CT as a primary diagnostic method in evaluating intraabdominal abscess

Comparison between the Transperitoneal and Retroperitoneal Approach Methods for Severe Retroperitoneal Abscess

Purpose: Retroperitoneal (RP) abscess is a rare condition with poor prognosis, unclear etiology, characteristics, and treatment. This study compared transperitoneal and RP approach methods in the treatment of RP abscess. Methods: There were 45 patients with RP abscess diagnosed at Inha University Hospital from January 2014 to August 2018, of which 22 patients with 2 RP zones and systemic inflammatory response syndrome were included. Characteristics, etiology, laboratory and radiological findings, surgical technique, complications, and total number of hospital days were examined. Patients were assigned to either the transperitoneal (TP) or RP approach group. Results: There were 22 patients with RP abscess who were treated with surgical drainage using either the TP (<i>n</i> = 13) or RP (<i>n</i> = 9) approach. There was no difference in characteristics between the 2 groups. The number of reinterventions in the RP group (<i>n</i> = 6) was more than in the TP group (<i>n</i> = 4; <i>p</i> = 0.02). Mortality in the TP group (<i>n</i> = 5) was higher than in the RP group (<i>n</i> = 1; p < 0.01). The total mean number of hospital days in the RP group (mean: 76, range: 29-180 days) was more than in the TP group (mean: 58, range: 18-280 days, <i>p</i> = 0.03). Conclusion: RP abscess requires rapid drainage using the TP or RP approach. Reintervention events and number of hospital days in the RP group was greater than the TP group; however, mortality in the RP group was lower than in the TP group.

A Spectrum of Entities That May Mimic Abdominopelvic Abscesses Requiring Image-guided Drainage

A variety of entities may mimic drainable abscesses. This can lead to misdiagnosis of these entities, unnecessary percutaneous placement of a pigtail drainage catheter, other complications, and delay in appropriate treatment of the patient. Types of entities that may mimic drainable abscesses include neoplasms (lymphoma, gallbladder cancer, gastrointestinal stromal tumor, ovarian cancer, mesenteric fibromatosis, ruptured mature cystic teratoma, recurrent malignancy in a surgical bed), ischemia/infarction (liquefactive infarction of the spleen, infarcted splenule), diverticula (calyceal, Meckel, and giant colonic diverticula), and congenital variants (obstructed duplicated collecting system). Postoperative changes, including expected anatomy after urinary diversion or Roux-en-Y gastric bypass and small bowel resection, may also pose a diagnostic challenge. Nonpyogenic infections (Mycobacterium tuberculosis, Mycobacterium avium complex, echinococcal cysts) and inflammatory conditions such as xanthogranulomatous pyelonephritis and gossypiboma could also be misinterpreted as drainable fluid collections. Appropriate recognition of these entities is essential for optimal patient care. This article exposes radiologists to a variety of entities for which percutaneous drainage may be requested, but is not indicated, and highlights important imaging findings associated with these entities to facilitate greater diagnostic accuracy and treatment in their practice. ^©RSNA, 2018.

Intra-Abdominal Abscesses: Emphasis on Image-Guided Diagnosis and Therapy

Infection of the peritoneal cavity can be divided into acute peritonitis and chronic abscess formation. While acute peritonitis is easier to diagnose and treatment is often straightforward, the diagnosis of an intra-abdominal abscess can be subtle and treatment can involve multiple diagnostic and therapeutic modalities. The advent of high-quality computed tomography and ultrasonography has revolutionized the care of these patients, and has allowed for the definitive management of these infections without open operation. We review the current techniques for the diagnosis, localization, and treatment of these serious infections, discuss important factors influencing the decision between percutaneous and operative approaches, and examine several other controversies In this challenging area.

Imaging for infection: from visualization of inflammation to visualization of microbes

BACKGROUND

With the development of high-resolution cross-sectional imaging, anatomic identification of most areas of infection has become routine. Imaging a site of infection allows for diagnosis and treatment. In the past, molecular imaging for infection involved mainly the use of radiolabeled leukocytes for functional targeting at infection sites. With the recent development of functional nuclear imaging, bacterial and viral metabolism can also be imaged directly for potential identification of early infection.

METHODS

Review of pertinent English-language literature.

