Appendicitis Mimics, Thompson et al.

Mimickers of Acute

Joel P. Thompson, M.D., MPH, Dhana Selvaraj, M.D., Refky Nicola, D.O.

Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY

Introduction of patients.2,3 The presence of intravenous and enteric contrast aids in identification of the .3 Acute abdominal pain is the most common reason The appendix arises from the inferior to the for an emergency department visit among patients age ileocecal junction (Fig. 1). MDCT signs of acute 15 and older, a large portion of them will complain of 1 appendicitis include appendiceal diameter > 7 mm pain localizing to the right lower quadrant. While with peri-appendiceal stranding of the mesenteric fat appendicitis is the most common cause of the surgical (Fig. 2A).4 Both findings are present in up to 93% of abdomen, a wide variety of acute gastrointestinal, appendicitis cases identified on MDCT.5 The diagnosis genitourinary, and gynecological pathologic processes of appendicitis should not be made using appendiceal can present in similar fashion (Table 1). Acute diameter alone; wall thickening and increased gastrointestinal diseases, such as Crohn’s disease, enhancement should also be present.6 Additional infectious , mesenteric adenitis, cecal findings include the presence of an appendicolith, , Meckel’s diverticulitis, epiploic cecal apical thickening (“arrowhead sign”), mesenteric appendagitis, and omental infarcts can present with adenopathy, fluid in the paracolic gutter, and the right lower quadrant. In addition, acute genitourinary presence of phlegmon.5 A focal wall defect, diseases, such as pyelonephritis and ureterolithiasis, extraluminal air, or presence of an abscess are signs of can present with similar symptoms. In a young perforation.5 While MDCT is currently the preferred woman, acute gynecological disease processes, such as imaging modality, in the pediatric and pregnant ovarian torsion, hemorrhagic , pelvic patient ultrasound as well as MRI has been shown to inflammatory disease, and , should perform comparable to CT.7 also be considered within the differential diagnosis. Ultrasound has a sensitivity and specificity of 78% Imaging modalities utilized in the emergency setting and 83%, respectively.8 The most common findings in to evaluate right lower quadrant pain include appendicitis are diameter > 6 mm, lack of computed tomography (CT), ultrasound (US), and compressibility, hyperemia of the appendiceal wall on magnetic resonance imaging (MRI). These modalities Doppler imaging, peri-appendiceal inflammatory may be value-added for patients with nonspecific changes, and the presence of peritoneal fluid (Fig. symptoms, thus it is useful to triage surgical and non- 2B). Occasionally, a calcified appendicolith may be surgical patients. It is important for the practicing seen with posterior shadowing (Fig. 2C). However, radiologist to be familiar with the various acute ruling out appendiceal pathology is often difficult with disease entities which can cause right lower quadrant US if the appendix cannot be visualized. One study pain in order to determine the best approach or reported positive ultrasound findings for appendicitis modality to make an accurate diagnosis. in about 20% of cases, but equivocal findings in almost 50% of cases (i.e. inability to identify the appendix).7 Imaging of the appendix Evaluation of the right lower quadrant is particularly difficult in pregnant women due to distorted The most common imaging modality for the abdominal and pelvic anatomy (particularly in the third evaluation of the right lower quadrant pain is MDCT. trimester). MRI has been shown to be superior at MDCT has a sensitivity of 97%, specificity of 98%, and localizing the appendix in comparison to ultrasound, accuracy of 98% in diagnosing acute appendicitis, with with a sensitivity and specificity of up to 89% and the additional benefit of suggesting an alternative 99%.8,9 diagnosis for acute abdominal pain in up to two-thirds

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Pathology Imaging Appearance Treatment Gastrointestinal Crohn’s Disease Bowel wall thickening and mural stratification, most commonly involving Initially medical. Indications for surgery the terminal . Chronic inflammation may result in fibrofatty include obstruction due to fibrotic stricture, proliferation along the mesenteric side of the bowel wall. Fistulas and perforation, abscess formation, and fistulas abscesses may form. not able to be managed medically.

