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The value of transrectal ultrasound guided needle aspiration in treatment of prostatic abscess
European Journal of Radiology 52 (2004) 94–98
Technical note
The value of transrectal ultrasound guided needle aspiration in treatment of prostatic abscess Ça˘gatay Gö˘gü¸s a,∗ , Eriz Özden a , Resul Karabo˘ga a , Cemil Ya˘gci b a b
Department of Urology, Ankara University, School of Medicine, Ankara, Turkey Department of Radiology, Ankara University, School of Medicine, Ankara, Turkey
Received 30 April 2003; received in revised form 15 July 2003; accepted 21 July 2003
Abstract Introduction: Prostatic abscess (PA) is a very uncommon disorder. The value of transrectal ultrasound (TRUS) guided aspiration in the treatment of PA has not been clearly defined. We present our experience with six such patients. Materials and methods: Between July 1997 and December 2002, six patients with PA were diagnosed by TRUS and treated by TRUS guided needle aspiration in our department. PA was defined as hypoechoic, inhomogenous, thick walled fluid collection. TRUS guided needle aspiration of the abscess was performed transrectally in all patients with a 20-cm long 18 gauge Chiba needle. Succesfull treatment criteria were defined as clinical improvement in symptoms and decrease of more than half of the estimated abscess volume on follow up TRUS control. Patients with continuing clinical symptoms were defined as treatment failures. Results: The most common TRUS finding was detection of a hypoechoic area with inhomogeneous structures, which was determined in all patients (100%). In some patients irregular contour and heterogeneous areas were additionally described. TRUS guided needle aspiration treatment of PA was successful in five of six patients (83.3%). In one patient treatment failed and the abscess recurred 3 weeks after the procedure. As this patient had additionally a bladder outflow obstruction, transurethral resection of the prostate was performed instead of a repeat procedure. There were no complications associated with the procedure. Conclusions: In conclusion, TRUS has an important value in diagnosis and treatment of PA. TRUS guided aspiration is an effective and minimally invasive treatment modality for PA which causes no serious complications. © 2003 Elsevier Ireland Ltd. All rights reserved. Keywords: Prostatic abscess; Transrectal ultrasonography; Treatment; Needle aspiration
1. Introduction Prostatic abscess (PA) is a very rare condition and diagnosed only in 0.2% of patients with urologic symptoms and 0.5–2.5% of patients with prostatic symptoms [1,2]. The preoperative diagnosis is not always easy due to similar symptoms with acute bacterial prostatitis. As it is very difficult to confirm the diagnosis with history and physical examination, imaging modalities have gained a wide acceptance in last years for detecting PA. Among these, transrectal ultrasonography (TRUS) has been used widely in diagnosis of PA. Aside confirming the diagnosis, TRUS also gives possibility for the management of the disease at the same time.
∗ Corresponding author. Address: Mahatma Gandhi Caddesi, 46/3, 06700, Gaziosmanpasa, Ankara, Turkey. Tel.: +90-312-447-3347; fax: +90-312-311-2167. E-mail address: [email protected] (Ç. Gö˘gü¸s).
The main problem for detecting the value of TRUS in the treatment of PA comes from the limited number of reports in the literature about TRUS guided needle aspiration [3–5]. Herein we present our experience on six such patients with PA who had undergone TRUS guided needle aspiration. The diagnosis and management of these cases were discussed.
2. Materials and methods Between July 1997 and December 2002, six patients with PA were diagnosed by TRUS and treated by TRUS guided needle aspiration in our department. The mean age of the patients was 55.6 years (27–78). All patients were evaluated with history, physical examination and laboratory tests including complete blood count, serum biochemistry, urinalysis and urine culture. Digital rectal examination was also performed in all patients. TRUS was performed using a Toshiba
0720-048X/$ – see front matter © 2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/S0720-048X(03)00231-6
Ç. Gö˘gü¸s et al. / European Journal of Radiology 52 (2004) 94–98
95
Fig. 1. Echogenic tip of the needle is seen in the abscess cavity (arrow: needle tract).
