gross haematuria can be a very distressing and frightening symptom and usually leads patients to seek immediate medical care . the cause of haematuria should be thoroughly evaluated and in adults should be regarded as a sign of malignancy until proven otherwise . ultrasound ( us ) is one of the initial examinations performed and is very useful in detecting kidney and bladder lesions . the sensitivity of us in detecting bladder tumours ( bt ) is variably reported to range from 26% to over 80% [ 1 , 2 ] . however , this rate is much lower in patients with tumours smaller than 5  mm or for tumours located on the bladder dome or anterior wall . similarly , specificity is decreased in the presence of coexisting focal cystitis , bladder trabeculations , and haematuria with clots . for this reason , a significant number of bladder us are normal or inconclusive , and cystoscopy is necessary to discard the presence of a bladder tumour . three - dimension us imaging has recently become a widely available feature in many ultrasound machines . this technology permits the acquisition and storage of a dataset , selected from a specific region of interest . this dataset can be further analysed , either by multiplanar display , surface rendering , or volume calculation . as there is a considerable contrast gradient between the bladder lumen and its wall , the surface rendering algorithm can usually display with sufficient detail the surface of the bladder , revealing a cystoscopic - like image , enhancing the characterization of bladder wall abnormalities . in this study , we examined the value of 3d us in diagnosing bladder tumours in patients with haematuria of unknown cause . patients admitted in the emergency department presenting with painless gross haematuria and without history of trauma or evidence of urinary tract infection were prospectively enrolled . all patients underwent conventional 2d bladder and kidney us in the emergency department performed by a radiologist . when needed , bladder clot evacuation was performed previous to the us . examining physicians were asked to report the bladder us as  with bt  or  no bt .  in some patients , the radiologist observed bladder lesions that were more difficult to characterize , because of unclear limits or image artefacts . patients diagnosed with kidney disease , bladder tumours , or calculi causing the haematuria were excluded . uncertain  bladder us findings were scheduled for a 3d us examination , usually the next day , followed by flexible or rigid cystoscopy . a philips hdi 4000 ultrasound system ( philips medical systems , best ; netherlands ) with a 3.55  mhz transabdominal probe was used . patients were asked to drink about 1  l of water and not to void 1  h before the study in order to perform it with near maximum bladder capacity ( volume  250  cc ) , a 2d us was carried out in the sagital and transverse plane , and afterwards several 3d acquisitions ( 2 to 5 datasets , mean 2,5 ) were made and evaluated using the surface rendering algorithm . comparative analysis was carried out between the imaging findings collected by 2d and 3d us to those of the cystoscopy . twenty one patients ( 19 men and 2 women , mean age 69.0 years old ) were enrolled in the study . twelve ( 57% ) where reported as  no bt  and 9 ( 43% ) as  uncertain  on the conventional 2d us performed in the emergency department . the 3d examination found  no bt  in 15 patients ( 71.4% ) . in 5 of these patients , uncertain ,  largely because they had bladder trabeculation that made the 2d us difficult to interpret . none of these patients had bladder tumour on cystoscopy ( figure 1 ) . in 5 ( 23.8% ) patients , 3d us identified bladder tumours that were not detected in the previous us examination . this was statistically different from the results of 2d us ( p = 0,025 ) . all these patients were found to have bladder tumours on cystoscopy , although in one patient cystoscopy revealed another 5  mm lesion that was not detected on us . in one patient all 6 patients with bladder tumours on cystoscopy underwent a transurethral resection ; 4 had transitional cell carcinomas ( tccs ) , 1 had a papilloma , and the remaining patient was revealed to have only inflammation . lesion diameter ranged from 5 to 20  mm ( mean 7  mm ) . in the population with negative 2d us , the 3d us showed a sensitivity of 83,3% and a specificity of 100% in identifying patients with bt , with a positive predictive value and negative predictive values of 100% and 93,8% , respectively . when evaluating patients with painless haematuria , it is mandatory to exclude the existence of tumours of the urinary tract . us imaging is one of the frontline examinations since it is widely available and noninvasive . when a us clearly shows a bladder tumour , a transurethral resection is usually subsequently performed ; however , when the us examination is normal or ambiguous , a diagnostic cystoscopy becomes mandatory . flexible cystoscopy , though less traumatic , is still an invasive procedure associated with patient discomfort and can by itself be the cause of urinary tract infections and haematuria . in order to overcome these problems , other imaging techniques such as contrast enhanced us [ 8 , 9 ] , and virtual cystoscopy performed with computed tomography or magnetic resonance imaging , have been developed with