Diverticulitis Thick-walled diverticulum with adjacent infiltrative changes; short or long Medical. Surgical intervention may be -segment bowel wall thickening. Abscesses may form. necessary for medically refractory cases, large abscesses, and fistula formation.

Infectious Long-segment circumferential wall thickening, usually without Medical. Enterocolitis mesenteric fat stranding.

Mesenteric Adenitis Cluster of 3 or more right lower quadrant lymph nodes >5 mm in shortest Medical. diameter, without identifiable cause.

Neutropenic Distended and thick-walled cecum, infiltrative changes, pericolic fluid. Medical. High risk of bowel perforation; CT (Typhlitis) may be used to monitor treatment response.

Meckel’s Blind-ending tubular structure in the right lower quadrant arising from Surgical resection. Diverticulitis the distal ileum; infiltrative changes, wall thickening, and hyperenhancement may be seen.

Epiploic Appendagitis Pericolic fatty mass with surrounding inflammatory changes, most Medical. commonly in the transverse and . A central thrombosed vein may be identified. Omental Infarct Pericolic fatty mass with surrounding inflammatory changes, most Medical. commonly in the right hemiabdomen between the colon and the anterior abdominal wall. Genitourinary/Gynecological Urolithiasis Obstructing calculus with hydronephrosis +/- hydroureter. Medical, unless calculus large.

Pyelonephritis Imaging most often normal. May see striated nephrogram or delayed Medical. contrast excretion on CT. US may show loss of corticomedullary differentiation.

Ovarian Torsion US: Enlarged and heterogeneous ovary; may be midline. May see Surgical detorsion. reduced or absent venous flow.

Hemorrhagic Ovarian US: Finely septated “fishnet” pattern of fibrin bands; retractile clot or None. Cyst avascular peripheral nodule non-acutely.

Pelvic Inflammatory Dilated tubular structures representing Fallopian tubes with wall Medical. Disease thickening. Ipsilateral ovary may be enlarged.

Ectopic Pregnancy Non-visualization of an intrauterine pregnancy with positive beta-hCG. Medical but may require surgical US: May see yolk sac, detect fetal heartbeat, or see “ring of fire” sign of intervention. peripheral hypervascularity around adnexal mass.

Mittelschmerz Normal. May see physiologic fluid in the pelvis. None.

Table 1. Overview of gastrointestinal and genitourinary causes of right lower quadrant pain.

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Figure 1. Normal appendix. Coronal MDCT with IV and enteric contrast (A) demonstrates a normal appendix (white arrow) arising from the cecum inferior to the ileocecal junction (yellow arrow). Longitudinal ultrasound image (B) shows a normal appearance of a blind-ending appendix, which measures 4 mm in diameter (caliper 2).

A B

A B C Figure 2. Acute Appendicitis. Axial MDCT image with oral contrast (A) demonstrates an enlarged appendix, measuring up to 14 mm in diameter (white arrow), wall thickening, and adjacent inflammatory changes with phlegmon formation (yellow arrow). Surgical pathology demonstrated appendicitis. Longitudinal ultrasound images in a different patientB ( ) demonstrate an enlarged appendix, measuring up to 10 mm, that is noncompressible, consistent with appendicitis. Ultrasound image at a different level in the same patient demonstrates a hyperechoic focus with posterior shadowing, consistent with an appendicolith (C).

On MRI, the appearance of acute appendicitis Differential Diagnosis includes an appendiceal diameter > 7 mm and adjacent fat stranding that is often best appreciated Crohn's Disease on T2 fat saturated sequences.10 An inflamed Crohn's disease can involve any segment of the appendix demonstrates restricted diffusion.10 The , but the most common location is appendix may be filled with high T2 fluid or edema, within the terminal ileum. Patients often present with which decreases in signal intensity if the fluid is abdominal cramps localized within right lower purulent (higher debris and protein quadrant and bloody stools. The initial presentation content). Appendicoliths are low in T1 and T2 signal typically occurs between 15 and 30 years of age. intensity, with blooming artifact on GRE images. A The imaging features of Crohn's disease consist of periappendiceal abscess is identified as a walled-off bowel wall thickening (greater than 4 mm), mural high T2 fluid collection with restricted diffusion. An stratification ("target" or stratified appearance ofthe appendix filled with high T2 fluid and diameter of 6-7 bowel wall due to submucosal edema), and abnormal mm is indeterminate (if no adjacent fat stranding of 11 10 enhancement (Fig. 3). Active inflammation leads to fluid) and should be closely followed up. engorgement of vasa recta (the "comb sign"). Chronic inflammation results in fibrofatty proliferation along the mesenteric side of the bowel wall, creating the "creeping fat" sign.12 Over time, the chronic

