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Original Report |
1 All authors: Second Department of Radiology, Athens University Medical School, Papadiamantopoulou 20, 115 28 Athens, Greece.
Received August 20, 2001;
accepted after revision March 5, 2002.
Presented at the annual meeting of the Radiological Society of North
America, Chicago, November 2000.
Abstract
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CONCLUSION. Splenic abscess is an uncommon entity that can be treated percutaneously. CT-guided drainage of splenic abscess seems to be a safe and effective alternative to surgery, allowing preservation of the spleen.
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Our study was undertaken to determine the current role of percutaneous CT-guided drainage as an alternative to surgical treatment of splenic abscesses. Previous studies reported a smaller number of patients with success rates that range between 67% and 100% [1, 2, 4,5,6,7,8]. For the reported period in our study, all splenic drainages were performed under CT guidance.
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A splenic abscess was defined as an intrasplenic pus collection. Differential diagnosis included other intrasplenic collections (e.g., hematoma) and space-occupying lesions. These other entities may often present nonspecific imaging features and require close coexamination of several parameters to reach an accurate diagnosis. Lesions of this nature were excluded from the study.
The patient's history, clinical signs, imaging evaluation, and drainage results were studied to characterize the lesion. Imaging evaluation included chest radiography in all patients, sonography of the upper abdomen in five of seven patients, and CT of the upper abdomen with IV contrast administration in all patients. CT revealed hypodense lesions in the splenic substance with a range of 2-12 cm (mean, 4.3 cm). An enhancing rim was present in four of seven lesions. This finding may be valuable in differentiating hematomas and cysts from abscesses. Six of seven lesions were unilocular in configuration; the presence of septa in the other lesion created a multilocular appearance (Fig. 1A,1B). In one lesion, an airfluid level was present, whereas in two lesions, gas bubbles were noted (Fig. 2A,2B).
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Clinical presentations of patients, laboratory findings, predisposing factors, and the identified causative microorganisms are presented in Table 1.
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Coagulation parameters were evaluated before intervention. The following values were considered acceptable: prothrombin time of less than 15 sec, partial thromboplastin time of less than 42 sec, international normalized ratio of less than 1:4, platelet count greater than 50,000/mm3, and bleeding time less than 8 min.
Drainage was performed solely under CT guidance using local anesthesia. No conscious sedation was applied. The "one-stick" trocar method was adopted in all patients using pigtail catheters of 8- to 10-French (Huisman Percutaneous Drainage Set, Cook, Bjaeverskov, Denmark; General-Purpose Drainage Set, Uresil, Skokie, IL; NG11 6HH, Tudor Health Care, United Kingdom). The 8-French diameter was selected for four patients: two, due to the catheter having to transverse normal splenic tissue; and two, due to severe coagulopathy (international normalized ratio, 1:26, 1:19; platelet count, 253,000/mm3 and 64,000/mm3, respectively). These parameters were borderline to the acceptable values and significantly different from the laboratory results of the two excluded patients with coagulopathy (international normalized ratio, 1:58, 2:43; platelet count: 16,000/mm3 and 158,000/mm3, respectively).
Through a small skin incision, the pigtail catheter was introduced into the abscess cavity, and fluid samples were sent for microbiologic evaluation that included bacterial and fungal cultures and a polymerase chain reaction test for tuberculosis. Postdrainage scans were obtained to exclude early complications (e.g., hematoma, pneumothorax). Patients underwent regular clinical and imaging follow-up during the year (mean follow-up time, 7.2 months). Imaging evaluation included sonography routinely and, in selected cases, CT.
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After the catheter placement, aspiration of purulent material confirmed the
diagnosis. Depending on the size of the abscess and the viscosity of the
material, a large proportion (
70%) of the collection was drained
immediately by manual aspiration. The remainder was left to drain
spontaneously.
During the following days, the patients were evaluated clinically. When there was no draining fluid, the catheter was closed for 24 hr. If it did not drain any more fluid when reopened, the catheter was removed. The drainage period ranged from 7 to 14 days (mean, 9.3 days). Sonography confirmed the resolution of the abscess.
In one patient with a multilocular abscess (Fig. 1A,1B), a residual cavity was noted 8 days after the insertion of the draining catheter, and a second catheter was introduced. In another patient with the draining catheter in place for 9 days, recurrence of the abscess occurred 4 days after removal of the catheter. The abscess became evident with clinical deterioration of the patient and was attributed to insufficient drainage of the original abscess that was not recognized on the final sonography. Again a second catheterization followed.
All patients received antibiotic therapy for 8-10 days, including a combination of second-generation cephalosporin and metronidazole. After the tuberculous abscess was identified, the appropriate triple regimen was administered.
Clinical improvement of the patients was apparent from the first day after the intervention. Successful drainage of all abscesses was achieved, and no early or late complications occurred. Among the studied patients, five are alive and well today, and two died from their underlying diseases (HIV and leukemia). No sepsis was encountered.
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In the past, antibiotic therapy and splenectomy were the only available treatments [3]. The spleen is important for proper immunologic function, and splenectomy carries an increased morbidity rate with the danger of overwhelming postsplenectomy infections. In addition, splenectomy in patients with splenic abscess has a significant mortality rate (14%) [3], especially in elderly patients.
