicolith is visualized
CT is used in large patients who are not good candidates for sono and when sono is not definitive

32. Acute Abdomen in Child and Adolescent -- RLQ
Acute appendicitis
Sonography: sensitivity of 85% and specificity of 92%
Sausage-shaped, blind-ended structure on longitudinal images
Target lesion on transverse images
Greater than 6 mm in diameter and noncompressible
Indistinctness of the layers, periappendiceal fluid collection, and echogenic surrounding mesentery
Doppler imaging shows increased flow

33. Acute Abdomen in Child and Adolescent -- RLQ

34. Acute Abdomen in Child and Adolescent -- RLQ

35. Acute Abdomen in Child and Adolescent -- Midabdomen
Bowel obstruction
Malrotation with volvulus
Intussusception
Bleeding disorder
Hematoma
Mesenteric adenitis
Hydronephrosis

36. Acute Abdomen in Child and Adolescent -- Midabdomen

37. Acute Abdomen in Child and Adolescent -- Midabdomen

38. Acute Abdomen in Child and Adolescent -- Gynecologic
Right-sided disorders may cause symptoms similar to acute appendicitis
Hemorrhagic ovarian cysts, ovarian torsion, pelvic inflammatory disease or abscess, ectopic pregnancy, and, infrequently, endometriosis

39. Acute Abdomen in Child and Adolescent -- Gynecologic

40. Acute Abdomen in Child and Adolescent -- Gynecologic

41. Non-Surgically Treated Disorder
Including gastroenteritis, primary peritonitis, and constipation
Physical examinations, laboratory studies, and imaging examinations are unrevealing
Sonography can be used to rule out other organic causes

42. Non-Surgically Treated Disorder

43. Referred Pain Include diseases of the spine and chest
Pneumonia, lower lobe
Sonography:
Serendipitous visualization of an abnormal nonaerated lung above the diaphragm

44. Referred Pain

45. Conclusion
Sonography continues to be an effective modality for evaluating the acute abdomen
Cause of the acute abdomen varies depending on the age of the child
Because it uses nonionizing radiation and is noninvasive, sonography is often the next imaging procedure performed