Seminal vesicle abscess, an exceptional complication of urinary tract infection

Clinical History

Male patient with history of ischaemic heart disease, admitted to emergency department complaining of malaise, persistent fever, pelvic tenderness and dysuria. Ineffectively treated with multiple empiric antibiotics during the past 3 months for recurrent urinary tract infections. Laboratory tests disclosed increased (135 mg/L) C-Reactive Protein, urinalysis revealed microhaematuria and leukocytes.

Imaging Findings

Under clinical diagnosis of persistent urinary infection, ultrasound (Fig.1) revealed a posterior compression on the urinary bladder by a right paramedian inhomogeneous hypoanechoic multiseptated mass.
At urgent contrast-enhanced CT (Fig.2) this uncommon sonographic finding corresponded to marked seminal vesicle enlargement (maximum diameter 8 cm), with thickened enhancing walls and septa, speckled calcifications, and internal liquefied areas, in contact with the upper posterior margin of the normal-sized, heterogeneously enhancing prostate. After its proximal tract, the spermatic cord appeared normal.
Diagnosis of seminal vesicle abscess resulting from untreated urinary tract infection or bacterial prostatitis was confirmed by clinical improvement, by partial size regression, disappearance of mass effect and colliquated portions at follow-up CT two weeks later (Fig.3) after intensive in-hospital antibiotic treatment, and by normalization of serum prostate specific agent (PSA, from 10 to 5 ng/mL) over two months. Persistently negative urine cultures after several antibiotics failed to disclose the causative pathogen.

Discussion

The seminal vesicles (SVs) are paired ancillary male urogenital organs whose function is to produce and secrete the seminal fluid, which contributes up to 80% of the ejaculate volume. The extraperitoneal SVs are located just above the prostate, posteriorly to the bladder and distal ureters, and anterior to the rectum. Although primary SV disorders are rare, these glands may be involved by disease processes arising in the surrounding organs [1, 2].
After the introduction of antibiotics, seminal vesicle abscess (SVA) has become a very rare disease, with less than 30 reported cases. Predisposing factors include urinary tract infection, diabetes, indwelling catheters, urological instrumentation, and anatomical abnormalities. The commonest pathogen is Escherichia coli, and in endemic countries Mycobacterium tuberculosis and schistosomiasis may cause chronic SV infections. Bacterial SV infection may be uni- or bilateral, and is more commonly secondary to acute prostatitis or epididymo-orchitis rather than isolated. Presenting symptoms commonly include fever (in 74% of patients), dysuria (58%), sometimes purulent ejaculation or haemospermia [3-8].
Whereas SV disorders are clinically difficult to diagnose, imaging modalities including transrectal ultrasound, CT, and MRI are increasingly used to investigate abnormalities of these glands. Although sometimes overlooked on abdomino-pelvic CT studies, as this case demonstrates the SVs may harbour unexpected but significant diseases [1, 2].
The normal SVs appear on CT and MRI images as finely septated fluid-containing paired structures, which may sometimes be moderately asymmetric in size, measure approximately 3 cm in length and 1.5 cm in width in the adult, and tend to shrink with advancing age. An abscess usually appears as unilateral or bilateral SV enlargement with enhancing mural thickening, internal hypoattenuating areas, and adjacent fat inflammatory changes. Bladder wall thickening and prostatic inhomogeneity are frequently associated [1-4, 8, 9].
Whereas most SVA were treated by percutaneous transvesical drainage, transrectal aspiration, or surgical incision, recently there is a trend towards a more conservative therapeutic approach [4, 5, 7].
In conclusion, although SV infections may be clinically unsuspected, cross-sectional imaging findings should not be underestimated in order to promptly initiate treatment [1, 2, 9].

Differential Diagnosis List

Final Diagnosis

Seminal vescicle abscess from lower urinary tract infection/prostatitis

URL:	https://www.eurorad.org/case/11346
DOI:	10.1594/EURORAD/CASE.11346
ISSN:	1563-4086