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Figure 3. Crohn’s disease. 11-year-old boy with acute abdominal pain and history of Crohn's disease. Oblique axial MDCT enterography image (A) demonstrates signs of active inflammation in the terminal ileum (white arrow), including mucosal hyperenhancement, wall thickening, and adjacent inflammatory changes. The appendix is normal (yellow A B arrow). MR enterography in the same patient 2 years later B( ) demonstrates wall thickening and fibrosis without adjacent inflammatory changes, consistent with sequela of multiple prior Crohn's flares. inflammatory process of Crohn's disease can result Mesenteric Adenitis intramural or interloop abscesses. Fistulous Mesenteric adenitis, or right lower quadrant anastomosis with the bowel, bladder, skin, and vagina lymphadenopathy, is defined as a cluster of 3 or more can occur. This is best evaluated by MDCT or MRI lymph nodes greater than 5 mm in shortest diameter enterography, which utilize IV contrast during the late in the right lower quadrant mesentery (Fig. 4).15 arterial phase and low density oral contrast to 13 Primary mesenteric adenitis is thought to be due to an facilitate evaluation of the small bowel mucosa. underlying . Secondary mesenteric adenitis has Bowel wall thickening (>3mm) and stratification, an identifiable cause on MDCT, such as appendicitis or mucosal hyperenhancement, inflammatory changes in Crohn's disease. Patients present with abdominal adjacent mesenteric fat, and engorged vasa recta pain, fever, and leukocytosis. This is an uncommon ("comb sign") are all findings on enterography 13 diagnosis, but may be considered in patients whose consistent with active inflammation. The initial only imaging abnormality is focal mesenteric management of Crohn’s disease is non-surgical. lymphadenopathy. However, surgery may be necessary if fistulas or stricture formation develop.

Infectious Enterocolitis Infectious enterocolitis can present clinically similar to appendicitis, particularly if caused by pathogens such as Yersinia, Campylobacter, or Salmonella, which may cause ileocecitis.12,14 The imaging findings on MDCT involve a long-segment circumferential wall thickening with homogenous enhancement, usually without stranding of the adjacent fat. In addition, mesenteric adenopathy and surrounding free fluid may be present.

Figure 4. Mesenteric adenitis. Coronal MDCT with oral contrast shows a cluster of right lower quadrant mesenteric lymph nodes greater than 5 mm in shortest diameter without identifiable cause (circled), consistent with mesenteric adenitis. The appendix was normal (white arrow).

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Neutropenic Colitis (Typhlitis) and , diverticula may also form along the Neutropenic colitis has a similar presentation of and present with right-sided acute appendicitis, but occurs particularly in abdominal pain. Diverticulitis is thought to be caused immunosuppressed patients with leukemia, post- by microperforation of a diverticulum. transplantation status, or acquired immunodeficiency. Mucosal damage secondary to both infection and ischemia is typically confined to the cecum and ascending colon.16 A prompt diagnosis is necessary due to the high risk of perforation. MDCT findings includes a distended cecum with circumferential wall thickening, peri-colonic infiltration, and peri-colic fluid (Fig. 5).6,16,17 Pneumatosis can also be present.6 Treatment includes bowel rest and antibiotics. MDCT is used to follow the progression of therapy, as evidenced by the improvement in the thickening of cecal wall.6 The extent of cecal wall thickening into the ascending colon as well as the patient’s history helps to differentiate neutropenic colitis from cecal Figure 6. Diverticulitis. wall thickening associated with appendicitis. 83-year-old woman with acute leukocytosis and right lower quadrant abdominal pain. Axial MDCT image with oral contrast shows diverticular wall thickening with infiltration of the adjacent fat (white arrow) in the ascending colon just above the cecum, consistent with acute diverticulitis.