RESULTS

Cross-sectional imaging is used routinely to identify and treat sources of infection in patients with fever, leukocytosis, or unexplained hemodynamic instability. Although ultrasound is preferred for the identification of biliary or hepatic sepsis, computed tomography (CT) has proved to be accurate for the identification and treatment of intra-abdominal fluid collections and abscesses. Biologic imaging is a non-invasive technique that identifies sites of infection in cases in which no definite abnormality is identified via cross-sectional imaging. This is made possible by imaging the accumulation of radioisotopes that have been attached to white blood cells or glucose. Biologic imaging is useful for the identification of anatomic sites where there is inflammation or high metabolic demand. However, a drawback of biologic imaging is that it is not specific for infection. Techniques that image microbes directly increase the specificity of imaging results significantly and can be used to quantify and track infectious processes. For example, radiolabeling of antimicrobial proteins and antibiotics is one technique that has been demonstrated to identify areas of infection accurately in animals but is not currently being used clinically in humans. With the advent of gene therapy, many researchers are inserting the herpes viral thymidine kinase gene into both viruses and bacteria. This allows for tracking of the infectious process by imaging the accumulation of radiolabeled thymidine analogues.

CONCLUSION

This review summarizes standard imaging for infection as it is currently practiced clinically. We will also explore the promising new methods of microbial imaging that are likely to become standards in clinical care in the near future.

Impact of Dose-Modified Protocols on Radiation Doses in Patients Undergoing CT Examinations following Image-Guided Catheter Placement

PURPOSE

To investigate the impact of dose-modified (DM) scan protocols on decreasing radiation exposure from computed tomography (CT) scans obtained following image-guided catheter procedures.

MATERIALS AND METHODS

In this retrospective analysis, between December 2012 and June 2014, 192 patients (mean age, 60.7 y; 102 men) who underwent abdomen/pelvis CT examinations for catheter placement follow-up were included. The standard-dose (SD) baseline CT parameters included tube potential of 120 kVp, tube current of 75-550 mA, and noise index (NI) of 18-22. Weight-based scan parameters applied for follow-up CT were based on two reconstruction algorithms: filtered back projection (FBP; 120 kVp, 75-350 mA, NI = 30) and iterative reconstruction technique (IRT; 100/120 kVp, 75-250/350 mA, NI = 35). Two readers reviewed image quality (IQ) of follow-up and baseline CT examinations for 22 randomly sampled patients. Radiation doses were retrieved by dose monitoring software.

RESULTS

Compared with baseline, DM follow-up CT protocols enabled substantial (62.4%) dose reductions (mean CT dose indexes: 4.1 mGy at follow-up, 10.9 mGy at baseline; P < .0001). Doses were significantly lower for IRT follow-up CT examinations compared with FBP (mean CT dose indexes: IRT, 3.6 mGy; FBP, 4.6 mGy; P < .05). In 47 patients with more than one follow-up CT examination (mean, 3.1 examinations per patient; range, 2-6), the observed cumulative radiation dose (CRD) was 42.1% lower than the expected CRD (observed, 1,437.9 mGy·cm; expected, 2,483.6 mGy·cm; P < .0001). Subjective IQ scores were acceptable for follow-up CT examinations (follow-up, 3.6; baseline, 4; P < .05).

CONCLUSIONS

DM CT examinations enable substantial dose reduction (62.4%) for each follow-up examination compared with SD baseline scans, without any IQ concerns. Use of IRT decreases dose by an additional 22%. The CRD is lowered by 42% in patients undergoing multiple DM follow-up CT examinations.

Diagnosis and treatment of intra-abdominal abscesses

Despite recent advances in the diagnosis and management of intra-abdominal abscesses, these infections still cause substantial morbidity and mortality. Low pH, large bacterial inocula, poor perfusion, the presence of hemoglobin, and large amounts of fibrin (which impedes antibiotic penetration) make the abscess a cloistered environment that is penetrated poorly by many antimicrobial therapies. Therefore, management of these infections requires prompt recognition, early localization, and effective drainage, as well as appropriate antimicrobial use. Although various imaging techniques, such as ultrasonography, gallium scans, and indium-labeled white-blood-cell scans, can be used for the diagnosis and localization of intra-abdominal abscesses, computer-assisted tomography is the most useful study. Once the diagnosis is made and the abscess is localized, treatment should begin promptly. Percutaneous or open surgical drainage should be used. Broad-spectrum antibiotics should be given until culture and sensitivity data are obtained. Once these data are obtained, a therapy with appropriate coverage that is likely to work in the abscess environment should be chosen. Percutaneous drainage is inappropriate for abscesses in the posterior subphrenic space or in the porta hepatis, for those among loops of small bowel, for suspected echinococcal cysts, and for abscesses containing necrotic or neoplastic tissues. Finally, surgeons need to be cognizant of risk factors, such as advanced age, obesity, complex abscesses, and high Acute Physiology and Chronic Health Evaluation (APACHE) II or APACHE III scores, which correlate with poor outcomes for these patients.

