Acute Abdominal Pain in the Child: Ultrasound versus CT

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1 Acute Abdominal Pain in the Child: Ultrasound versus CT Harriet J. Paltiel, MD Children s Hospital Boston Harvard Medical School

2 Educational Objectives Review imaging evaluation of several common causes of acute abdominal pain in children Emphasize relative roles of US and CT in workup of each entity

3 Acute Abdominal Pain Infectious gastroenteritis most common often associated with fever, vomiting and diarrhea improvement with rehydration surgical conditions do not usually present in this manner Acute appendicitis most frequent indication for emergency abdominal surgery clinical diagnosis often difficult many nonsurgical conditions mimic acute appendicitis When surgery contemplated imaging plays key role

4 Imaging Evaluation of Acute Abdominal Pain Acute appendicitis Abdominal trauma Mesenteric adenitis Intussusception Inflammatory bowel disease Genitourinary abnormalities acute pyelonephritis renal colic ovarian cyst, torsion, tumor

5 Acute Appendicitis Diagnosed by US or CT Does greater diagnostic accuracy of CT warrant associated exposure to ionizing radiation and higher operating costs compared to US? Children especially sensitive to negative consequences of radiation exposure Potentially long period during which radiationinduced tumor may develop A negative US examination does not exclude appendicitis unless normal appendix identified

6 Normal Appendix

7 Acute Appendicitis

8 Acute Appendicitis

9 Perforated Appendicitis

10 Peritonitis Post-Perforation

11 Acute Appendicitis US detection rates for acute appendicitis vary widely in literature (22% to 98%) Techniques to improve visualization have had mixed results scanning through full bladder scanning after saline enema posterior body wall compression posterolateral scanning to identify retrocecal appendix Confidence of radiologist in their interpretation influenced by choice of modality radiologists more confident about CT interpretations regardless of training level (Peña et al., AJR 2000)

12 Acute Appendicitis Effective imaging protocol should probably include both US and CT Perform IV contrast-enhanced CT if appendix not visualized by US or findings inconclusive Consider body habitus of patient US visualization of appendix decreased in obese children Ideal protocol depends on resources and expertise available at a particular institution

13 Retrocecal Appendix Limits US Visualization

14 10-Year-Old Girl with Suspected Appendicitis

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16 Acute Appendicitis Best outcomes require ongoing collaboration between experienced clinicians performing initial patient evaluation and radiologists until acceptable level of diagnostic certainty reached Implementation of clinical scoring system with patient stratification into low-, intermediate- and high-risk categories for presence of appendicitis may eventually lead to more reasoned consumption of imaging resources and radiation dose reduction

17 Abdominal Trauma Leading cause of morbidity and mortality in childhood CT imaging method of choice after blunt trauma in hemodynamically stable children permits accurate detection and quantification of injury to solid and hollow viscera and associated intra/extraperitoneal fluid and blood US used primarily to detect hemoperitoneum detection of hemoperitoneum has limited impact on management in hemodynamically stable children

18 Abdominal Trauma Limitations of US provides no diagnostic information regarding bony pelvis or lumbar spine cannot diagnose hollow viscus injury misses one fourth to one third of solid viscus injuries Utility of US helpful in assessing hemodynamically unstable patient can be performed rapidly at bedside prior to surgery serves as a rapid, noninvasive replacement for diagnostic peritoneal lavage

19 Grade 4 Renal Injury and Splenic Contusion

20 Fall in Hematocrit and Abdominal Distention After Liver Tx

21 Mesenteric Adenitis An inflammatory condition Symptoms similar to acute appendicitis abdominal pain, fever, elevated WBC Most common diagnosis in children found to have a normal appendix at surgery

22 Mesenteric Adenitis Primary right-sided mesenteric lymphadenopathy without identifiable acute inflammatory process, or with mild (< 5 mm) mural thickening of the terminal ileum most cases believed to be due to underlying infectious terminal ileitis Secondary associated inflammatory conditions include appendicitis, Crohn s disease and celiac disease may only be diagnosed by CT

23 Mesenteric Adenitis Primary mesenteric adenitis more common in children than adults US or CT depicts a cluster of 3 or more enlarged mesenteric nodes 5 mm in diameter Role of imaging is to exclude an associated inflammatory process

24 ? Appendicitis in 10-Year-Old Boy

25 Gastroenteritis

26 Intussusception Prolapse of bowel segment (intussusceptum) into more caudal segment (intussuscipiens) Most common in first 2 years of life Temporal relationship with respiratory infections and gastroenteritis 90% ileocolic 10% ileoileocolic, colocolic, or ileoileal No lead point in > 90%

27 Intussusception Clinical presentation paroxysmal abdominal pain palpable abdominal mass currant jelly stool bowel obstruction Imaging plain films US contrast enema

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29 Air Reduction of Intussusception

30 Intussusception Presence of lead point common in neonates, older children and adults Meckel s diverticulum, polyp, duplication most common lead points Lymphoma Hematoma Air enema less successful CT useful in delineating underlying cause Most patients require surgical exploration

