Mark S. Asay, MDCarl M. Black, MD

S. Douglas Brown, MDSeth Y. Cardall, MDJohn S. Collins, MDDaniel L. Corey, MDDavid R. Cottam, MDTyler L. Crawford, MD

John A. Dana, MDVal D. Dunn, MD

Gary V. Halversen, MDRoy C. Hammond, MDDaniel J. Hatch, MD

Dennis K. Heaston, MDKurtis R. Kendell, MD

Jeffrey S. McClellan, MDMatthew A. McNairy, MD

Ryan B. Nielsen, MDMatthew E. Nokes, MD

Robin R. Ockey, MDJ. Daniel Rasband, MDThomas B. Sanders, MDKimball B. Taylor, MD

S. Douglas Wing, MD, FACR

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URA Newsletter 2011; 3(2)

IMAGING FOR RIGHT LOWER QUADRANT PAIN

IntroductionRight lower quadrant (RLQ) pain is an extremely common presentation for patients in emergency rooms and doctors’ offices. Besides pain, the typical associated symptoms are very nonspecific, including nausea, vomiting, leukocytosis, fever, etc. Once a thorough history and physical exam have been performed, differential considerations begin to form based on those data as well as demographics. Occasionally, sufficient information is provided by the clinical picture for firm diagnosis and confident therapy. More often than not, however, the spectrum of differential considerations is sufficiently broad and impactful on therapy that additional tools are needed for proper patient management. This typically means medical imaging.

Imaging in RLQ pain comes in several different modalities, some more and some less useful than others. The right tool for the job will often depend on the type of patient and their individual presentation. There is often not a “one-size-fits-all” approach that can be universally applied. This is an issue that has been addressed on many fronts, including having been tackled by the American College of Radiology, which has

accuracy of these has been shown to be inferior to imaging, however.1

Differential considerations for RLQ pain often start with acute appendicitis. This is the most common cause of RLQ pain and is the most common acute abdominal disorder requiring surgery. The list of other considerations is quite long and varies from the extremely benign to life threatening. As this is a newsletter, only a few of the most common disorders will be addressed in these pages.

Acute AppendicitisAs stated, this is an extremely common problem faced by patients and their treating physicians. Once the decision has been made to pursue imaging, what next? Which is the best test to order in terms of sensitivity and specificity, but not forgetting other important considerations such as cost, radiation exposure, timeliness of results, etc? The ACR appropriateness criteria for RLQ pain (table 1) are useful and illuminating in this application. Radiography and fluoroscopy (barium enema) have very limited utility in this problem. Computed tomography (CT) and ultrasound (US) are truly the workhorses

DIAGNOSTIC IMAGING UPDATE

published appropriateness criteria for different imaging studies in RLQ pain. Clinical tools are also available to guide and assist in the work-up of RLQ pain, such as the Alvarado scale in predicting and identifying patients with acute appendicitis. The

Imaging for Right Lower Quadrant Pain

1, variants 1 and 2). Particularly with the availability of multidetector CT providing sagittal and coronal reformats without any additional irradiation, this test will most often provide a diagnosis for this presentation. CT is also able to offer much information about alternative disorders that may mimic acute appendicitis and can often provide additional detail for planned intervention. Our preferred CT protocol is to include IV and oral contrast whenever possible. Contrast should only be eliminated in cases of contrast allergies or situations where severe time constraints (ER cases). Unenhanced CT scans are less sensitive but still generally useful in evaluating RLQ pain.

Pediatrics and PregnancyIn imaging for acute appendicitis, special considerations exist for two patient populations: pediatric age patients and pregnant women. In pediatric age groups, CT maintains the edge in terms of both sensitivity and specificity. However, with the added importance of greater radiosensitivity, US with its absence of ionizing radiation is the first line imaging choice in the pediatric population, especially with follow-up CT in equivocal cases. The CT-after-US approach has a reported sensitivity and specificity of 94%3. Additionally, a recent study shows high negative predictive value in cases where the appendix is not visible (98.7%)4. (Table 1 – Variant 4) In children, CT for RLQ pain less than 24

Figures 1 & 2 - Axial CT (left) shows a typical thickened and inflamed appendix. A coronal image from a different patient (right) shows similar findings in addition to an appendicolith.

Table 1 - American College of Radiology - ACR Appropriateness Criteria

for this disorder with special applications of magnetic resonance imaging (MRI).