Musculoskeletal complications of Crohn's disease: the role of computed tomography in diagnosis and patient management

The delayed diagnosis of musculoskeletal complications of Crohn's disease may produce major morbidity in patients. This study compared abdominal and pelvic computed tomography (CT) with conventional radiography in the diagnosis of musculoskeletal complications in 23 of 552 patients with Crohn's disease examined by CT over a 7-year period. Surgical confirmation was available in 15 of 21 patients. The clinical features of psoas/gluteal abscesses, abdominal wall fistulae, and sacral osteomyelitis are described. Because the clinical manifestations of these musculoskeletal complications are often nonspecific, CT is often useful in diagnosing and directing therapeutic interventions.

Development and implementation of an appropriateness guideline for use of CT in cases of suspected intraabdominal abscess

RATIONALE AND OBJECTIVES

The purpose of this study was to develop an evidence-based guideline for use of computed tomography (CT) in the evaluation of suspected abdominal abscess. The goal of the guidelines was to decrease the absolute number of CT examinations performed for suspected abdominal abscess and to increase the rate of positive CT examinations while not missing clinically relevant abscesses.

MATERIALS AND METHODS

A multidisciplinary team developed an evidence-based guideline regarding use of CT to evaluate for suspected abscess. A control group consisted of patients scanned for suspected abscess during a 6-month period. The intervention group consisted of patients scanned in the 6 months after guideline implementation. Focal fluid collections depicted on CT scans were reviewed for both patient groups to determine if these collections were abscesses. The number and proportion of abscesses in each group were then compared.

RESULTS

During the control period, 263 CT examinations for suspected abscess were performed, 75 of which (28.5%; 90% confidence interval [CI], 24%, 33%) depicted focal fluid and 25 of which (9.5%; 90% CI, 7%, 12%) depicted abscess. During the intervention period, 238 CT examinations were performed, 54 of which (22.7%; 90% CI, 18%, 27%) depicted fluid and 41 of which (17.2%; 90% CI, 13%, 21%) depicted abscess.

CONCLUSION

A guideline was successful at decreasing the number of CT examinations and increasing the proportion of positive CT results for abdominal abscess. As with other inpatient utilization interventions, each practice must assess the cost-benefit trade-off of guideline implementation in complex clinical situations.

Can Oral Metronidazole Substitute Parenteral Drug Therapy in Acute Appendicitis?: A New Policy in the Management of Simple or Complicated Appendicitis with Localized Peritonitis: A Randomized Controlled Clinical Trial

To demonstrate the efficacy of oral metronidazole (OM) in simple or complicated appendicitis with localized peritonitis, a randomized prospective study was carried out in 1083 patients, ranging in age from 4 to 50 years (mean age, 21.38).

The patients were randomly divided into two groups. The study group (SG) (524 patients) received OM (500 mg for adults, 7–10 mg/kg if less than 15 years) 2–3 hours before operation. The drug was continued 4 to 5 hours after operation, every 8 hours, for three doses if the appendix was mild to severely inflamed. In the case of complicated appendicitis (114 patients), the same dose was given for 3 to 6 days, depending on the absence or presence of pus. Ceftizoxime was administered to the control group (CG) (559 patients) 2 to 3 hours before operation and then postoperatively every 6 hours for three doses if the appendix was mild to severely inflamed. The complicated cases in the CG (120 patients) received a combination of penicillin, chloramphenicol, and gentamicin for 3 to 6 days, depending on the absence or presence of pus.

The serum concentration of metronidazole measured in 43 patients was at bactericidal level in 40 (mean ± SD standard deviation, 10.65 ± 4.89 μg/mL).

The rate of wound infection was not significantly different in the SG and the CG with the same degree of pathology (3.17% vs 2.96% if uncomplicated; 15.78% vs 14.16% if complicated, respectively). Pelvic collection occurred in four adults and one child in the CG with perforated appendicitis (4.16%). The same complication developed in two adults and two children in the SG with perforated appendicitis (3.5%). All six adults and one of the children in the SG had to be re-explored, whereas the remaining two children responded to conservative management (OM and gentamicin). In uncomplicated cases, hospital stay and hospital charge were both almost the same in both groups. However, length of hospitalization was nearly 1 day shorter and hospital cost per day was about 30 per cent less in complicated cases in the SG as compared with the CG.