SSA-250-A ultrasonography system with a 6 MHz end-fire convex and 7 MHz lineer probe (Toshiba, Tokyo, Japan) by an experienced radiologist who was specialized on uroradiology (E.Ö). PA was defined as hypoechoic, inhomogenous, thick walled fluid collection. Debris like material within the collections showed movement with the change of the position of the patient. All patients were applied cleansing enema before the procedure in order to eliminate feces in the rectum. Antibiotic prophylaxis with oral quinolone and IM metranidazole was started the day before the aspiration and continued with parenteral antibiotic therapy according to the culture results. TRUS guided needle aspiration of the abscess was performed transrectally in all patients with a 20-cm long 18 gauge Chiba type needle. After placement of the probe into rectum, in the left lateral decubitis knee–chest position, the needle was inserted through the biopsy guide attachment into the abscess cavity under sonographic guidance using the end-fire convex probe (Fig. 1). During the aspiration, decreasing volume of the abscess cavity was monitored by TRUS. Succesfull treatment criteria were defined as clinical improvement in symptoms and decrease of more than half of the estimated abscess volume on follow up TRUS control. Patients with continuing clinical symptoms were defined as treatment failures [3]. Patients were than followed up at 3 month intervals by history, physical examination, TRUS and urine culture.
3. Results The main clinical symptom was dysuria which was seen in five patients (83.3%). Other clinical presentations in-
cluded fever, pollacuria, perineal pain, acute urinary retention, hematuria and urethral discharge. As a predisposing factor for PA, two patients were diabetic (33.3%), two patients had previous urinary tract infection (33.3%) and one patient (16.6%) had bladder outflow obstruction. Leukocytes in midstream urine was demonstrated in all patients. Two patients (33.3%) had more than 10 leukocytes per high power field, two had (33.3%) between 5 and 9 and two had fewer than 4 (33.3%). Bacteriuria was not seen in any patients. Urine culture was performed in all patients but was positive only in one patient (16.7%). Escherishia coli was isolated in that patient. Digital rectal examination was performed in all patients. Pain and tenderness was detected in five (83.3%) patients but fluctuation was palpated only in two (33.3%) of them. In all patients the diagnosis was made by TRUS and only in one patient was confirmed by computerized tomography (CT). The most common TRUS finding was detection of a hypoechoic area with inhomogeneous structures which was determined in all patients (100%) (Figs. 2 and 3). In some patients irregular contour and heterogeneous areas were additionally described. The mean prostate weight was 93 g (range 42–162) and the mean abscess volume was 31.6 ml (range 17–65). The TRUS findings in six patients were summarized in Table 1. TRUS guided needle aspiration treatment of PA was successful in five of six patients (83.3%). On follow-up TRUS, no remaining or recurrent abscess formation were found in these five patients. In one patient treatment failed and the abscess recurred 3 weeks after the procedure. As this patient had additionally a bladder outflow obstruction, a repeat procedure was not performed and he underwent a transurethral resection of the prostate (TUR-P). There were no complica-
96
Ç. Gö˘gü¸s et al. / European Journal of Radiology 52 (2004) 94–98
Fig. 2. Longitidunal sonogram shows the abscess as a heterogeneous hypoechoic area with posterior acoustic enhancement which indicates that the content is not solid (arrows).
Fig. 3. Longitidunal sonogram shows an abscess cavity in the inner part of the gland as a well-defined heterogenous hypoechoic area.
tions associated with the procedue. The mean hospital stay was 1.66 days (range 1–3).