On MDCT, diverticulitis is associated with wall thickening of the colon with infiltration of the adjacent mesenteric fat (Fig. 6).6 The vasa recta is engorged due to inflammation. Complications of acute diverticulitis include colonic perforation and abscess formation. Long-standing diverticulitis can result in colovesical or colovaginal fistula formation. Treatment of acute diverticulitis includes bowel rest and antibiotics; complicated diverticulitis requires drain placement or partial colectomy. It can be difficult to Figure 5. Neutropenic colitis/Typhlitis. exclude an underlying neoplasm in the setting of acute 57-year-old man with acute myeloid leukemia, neutropenia, diverticulitis. However, signs concerning for right lower quadrant pain, and persistent fever. Axial MDCT malignancy include a short-segment of involved colon image with oral contrast demonstrates cecal wall thickening (< 10 cm), colonic mass with overhanging shoulders, (white arrow) with surrounding inflammatory changes, 6,18 consistent with typhlitis. The appendix was normal (yellow and peri-colic lymphadenopathy. Colonoscopy is arrow). recommended as a follow-up examination once the patient's symptoms subside to exclude an underlying Diverticulitis neoplasm.6 CT colonoscopy can be performed; Diverticulitis is a common cause of abdominal pain, however, the discussion of CT colonoscopy is beyond particularly in patients over 40 years of age. the scope of this review article. Diverticula form in the weakest portion of the colonic wall where vasa recta, the nutrient arteries, penetrate and extend into the submucosal layer. While diverticulitis most commonly involves the descending

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Figure 7. Meckel’s diverticulitis. 16-year-old girl with right lower quadrant abdominal pain and small amount of free fluid on pelvic ultrasound. Axial MDCT image with IV contrast (A) demonstrates a blind-ending tubular structure arising from the distal ileum with adjacent inflammatory changes (white arrow). Superiorly (B), the appendix (white arrow) was mildly dilated to 8 mm with wall thickening, but with minimal adjacent inflammatory changes. Surgical pathology demonstrated an inflamed Meckel’s diverticulum and a normal appendix (apparent wall thickening A B may have been due to reactive changes from the Meckel’s diverticulitis).

Meckel’s Diverticulitis epiploic appendages increase from the cecum to the Meckel's diverticulum is a congenital anomaly due sigmoid colon, epiploic appendagitis usually results in to the persistence of the omphalomesenteric left-sided abdominal pain. However, epiploic (vitelline) duct, which connects the yolk sac to the appendagitis can occur in the ascending colon and midgut lumen in the developing fetus. Meckel's even the cecum. On ultrasound, epiploic appendagitis is seen as a hyperechoic mass with a hypoechoic rim diverticula are located 60-100 cm from the ileocecal 22 valve, typically in the right lower quadrant or lower deep to the abdominal wall. The MDCT findings central abdomen.19 Inflammation occurs due to include a peri-colic fatty mass with surrounding mucosal ulceration from ectopic or due infiltrative changes; a high-attenuation central dot may 12 be seen, which represents a thrombosed vein (Fig. to luminal obstruction by an enterolith. Meckel's 14 diverticulum may also act as a lead point for 8). Treatment is usually supportive with anti- intussusception. Meckel's diverticulum are identified inflammatory agents. on MDCT as a blind-ending tubular structure arising from the anti-mesenteric side of the distal ileum.20 Wall thickening, hyperenhancement, and adjacent mesenteric fat stranding suggest active inflammation (Fig. 7). A Meckel's diverticulum can also be identified using radionuclide scanning with 99mTc-pertechnetate; however, sensitivity and specificity are lower in adults patients when compared to children due to the decreased prevalence of ectopic gastric mucosa.21 Management is surgical resection.

