The acute right lower quadrant: CT evaluation

Acute right lower quadrant pain is a nonspecific but common clinical complaint. Appendicitis is the most common cause of acute right lower quadrant pain and CT has become the most reliable imaging method in the evaluation of these patients. Although there is controversy regarding the best way to perform CT in this setting, oral and i.v. contrast-enhanced CT remains the most commonly used technique. CT with oral and i.v. contrast material facilitates diagnosis of appendicitis and the numerous other entities that may cause right lower quadrant pain.     

Case report: transient small bowel intussusception presenting as right lower quadrant pain in a 6-year-old male

In children presenting to the emergency room with right lower quadrant pain, ultrasound is the preferred initial modality. In our patient, a 6-year-old male with a sudden onset of severe right lower quadrant pain, the differential is broad, including appendicitis and intussusception. In order to narrow our differential and secure the diagnosis, our first modality was ultrasonography. With the increased use of point-of-care ultrasound in the emergency department, the diagnosis of appendicitis and ileo-colic intussusception has been made more frequently. In addition, other entities such as transient small bowel intussusception may be identified. As in our case, obstruction secondary to intussusception must be ruled out with observation, serial abdominal exams, clinical improvement, or further imaging.     

Right lower quadrant pain: Imaging with computed tomography

Computed tomography (CT) is a fast and accurate way to evaluate patients with acute right lower abdominopelvic pain. In the emergency setting, appendicitis is the most common etiology. A tailored CT examination can visualize the normal or abnormal appendix with accuracy, confirming or excluding appendicitis in 90–95% of cases. If the appendix is normal, CT often identifies an alternative etiology for the pain. This exhibit reviews the CT appearance of the normal appendix, usual and unusual presentations of appendicitis and complicated appendicitis, and pitfalls in diagnosis. The CT appearance of other conditions included in the differential diagnosis of acute right lower quadrant pain and clinically mimicking appendicitis is also presented, including disorders arising from the gastrointestinal tract, genitourinary tract, and vascular and musculoskeletal systems.     

MDCT of acute cecal conditions

The cecum comprises a relatively short segment of the gastrointestinal tract, but it can be affected by numerous acute conditions. Acute conditions may arise from processes primary to the cecum, such as volvulus, bascule, neoplasm, and trauma. Alternatively, acute conditions can be due to secondary to systemic or nearby pathology, such as infection, inflammatory processes, ischemia, and infarction. While it is common to suspect appendicitis as the etiology of acute right lower quadrant abdominal pain, the cecum should also be considered as a potential cause of pain, especially in the setting of an abnormal or absent appendix. Multi-detector computed tomography (MDCT) has evolved to become the best imaging modality to evaluate patients presenting with right lower quadrant abdominal pain or suspected acute cecal pathology. Strengths of MDCT include rapid acquisition of images, high spatial resolution, and ability to create multi-planar reconstructed images. In this pictorial review, we illustrate and describe key MDCT findings for various acute cecal conditions with which the emergency radiologist should be familiar.     

Chronic appendicitis “syndrome” manifested by an appendicolith and thickened appendix presenting as chronic right lower abdominal pain in adults

In this short report, we describe a small series of adult patients with chronic appendicitis presenting with chronic right lower quadrant abdominal pain. The clinical presentation was unusual and atypical for classic appendicitis because of the absence of fever, peritoneal tenderness on focused graded compression of the abdomen, and leukocytosis. Computed tomography (CT) findings included the presence of an appendicolith and appendiceal thickening, without mesenteric infiltration, abscess, or collection. In this series, the appendicolith appeared to represent a marker rather than an actual cause of appendicitis. Focused CT scans with additional lung and bone windows proved optimal in detecting appendicoliths, which were not visible on the scout localizer scans, despite windowing modifications. Our findings suggest that chronic appendicitis may be a phenomenon unique to adults and should be included in the differential diagnosis of chronic right lower quadrant pain in patients seen in the emergency room setting. Surgery is curative in such patients, although expectant management is an alternative when tolerated by the patient.     