4. Discussion PA is a very rare clinical entity and is found in about 0.5% of all prostatic disease [6]. In early years, N. gonorrhea was the primary microorganism comprising about 75% of all cases [7] and the mortality rate was between 30 and 60%
[5]. Nowadays, the incidence of PA was decreased due to widespread use of antibiotics and today gram-negative bacili mainly E. coli are responsible from 60 to 80% of cases [3,4]. There are two mechanisms in pathogenesis of PA. The first and the most common is due to reflux of infected urine. The most frequent microorganisms in that situation is E. coli and other coliform bacteria [2,4]. The second and rarely responsible mechanism is the hematogenous dissemination from a primary focus. Staphylococcus aureus is the most common microorganism in patients in whom the PA is result of
Ç. Gö˘gü¸s et al. / European Journal of Radiology 52 (2004) 94–98 Table 1 TRUS findings in patients with PA Patient
Mean diameter (cm)
Sonographic appearance
Borders
1
3.3
Inhomogeneous Hypoechoic
Well defined Thick wall
2
4.2
Inhomogeneous Hypoechoic
Well defined Thick wall
3
4
Inhomogeneous Hypoechoic
Well defined Thick wall
4
3.5
Inhomogeneous Hypoechoic
Irregular contour
5
2.2
Inhomogeneous Hypoechoic
Irregular contour
6
7
Inhomogeneous Hypoechoic
Well defined Thick wall
hematogenous dissemination [4,8]. The main risk factor for development of PA is diabetes mellitus [5]. Additionally, patients with bladder outlet obstruction, previous urinary tract infection, chronic liver disease, acguired immunodeficiency syndrome and who are on dialysis are at higher risk for developing PA [2,4]. In our study group, showing similarity with the literature, predisposing factors for PA were diabetes mellitus in two patients, previous urinary tract infections in two and bladder outflow obstruction in one patient. Therefore, the clinician should be alert about PA in patients with prostatic symptoms and who has one of the above mentioned predisposing factors. PA usually shows similar symptoms like acute prostatitis. Patients mostly present with dysuria, urinary frequency, perineal pain, fever, acute urinary retention and hematuria [2–4] but they are all nonspecific [6]. The most common finding is pain on digital rectal examination which was seen in 48–100% of patients [4]. Although the typical fluctuant mass for PA has been reported as high as 88% in some published series [6], it is rarely found on digital rectal examination as in our study group [2,3,5]. Thus, it is very difficult to confirm the diagnosis only by physical examination and history. In last years prostatic imaging modalities gained a wide acceptance in diagnosis of PA [9–13]. Of these imaging modalities TRUS is widely used in diagnosis of PA. Except a few conditions that might be a contraindication for TRUS such as in patients with severe hemorrhoids, anal fistulas, fissures or after abdominoperineal resection [14], TRUS can be safely used for this purpose. The most common finding of PA on TRUS is detection of a hypoechoic or anechoic area which is usually well-defined and having thick walls [3–5]. Heterogenous areas and hypoechoic areas with poorly defined walls are less frequently seen [3,4]. The sonographic appearance of PA is usually characteristic and is easily dif-
97
ferantiated from other glandular lesions. However, when the abscess is small and in an early stage, it is not always easy to make the differantial diagnosis with other pathologies like cystic lesions, granulomas and especially with prostatic carcinoma [3,5]. There are several criterias which helps to discriminate PA from prostate cancer and these can be listed as following: prostate cancer is usually detected in the peripheral zone however PA is located in the central and transitional zone of the prostate; tumors are usually small and easily distinguished from the surrounding gland whereas PA contains a large area; PA usually appears as a wider hypoechoic area and is less easily definable during initial phases; color and power Doppler ultrasonography show a high perilesional vascularity in PA which is absent in prostate cancer [3,5]. In our study all patients revealed the characteristic TRUS findings for PA and it was not difficult to confirm the diagnosis. Besides TRUS, CT and magnetic (MR) resonance imaging have also been used in diagnosis of PA. The appearance of low attenuating, round, well demercated fluid collections within the prostate gland by CT is suggestive of PA [10,11]. The MR of PA shows low signal intensity on short echo-time (TE) images, with increased signal intensity on long TE images [12]. These findings show concordance