Transcript imaging resources

Acute Abdominal Pain in the Child:
Ultrasound versus CT
Harriet J. Paltiel, MD
Children’s Hospital Boston
Harvard Medical School
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
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
Imaging Evaluation of
Acute Abdominal Pain
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Acute appendicitis
Abdominal trauma
Mesenteric adenitis
Intussusception
Inflammatory bowel disease
Genitourinary abnormalities
– acute pyelonephritis
– renal colic
– ovarian cyst, torsion, tumor
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
Normal Appendix
Acute Appendicitis
Acute Appendicitis
Perforated Appendicitis
Peritonitis Post-Perforation
Acute Appendicitis
• US detection rates for acute appendicitis vary widely
in literature (22% to 98%)
• Techniques to improve visualization have had mixed
results
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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)
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
Retrocecal Appendix Limits US
Visualization
10-Year-Old Girl with Suspected
Appendicitis
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
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
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
Grade 4 Renal Injury
and Splenic Contusion
Fall in Hematocrit and Abdominal
Distention After Liver Tx
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
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
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
? Appendicitis in 10-Year-Old Boy
Gastroenteritis
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%
Intussusception
• Clinical presentation
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paroxysmal abdominal pain
palpable abdominal mass
currant jelly stool
bowel obstruction
• Imaging
– plain films
– US
– contrast enema
Air Reduction of Intussusception
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
Meckel’s Diverticulum
? Appendicitis in 11-year-Old Boy
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)
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
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
New Onset of Abdominal Pain and
Weight Loss
Crohn’s Flare and Perirectal Pain
Genitourinary Abnormalities
• Pyelonephritis
• Renal colic
• Ovarian cyst, torsion, tumor
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
Immune Compromised Teenager
With Fever and Abdominal Pain
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
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
12-Year-Old Boy With Fever and
Back Pain
? Renal Stone in 8-Year-Old Boy with
MRCP and Scoliosis
Gynecological Conditions
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Frequent cause of RLQ pain
Ovarian cyst
Ovarian torsion
(PID)
(Ectopic pregnancy)
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
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
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
4-Year-Old Girl with Right Pelvic Pain
Newborn with Abdominal Mass and
Tenderness to Palpation
5.5 Months of Age
Ovarian Tumor
• Benign- 65%
– cystic teratoma
– cystadenoma
• Malignant- 35%
– Primary:
• germ cell
• stromal sex cord
• epithelial
– Metastatic
Cystic Teratoma
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> 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
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
Cystic Teratoma
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
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Acute appendicits
Abdominal trauma
Mesenteric adenitis
Intussusception
Inflammatory bowel disease
Genitourinary abnormalities
• acute pyelonephritis
• renal colic
• ovarian cyst, torsion, tumor