Another aspect of acute urinary retention in young patients.

Four homosexual men and one heterosexual woman presented with acute urinary retention secondary to intense anal intercourse. All had normal urologic histories. Their residual urine volumes ranged from 475 ml to 1,400 ml. Urinalyses and urine cultures were negative. All were treated with an indwelling Foley catheter and then with bethanechol and dibenzyline. Normal micturition was restored. To evaluate the influence of anal dilatation on detrusor function, five control patients with urge incontinence were studied. A cystometrogram (CMG) displayed a hyperreflexic bladder pattern in all five patients. Average bladder capacity was 86 ml. Calibrated anal dilatation increased bladder capacity to the average value of 406 ml on CMG. The diameter of anal dilatation ranged from 3.5 cm to 5 cm. Intense anal intercourse producing severe anal dilatation triggers reflex bladder inhibition leading to acute urinary retention. The sensory input travels from the dilated anus to the sacral spinal micturition center, which sends inhibitory stimuli to the urinary bladder.