with the MR appearance of abscesses elsewhere in the body [12]. CT and MR are both especially useful for defining the extend of the disease [10–12]. Delay in diagnosis and treatment of PA may cause a lot of serious complications and even death. The basic treatment of PA is adequate drainage and proper use of antibiotic therapy [2–5]. Although the surgical drainage is the best method in treatment of PA, the gold standard has not yet been defined. Perineal incision and drainage, percutaneous transperineal drainage and TUR of the prostate are the alternatives for surgical drainage [4,5]. The restrictive problem with these techniques is that, they may have some serious complications. Perineal incision could cause impotence due to nerve damage [5]. TUR prostate could have standard complications as retrograde ejaculation, urethral stricture and urinary incontinenece [2]. Additionally, it has the risk of hematogenous spread of infected organisms [3,5]. In recent years, TRUS guided ultrasound drainage of PA has been also performed for the treatment of PA. It has the advantages of easy performance and low complication rates [3–5]. The aim of the TRUS guided drainage is to empty the collection and thereby to give permission the antibiotics for entering into the abscess cavity by pressure reduction within the PA [4]. A cystostomy catheter may be placed before the procedure in patients with acute urinary retention or in those who carry a indwelling bladder catheter [15]. TRUS guided drainage procedure may be performed by either tranrectally or transperineally [16]. Transperineal drainage of PA causes more pain and prolonged catheter use when compared with transrectal approach [3,4]. Additionally, bleeding, injury to adjacent organs and spread of infection is minimal with transrectal approach due to direct access through the rectal wall [3,4]. In our six patients we preferred to use transrectal
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approach and all our patients tolerated the procedure well. Some authors prefer to leave a catheter for drainage after the procedure [16]. Although, it is true that catheters provide continuous drainage and make the repeat procedure more easier, we did not place a catheter for transrectal drainage. As it was pointed out by Lim et al., catheters may be uncomfortable for patients [3]. Additionally, as the results of TRUS guided drainage of PA is very successful and few cases need a repeat procedure [4], we also think that a routine catheter placement is not necessary after the procedure. There are just few published reports about TRUS guided PA drainage. In the largest series in literature, Collado et al. reported a success rate of 83.3% in 24 patients treated by TRUS guided drainage [4]. Only two patients needed a second procedure. In that study, they performed also TUR-P in five patients but concluded that TUR-P was indicated in patients with associated bladder outflow obstruction or in those in whom ultrasound drainage was not successful [4]. Lim et al. reported a high success rate of 85.7% in 14 patients. A second procedure was needed in four patients. They also concluded that TRUS guided needle aspiration was an effective method for treating PA without causing any severe complications [3]. Barozzi et al. determined a 100% success rate with TRUS guided aspiration through transperineal approach on five patients with PA [5]. In our study, TRUS guided aspiration was successful in five out of six patients (83%). The treatment failed only in one patient. A repeat procedure was not performed and the patient underwent a TUR-P due to associated bladder outflow obstruction. No serious complications were occured. Although the number of patients in our series and in other series were small, we, as do others, think that patients with PA may benefit from TRUS guided aspiration.
5. Conclusion In conclusion, TRUS has an important value in diagnosis and treatment of PA. TRUS guided aspiration is an effective and minimally invasive treatment modality for PA which causes no serious complications.