Conclusively, OM may not only substitute parenteral antibiotics in acute appendicitis as a prophylactic agent, but it may also be used as a cost-effective drug and is more convenient to the patient.

CT in searching for abscess after abdominal or pelvic surgery in patients with neoplasia: do abdomen and pelvis both need to be scanned?

PURPOSE

This prospective study was undertaken to determine the incremental yield of combined abdominal and pelvic CT in searching for clinically suspected postoperative abscess in oncologic patients.

METHOD

One hundred seventeen oncologic patients underwent CT to exclude a clinically suspected abscess within 30 days of abdominal or pelvic surgery during an 8 month period. Scans were evaluated for the presence of ascites, loculated fluid collections, or other possible sources of fever. The clinical course and any intervention in the abdomen or pelvis within 30 days after CT were recorded.

RESULTS

After abdominal surgery, 44 of 69 [64%; confidence interval (CI) 51-75%] patients had loculated fluid collections in the abdomen; no patient (0%; CI 0-5%) had a loculated fluid collection present only in the pelvis. After pelvic surgery, 22 of 48 (46%; CI 31-61%) patients had loculated fluid collections in the pelvis; no patient (0%; CI 0-7%) had a loculated collection present only in the abdomen. Loculated collections were present in both the abdomen and the pelvis in 4 of 69 (6%; CI 1.6-14%) patients after abdominal surgery and 3 of 48 (6%; CI 1.3-17%) after pelvic surgery.

CONCLUSION

Isolated pelvic abscesses after abdominal surgery and isolated abdominal abscesses after pelvic surgery appear to be very uncommon in oncologic patients. CT initially need be directed only to the region of surgery in this particular patient population.

Psoas abscess: making an early diagnosis in the ED

The variable and nonspecific presentations of psoas abscess, as well as its infrequent incidence in the emergency department (ED), can result in delayed diagnosis or misdiagnosis. Previous reports have not discussed the diagnostic difficulties of psoas abscess from the viewpoint of emergency physicians (EPs), especially in light of the widespread use of ED ultrasonography. This report describes a 1-year experience between November 1993 and October 1994, during which 10 ED patients were diagnosed to have psoas abscess; in 7 cases, diagnoses were established in the ED. Patients' mean age was 64.6 years (range, 46 to 76). Pain was the most frequently encountered symptom (80%), with 5 patients (50%) complaining of flank pain. The triad of fever, flank pain, and limitation of hip movement, which is specific for psoas abscess, was present only in 3 patients (30%). The mean duration of symptoms was 10.6 days (range, 1 to 30 days). The mean time spent to establish the diagnosis was 1.7 days (range, 0 to 7 days). The diagnosis of psoas abscess was established by ultrasound in 6 patients, by computed tomography (CT) in 3 patients, and by surgery in 1 patient. Four patients who presented with either sepsis and nonspecific abdominal/flank pain or sepsis and thigh swelling were diagnosed to have psoas abscess by ultrasound performed by EPs. Only 3 patients were admitted to the ED with an initial diagnosis of psoas abscess. The remaining 7 had the following initial ED diagnoses: 2, fever of unknown origin; 2, septic shock; 1, shock; 1, sepsis; and 1, peritonitis. All but one had manifestations of sepsis. Two patients died of septic shock; these two patients had failed to be drained well. This report also includes a discussion of the role of EPs and ultrasonography in the diagnosis of psoas abscess. With their alertness and their expertise in ultrasonographic techniques, EPs can make an immediate diagnosis and arrange an early drainage procedure. For patients with sepsis of unknown origin, prolonged fever of unknown origin, and some specific manifestations suggestive of psoas abscess, the screening ultrasound should scan not only abdominal solid organs but also peritoneal cavity and retroperitoneal space. In addition, a flow chart is presented for facilitating the diagnosis of psoas abscess in the ED.

Actinomycosis of the greater omentum

A case of histologically proven actinomycosis of the greater omentum is reported. Computed tomography (CT) showed a mass at the greater omentum near the left flank area; it was hypervascular on angiograms and was supplied by the omental artery originating from the splenic artery. Sonography showed that the echogenecity of the lesion was complex. Actinomycosis of the greater omentum, although rare, should be included in the differential diagnosis of omental mass.