Accuracy of nonfocused helical CT for the diagnosis of acute appendicitis: a 5-year review

OBJECTIVE: The clinical usefulness of routine, nonfocused helical CT was evaluated in diagnosing acute appendicitis or providing an alternative diagnosis in patients presenting to the emergency department with acute lower abdominal pain. MATERIALS AND METHODS: We reviewed CT reports and clinical records of 650 consecutive adult patients who presented between January 1996 and December 2000 with right lower quadrant pain or lower abdominal pain and clinical findings suggestive of appendicitis. Helical CT was performed with oral contrast material in 610 cases (93.8%) and IV contrast in 572 cases (88.0%). Both vascular and enteric contrast media were administered in 544 cases (83.7%). Rectal contrast material was administered in 52 cases (8.0%). The abdomen was helically scanned from the dome of the diaphragm to the iliac crests with a collimation of 7 mm, from the iliac crests to the acetabular roof at a 5-mm collimation, from the acetabular roof to the symphysis pubis with a collimation of 5-10 mm. The surgical or clinical record was used for follow-up. RESULTS: Of the 650 patients, 552 (84.9%) had adequate clinical follow-up. There were 137 true-positive, eight false-positive, five false-negative, and 402 true-negative cases. The sensitivity, specificity, and accuracy of nonfocused helical CT were 96.5%, 98.0%, 97.6%, respectively. The positive and negative predictive values were 94.5% and 98.8%, respectively. In patients without acute appendicitis, CT suggested an alternative diagnosis, which clinically explained the patient's acute abdominal pain in 266 patients (66.2%). CONCLUSION: Nonfocused helical CT was highly accurate in diagnosing acute appendicitis or suggesting an alternative diagnosis in patients with acute lower abdominal pain or right lower quadrant pain.     

Clinical and imaging mimickers of acute appendicitis in the pediatric population

OBJECTIVE: The purpose of this article is to present the imaging appearance of common mimickers of appendicitis in children with right lower quadrant pain. CONCLUSION: The majority of children who undergo imaging for suspected appendicitis will end up having an alternative diagnosis. These mimickers can be gastrointestinal, genitourinary, or pulmonary. Familiarity with these alternative diagnoses can aid in the challenging task of imaging right lower quadrant pain in the pediatric population.     

Isolated infarction of the cecum: CT findings in two patients

Colonic ischemia isolated to the cecum is a rare entity. The authors evaluated two patients who underwent computed tomography (CT) because appendicitis was suspected at clinical examination. CT findings were suggestive of isolated cecal ischemia or infarction. Surgical-histopathologic findings helped confirm the presumptive CT diagnoses. Isolated cecal infarction should be included in the differential diagnosis of acute right lower quadrant pain.     

Alternative diagnoses of acute appendicitis on helical CT with intravenous and rectal contrast

At our institution, helical CT of the abdomen and pelvis with intravenous and rectal contrast (CTRC) has become the modality of choice for investigation of patients with right lower quadrant pain and clinical suspicion of acute appendicitis. CTRC has proven useful for the diagnosis of acute appendicitis (AA) and at the same time identifies alternative diagnoses mimicking AA. This pictorial assay illustrates the imaging findings of AA and its mimickers including primary epiploic appendagitis, right-sided diverticulitis, torsion of Meckel's diverticulum, gynecologic disorders, obstructive uropathy, right lower lobe pneumonia, and other conditions.     

The nonvisualized appendix: incidence of acute appendicitis when secondary inflammatory changes are absent

OBJECTIVE: The objective of our study was to assess the importance of nonvisualization of the appendix and its association with acute appendicitis on helical CT when secondary inflammatory changes are absent. MATERIALS AND METHODS: After we received institutional review board approval, CT scans of 366 consecutive patients obtained for lower abdominal or right lower quadrant pain and to rule out appendicitis were retrospectively reviewed. Images were reviewed by an experienced abdominal radiologist and compared with the formal interpretation. The amount of right lower quadrant and pericecal fat was quantified on a scale of 0 (none) to 2 (abundant). Patients with a nonvisualized appendix and other findings compatible with acute appendicitis-such as abscess formation, localized perforation, periappendiceal fat stranding, or appendicolith-were excluded. RESULTS: The appendix could not be visualized by both reviewers in 46 (13%) of 366 cases. CT findings indicated another cause for the patient's symptoms in 12 cases (26%), including gastrointestinal and genitourinary processes. An alternate diagnosis was subsequently reached in 11 additional patients (24%) with follow-up imaging or clinical evaluation. Only one patient (2%) with a nonvisualized appendix had acute appendicitis, proven by surgical pathology. In this patient, there was paucity of fat in the right lower quadrant. CONCLUSION: In the absence of a distinctly visualized appendix and secondary inflammatory changes, the incidence of acute appendicitis is low. Nonvisualization of the appendix even when a small amount of fat is present in the right lower quadrant may safely exclude acute appendicitis if no secondary CT findings are present.     