promising results [ 1013 ] . these techniques seem to be more sensitive than us but significantly more time consuming , expensive , and frequently inaccessible for clinicians . moreover , all these imaging techniques are unable to detect subtle alterations of bladder mucosa such as carcinoma in situ . for such lesions , cystoscopy and , more recently , fluorescence cystoscopy and narrow - band imaging cystoscopy are still the most accurate examinations [ 14 , 15 ] . three - dimensional ultrasound is now an established imaging tool in several specialities , this technology is available in most medium and upscale equipments and is routinely used in obstetric us . in urology , it has been used in planning and guiding prostate cancer treatments , to accurately measure bladder volume   and in imaging the urethral sphincter in pelvic floor disorders . recently , the use of 3d us in the evaluation of bladder tumours has been reported showing a moderate - to - perfect interobserver agreement . wagner et al .   studied 3d us as a staging tool in distinguishing invasive from noninvasive bladder tumours , showing an overall accuracy of 79% . this technology has also been studied as a screening tool ; mitterberger et al .   studied 42 patients with painless haematuria , all of whom had an abnormal 2d us . they found that 3d us diagnosis was correct in 86% of patients whereas 2d us diagnosis was correct only in half of them . another group   compared the accuracy of 2d and 3d us in 14 patients with proven bt and found 3d us to have better sensitivity . in our study , we evaluated only patients with an undetermined cause of haematuria after 2d us , and we similarly found greater sensitivity of 3d us in detecting bladder tumours ( table 1 ) . however , this sensitivity was not related to lesion size since 57% of lesions were 10  mm or more . this might be explained by the fact that the 3d reconstruction facilitates the distinction of tumour lesions from bladder folds , becoming particularly useful in patients with bladder trabeculations and diverticula . although cystoscopy is still mandatory in those patients with an unidentified cause of haematuria , we think that 3d us can avoid cystoscopies by clearly identifying and accurately characterizing bladder lesions . in this series , 5 patients ( 23.8% ) could have skipped cystoscopy and be directly referred for a transurethral resection , saving patient discomfort , time , and money . although not prospectively assessed in this study , the specificity of 3d us seems to be superior to 2d us . in our series , in 5 patients which had uncertain findings on 2d us , the subsequent 3d reconstruction has shown better characterization of their lesions and clearly identified bladder trabeculae and prostatic median lobe that could mimic a bt on 2d us . further investigation is necessary to determine the actual improvement in specificity of 3d us in these patients . we are aware that in this study 2d and 3d us were performed under different conditions : the first was done in the emergency department by a radiologist , and the second in a different day by a urologist . the degree of haematuria may also have been different between the two examinations , however , clot removal was performed before the us whenever necessary , so the degree of haematuria should not have a major impact on the exam performance . we usually carry out 2 to 3 volume acquisitions with a mechanical motor - driven transducer and evaluate the images using a surface - rendering algorithm . bladder tumours appear as round or oval protrusions into the bladder lumen and most software allows navigation through the surface of the bladder , and looking at the lesions from different angles . overall , this procedure may add as little as 5 to 10 minutes to the examination time but substantially improves the overall accuracy of the exam , therefore , we think that this technology when available should be used in the diagnostic workup of patients with haematuria of unknown cause . three - dimensional bladder us has superior sensitivity than 2d us in diagnosing bladder tumours in patients with haematuria . although cystoscopy is still the gold standard examination , 3d us is a promising tool in diagnosing bladder tumours and might reduce the number of cystoscopies needed to study these patients .
purpose . bladder cancer is a frequent cause of haematuria in elderly patients , and bladder ultrasound ( us ) is a valuable tool in diagnosing these malignancies . 
 we examined the accuracy of 3d bladder us in diagnosing bladder tumors in patients with haematuria . 
 patients and methods . 
 twenty - one patients observed in the emergency department for haematuria underwent a kidney and bladder us . 
 patients with normal or uncertain bladder us findings underwent a 3d us and a cystoscopy . 
 results . in 5 ( 23.8% ) patients , 
 the 3d us detected bladder tumours not seen in 2d us . 
 all these patients were found to have bladder tumours on cystoscopy . 
 another 5 ( 23.8% ) patients with uncertain findings on 2d us had normal 3d us and cystoscopy . 3d us showed a sensitivity of 83.3% and a specificity of 100% with a positive predicted value and negative predictive values of 100% and 93.8% , respectively . conclusion . 
 3d us was more sensitive than 2d us in diagnosing bladder tumours in patients with haematuria .