Epiploic Appendagitis Epiploic appendages are small fat protrusions arising from the serosal surface of the colon; these are not usually identifiable on cross sectional imaging. Figure 8. Epiploic appendagitis. Torsion of an epiploic appendix causes vascular 63-year-old man with a history of diverticulitis presents with occlusion, ischemia, and acute onset abdominal pain. right-sided abdominal pain that is worse with movement and deep breathing; no leukocytosis. Axial MDCT image An inflammatory process within the abdomen can also demonstrates a focus of inflammatory changes just superior extend to the epiploic appendages, causing secondary to the with a high attenuation central dot epiploic appendagitis. Since the number and size of (white arrow), consistent with epiploic appendagitis.

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Omental Infarction Acute Genitourinary Diseases In contrast to epiploic appendagitis, omental Urolithiasis infarction is most commonly a right-sided entity, perhaps due to longer length and mobility of the Urolithiasis may present with right lower quadrant omentum in the right hemiabdomen compared to the pain, particularly if an obstructing calculus is present in left.17,23 Omental infarction is caused by torsion or the right ureterovesicular junction. Ultrasound vascular secondary to postoperative evaluation of the abdomen may demonstrate omental adhesions, trauma, or increased intra- hydroureter, which can be differentiated from bowel abdominal pressure (coughing, obesity, strenuous due to the lack of bowel signature (alternating exercise).23 The most common presenting symptom is hyperechoic and hypoechoic tissue layers) (Fig. 10). If acute-onset abdominal pain. MDCT imaging findings the bladder is distended, the obstructing calculus may vary from an ill-defined, heterogeneous fat- be visualized as an echogenic focus in the region of the attenuation lesion to a - well defined heterogeneous ureterovesicular junction. Identification is improved by fatty mass, classically located between the anterior creation of the twinkle artifact on Doppler images, abdominal wall and ascending or transverse colon (Fig. which is rapidly changing red and blue colors behind 9).12,23 Omental infarction may be differentiated from the calcification due to "phase jitter" within the 24 epiploic appendagitis by location (between the colon machine. and anterior abdominal wall), larger size (often greater CT images demonstrate a high attenuation calculus than 5 cm in diameter), absence of a peripheral rim, within the ureter, with or without proximal ureteral and absence of a central dot sign.17,23 Management is dilatation. Ureteral wall thickening and adjacent fat typically supportive; complications are rare. stranding may be present. Pelvic phleboliths may simulate distal ureteral calculi. If the ureter cannot be followed in its entirety and the calcification is indeterminate, the presence of a soft tissue rim ("rim sign" due to inflamed ureteral walls) and the absence of a soft tissue tail ("tail sign" due to thrombosed vein leading into the calcification) may help characterize urolithiasis.25,26 Treatment for ureteral calculi less than 4 mm in diameter is supportive.

Pyelonephritis Pyelonephritis is most commonly associated with an ascending genitourinary tract infection and is a clinical diagnosis; often times, the sonographic and MDCT findings are normal.27 However, imaging is useful in excluding complications, such as abscess formation, emphysematous pyelonephritis (typically in diabetics and immunocompromised patients), or Figure 9. Omental infarct. xanthogranulomatous pyelonephritis. Findings of 72-year-old man presents with 3 days of right lower pyelonephritis on CT include nephromegaly due to quadrant pain. Axial MDCT demonstrates infiltrative changes with central fat density between the cecum and the edema, a striated or delayed nephrogram, perinephric anterior abdominal wall (white arrow), consistent with the fat stranding, and wall-thickening and enhancement of appearance of omental infarct. The appendix was normal. the renal collecting system (Fig. 11).28 Delayed appearance of the calices may also be seen; however, since pyelonephritis is often bilateral, comparison between the two kidneys may not be helpful.

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Figure 10. Nephrolithiasis. 43-year-old man with right groin pain and history of renal calculi. Axial unenhanced MDCT image (A) demonstrates a 4 mm calculus at the right ureterovesicle junction (white arrow). Axial CT image above the level of the bladder (B) demonstrates a normal appendix (yellow arrow).

