Uroflowgram is evaluated based on the following parameters:
- voided volume;
- average flow rate;
- maximum flow rate;
- uroflow index;
- flow acceleration;
- flow time;
- voiding time;
- time of maximum flow;
- waiting time;
- character of the uroflow curve.
Voided volume (V) — the volume of the urine discharged through the external urethral opening during study. The results are most reliable when the voided volume is between 150 and 350 ml. Unit – ml.
Flow time (T) — time interval when voiding occurs, without intervals between separate micturitions. Unit – s.
Voiding time — time interval from the beginning to the end of voiding, including intervals between separate micturitions. Unit – s.
Average flow rate (Qavg) — the ratio of the voided volume in milliliters to the flow time in seconds. Most often, it is used as an index for the entire uroflow curve. Unit – ml/s.
Maximum flow rate (Qmax) — the maximum voided volume discharged through the external urethral opening per time unit. The given index is defined on uroflow curve as its maximum value. Unit – ml/s.
Uroflow index (UI) — the value calculated using a mathematical approximation of the Siroky nomogram. The uroflow index allows estimation of urodynamics independently of the voided volume.
The values UI>1.1 should be considered as normal.
At UI=0.8-1.1 further examination of the patient is necessary.
Values UI<0,8 indicate definite pathology.
Time to maximum flow rate (TQmax) — time interval from the voiding beginning to the maximum volume rate. The given index depends on maximum flow rate and discharged urine volume. Unit – s.
Waiting time (Tw) — time interval from the beginning of the study to the actual start of voiding. Unit – s.
Character of the uroflow curve (uroflowgram) — different types of uroflowgrams can be observed with various voiding dysfunctions. In typical cases the uroflow curve can indicate clear abnormality but it never can be diagnostically specific. Irregular curves can be caused by an insufficient activity of the detrusor, abdominal wall tension, bladder ptosis that bends the urethra, sphincter dyssynergia or psychological inhibition.
More information about the different types of uroflow curves can be found in the Uroflow study repository section.
Flow-K is equipped with the ability to construct nomograms.
Uroflow nomograms represent a generalization of the experimental data received from uroflow studies of a considerable number of patients. Nomograms allow visual estimation of the patient’s voiding quality without dependence on voided volume and the patient’s age. A nomogram represents the relationship between two variables: maximum flow rate and voided volume, or average flow rate and voided volume. Several similar graphs are plotted. Each graph corresponds to a certain percentile – percent number. For example, if the graph is marked as 5 %, it means, that the flow rate and the points corresponding to these rates that fall under the given graph are observed in 5% of patients.
When the point corresponding to the patient’s uroflow parameters is below the 50th percentile curve, further examination is required. If the point is below the 5th percentile curve, it indicates definite pathology.