Abdominal Pain in Pediatric Patients Image Gently

Transcription

1 Abdominal Pain in Pediatric Patients Image Gently Susan D. John, M.D. Baptist Health Emergency Radiology 2017 Disclosure I have no financial relationships with a commercial entity producing healthcarerelated products and/or services. Challenges of Imaging Infants and Children with Abdominal Pain History and physical findings overlap Diarrhea Bilious vomiting Blood in stool Episodic crying Poorly localized pain Pathologies cluster in specific age groups Newborn Congenital obstructive lesions 1 week 2 months Hypertrophic pyloric stenosis 2-5 months Incarcerated hernia 5 months 2 years Intussusception 3 yrs adolescence Appendicitis 1

2 Learning Objectives Understand varieties of pathology that cause abdominal pain and vomiting in infants and children Plan safe and effective imaging protocols for children with abdominal based on the latest evidence Image Gently Reducing radiation exposure to children during medical imaging Using lower dose CT, DR protocols Implementing dose saving techniques during fluoroscopy Developing guidelines for when imaging is needed Creating imaging algorithms that begin with low dose, effective imaging modalities Most Appropriate Imaging Many factors involved Clear clinical indications Scientific data ACR appropriateness guidelines Patient expectations Referring physician input Sedation requirements Availability of equipment and expertise 2

3 Abdominal Radiographs (Get No Respect) Can be diagnostic When not diagnostic, can provide useful information Bowel obstruction Presence Location Guidance for next exam Small bowel entrapment by magnetic beads Duodenal web XR Non-diagnostic Normal or findings of proximal obstruction Fluoroscopy bilious vomiting Ultrasound most often in children >5 months of age Distal obstruction Fluoroscopy US CT/MRI select circumstances 3

4 3 month old with increasing vomiting Duodenal Web Duodenal Web (missed on initial UGI series 4

5 9 month and old fever with fever and vomiting Intussusception Most likely cause of small bowel obstruction between 5 months to 2 years or age 1 to 8 Weeks of Age Projectile vomiting Gastroesophageal reflux Gastric outlet obstruction Pyloric muscle Spasm Hypertrophy Hypertrophic pyloric stenosis Most common 3-6 wks of age Not seen in first week of life Very uncommon after 8 weeks of age Normal Pylorus 1-2 mm muscle Length negligible Opens frequently Emptying usually evident D 5

6 Hypertrophic Pyloric Stenosis Transverse 3 mm + muscle 1.5 cm + length Little or no emptying Longitudinal False Positives Contracted, elongated antrum secondary to spasm, inadequate fluid in antrum Incorrect measurements Avoid Gastric Overdistention Stomach Pylorus and duodenum more posteriorly positioned Can make them less easily visible 6

7 Look for other causes of obstruction Gastric antral web Antral masses Adjacent masses/cysts Gastroesophageal Junction The Other Gastric Outlet Often clearly seen with a fluid-distended stomach Gastroesophageal reflux can be identified May obviate the need for an UGI series Often imaged inadvertently Transverse Longitudinal US of the GE Junction 7

8 GE Junction Pylorus L S D GE junction S Duodenal Web Acute Duodenal Obstruction SMV to the Rt of SMA is abnormal, suggests malrotation Midgut volvulus Bilious vomiting Can occur at any age Whirlpool sign 8

9 Signs of midgut volvulus Abnormal duodenojejunal junction position + swirling Complete obstruction in D3 Midgut Volvulus Intussusception Acute ileocolic obstruction (5months 3 yrs age) Often obstruction not evident on radiographs Symptoms nonspecific Vomiting Intermittent crying Lethargy Early identification of intussusception makes nonsurgical reduction more likely 9

10 Ultrasound for Intussusception High frequency (7-12 mhz) transducer Complex mass Target, donut appearance Transverse High sensitivity and specificity If US negative, contrast enema not needed Long Signs of Difficult Enema Reduction Symptoms for more than 48 hours Age under 3 months Small bowel obstruction Target rim > 1 cm in thickness Large amount of trapped fluid Distal migration of intussusceptum 10

11 Absent Doppler Flow in Intusussceptum Suggests ischemia, but not a contraindication to enema reduction Be prepared to decompress Free Fluid with Intussusception Small amounts are common and do not indicate perforation Complex fluid consult with surgery Transient Intussusception Common in patients with hyperperistalsis Only need surgery if persistent and longer than 3.5 cm in length Munden, AJR 2007;188:

12 18 month old with abdominal pain and fever Perforated Appendicitis Mimics Intussusception Fluid Thickened bowel can resemble intussusceptum Complex free fluid is a clue Pseudomembranous colitis Shiga toxin positive colitis Henoch Schoenlein purpura Regional enteritis 12