References [1] Trapnell J, Roberts M. Prostatic abscess. Br J Surg 1987;57: 565–9. [2] Meares EM. Prostatitis and related disorders. Walsh PC Retik AB Stamey TA, et al (Eds.), Campell’s Urology7th ed 1992;WB SaundersPhiladelphia. [3] Lim JW, Ko YT, Lee DH, et al. Treatment of prostatic abscess: value of transrectal ultrasonographically guided needle aspiration. J Ultrasound Med 2000;19:609–17. [4] Collado A, Palou J, Garcia-Penit J, Salvador J, De La Torre P, Vicente J. Ultrasound-guided needle aspiration in prostatic abscess. Urology 1999;53:548–52. [5] Barozzi L, Pavlica P, Menchi I, De Matteis M, Canepari M. Prostatic abscess: diagnosis and treatment. AJR 1998;170:753–7. [6] Granados EA, Riley G, Salvador J, Vincente J. Prostatic abcess: diagnosis and treatment. J Urol 1992;148:80–2. [7] Sargent JC, Irwin R. Prostatic abscess: clinical study of 42 cases. Am J Surg 1931;11:334–7. [8] Savarirayan S, Shenykin Y, Gerard P, Wise GJ. Staphylococcus periprostatic abscess:an unusual cause of acute ureinary retention. Urology 1995;46:573–4. [9] Cytron S, Weinberger M, Pitlik SD, Servadio C. Value of transrectal ultrasonography for diagnosis and treatment of prostatic abscess. Urology 1988;32:454–8. [10] Dennis MA, Donohoue RE. Computed tomography of prostatic abscess. J Comput Assist Tomogr 1985;9:201–2. [11] Washecka R, Rumancik WM. Prostatic abscess evaluated by serial computed tomography. Urol Radiol 1985;7:54–6. [12] Papanicolou N, Pfister RC, Stafford SA, Parkhurst EC. Prostatic abscess: Imaging with transrectal ultrasonography and MR. AJR 1987;149:981–2. [13] Thornhill BA, Morehouse HT, Coleman P, Hoffman Tretin JC. Prostatic abscess: CT and sonographic findings. AJR 1987;148:899– 900. [14] Prassopoulos P, Charoulakis N, Anezinis P, Daskalopoulos G, Cranidis A, Gourtsoyiannis N. Suprapubic versus transrectal ultrasonography in assessing the volume of the prostate and the transition zone in patients with benign prostatic hyperplasia. Abdom Imaging 1996;21:75–7. [15] Angwafo FF, Sosso AM, Maria WF, Edzoa T, Juimo AG. Prostatic abscess in sub-Saharan Africa: a hospital based experience from Cameroon. Eur Urol 1996;30:28–33. [16] Bachor R, Gottfried HW, Hautmann R. Minimal invasive therapy of prostatic abscess by transrectal ultrasound-guided perineal drainage. Eur Urol 1995;28:320–4.
Technical note
The value of transrectal ultrasound guided needle aspiration in treatment of prostatic abscess Ça˘gatay Gö˘gü¸s a,∗ , Eriz Özden a , Resul Karabo˘ga a , Cemil Ya˘gci b a b
Department of Urology, Ankara University, School of Medicine, Ankara, Turkey Department of Radiology, Ankara University, School of Medicine, Ankara, Turkey
Received 30 April 2003; received in revised form 15 July 2003; accepted 21 July 2003
Abstract Introduction: Prostatic abscess (PA) is a very uncommon disorder. The value of transrectal ultrasound (TRUS) guided aspiration in the treatment of PA has not been clearly defined. We present our experience with six such patients. Materials and methods: Between July 1997 and December 2002, six patients with PA were diagnosed by TRUS and treated by TRUS guided needle aspiration in our department. PA was defined as hypoechoic, inhomogenous, thick walled fluid collection. TRUS guided needle aspiration of the abscess was performed transrectally in all patients with a 20-cm long 18 gauge Chiba needle. Succesfull treatment criteria were defined as clinical improvement in symptoms and decrease of more than half of the estimated abscess volume on follow up TRUS control. Patients with continuing clinical symptoms were defined as treatment failures. Results: The most common TRUS finding was detection of a hypoechoic area with inhomogeneous structures, which was determined in all patients (100%). In some patients irregular contour and heterogeneous areas were additionally described. TRUS guided needle aspiration treatment of PA was successful in five of six patients (83.3%). In one patient treatment failed and the abscess recurred 3 weeks after the procedure. As this patient had additionally a bladder outflow obstruction, transurethral resection of the prostate was performed instead of a repeat procedure. There were no complications associated with the procedure. Conclusions: In conclusion, TRUS has an important value in diagnosis and treatment of PA. TRUS guided aspiration is an effective and minimally invasive treatment modality for PA which causes no serious complications. © 2003 Elsevier Ireland Ltd. All rights reserved. Keywords: Prostatic abscess; Transrectal ultrasonography; Treatment; Needle aspiration
1. Introduction Prostatic abscess (PA) is a very rare condition and diagnosed only in 0.2% of patients with urologic symptoms and 0.5–2.5% of patients with prostatic symptoms [1,2]. The preoperative diagnosis is not always easy due to similar symptoms with acute bacterial prostatitis. As it is very difficult to confirm the diagnosis with history and physical examination, imaging modalities have gained a wide acceptance in last years for detecting PA. Among these, transrectal ultrasonography (TRUS) has been used widely in diagnosis of PA. Aside confirming the diagnosis, TRUS also gives possibility for the management of the disease at the same time.