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32 Meckel s Diverticulum

33 ? Appendicitis in 11-year-Old Boy

34 Inflammatory Bowel Disease Crohn s disease and ulcerative colitis most common Neither disease usually presents primarily with acute abdominal pain Plain films, endoscopy and contrast radiographic studies main imaging tools in children Acute presentation usually due to complications in patients with chronic disease postoperative adhesions -abscess due to perforation or fistula toxic megacolon (in patients with UC)

35 Inflammatory Bowel Disease Diagnosis may be less obvious in young children, especially during a first episode of abdominal pain IBD can involve periappendiceal tissues, mimicking acute appendicitis clinically and radiographically US can directly visualize thickened bowel loops, abscesses and fistulas Affected bowel has decreased peristalsis and loss of normal compressibility Vessel density by color Doppler may reflect disease activity

36 Inflammatory Bowel Disease US shows mural thickening and adjacent inflammation depicts fibrofatty mesenteric proliferation in Crohn s disease often underestimates bowel involvement correlation between color Doppler US features and clinical activity controversial CT imaging of complications such as abscesses when US findings equivocal and to guide abscess drainage MR used for non-emergent assessment of disease

37 New Onset of Abdominal Pain and Weight Loss

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39 Crohn s Flare and Perirectal Pain

40 Genitourinary Abnormalities Pyelonephritis Renal colic Ovarian cyst, torsion, tumor

41 Acute Pyelonephritis Frequent presentation with fever, vomiting, flank pain and elevated WBC Right-sided acute pyelonephritis may mimic acute appendicitis US efficient, cost-effective method to assess anatomy of the upper urinary tract compared to CT work-up of first UTI in girls and boys UTI with palpable abdominal mass UTI unresponsive to antibiotic therapy Acutely infected kidneys often normal by US CT evaluation reserved for imaging of complications

42 Immune Compromised Teenager With Fever and Abdominal Pain

43 Renal Colic Stones occur with increased frequency in children with urinary tract obstruction due to anatomical or neurogenic abnormalities Usually due to infection (Proteus and Klebsiella) and metabolic disease Acute presentation in children relatively uncommon Usually discovered during investigation of nonspecific abdominal pain or UTI Both US and CT used for diagnosis in children

44 Renal Colic US usual first-line imaging tool CT useful in patients with obesity, severe scoliosis, and negative renal US where clinical suspicion is high Non-contrast CT increasingly used for primary diagnosis due to higher sensitivity for stone detection and demonstration of secondary signs of obstruction perinephric or periureteral stranding ureteral wall edema and dilation blurring of renal sinus fat

45 12-Year-Old Boy With Fever and Back Pain

46 ? Renal Stone in 8-Year-Old Boy with MRCP and Scoliosis

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49 Gynecological Conditions Frequent cause of RLQ pain Ovarian cyst Ovarian torsion (PID) (Ectopic pregnancy)

50 Gynecologic Conditions US primary imaging modality transabdominal and transvaginal scanning MRI or CT complex cases to determine full extent of a tumor for definitive diagnosis of teratoma

51 Ovarian Cyst May cause abdominal pain if significantly enlarged or complicated by hemorrhage, rupture or torsion Uncomplicated cyst has thin wall and anechoic contents by US Variable US appearance after hemorrhage contents echogenic or hypoechoic cyst wall thin or thick and irregular internal septations Treatment usually conservative Follow-up US to exclude underlying neoplasm

52 Ovarian Torsion Most common in adolescents and young adults May occur in association with adnexal cyst or neoplasm Underlying lesions more common in younger patients Acute onset of lower abdominal pain Nausea, vomiting, leukocytosis Ovary markedly swollen with multiple enlarged peripheral follicles

53 4-Year-Old Girl with Right Pelvic Pain

54 Newborn with Abdominal Mass and Tenderness to Palpation

55 5.5 Months of Age

56 Ovarian Tumor Benign- 65% cystic teratoma cystadenoma Malignant- 35% Primary: germ cell stromal sex cord epithelial Metastatic

57 Cystic Teratoma > 90% of all benign ovarian neoplasms >80% occur in pubertal girls Asymptomatic palpable mass Acute abdominal or pelvic pain due to hemorrhage, torsion, or rupture Contains mature elements from all 3 germ cell layers 5-10 cm diameter and < 50% soft tissue elements

58 Cystic Teratoma US features depend on relative amounts of various tumor components (fat, sebum, fluid, calcium, hair) anechoic, solid, or mixed cystic-solid mass calcification, mural nodules, tip of iceberg sign, fluid-fluid levels CT and MR readily detect fat, fat-fluid levels and calcification

59 Cystic Teratoma

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61 Summary Reviewed imaging evaluation features of most common causes of acute abdominal pain in children with emphasis on relative roles of US and CT in workup of each entity Acute appendicits Abdominal trauma Mesenteric adenitis Intussusception Inflammatory bowel disease Genitourinary abnormalities acute pyelonephritis renal colic ovarian cyst, torsion, tumor