Hepatic abscess: sensitivity of imaging tests and clinical findings

The imaging studies of 63 patients with hepatic abscess were evaluated to determine the sensitivity of specific imaging tests and define causes of false-negative test results. Computed tomography (CT) detected 57 of 59 (97%) separate episodes of hepatic abscess. The two false-negative CT examinations were in patients with a diffuse low-density pattern throughout the liver. The radionuclide (RN) examination detected 16 of 20 (80%) cases, missing abscesses less than 2 cm in diameter. Ultrasound detected 33 of 42 (79%) cases, missing abscesses in the dome of the liver, small abscesses, and 2 large early abscesses. For all three imaging modalities, a specific diagnosis of abscess was possible only in those patients in whom CT scans demonstrated abscess gas (15%). The results of the imaging studies were correlated with the patients' clinical condition and laboratory findings. Thirty-one percent of patients were afebrile while 23% had normal white blood cell counts. Thirteen percent had totally normal liver function tests. We conclude that the clinical absence of fever, leukocytosis, or elevated liver function tests does not permit exclusion of the diagnosis of hepatic abscess. A CT scan is highly specific in excluding the diagnosis of hepatic abscess in the absence of diffuse liver disease. In this retrospective study CT was the most sensitive imaging modality available for the detection of hepatic abscess.

CT appearance of giant colonic diverticulum

The plain film, barium enema, and CT findings in a case of giant colonic diverticulum with the atypical feature of marginal calcifications are presented. The value of CT in the diagnosis and evaluation of giant colonic diverticulum is discussed.

CT abnormalities in right lower quadrant inflammatory disease: review of findings in 26 adults

Abnormal abdominal computed tomographic (CT) examinations, performed on 26 adults who presented with clinical evidence of right lower quadrant inflammatory disease, were retrospectively studied. Final diagnoses, established surgically in each case, included complicated appendicitis (15 patients), diverticulitis of the ileum or right colon (4), previously undiagnosed Crohn's disease (3), perforated cecal neoplasm (2), right tuboovarian abscess (1), and paracolic abscess of unknown cause (1). The CT features in each diagnostic group are presented in detail. Solid or ring calcification within a pericecal inflammatory mass was specific for appendicitis, occurring in 40% of the 15 patients. Without calcification, the differentiation of complicated appendicitis from Crohn's disease or diverticulitis, based on CT features alone, may be difficult in some cases.

Postoperative intra-abdominal sepsis

Postoperative intra-abdominal sepsis carries a high mortality. Diagnosis by clinical examination is often difficult, and imaging techniques may be helpful. Diagnostic laparotomy should be considered early, even in the absence of localizing signs. The use of aggressive surgical techniques may improve prognosis. The timing of surgical intervention is as important as the technique. Early diagnosis and treatment is particularly crucial in critically ill patients.

The complementary role of indium-111 labeled leukocyte imaging, ultrasonography and computed tomography in the evaluation of postoperative infection or abscess

We report our experiences with the combined use of indium-111 labeled leukocyte imaging (In-III WBC scan.), computed tomography (CT) and ultrasonography (US) for evaluation of suspected postoperative infection or abscess, and discuss the complementary roles of these modalities. Postoperative abscesses or infections were diagnosed in 9 of 20 patients. All patients were correctly diagnosed by In-111 WBC imaging and 4 patients could not be diagnosed by US because of bowel gas. One false-positive CT examination and another artifact on CT images due to respiratory movements were obtained. The three modalities were found to be complementary: CT and US were efficient imaging methods for diagnosis and treatment of abscess. In-111 WBC imaging could estimate the activity of inflammation.

Management and outcome of retroperitoneal abscesses

Retroperitoneal space abscesses are unusual clinical problems encountered by general surgeons, internists, and surgical subspecialists. An insidious, occult illness marked by diagnostic delay, inadequate drainage, and considerable morbidity and mortality is common. Anatomic reviews detailing the complex extraperitoneal spaces have been published, but less attention has been focused on diagnostic and drainage techniques useful to the practicing surgeon. In a retrospective review of 50 extraperitoneal abscesses, attention was directed to clinical presentation, diagnosis, and therapy. On the average, 12.7 days were required to establish the diagnosis; 50% of patients suffered major complications. A strikingly high mortality was associated with positive blood cultures and persistent fever within 48 hours of drainage (75% and 71%, respectively). Computed tomography has greatly enhanced the diagnosis of extraperitoneal abscesses, and radiologic drainage in selected cases appears to be a useful initial approach. A simplified anatomic classification and treatment plan is proposed to facilitate comparison between clinical series.

