Study designs of evaluations included in the review
Observer agreement and method comparison studies were eligible for inclusion in the review. A paper was classified as a reliability study if the observer agreement for bladder volume estimation was evaluated. A paper was classified as a validity study if it compared the ultrasound estimation to the actual volume determined by a suitable reference standard.
Specific interventions included in the review
To be eligible for inclusion in the review, the studies had to use real-time ultrasonic estimation of bladder volume (content or residue).
Reference standard test against which the new test was compared
No inclusion criteria were specified with respect to the reference standard test.
The included studies used instilled volume,catheter, voided volume, voided volume plus instilled volume, voided volume plus catheter, or catheter plus instilled volume, as the reference standard.
Participants included in the review
The participant inclusion criteria specified only patients and volunteers on whom real-time ultrasonography was performed.
Of the primary studies included in the review, seven focused on females (n=188), 5 on males (at least 51; one study did not state the number of participants), and 4 on a mixture of males and females (n=265). The study groups included: postpartum (n=38), gynaecology surgery (n=96), urodynamic clinic (n=49), urinary tract infection (n=5), benign prostatic hyperplasia (n=34), neurogenic bladder (n not stated), volunteers (and voiding) (n=53), dysuria (n=7), unspecified patients (n=100), stroke patients (n=41) and urological problems (n=81).
Outcomes assessed in the review
No inclusion criteria relating to the outcome measures were specified.
The outcomes assessed in the included studies were the estimated bladder volume (total content or residue) by ultrasonic measurement and the 'true' bladder volume. The reliability and validity outcomes were: the standard product-moment correlation coefficient; the intra-class correlation; the limits of agreement; the mean error, i.e. the difference between the estimated and actual bladder volume, presented as a percentage of the estimated bladder volume; the estimated bladder volume as a percentage of the actual volume; and semi-quantitative estimates of the ability of ultrasound to detect bladder volumes greater than 50 mL.
How were decisions on the relevance of primary studies made?
The citation lists without the authors' names, their institutional affiliation, and the journal in which they were published, were independently reviewed by two authors. Any disagreements in selecting the studies were resolved by consensus or arbitration by other reviewers.