Current therapeutic strategies established spleen-preserving treatment in cases of trauma and benign lesions. Thus, percutaneous drainage of splenic abscesses is used instead of surgical treatment with good results (51-72% success rate) [1, 2, 10], provided that certain conditions are present.
Percutaneous drainage is most apt to succeed when the abscess collection is unilocular or bilocular, with a discrete wall and no internal septations, and when its content is liquefied enough to be drained and located at the periphery and at the middle or lower pole of the spleen. The number of the collections is an important factor. If there are more than two collections, surgical treatment is preferred. Multilocular abscesses with thick septations or necrotic debris are less amenable to percutaneous drainage. Likewise phlegmonous, poorly defined cavities, or multiple small deep collections are also generally not curable by this approach [1, 5,6,7,8]. Nevertheless, in the presence of a complex abscess that is treated percutaneously, an improvement of the patient's general condition and no adverse effect on subsequent surgery may be noted [2, 11].
Percutaneous drainage is indicated especially when patients are in critical health postoperatively or when the risks of general anesthesia, surgical drainage, or splenectomy are substantial. Some authors report that percutaneous drainage should be considered as a first line of treatment, reserving splenectomy for only exceptional cases [6, 8].
The advantages of percutaneous drainage compared with surgery include external drainage without significant risks of intraabdominal spillage, avoidance of perioperative complications, conservation of time and expense, better acceptance by the patient, and easier nursing care. Also, immunologic dysfunction after splenectomy is avoided, and this outcome is desirable, especially in young patients [1, 6, 8].
Complications associated with percutaneous drainage of splenic abscesses include hemorrhage, pleural empyema, pneumothorax (transpleural catheterization), and fistula [1, 6]. These complications are rarely encountered if the exclusion criteria are carefully followed.
Our study refers to patients with this uncommon entity who were treated percutaneously. The number of treated patients in our study is larger than those in previous reports [1, 2, 5,6,7,8]. All splenic abscesses were successfully drained without any complications. The greater accuracy of CT over sonography in detecting even small splenic lesions, the reduction of catheter manipulations, and the availability of the modality in our institution directed our choice of CT guidance.
The high success rate in our study is attributed to the careful selection of patients. Exclusion criteria were severe impairment of coagulation mechanism in two patients, a multiloculated abscess in one patient, and a small (<3 cm in diameter) abscess located adjacent to the splenic hilum in another. In these four patients, surgery was preferred.
However, the abscesses of two patients were drained twice: one, because of the presence of a residual cavity in a multilocular abscess; the other, because of early removal of the catheter that resulted in recurrence of the abscess 4 days later.
Because seven patients presented with nonspecific signs, a detailed diagnostic approach appeared valuable in the treatment of these patients. Assiduous evaluation and correlation of both history and laboratory findings are advocated and may often influence both the diagnostic and the therapeutic algorithms. In our series, the patient with a history of blunt abdominal trauma (Fig. 3A,3B) presented with left-sided upper quadrant pain and high fever. Although CT depicted a small (2-cm) hypodense lesion in the spleen, with no peripheral contrast enhancement that could be attributed to a hematoma, his workup revealed leukocytosis. This finding and the severity of his general condition strongly suggested the presence of splenic abscess, which was confirmed by subsequent drainage.
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The drainage technique adopted was the trocar method using pigtail catheters. With this method, reduction of catheter manipulations avoids damage of the splenic substance. Careful localization of the lesion and proper selection of the entry site are required. An optimal route of access must traverse the least possible amount of splenic parenchyma and avoid the bowel and pleura. Penetration through normal tissue of approximately 2.3-cm thickness was required in two patients and was performed successfully without complications.
We recommend 8-French catheters primarily because our experience with them showed that they are sufficient to drain splenic abscesses, and pus viscosity was not greatly increased. If there is insufficient drainage, percutaneous secondary replacement of 8-French catheters with 10-French catheters using the Seldinger technique is recommended. Moreover, intracavitary injection of urokinase, which has been applied with good results for the drainage of abdominal abscesses, could be attempted, especially in persistent multiloculated splenic abscesses [12].
Nevertheless, if persistence of clinical signs is combined with poor drainage, the correct location of the catheter should be verified. The use of catheters larger than 10-French to drain splenic abscesses has not been attempted.
In a multilocular abscess, we recommend placement of a single catheter primarily; the hydrostatic pressure gradient that is created when one of the cavities is drained may sometimes cause spontaneous drainage of the other cavities. The possibility of placing an additional catheter should always be examined if the abscess persists. In our patient with the bilocular abscess, we attempted drainage using primarily a single 10-French catheter. A residual cavity that was present 8 days later required the placement of an additional catheter.
Removal of the catheter is advocated when there is minimal draining fluid (<5 mL daily), the patient is symptom-free, and imaging of the spleen reveals no residual cavity. In our study, the mean time of drainage was 9.3 days. However, in one patient, sonographic misinterpretation caused premature removal of the drain that resulted in recurrence of the abscess.
In conclusion, splenic abscess is an uncommon potentially fatal entity. Early diagnosis and effective treatment have currently limited mortality rates to 10%. Our study suggests that percutaneous drainage with CT guidance is a safe and effective alternative to surgery, allowing preservation of the spleen. It should be considered as the first line of treatment.
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