A B

Figure 12. Ovarian torsion. 22-year-old woman with right lower quadrant pain. Figure 11. Pyelonephritis. Transabdominal ultrasound image with power Doppler 35-year-old woman with right flank and abdominal pain. shows an enlarged right ovary with a large simple cyst (long Axial MDCT with IV contrast demonstrates a striated white arrow), echogenic stroma (long black arrow), a few appearance of the right kidney, an appearance consistent peripherally displaced follicles (short white arrows), and with pyelonephritis or glomerulonephritis. Patient history decreased flow within the ovary. Diagnosis of ovarian was indicative of pyelonephritis and she was treated with torsion was made based on the above findings and antibiotics. confirmed at surgery; the patient underwent right salpingo- oophorectomy. Ultrasound may show nephromegaly and loss of renal sinus fat due to inflammation, as well as loss of the pathologies include ovarian torsion, hemorrhagic corticomedullary junction. The kidneys may be ovarian cyst, pelvic inflammatory disease, ectopic abnormally hyperechoic or hypoechoic. In the pregnancy, and Mittelschmerz. Ultrasound, preferably absence of complications, treatment includes transvaginal, is the preferred initial imaging evaluation antibiotics and supportive measures. in these cases.

Gynecologic Diseases Ovarian Torsion Gynecologic emergencies, especially those affecting Ovarian torsion results from twisting of the ovary on the right adnexa, are important in the differential its supporting ligaments. Patients are usually in the diagnosis of acute appendicitis in young women. reproductive age group and present with acute onset Screening the right ovary is routinely performed along lower abdominal pain on the side of the ovary with ultrasound evaluation of the appendix in involved. Torsion usually occurs in the presence of pediatric patients. Commonly encountered underlying pathology, such as enlarged ovaries from

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A B C Figure 13. Hemorrhagic cyst. 28-year-old woman with acute right lower quadrant and pelvic pain. Transvaginal ultrasound with Doppler of the right ovary (A) shows a complex cyst (arrow) with fine reticular pattern and echogenic areas; no internal vascularity is seen. Transvaginal ultrasound image of the same patient superior to the uterusB ( ) demonstrates hemoperitoneum with debris (arrow) from rupture of the hemorrhagic cyst. Pregnancy test was negative, excluding the possibility of ectopic pregnancy. Follow up transvaginal ultrasound at a 2 weekter in val (C) shows decrease in the size of the cyst with changes in the internal architecture from retraction of the clot (arrow). cysts, tumors, enlarged corpus luteum, or ovulation vascularity. Echogenic fluid can be seen in the cul-de- induction for infertility. Ultrasound is performed as the sac in cases of ruptured cyst (Fig. 13B). In first line of imaging, demonstrating increased size (>4 indeterminate cases, MRI may be performed to show cm in greatest diameter) and volume of the involved the blood products, or a follow-up sonogram can show ovary, heterogeneous appearance from edema and change in the echo pattern or resolution of the cyst hemorrhage, and typically an associated cyst or mass (Fig. 13C). Correlation with menstrual history is (Fig. 12). Multiple small follicles can be seen in the helpful as these typically occur in the luteal phase. periphery of the enlarged ovary due to displacement Treatment is typically supportive. from stromal edema, described as “string of pearls” sign.29 On Doppler, venous flow is often reduced or absent, but this is less sensitive than gray-scale Pelvic Inflammatory Disease findings. The arterial blood flow may be dampened or Acute pelvic inflammatory disease can present with absent as well, but this finding is variable due to dual fever and lower abdominal pain, similar to that of blood supply (ovarian artery and uterine branch acute appendicitis. Neisseria gonorrhoeae and artery). Comparison with the normal unaffected ovary Chlamydia trachomatis are the most commonly is often helpful. Treatment is surgical detorsion and implicated organisms. Patients may have additional removal of necrotic tissue. symptoms relating to the urogenital tract, including dysuria, dyspareunia, and vaginal discharge. On