∗ Corresponding author. Address: Mahatma Gandhi Caddesi, 46/3, 06700, Gaziosmanpasa, Ankara, Turkey. Tel.: +90-312-447-3347; fax: +90-312-311-2167. E-mail address: [email protected] (Ç. Gö˘gü¸s).
The main problem for detecting the value of TRUS in the treatment of PA comes from the limited number of reports in the literature about TRUS guided needle aspiration [3–5]. Herein we present our experience on six such patients with PA who had undergone TRUS guided needle aspiration. The diagnosis and management of these cases were discussed.
2. Materials and methods Between July 1997 and December 2002, six patients with PA were diagnosed by TRUS and treated by TRUS guided needle aspiration in our department. The mean age of the patients was 55.6 years (27–78). All patients were evaluated with history, physical examination and laboratory tests including complete blood count, serum biochemistry, urinalysis and urine culture. Digital rectal examination was also performed in all patients. TRUS was performed using a Toshiba
0720-048X/$ – see front matter © 2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/S0720-048X(03)00231-6
Ç. Gö˘gü¸s et al. / European Journal of Radiology 52 (2004) 94–98
95
Fig. 1. Echogenic tip of the needle is seen in the abscess cavity (arrow: needle tract).
SSA-250-A ultrasonography system with a 6 MHz end-fire convex and 7 MHz lineer probe (Toshiba, Tokyo, Japan) by an experienced radiologist who was specialized on uroradiology (E.Ö). PA was defined as hypoechoic, inhomogenous, thick walled fluid collection. Debris like material within the collections showed movement with the change of the position of the patient. All patients were applied cleansing enema before the procedure in order to eliminate feces in the rectum. Antibiotic prophylaxis with oral quinolone and IM metranidazole was started the day before the aspiration and continued with parenteral antibiotic therapy according to the culture results. TRUS guided needle aspiration of the abscess was performed transrectally in all patients with a 20-cm long 18 gauge Chiba type needle. After placement of the probe into rectum, in the left lateral decubitis knee–chest position, the needle was inserted through the biopsy guide attachment into the abscess cavity under sonographic guidance using the end-fire convex probe (Fig. 1). During the aspiration, decreasing volume of the abscess cavity was monitored by TRUS. Succesfull treatment criteria were defined as clinical improvement in symptoms and decrease of more than half of the estimated abscess volume on follow up TRUS control. Patients with continuing clinical symptoms were defined as treatment failures [3]. Patients were than followed up at 3 month intervals by history, physical examination, TRUS and urine culture.
3. Results The main clinical symptom was dysuria which was seen in five patients (83.3%). Other clinical presentations in-
cluded fever, pollacuria, perineal pain, acute urinary retention, hematuria and urethral discharge. As a predisposing factor for PA, two patients were diabetic (33.3%), two patients had previous urinary tract infection (33.3%) and one patient (16.6%) had bladder outflow obstruction. Leukocytes in midstream urine was demonstrated in all patients. Two patients (33.3%) had more than 10 leukocytes per high power field, two had (33.3%) between 5 and 9 and two had fewer than 4 (33.3%). Bacteriuria was not seen in any patients. Urine culture was performed in all patients but was positive only in one patient (16.7%). Escherishia coli was isolated in that patient. Digital rectal examination was performed in all patients. Pain and tenderness was detected in five (83.3%) patients but fluctuation was palpated only in two (33.3%) of them. In all patients the diagnosis was made by TRUS and only in one patient was confirmed by computerized tomography (CT). The most common TRUS finding was detection of a hypoechoic area with inhomogeneous structures which was determined in all patients (100%) (Figs. 2 and 3). In some patients irregular contour and heterogeneous areas were additionally described. The mean prostate weight was 93 g (range 42–162) and the mean abscess volume was 31.6 ml (range 17–65). The TRUS findings in six patients were summarized in Table 1. TRUS guided needle aspiration treatment of PA was successful in five of six patients (83.3%). On follow-up TRUS, no remaining or recurrent abscess formation were found in these five patients. In one patient treatment failed and the abscess recurred 3 weeks after the procedure. As this patient had additionally a bladder outflow obstruction, a repeat procedure was not performed and he underwent a transurethral resection of the prostate (TUR-P). There were no complica-
96
Ç. Gö˘gü¸s et al. / European Journal of Radiology 52 (2004) 94–98
Fig. 2. Longitidunal sonogram shows the abscess as a heterogeneous hypoechoic area with posterior acoustic enhancement which indicates that the content is not solid (arrows).