Helical CT evaluation of acute right lower quadrant pain: part I, common mimics of appendicitis

OBJECTIVE: The purpose of our pictorial essay is to present common mimics of appendicitis as noted on helical CT in patients with right lower quadrant pain and to highlight the features that provide clues to the diagnosis. CONCLUSION: Recognition of the findings of common diseases that simulate acute appendicitis on helical CT, along with features that help to differentiate these entities from appendicitis, is important in establishing a correct diagnosis and in guiding appropriate therapy.     

Segmental omental infarction

Acute right-sided abdominal pain is a common presenting symptom in the emergency department. Acute cholecystitis and acute appendicitis are the most likely etiologies for right upper and lower quadrant pain, respectively. However, other differential possibilities include right-sided diverticulitis and perforated colon carcinoma. This case report of an 18-year-old man with segmental omental infarction highlights a much less frequent, self-limited cause of right-sided abdominal pain, which is increasingly identified on computed tomography scans.     

The echographic diagnosis of acute appendicitis and its complications

The authors report their experience with emergency US in patients hospitalized for clinical suspicion of acute appendicitis or presenting with pain in the right lower abdominal quadrant. One hundred fifty-two patients were examined with US: 93/152 had pathologies of the right iliac region; 81 of them underwent surgery (50/81 appendectomies). In 27 of these patients the inflamed appendix presented with a typical US pattern. All of them had surgical confirmation. In 13/50 cases, US findings followed an atypical pattern (6 patients had a periappendiceal mass in the right iliac region, 3 had small amounts of fluid in the Douglas pouch, and 4 had gas-filled bowel loops of the ileum). The false negatives were 10/50. US sensitivity was 80%, and its specificity was 54%. The most common pathologic conditions are described whose symptoms mimic those of acute appendicitis. US role in inflamed acute appendicitis is still to be defined. Nonetheless, the authors suggest that US be performed on all patients with atypical pain in the lower abdominal quadrants, because of its high diagnostic accuracy in many common pathologies mimicking appendicitis, especially urinary and uterine adnexal pathologies.     

"Cecal gangrene": a rare cause of right-sided inferior abdominal quadrant pain, fever, and leukocytosis

We report on a 58-year-old man with known diabetes, congestive heart failure, and need for chronic hemodialysis presenting with right lower abdominal quadrant pain, fever, and leukocytosis. Although initial clinical findings were highly suggestive of acute appendicitis, CT revealed marked circumferential wall thickening of the cecum, which was interpreted as cecal infarction by the radiologist. Intraoperatively, cecal necrosis was confirmed, but the ileocecal valve and, especially, the appendix showed no ischemia. No vascular occlusions were found. Histopathologic analysis of the resected cecum demonstrated isolated transmural cecal necrosis with marked infiltration of the cecal wall by numerous bacteria and neutrophils. We present the CT features and histopathologic findings of isolated cecal gangrene, review the pathogenesis of occlusive and nonocclusive cecal ischemia or infarction, and discuss the role of bacterial superinfection as a potential cofactor in the pathogenesis of isolated cecal necrosis which should be included in the differential diagnosis of right-sided inferior abdominal quadrant pain. Electronic Publication     

Fitz-Hugh–Curtis syndrome: CT findings of three cases

Clinical manifestations and computed tomography (CT) findings of Fitz-Hugh–Curtis syndrome (FHCS) are relatively well stabilized as right upper quadrant abdominal pain and hepatic capsular enhancement because of perihepatitis associated with pelvic inflammatory disease caused by N. gonorrhoeae and C. trachomatis. We encountered three patients with serial FHCS associated with pelvic inflammatory disease, who visited the emergency room with right upper quadrant abdominal pain. Abdominal CT revealed hepatic capsular or pericapsular enhancement along the anterior surface of the liver on the arterial phase. Recently, multi-detector CT has evolved as the first-line imaging modality of acute abdomen at the emergency room; we reemphasized the importance of the CT findings of this syndrome for differential diagnosis of right upper quadrant abdominal pain in sexually active young women. Physicians at the emergency room acknowledge the syndrome and should perform dynamic abdominopelvic CT including the arterial phase.     