transvaginal ultrasound, enlarged and heterogeneous Hemorrhagic Ovarian Cyst appearing ovaries, thickened adnexal structures, Hemorrhage into an ovarian cyst can cause abrupt dilated fallopian tubes containing simple fluid or lower abdominal or pelvic pain. Hemorrhagic cysts echogenic contents, and pelvic fluid collections can be have a thin wall with posterior through transmission. seen (Fig. 14). CT findings include enlarged ovaries The internal architecture depends on the stage of with abnormal enhancement, dilated and fluid filled evolution of the hemorrhage, from anechoic fluid in fallopian tubes with enhancing wall from pyosalpinx, the acute stage to echogenic clot in later stages, giving stranding of the pelvic fat, enhancement of the rise to varied sonographic appearances.30 The most adjacent , and pelvic abscesses in common appearance is a finely septated fishnet advanced cases (Fig 14C).31 Similar findings can be pattern resulting from fibrin bands (Fig. 13A). seen involving the endometrium and cervix in Additional findings include a fluid-debris level, a endometritis and cervicitis. Treatment is supportive, nodule from retracting clot, or a completely echogenic including antibiotic therapy. lesion. These typically do not show internal

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A B

Figure 14. Tubo-ovarian abscess. 26-year-old woman with acute right lower quadrant pain. Transvaginal ultrasound image with Doppler (A) shows an enlarged, complex appearing, and hyperemic right ovary (arrows) from tubo-ovarian abscess. Transvaginal ultrasound with Doppler (B) reveals thickened and hyperemic left adnexal structures (arrow) with adjacent fluid collection. Axial post-contrast CT image of the pelvis (C) shows a heterogeneously enhancing right ovary (long arrow) and thickened adherent left adnexal structures with pyosalpinx (short arrow). The patient improved on antibiotics.

C

Ectopic Pregnancy from hemoperitoneum can be seen in the pelvis and Ectopic pregnancy needs to be excluded in all abdomen in cases of rupture. If diagnosed early, women of reproductive age who present with treatment is medical including methotrexate to abdominal pain. As with other gynecologic terminate the non-viable preganancy. Surgical emergencies, transvaginal ultrasound along with treatment may be pursued in the presence of serum beta-hCG level plays crucial role in diagnosis. hemodynamic instability, ongoing rupture, or Non-visualization of an intrauterine gestational sac on contraindication to methotrexate. transvaginal ultrasound with a beta-hCG level greater than 2000 mIU/ml should raise the suspicion for Mittelschmerz ectopic pregnancy. Ninety-five percent of ectopic pregnancies are tubal, and visualization of a complex This is pain associated with rupture of the dominant mass separate from the ovary helps in differentiating it follicle during ovulation, occurring in the mid from a complex ovarian cyst (Fig. 15). Presence of yolk menstrual cycle, usually felt in the lower abdomen. sac or a live embryo with cardiac activity makes the The laterality of pain varies corresponding to the side diagnosis.32 Other findings include the “tubal ring” of ovulation. Sometimes, the pain can be severe, sign, referring to a hyperechoic ring around the associated with , and mimic appendicitis if adnexal gestational sac. On Doppler, peripheral occurring on the right side. Correlation with menstrual vascularity with high velocity and low impedance can cycle, spotting, and history of prior such episodes can be seen around the adnexal mass, separate from the help. ovary, called the “ring of fire” sign.33 Echogenic fluid