In adolescents and adults, CT has been shown to have a clear edge over US with both higher sensitivity (91% vs. 78%) and specificity (90% vs. 83%)2. Technical issues are much larger with US and more difficult to overcome. This makes CT the first line imaging choice in this patient population (table

Variant 2: Fever, leukocytosis; possible appendicitis, atypical presentation, adults and adolescents.

Radiologic Procedure Rating Comments RRL*

CT abdomen and pelvis with contrast 8 Use of oral or rectal contrast depends on institutional preference.

X-ray abdomen 6 May be useful in excluding free air or obstruction.

US abdomen RLQ 6 With graded compression. O

US pelvis 6 O CT abdomen and pelvis without contrast 6 Use of oral or rectal contrast depends on

institutional preference.

MRI abdomen and pelvis with or 5 See statement regarding contrast in text under “Anticipated Exceptions.” O

X-ray contrast enema 3

Tc-99m WBC scan abdomen and pelvis 3

Rating Scale: 1,2,3 Usually not appropriate; 4,5,6 May be appropriate; 7,8,9 Usually appropriate *Relative Radiation Level

without contrast

Variant 4: Fever, leukocytosis, possible appendicitis, atypical presentation in children (less than 14 years of age).

Rating Comments RRL*

8 With graded compression. O

7

May be useful following negative or equivocal US. Use of oral or rectal contrast depends on institutional preference. Consider limited RLQ CT.

6 May be useful in excluding free air or obstruction.

5 O

5 Use of oral or rectal contrast depends on institutional preference. Consider limited RLQ CT.

5 See statement regarding contrast in text under “Anticipated Exceptions.” O

3

2

Radiologic Procedure

US abdomen RLQ

CT abdomen and pelvis with contrast

X-ray abdomen

US pelvis

CT abdomen and pelvis without contrast

MRI abdomen and pelvis with or without contrast X-ray contrast enema

Tc-99m WBC scan abdomen and pelvis Rating Scale: 1,2,3 Usually not appropriate; 4,5,6 May be appropriate; 7,8,9 Usually appropriate *Relative Radiation Level

Clinical Condition: Right Lower Quadrant Pain — Suspected Appendicitis Variant 3: Fever, leukocytosis, pregnant woman.

Radiologic Procedure Rating Comments RRL*

US abdomen RLQ O

MRI abdomen and pelvis without contrast

May be useful following negative or equivocal US. O

US pelvis O

CT abdomen and pelvis with contrast

CT abdomen and pelvis without contrast X-ray abdomen

X-ray contrast enema

Tc-99m WBC scan abdomen and pelvis

Rating Scale: 1,2,3 Usually not appropriate; 4,5,6 May be appropriate; 7,8,9 Usually appropriate *Relative Radiation Level

With graded compression. Better in first and early second trimester.

Use of oral or rectal contrast dependson institutional preference. Use of oral or rectal contrast dependson institutional preference.

8

7

6

6

5

2

2

2

Variant 1: Fever, leukocytosis, and classic presentation clinically for appendicitis in adults. Clinical Condition: Right Lower Quadrant Pain — Suspected Appendicitis

Radiologic Procedure RRL*

Rating Scale: 1,2,3 Usually not appropriate; 4,5,6 May be appropriate; 7,8,9 Usually appropriate *Relative Radiation Level

CT abdomen and pelvis with contrast Use of oral or rectal contrast depends on institutional preference.

CT abdomen and pelvis without contrast Use of oral or rectal contrast depends on institutional preference.

US abdomen RLQ O

US pelvis O

X-ray abdomen May be useful in excluding free air or obstruction.

MRI abdomen and pelvis with or without contrast

See statement regarding contrast in text under “Anticipated Exceptions.” O

X-ray contrast enema

Tc-99m WBC scan abdomen and pelvis

With graded compression.

Rating

8

7

6

5

5

4

3

3

Comments

a.

b.

Imaging for Right Lower Quadrant PainFor pregnant patients, avoiding ionizing radiation is of even greater importance and therefore US is again the preferred initial modality. Although CT following equivocal US has been shown to be effective (sensitivity of 86% and specificity of 97%), MRI which does not utilize radiation shows similar results (sensitivity of 80% and specificity of 99%) and is the preferred follow-up examination after inconclusive US (Figure 4). MRI imaging can be performed without the need for oral or IV contrast agents. (Table 1 – Variant 3)

Differential DiagnosisAgain, many different etiologies can present with similar physical and historical findings. Some of the more common problems with an associated finding are listed below:

hours should most often be performed with IV contrast, with the addition of oral contrast in cases of greater uncertainty or longer duration of symptoms. In pre-teen and teenage girls, US can be used initially to simultaneously evaluate the appendix and right adnexa.

