Aims of study
An essential part of investigation of the lower urinary tract is pressure/flow studies (PFS). There are controversies regarding whether or not oral prophylactic antibiotic treatment is necessary. This prospective study was carried out in order to determine the frequency of infections and/or distress following PFS performed without the use of antibiotic prophylaxis.

Patients and Methods.
A total number of 126 patients were included in the present study. They were all requested to answer a questionnaire one week following PFS. Questions were asked as for symptoms concerning voiding disorders, dysuria, hematuria, incidence of fever and the patient's acceptance of the investigation after the PFS procedure. Bladder cooling test was performed followed by PFS. No patients hade symptoms of UTI prior to the investigation. Urine was obtained for culture immediately before the PFS and 3 and 7 days following the PFS. UTI was defined as a culture of organism in excess of 100.000 colony forming units.

Results.
46 percent of the patients experienced some degree of transient dysuria following PFS. 18.5 percent experienced voiding problems of various nature. Five percent of the patients had hematuria and 2.5 percent reported fever. 50 percent of the patients experienced some degree of discomfort during the PFS investigation. Of the 126 patients involved in the study, four patients were lost to follow-up and two had unsuspected ongoing infection at the time of PFS, leaving 120 patients to be assessed. Fourteen patients out of 120 (11.67%) were diagnosed with UTI. Four of them did not receive antibiotics, due to transient significant bacteruria which disappeared without symptoms. Ten patients (8,33%) received antibiotic treatment, five of which (4,17%) had UTI related symptoms whereas the remainder had transient asymptomatic bacteruria with a positive culture three days after PFS with a spontaneous conversion to negative culture after an additional four days (prior to antibiotic treatment).

Conclusion.
In our present series, the PFS was well accepted. Less than ten percent of the patients reported moderate/severe distress during the investigation. Problems after PFS were in all cases mild and transient. The low risk of developing symptomatic UTI after PFS makes the use of prophylactic antibiotics doubtful. Yet, we believe that patients with increased risk of cerious complications from infections (e.g. prosthetic heart valve, orthopedic prosthesis) should receive prophylactic antibiotics.