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4. Duda JB, Lynch ML, Bhatt S, Dogra VS. Computed tomography mimics of acute appendicitis: predictors of appendiceal disease confirmed at pathology. Journal of clinical imaging science 2012;2:73. 5. Rao PM, Rhea JT, Novelline RA. Sensitivity and specificity of the individual CT signs of appendicitis: experience with 200 helical appendiceal CT examinations. Journal of computer assisted tomography 1997;21:686-92. 6. Thoeni RF, Cello JP. CT imaging of colitis. Radiology 2006;240:623-38. 7. Aspelund G, Fingeret A, Gross E, et al. Ultrasonography/MRI Versus CT for Diagnosing Appendicitis. Pediatrics 2014;133:586-93. 8. Rosen MP, Ding A, Blake MA, et al. ACR Appropriateness Criteria(R) right lower quadrant pain--suspected appendicitis. Journal of the American College of Radiology : JACR Figure 15. Ectopic pregnancy. 2011;8:749-55. 30-year-old woman with severe lower abdominal pain. 9. Rapp EJ, Naim F, Kadivar K, Davarpanah A, Cornfeld D. Patient’s last menstrual period was 7 weeks prior; urine Integrating MR imaging into the clinical workup of pregnant pregnancy test was positive with a serum beta hCG of patients suspected of having appendicitis is associated with a 62,157. Transabdominal ultrasound image shows a lower negative rate: single-institution study. complex lesion with thick hyperechoic rim (long arrow) in Radiology 2013;267:137-44. the right adnexal location, seen separate from the right 10. Dewhurst C, Beddy P, Pedrosa I. MRI evaluation of acute ovary (short arrow). The patient underwent salpingectomy appendicitis in pregnancy. Journal of magnetic resonance and the diagnosis of ectopic pregnancy was confirmed. imaging : JMRI 2013;37:566-75. 11. Furukawa A, Saotome T, Yamasaki M, et al. Cross-sectional imaging in Crohn disease. Radiographics : a review publication Conclusion of the Radiological Society of North America, Inc 2004;24:689- 702. A variety of acute gastrointestinal genitourinary, 12. Purysko AS, Remer EM, Filho HM, Bittencourt LK, Lima RV, and gynecological pathologic processes are associated Racy DJ. Beyond appendicitis: common and uncommon with clinical symptoms similar to that of appendicitis. gastrointestinal causes of right lower quadrant abdominal Imaging with ultrasound, CT, and MRI is useful for pain at multidetector CT. Radiographics : a review publication of the Radiological Society of North America, Inc 2011;31:927- identifying appendicitis and associated complications, 47. as well as identifying alternative diagnoses for the 13. Towbin AJ, Sullivan J, Denson LA, Wallihan DB, Podberesky DJ. patient’s symptoms. Familiarization with various CT and MR enterography in children and adolescents with processes causing right lower quadrant pain, such as inflammatory bowel disease. Radiographics : a review publication of the Radiological Society of North America, Inc those covered in this paper, will aid in providing timely 2013;33:1843-60. and appropriate care to the patient. 14. van Breda Vriesman AC, Puylaert JB. Mimics of appendicitis: alternative nonsurgical diagnoses with sonography and CT. AJR American journal of roentgenology 2006;186:1103-12. 15. Macari M, Hines J, Balthazar E, Megibow A. Mesenteric adenitis: CT diagnosis of primary versus secondary causes, incidence, and clinical significance in pediatric and adult References patients. AJR American journal of roentgenology 2002;178:853-8. 1. National Hospital Ambulatory Medical Care Survey: 2010 16. Horton KM, Corl FM, Fishman EK. CT evaluation of the colon: Emergency Department Summary Tables. 2010. (Accessed inflammatory disease. Radiographics : a review publication of Accessed May 9, 2014., at http://www.cdc.gov/nchs/data/ the Radiological Society of North America, Inc 2000;20:399- ahcd/nhamcs_emergency/2010_ed_web_tables.pdf.) 418. 2. Raman SS, Lu DS, Kadell BM, Vodopich DJ, Sayre J, Cryer H. 17. Lubner MG, Simard ML, Peterson CM, Bhalla S, Pickhardt PJ, Accuracy of nonfocused helical CT for the diagnosis of acute Menias CO. Emergent and nonemergent nonbowel torsion: appendicitis: a 5-year review. AJR American journal of spectrum of imaging and clinical findings. Radiographics : a roentgenology 2002;178:1319-25. review publication of the Radiological Society of North 3. Rao PM, Rhea JT, Novelline RA, et al. Helical CT technique for America, Inc 2013;33:155-73. the diagnosis of appendicitis: prospective evaluation of a focused appendix CT examination. Radiology 1997;202:139- 44.

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