Figure 3 – Ultrasound demonstrates the typical “target” sign produced by edema within the wall.

Figure 4 – T2 weighted MRI showing a thickened and inflamed appendix in a pregnant patient.

Mesenteric Adenitis: Nonspecific inflammatory lymph node response to systemic infection. Presents with abdominal pain, malaise, lethargy, and sometimes fever. Usually not a primary indication for imaging, but often identified incidentally.

Diverticulitis: Most frequently in the left lower quadrant, but not infrequently presenting on the right. Disease prevalence increases with patient age. CT is the preferred imaging modality.

Inflammatory/Infectious Bowel disease: Crohn’s disease can involve any portion of the GI tract, but has a certain predilection of the terminal ileum (curved arrow) in the right lower quadrant. Several infectious diseases will also preferentially involve this portion of small bowel and the cecum (straight arrow). CT is the preferred imaging modality.

Ovarian Cysts: Frequent cause of pain in younger women, even in premenarchal girls. Signs and symptoms of infection are typically absent. US is the first line imaging modality. CT and MRI can be used for further evaluation.

Ureterolithiasis/Uropathy: Right sided urolithiasis often presents with RLQ pain, often associated with flank pain. CT is the best modality to detect these stones and look for other urinary tract abnormalities. Pyelonephritis can cause similar symptoms and often will not be visible with imaging.

Ectopic Pregnancy: US evaluation should be used to confirm an intrauterine pregnancy in pregnant females presenting with RLQ pain. If absent, ectopic pregnancy must be considered.

Meet Our RadiologistsReferences1. Sun JS, Noh HW, Min YG, et al. Receiver operating characteristic analysis of the diagnostic performance of a computed tomographic examination and the Alvarado score for diagnosing acute appendicitis: emphasis on age and sex of the patients. J Comput Assist Tomogr 2008; 32(3):386-391.2. van Randen A, Bipat S, Zwinderman AH, Ubbink DT, Stoker J, Boermeester MA. Acute appendicitis: meta-analysis of diagnostic performance of CT and graded compression US related to prevalence of disease. Radiology 2008; 249(1):97-106.3. Garcia Pena BM, Mandl KD, Kraus SJ, et al. Ultrasonography and limited computed tomography in the diagnosis and management of appendicitis in children. JAMA 1999; 282(11):1041-1046.4. Garcia K, Hernanz-Schulman M, Bennett DL, Morrow SE, Yu C, Kan JH. Suspected appendicitis in children: diagnostic importance of normal abdominopelvic CT findings with nonvisualized appendix. Radiology 2009; 250(2):531-537.

Matthew A. McNairy, M.D. Dr. Matthew A. McNairy’s professional areas of interest are musculoskeletal radiology and breast imaging. He is fellowship trained in musculoskeletal radiology and co-chairs sports medicine and musculoskeletal conferences at the Utah Valley Regional Medical Center. He is also fellowship trained in breast imaging and specializes in breast cancer diagnosis using mammography, ultrasound and MRI.

After graduating Magna Cum Laude in his undergraduate work at Brigham Young University, Dr. McNairy attended the University of California, San Diego School of Medicine. Following medical school, he did his residency at the University of New Mexico Health Sciences Center and earned board certification in diagnostic radiology. He then completed two fellowships at the University of California, San Diego, one in musculoskeletal radiology and one in breast imaging. His professional associations include the Radiological Society of North America, the American College of Radiology, and the American Medical Society.

J. Daniel Rasband, M.D. An early interest in anatomy combined with Dr. J. Danial Rasband’s desire to be actively involved with physicians of all types in the diagnosis of disease led to an easy fit within this discipline.

After graduating from medical school at the University of Rochester School of Medicine and Dentistry in New York, Dr. Rasband completed a transitional medicine internship at the LDS Hospital. This was followed by a residency in diagnostic radiology at the University of Utah. Dr. Rasband’s primary training is in general diagnostic radiology, with skill in interpreting many different imaging modalities, including MRI, CT, ultrasound, and general radiography. Following residency, Dr. Rasband pursued further training at Duke University Medical Center with a fellowship in nuclear radiology.

Dr. Rasband’s particular area of interest and expertise is in positron emission tomography (PET) combined with CT. Oncology is the primary use for this imaging modality. His professional associations include the Radiological Society of North America, the American College of Radiology, and the Society of Nuclear Medicine.