Fig. 3. Longitidunal sonogram shows an abscess cavity in the inner part of the gland as a well-defined heterogenous hypoechoic area.
tions associated with the procedue. The mean hospital stay was 1.66 days (range 1–3).
4. Discussion PA is a very rare clinical entity and is found in about 0.5% of all prostatic disease [6]. In early years, N. gonorrhea was the primary microorganism comprising about 75% of all cases [7] and the mortality rate was between 30 and 60%
[5]. Nowadays, the incidence of PA was decreased due to widespread use of antibiotics and today gram-negative bacili mainly E. coli are responsible from 60 to 80% of cases [3,4]. There are two mechanisms in pathogenesis of PA. The first and the most common is due to reflux of infected urine. The most frequent microorganisms in that situation is E. coli and other coliform bacteria [2,4]. The second and rarely responsible mechanism is the hematogenous dissemination from a primary focus. Staphylococcus aureus is the most common microorganism in patients in whom the PA is result of
Ç. Gö˘gü¸s et al. / European Journal of Radiology 52 (2004) 94–98 Table 1 TRUS findings in patients with PA Patient
Mean diameter (cm)
Sonographic appearance
Borders
1
3.3
Inhomogeneous Hypoechoic
Well defined Thick wall
2
4.2
Inhomogeneous Hypoechoic
Well defined Thick wall
3
4
Inhomogeneous Hypoechoic
Well defined Thick wall
4
3.5
Inhomogeneous Hypoechoic
Irregular contour
5
2.2
Inhomogeneous Hypoechoic
Irregular contour
6
7
Inhomogeneous Hypoechoic
Well defined Thick wall
hematogenous dissemination [4,8]. The main risk factor for development of PA is diabetes mellitus [5]. Additionally, patients with bladder outlet obstruction, previous urinary tract infection, chronic liver disease, acguired immunodeficiency syndrome and who are on dialysis are at higher risk for developing PA [2,4]. In our study group, showing similarity with the literature, predisposing factors for PA were diabetes mellitus in two patients, previous urinary tract infections in two and bladder outflow obstruction in one patient. Therefore, the clinician should be alert about PA in patients with prostatic symptoms and who has one of the above mentioned predisposing factors. PA usually shows similar symptoms like acute prostatitis. Patients mostly present with dysuria, urinary frequency, perineal pain, fever, acute urinary retention and hematuria [2–4] but they are all nonspecific [6]. The most common finding is pain on digital rectal examination which was seen in 48–100% of patients [4]. Although the typical fluctuant mass for PA has been reported as high as 88% in some published series [6], it is rarely found on digital rectal examination as in our study group [2,3,5]. Thus, it is very difficult to confirm the diagnosis only by physical examination and history. In last years prostatic imaging modalities gained a wide acceptance in diagnosis of PA [9–13]. Of these imaging modalities TRUS is widely used in diagnosis of PA. Except a few conditions that might be a contraindication for TRUS such as in patients with severe hemorrhoids, anal fistulas, fissures or after abdominoperineal resection [14], TRUS can be safely used for this purpose. The most common finding of PA on TRUS is detection of a hypoechoic or anechoic area which is usually well-defined and having thick walls [3–5]. Heterogenous areas and hypoechoic areas with poorly defined walls are less frequently seen [3,4]. The sonographic appearance of PA is usually characteristic and is easily dif-
97
ferantiated from other glandular lesions. However, when the abscess is small and in an early stage, it is not always easy to make the differantial diagnosis with other pathologies like cystic lesions, granulomas and especially with prostatic carcinoma [3,5]. There are several criterias which helps to discriminate PA from prostate cancer and these can be listed as following: prostate cancer is usually detected in the peripheral zone however PA is located in the central and transitional zone of the prostate; tumors are usually small and easily distinguished from the surrounding gland whereas PA contains a large area; PA usually appears as a wider hypoechoic area and is less easily definable during initial phases; color and power Doppler ultrasonography show a high perilesional vascularity in PA which is absent in prostate cancer [3,5]. In our study all patients revealed the characteristic TRUS findings for PA and it was not difficult to confirm the diagnosis. Besides TRUS, CT