13 2 yrs old and greater Inflammatory conditions predominate Appendicitis Mesenteric adenitis Ileocolitis/gastroenteritis Henoch-Schoenlein purpura Hemolytic uremic syndrome Regional enteritis All can be diagnosed with US Pediatric Appendicitis Score Clinical decision rule 8 clinical signs and symptoms Further imaging indicated with scores between 4-7 Imaging with US when scores fall in the intermediate range diagnoses appendicitis with high sensitivity and specificity Samuel M. Pediatric appendicitis score. J Pediatr Surg. 2002;37(6): Saucier A. Prospective evaluation of a clinical pathway for suspected appendicitis. Pediatrics. 2014;133 (1): e88. US for Appendicitis Still accepted as best first screening exam Staged approach using CT for equivocal cases highly accurate Sensitivity 98.6% Specificity 90.6% CT avoided in 53% Krishnamoorthi, Radiol Jan

14 Normal Appendix Freely mobile Normal bowel peristalsis Minimal visible periappendiceal fat Appendix Size in Appendicitis 6 mm or > in diameter abnormal PPV 63% NPV 100% More useful for excluding appendicitis Rettenbacher, Radiology 2011; 218: mm or > Similar accuracy Goldin, Pediatr Radiol 2011; 41: 993. Causes of Variable Appendix Size Overlap in diameter between normal and inflamed appendices CT normal can be up to 8.7 mm Benign processes can distend the normal appendix Patient-specific factors influence diameter Grows with age Contents such as stool increase diameter Technical factors and variability in measurement Coronal measurements slightly larger than axial Differences between observers Trout AT, AJR 2014; 202:936. Dietz KR, Pediatr Radiol 2013; 43:232. Trout AT, Pediatr Radiol 2016; 46:

15 Lymphoid Hyperplasia of the Appendix Enlarged lymphoid tissue in the wall of appendix Response to viral infection Can mimic a fluid-filled appendix Look for central mucosal stripe May result in increased size Can cause obstruction of the appendiceal lumen Tip appendicitis Swischuk, et al, Emergency Radiology (2015) 22: Acute suppurative appendicitis Normal appendix Compressibility can be difficult to demonstrate Appendicitis Normal Lack of compressibility one of the most common findings in false positive US Trout AT et. al. A critical evaluation of US for the diagnosis of pediatric acute appendicitis in a real-life setting: how can we improve the diagnostic value of sonography? Pediatr Radiol (2012) 42:

16 Perforated Appendix Dilated small bowel RLQ mass Colon cut-off Flank stripe Perforated appendicitis with abscess Most common cause of SBO over the age of 2 years Secondary findings can be strong indicators of appendicitis Thickened Echogenic Fat = Inflammation Absent peristalsis = ileus Calcifications/fecaliths Localized RLQ tenderness Complex peritoneal fluid Wiersma, Eur Radiol 2009; 19:

17 Standardized Reporting Most valuable for indeterminate exams Ensures that sonographer evaluates for all secondary findings Improves radiologist s accuracy Allows referring physician to understand the radiologist s decision-making process Nielsen JW et.al., Reducing CT scans for appendicitis by introduction of a standardized and validated US report template. J Pediatr Surg 3015; 50: Fallon SC et.al., Development and validation of an US scoring system for children with suspected acute appendicitis. Pediatr Radiol 2015; doi: /s Abdominal/Pelvic CT in Children Often challenging because of lack of abdominal fat Child-size your CT protocols Image Gently website Scan only when necessary Scan only the indicated region Scan only once Ultrafast MRI for Appendicitis Children of age 4-17 years No sedation or contrast Limited exam Axial and coronal SSFSE w/wo fat sat Axial DWI Scan times less than 9 minutes Normal appendix seen 43% of the time Sens/spec 100/99% PPV 98% NPV 100% Johnson, AJR 2012, Jun 198:1424 No difference in time to antibiotics or surgery, negative appendectomy rate, perforation rate, or length of stay. Gudrun A et al, Pediatrics 2014 ;133:

18 MRI for Appendicitis Multiple studies comparing MRI to CT Meta-analysis of accuracy of MRI for appendicitis (Duke E, et al. AJR 2016; ) Sensitivity and specificity 96% Children and pregnant women Personal experience patients CT almost completely eliminated Time from first image to incision (10.7 hours) Negative appendectomy rate (3.7 %) Median imaging costs increased Appendicitis Normal appendix 18

19 Non-GI Causes of Abdominal Pain 5 yr old with abdominal pain, fever, and vomiting Hospital 1 Abdominal US Hospital 2 Abdominal US Abdomen MRI All normal. Right Upper Lobe Pneumonia Imaging Abdominal Emergencies in Children Use age and clinical signs to select best first exam Radiographs can have value US highly reliable with experience and when performed with proper technique Proper fluid distension and positioning Taking time to assess dynamic factors Noting important secondary findings Consider MRI as alternative to CT susan.dsusan.d.john@uth.tmc.edu 19