The significance of abdominal straining in men with lower urinary tract symptoms

To determine the relationship between the symptom of straining to void, the presence of objectively demonstrated abdominal straining and bladder outflow obstruction in men with lower urinary tract symptoms (LUTS), and to assess the effect of straining on flow rate in these men.

The presence of straining to void as a symptom was determined from a symptom questionnaire in 61 men presenting with LUTS. Objective evidence of straining to void was assessed by rectal pressure measurement and the presence of bladder outflow obstruction was determined by pressure-flow studies. The effect of straining on flow rate was assessed in a separate group of 58 men with LUTS, by comparing the maximum flow rate on non-strain and strain voids of similar volume.

There was poor agreement between the complaint of straining and the presence of straining as measured by rectal pressure recording. Twelve of the 53 patients who claimed they never or occasionally strained to void in fact showed straining on each of four voids. There was no significant difference in the proportion of men who complained of straining in the obstructed and non-obstructed groups (P = 0.86). The probability of obstruction in those men with objective evidence of straining on all voids was 80% and in those who did not strain on all voids was 51%, but this difference was not statistically significant (P = 0.53). There was no clinically significant effect of straining on maximum flow rate in men with LUTS.

As a symptom, straining is an uncommon complaint in men with benign prostatic hyperplasia (BPH), and the relationship between the symptom and objective evidence of its presence is poor. Both as a symptom and as an objectively measured voiding disorder, straining lacks sufficient sensitivity and specificity for it to be of value in the diagnosis of bladder outlet obstruction (BOO). Abdominal straining does not have a marked effect on flow rate in men with BPH. This study suggests that straining is an unreliable symptom of BOO, that it does not influence voiding function in elderly men and that its inclusion in symptom scores for BPH should be reconsidered.