Right-lower-quadrant pain and suspected appendicitis in pregnant women: evaluation with MR imaging--initial experience

PURPOSE: To determine if there is a role for magnetic resonance (MR) imaging in evaluation of pregnant women with acute right-lower-quadrant pain in whom acute appendicitis is suspected. MATERIALS AND METHODS: Informed consent and institutional review board approval were obtained. Images obtained with a 1.5-T MR imager and medical records of 23 pregnant women (age range, 19-34 years; mean age, 24.7 years) who presented with acute right-lower-quadrant pain were retrospectively reviewed. MR protocol included use of transverse, coronal, and sagittal noncontiguous T2-weighted single-shot fast spin-echo (SE) sequences; transverse fat-suppressed T2-weighted fast SE sequences; transverse T1-weighted gradient-recalled-echo sequences; and transverse and coronal short inversion time inversion-recovery sequences performed through the lower abdomen and pelvis. MR findings were evaluated by two radiologists and compared with surgical and pathologic findings and clinical follow-up data. RESULTS: Appendix was detected in 20 (86.9%) of 23 patients. Seven patients underwent surgery; four had acute appendicitis, and three had ovarian torsion. Two patients with pelvic abscesses not related to appendicitis underwent percutaneous drainage. Fourteen patients were treated medically. Dilated thick-walled appendix and periappendiceal inflammation were detected in three (75%) of four patients with acute appendicitis. In one patient with appendicitis, the appendix could not be visualized, but inflammation was present in the right lower quadrant. In three patients with ovarian torsion, MR imaging demonstrated right adnexal mass or inflammation. MR imaging was used to correctly identify pelvic abscesses and healthy appendix in two patients. A healthy appendix was depicted in 17 (89.5%) of 19 patients without acute appendicitis. CONCLUSION: MR imaging shows promise for evaluation of pregnant women in whom acute appendicitis is suspected by enabling diagnosis of other possible causes of right-lower-quadrant pain, including ovarian torsion or pelvic abscesses, and demonstrating a healthy or unhealthy appendix.     

Diseases of the cecum: a CT pictorial review

Cecal pathology is commonly encountered and may represent a diagnostic challenge in patients with either acute or chronic clinical presentations. Although appendicitis accounts for the majority of surgical conditions presenting with right lower quadrant pain, readers should be aware of the broad spectrum of cecal pathologies and characteristic CT findings, which can be useful in establishing the correct diagnosis.     

ACR Appropriateness Criteria Right Lower Quadrant Pain—Suspected Appendicitis

The diagnostic imaging of patients presenting with right lower quadrant pain and suspected appendicitis may be organized according to age and gender and to the presence or absence of "classic" signs and symptoms of acute appendicitis. Among adult patients presenting with clinical signs of acute appendicitis, the sensitivity and specificity of CT are greater than those of ultrasound, with improved performance when CT is performed with intravenous contrast. The use of rectal contrast has been associated with decreased time in the emergency department. Computed tomography has also been shown to reduce cost and negative appendectomy rates. Both CT and ultrasound are also effective in the identification of causes of right lower quadrant pain unrelated to appendicitis. Among pediatric patients, the sensitivity and specificity of graded-compression ultrasound can approach those of CT, without the use of ionizing radiation. Performing MRI after inconclusive ultrasound in pregnant patients has been associated with sensitivity and specificity of 80% to 86% and 97% to 99%, respectively. The ACR Appropriateness Criteria(?) are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.     

Mesenteric adenitis-acute ileitis: A constellation of findings definable with ultrasound

We present the ultrasonographic findings in 45 pediatric patients referred to us for acute abdominal pain mimicking appendicitis. All of the patients demonstrated right lower quadrant or para-aortic tender adenopathy consistent with the diagnosis of mesenteric adenitis, but in addition, many of the patients demonstrated other findings, including intestinal hyperperistalsis, small bowel (jejunal and ileal) mucosal thickening (both circumferential and nodular), mesenteric thickening around the nodes, fluid-filled loops of intestine, a visible appendix which was often fluid filled, free fluid, a right lower quadrant mass, and cecal involvement. These diverse findings suggest that mesenteric adenitis need not be limited to adenopathy and ileocolitis in the right lower quadrant. These additional findings are helpful in differentiating mesenteric adenitis from appendicitis, even in those patients in whom a fluid-filled appendix is visualized.     

Accuracy of ultrasonography in acute right lower quadrant problems in children

The ultrasonographic findings in 139 consecutive children examined for right lower quadrant pain were prospectively documented. The following diagnoses were offered: (1) normal, (2) appendicitis, (3) mesenteric adenitis-enteritis, (4) adnexal problems, and (5) other. These diagnoses were then compared to the final operative or nonoperative clinical diagnoses in each case and overall percent accuracy was determined. The overall percent accuracy was 98 %, and with this result ultrasound of the acute abdomen, especially the right lower quadrant, can be placed into the forefront of primary care imaging of patients with right lower quadrant pain. Ultrasound provides more useful information, quicker, and more consistently than do clinical or laboratory evaluations. Consideration should be given to the performance of this study early in the work-up of these patients.