CT and ultrasound in abscess detection at specific anatomic sites: a study of 198 patients

Records of 902 patients with possible abdominal abscess were reviewed and of these 198 had abscesses on at least one occasion imaged either with ultrasound (US) or computed tomography (CT). There were 235 episodes of either one or simultaneous multiple abscesses. Sensitivities of CT and US were analyzed according to anatomic site. The nature of errors made was tabulated. CT was significantly more sensitive than US for the detection of abdominal abscess. Causes of CT and US error in abscess detection are discussed, and recommendations regarding choice of exam and means of improving performance are made.

Duodenal fistula--a rare complication following the removal of an infected aortic graft: case report

We present a rare case of fistulation from the duodenum into the prosthesis site of an aortic Y graft removed 8 months previously owing to infection. We have verified the topographical and anatomical location of the fistulation by fistula filling and CT and MR examination. To our knowledge such a postoperative complication has not been previously documented. In evaluating and comparing our observation we discuss their significance for topographical associations and prognosis and as an indication for surgical intervention.

Imaging of the ischiorectal fossa

A retrospective evaluation of 500 routine abdominal computed tomography scans revealed 21 cases of ischiorectal fossa disease in 16 patients. Pathologic processes included involvement by primary and secondary neoplasms, usually of gynecologic origin; rectal prolapse; and abscess. These abnormalities can be missed if the ischiorectal fossae are not included in routine abdominal scans. The anatomy of the ischiorectal fossae and their relationship to other pelvic organs are well demonstrated with high-resolution computed tomography scans as well as by magnetic resonance imaging.

Renal and perirenal infection: the role of computerized tomography

Predisposing factors, onset of symptoms to diagnosis interval, computerized tomography findings and the impact of computerized tomography on the outcome were studied retrospectively in 24 patients with renal or perirenal infections. The most common predisposing factors were diabetes mellitus and urinary tract calculi. The mean interval from the onset of symptoms to diagnosis was 6.8 days. The most common computerized tomography findings were thickening of Gerota's fascia, renal enlargement, focal decreased renal attenuation, perirenal fluid and focal gas. Four patients died despite early diagnosis and appropriate therapy. Computerized tomography aided in the diagnosis, assessment of the extent of disease, treatment and followup. Computerized tomography is the most direct method to evaluate patients with suspected renal or perirenal infection, although mortality may not be altered significantly.

MRI of a retained sponge in a dog

Retained sponges after laparotomy may cause a broad spectrum of clinical symptoms and present a difficult diagnostic problem. We report a case of retained surgical sponge in a dog to illustrate the MRI findings of this infrequent but important cause of postoperative complications.

Computed tomographic detection of gas within spontaneously necrotic tissue

Computed tomography (CT) is a widely accepted modality for the detection, localization, and potential therapeutic drainage of abdominal abscesses. The CT demonstration of extraluminal gas within the abdomen usually signifies the presence of an abscess. We report two cases of nonpurulent spontaneous tissue necrosis which simulated a gas containing abscess on CT. The significance of a gas-containing mass detected by CT must be interpreted cautiously since this appearance is not necessarily pathognomonic of a drainable abscess. Confirmation of purulent material within a suspected abscess collection requires documentation by percutaneous aspiration or surgery.

Computed tomography evaluation of local and extraintestinal complications of Crohn's disease

Complications of Crohn's disease were demonstrated by computed tomography of the abdomen and pelvis in 7 patients. Four patients had developed abscesses, 2 located in the psoas region and 2 involving the retroperitoneum or the liver. Other abnormalities documented on CT included inflammatory masses, fistulae, carcinoma, mesenteric thickening, and extraintestinal complications such as gallstones, renal calculi, and sacroileitis. Computed tomography was found to be useful in the detection and follow-up of abdominal complications of Crohn's disease.

Abnormal intraabdominal gas collections visualized on computed tomography: a clinical and experimental study

Abnormal intraabdominal gas collections visualized on CT scans during a 1-year period were reviewed. There were 34 collections in 29 patients. Sixty-two percent of these abnormalities were noninfectious and iatrogenic in origin, usually a direct result of procedures such as surgery, diagnostic tests, and needle or tube placement. Infections/abscesses (18%), hernias (15%), and gastrointestinal perforations (6%) produced the other abnormal gas collections. In the experimental animal study, gas collections as small as 5cc could be visualized on CT images. Collections of up to 20cc were visible for similar periods of time on both CT scans and conventional radiographs. It is concluded that most abnormally placed gas collections seen on CT are iatrogenic and that CT scans are very sensitive for the detection of such collections.