and magnetic (MR) resonance imaging have also been used in diagnosis of PA. The appearance of low attenuating, round, well demercated fluid collections within the prostate gland by CT is suggestive of PA [10,11]. The MR of PA shows low signal intensity on short echo-time (TE) images, with increased signal intensity on long TE images [12]. These findings show concordance with the MR appearance of abscesses elsewhere in the body [12]. CT and MR are both especially useful for defining the extend of the disease [10–12]. Delay in diagnosis and treatment of PA may cause a lot of serious complications and even death. The basic treatment of PA is adequate drainage and proper use of antibiotic therapy [2–5]. Although the surgical drainage is the best method in treatment of PA, the gold standard has not yet been defined. Perineal incision and drainage, percutaneous transperineal drainage and TUR of the prostate are the alternatives for surgical drainage [4,5]. The restrictive problem with these techniques is that, they may have some serious complications. Perineal incision could cause impotence due to nerve damage [5]. TUR prostate could have standard complications as retrograde ejaculation, urethral stricture and urinary incontinenece [2]. Additionally, it has the risk of hematogenous spread of infected organisms [3,5]. In recent years, TRUS guided ultrasound drainage of PA has been also performed for the treatment of PA. It has the advantages of easy performance and low complication rates [3–5]. The aim of the TRUS guided drainage is to empty the collection and thereby to give permission the antibiotics for entering into the abscess cavity by pressure reduction within the PA [4]. A cystostomy catheter may be placed before the procedure in patients with acute urinary retention or in those who carry a indwelling bladder catheter [15]. TRUS guided drainage procedure may be performed by either tranrectally or transperineally [16]. Transperineal drainage of PA causes more pain and prolonged catheter use when compared with transrectal approach [3,4]. Additionally, bleeding, injury to adjacent organs and spread of infection is minimal with transrectal approach due to direct access through the rectal wall [3,4]. In our six patients we preferred to use transrectal
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approach and all our patients tolerated the procedure well. Some authors prefer to leave a catheter for drainage after the procedure [16]. Although, it is true that catheters provide continuous drainage and make the repeat procedure more easier, we did not place a catheter for transrectal drainage. As it was pointed out by Lim et al., catheters may be uncomfortable for patients [3]. Additionally, as the results of TRUS guided drainage of PA is very successful and few cases need a repeat procedure [4], we also think that a routine catheter placement is not necessary after the procedure. There are just few published reports about TRUS guided PA drainage. In the largest series in literature, Collado et al. reported a success rate of 83.3% in 24 patients treated by TRUS guided drainage [4]. Only two patients needed a second procedure. In that study, they performed also TUR-P in five patients but concluded that TUR-P was indicated in patients with associated bladder outflow obstruction or in those in whom ultrasound drainage was not successful [4]. Lim et al. reported a high success rate of 85.7% in 14 patients. A second procedure was needed in four patients. They also concluded that TRUS guided needle aspiration was an effective method for treating PA without causing any severe complications [3]. Barozzi et al. determined a 100% success rate with TRUS guided aspiration through transperineal approach on five patients with PA [5]. In our study, TRUS guided aspiration was successful in five out of six patients (83%). The treatment failed only in one patient. A repeat procedure was not performed and the patient underwent a TUR-P due to associated bladder outflow obstruction. No serious complications were occured. Although the number of patients in our series and in other series were small, we, as do others, think that patients with PA may benefit from TRUS guided aspiration.
5. Conclusion In conclusion, TRUS has an important value in diagnosis and treatment of PA. TRUS guided aspiration is an effective and minimally invasive treatment modality for PA which causes no serious complications.
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