PREVESICAL ABSCESS SECONDARY TO PUBIS SYMPHYSIS SEPTIC ARTHRITIS

Abstract

Abscess formation in the prevesical or retropubic space is a rare condition. Secondary abscesses in this area have been described in adults after corrective surgical procedures done for urinary incontinence 1 and after Mycobacterium tuberculosis infection. 2 To our knowledge only one case of spontaneous formation abscess associated with urachus cyst infection has been reported. 3 Here, we describe a case of spontaneous prevesical abscess in a 12-year-old girl. Case report. A 12-year-old girl was admitted to our hospital with a 5-day history of fever (39–40°C) and malaise. The only remarkable finding was a 15-day history of discomfort in gait that had become painful in the left groin 3 days before admission. She practices classical ballet regularly and had recently been doing the “grand ecart” or “splits,” a movement consisting in the simultaneous 90-degree abduction of both hips that involves sliding the lower limbs over the floor. The patient had a septic appearance with skin, but not mucosal, paleness. Body temperature was 39.4°C and heart rate was 120 beats/min. A systolic heart murmur was heard along the left sternal border and lung auscultation showed diminished breath sounds. An irritative and persistent cough was present. She complained of pain when the left groin and ischiatic area were palpated, with loss of strength in her left lower limb. On passive mobilization of the left hip, no movement limitation, muscle contracture or pain was found. Laboratory evaluation revealed a white blood cell count of 5600/mm 3, with 25% band forms in the peripheral blood smear; hemoglobin 11.5 g/dl; hematocrit 34.4%; erythrocyte sedimentation rate 75 mm/h; prothrombin time 49%; and fibrinogen 829 mg/dl. After admission and despite treatment with intravenous cefotaxime and oral ibuprofen, the patient’s clinical condition remained unchanged, and daily temperature peaks of 38–39°C were recorded. No abnormalities were observed in the pelvic radiographs or in hip echography. Pelvic computed tomography (CT) revealed a distinct extraperitoneal abscess-like image, close to the pubis symphysis with involvement of the amphydiarthrosis (Fig. 1). A CT-guided percutaneous needle aspiration of the abscess was performed, and a Gram-stained smear of the obtained material revealed Gram-positive cocci; growth of Staphylococcus aureus was obtained from the abscess material and from two blood culture bottles.Fig. 1: CT scan of the pelvis. Abscess-like image in the prevesical space involving the joint area and regional muscles, pectinal and internal obturator.An extraperitoneal fasciotomy with surgical cleaning of the area was performed. No hematoma was observed. The muscles were edematous, but muscle necrosis was not observed. The patient received a 4-week course of cloxacillin (2 weeks iv and 2 weeks po). A CT scan performed 2 weeks after open debridement revealed a bone sequestrum in the left ramus pubis, close to the symphysis, showing the joint involvement in the abscess formation. The patient improved and defervescence ensued 24 h postsurgery; 6 months later she remained asymptomatic. Discussion. Abscesses involving soft tissues in the pelvic or retroperitoneal space (like piriformis or psoas muscles) usually cause gait disturbances, 4, 5 with symptoms similar to those in infectious conditions involving both bone and joints in the pelvic girdle. 6, 7 The organisms most commonly involved in these events are S. aureus6, Streptococcus spp., 8Pseudomonas aeruginosa, when surgical procedures or intravenous drug abuse are associated 9, 10 and, rarely, Mycobacterium tuberculosis.2 The suggested pathogenic mechanisms of local infection in the pelvic girdle include mechanical trauma, vascular abnormalities and reflex sympathetic dystrophy; any of them might be related to urologic or gynecologic surgery, pyelonephritis, herniorrhaphy or pregnancy. 11 Children with septic arthritis of the pubic symphysis usually have abnormal gait, pain at the groin area and systemic symptoms such as fever or malaise related to the septic process developed from the infective focus. S. aureus is the most common causative microorganism. 6, 8 The clinical diagnosis must be secured with imaging (computed tomography and magnetic resonance) and radionuclide techniques. In our patient the clinical manifestations and bone involvement signs of the ramus pubis found in CT suggest abscess development secondary to septic arthritis of the pubic symphysis. Although described as a scarcely suppurative condition, abscess formation has occasionally been observed. 8 Generally in spontaneous S. aureus osteomyelitis of the pubis, the portal of entry is not demonstrated, and the mechanism involved in bacterial colonization at these sites is not clear, although continuous local microtraumas have been described as a possible triggering factor for this condition in healthy children. 8 In our patient the frequent and repeated vigorous physical activities during ballet practice could have led to joint tissue microtrauma in the pubic symphysis, favoring S. aureus colonization and subsequent small abscess formation with few local symptoms and ultimately resulting in septic pattern. In the pathogenic process of musculoskeletal tissue infection, staphylococcal surface components 12 can bind to host cell surfaces and to various tissue proteins in the extracellular matrix. 13 Exposure of extracellular matrix is increased during traumatic tissue damage. These phenomena lead to enhanced adherence of the microorganism to the vascular endothelium and exotoxin synthesis. 12