Lumbar abscess resulting from appendicitis

Images

Re-operation for intra-abdominal sepsis. Indications and results in modern critical care setting

In a 2-year period (1981-1983), 87 abdominal re-explorations (1.6% of total laparotomies) were performed on 77 patients for sepsis in five Downstate hospitals. Fifty-one patients were re-explored solely on clinical grounds, 21 on clinical plus radiographic criteria, four solely on radiographic grounds, and 11 for multiple organ failure. The overall mortality rate was 43%. As expected, the most common laparotomy finding was intra-abdominal abscess (47); other findings included anastomotic leak (14), necrotic bowel (10), evidence of technical error (five), and acalculous cholecystitis (two). The most common clinical findings were localized tenderness, fever, and absent bowel sounds (85%). Fifty-four special studies were performed with an overall accuracy rate of 76%. CAT scans and contrast radiographs were most accurate (92% and 81%) while sonography and gallium scans were less useful (59% and 60%). Seven patients had negative laparotomies. While all were distended and six were febrile, only one patient had focal tenderness. In the 11 patients explored solely for multiple organ failure, six patients had drainable pus despite negative radiographic studies, and two survived. The other five patients had negative laparotomies, and all died. Factors correlated with mortality were age over 50, peritonitis at the primary operation, and multiple organ failure. The approach to these seriously ill patients should be governed by a high index of suspicion. Clinical findings are at least as reliable as sophisticated radiographic modalities of which CAT scan appears to be the most accurate. Re-exploration for multiple organ failure alone will yield a significant group of patients with drainable septic foci and some survivors; thus, exploration for this indication appears to be defensible.

Radiological diagnosis in proven intraabdominal abscess formation: a comparison between plain films of the abdomen, ultrasonography and computerized tomography

Plain films of the abdomen, ultrasonography, and computed tomography were performed on 180 patients to rule out an intraabdominal abscess. The efficacy of the different modalities was reviewed in retrospect. Thirty-six of these 180 patients had a definite abscess formation. This was demonstrated in 65% of the plain film examinations, in 44% by ultrasonography, and in 94% by computerized tomography. Computed tomography seems efficient in ruling out abdominal abscess.

Computerized tomography in diagnosis of pelvic abscess in spinal-cord-injured patients

Twenty-four spinal-cord-injured patients with pressure sores, and suspected of having other complications were studied by CT, gallium scanning, and ultrasonography. CT was found to be by far the modality of choice for evaluation of the extent and depth of the pressure sore, assessment of the thickness of fibrous tissue scar alongside its boundaries and at its base, detection of associated peri-pelvic and intra-pelvic soft tissue abscesses, sinus tracts and osteomyelitis of the pelvic bones.

Computed tomography of pressure sores

Twenty-three paralyzed patients admitted for treatment of recurrent pressure sores were evaluated by computed tomography, bone scanning, gallium scanning, and sonography. Computed tomography was helpful in detecting associated peripelvic and pelvic abscesses and pelvic osteomyelitis, which were undiagnosed by all other modalities combined in more than half of the patients. Computed tomography was also useful in preoperative planning by revealing the extent of the undermining of the pressure sore, the thickness of the fibrous scar at its base, and the size and status of the adjacent muscles.

Localized colonic perforation following renal transplantation

Well-contained abdominal abscesses developed in two renal transplant patients ten years and six months, respectively, after transplantation. Investigations including gastrointestinal series and CT scan demonstrated cystic collections within the abdominal cavity. Laparotomy in each case revealed an infected cystic mass arising from the sigmoid colon. In both patients deroofing the abscess and, in one patient, defunctioning colostomy were performed. Both patients did well in the postoperative period.

Morphologic aspects of hepatic abscesses at computed tomography and ultrasound

The morphologic criteria of hepatic abscesses as demonstrated at computed tomography (CT) and ultrasound (US) were investigated in 27 patients and the diagnostic efficiency of both methods evaluated. Different appearances of hepatic abscess at CT and US were observed and investigated. No specific morphologic signs could be defined, since malignant neoplasms may show similar findings. Therefore, fine needle aspiration of possible hepatic abscesses should be performed to provide specific and bacteriologic diagnosis. US is an accurate method to evaluate patients with possible hepatic abscess. However, CT should be preferred in critically ill patients and postoperatively, since the diagnostic accuracy of CT is not limited by bowel gas, sutures and drainage tubes.

Computed tomography of intraperitoneal abscesses

Eighty-seven patients with the clinical suspicion of an intraperitoneal abscess were examined by computed tomography. In 83 of these patients CT gave true positive or true negative results in reference to the diagnosis of local intraperitoneal fluids. The final diagnosis confirmed 28 abscesses in 26 patients. Most of these abscesses were in the left subphrenic space, the right subphrenic space, the right anterior subhepatic space, and the pelvis. The morphological criteria for intraperitoneal abscesses, shown by CT, are defined. Direct signs include form, impression on nonintestinal organs, density value, gas collection, pyogenic membrane, and infiltration in surrounding tissue. Indirect signs include ascites and pleural effusion and/or pulmonary infiltration. Differential diagnostic problems of intraperitoneal abscesses are discussed.

Computed tomographic guidance of percutaneous needle aspiration and drainage of abdominal abscess

Percutaneous thin needle aspiration biopsy (TNAB) of solid abdominal masses is an established technique. Combining the techniques of TNAB with those of percutaneous biliary and renal drainage can result in successful nonoperative management of abdominal abscesses. Twenty consecutive patients were referred for this procedure. TNAB alone was performed in 4 patients. TNAB followed by percutaneous drainage was accomplished in 16 patients. Of the 4 patients who had TNAB alone, it was curative in 2, and 2 were elected to have surgical drainage. Of the 16 patients who underwent percutaneous drainage, it was curative in 14. One patient was discovered at surgery to have a necrotic malignant tumor. A second patient required surgery.

Role of ultrasonography, gallium scanning, and computed tomography in the diagnosis of intraabdominal abscess

Ultrasonography is reasonable in cost and allows confirmatory needle aspiration. It is especially valuable when the clinical impression suggests a particular area where the abscess is probably located. Gallium scanning is useful to detect the abscess when examination suggests a septic process without clinical localization. Several false-positive findings were seen in postsplenectomy patients. Computed tomography should be reserved for patients in whom localization is by other means difficult. By correlating the results of these techniques with clinical findings, only one unnecessary operation resulted from false-positive studies, and no surgery was delayed due to improper reliance on negative findings.

Non-surgical drainage of intra-abdominal and mediastinal abscesses: a report of twelve cases

Twelve patients with intra-abdominal or mediastinal abscesses were treated by percutaneous drainage. Three abscesses were subphrenic, three were adjacent to enteric leaks, two were intrahepatic, two were pancreatic pseudocysts, one was a pancreatic abscess extending to the lesser sac, and one was an infected adrenal hematoma. All 12 lesions were entered percutaneously using fluoroscopic guidance without traumatizing the adjacent normal tissue. Localization was frequently aided by computed tomography. Various catheters were positioned using basic angiographic techniques. Following drainage all patients had a favorable clinical response. Seven of the 12 patients required no surgical management. Careful radiologic follow-up and frequent changing of catheters was necessary in six of the patients. Two patients benefited from the addition of auxiliary drains. Five of the 12 patients were electively operated upon because of incomplete drainage of the abscess cavity. Causes of failure were: persistent anastomotic leak (two patients), sequestered, loculated extension of abscess cavity (two patients), or necrotic, viscous hepatic tissue requiring removal at laparotomy (one patient).

111Indium-labelled leucocyte scintigraphy in the diagnosis of inflammatory disease--first results

In 61 patients, 66 scans were performed with 111In-labelled autologous leucocytes to evaluate this method in the diagnosis of inflammatory disease. All scintigraphic results were compared with clinical, operative or postmortem findings. In the first 20 examinations in 19 patients, 2 scintigrams were true positive, 9 true negative one of false positive, whereas 9 scintigrams had to be considered as false negative. These false negative results were probably due to loss of viability of the labelled cells. A modified labelling technique, in which a much lower concentration of oxine was used, was employed for a further 46 examinations in 42 patients. Twenty-four scintigrams were true positive and 22 true negative, while no false positive or false negative results were observed. These results suggest that this modified technique is useful in the diagnosis of inflammatory disease.

Subphrenic abscess: the radiological approach

Subphrenic abscess will continually plague the post-laparotomy patient. The high mortality associated with these abscesses can be reduced by diagnosing and draining them early. In 42 patients with 55 subphrenic abscesses, the most important diagnostic modality proved to be conventional radiographs of the abdomen allowing 65% of the subphrenic abscesses to be detected. Other procedures were largely confirmatory in suspicious cases. Thus ultrasound is useful in right subphrenic suprahepatic abscesses while modified upper and lower gastrointestinal studies allow rapid diagnosis of extra-intestinal abscess gas or mass effect.