The effect of sacral nerve stimulation on uterine activity: a pilot study

Sacral nerve stimulation (SNS) is a treatment for consecutive therapy resistant faecal incontinence or constipation. Little is known about the effects of SNS on uterocervical function. Therefore, it is advised to turn off the stimulator during pregnancy or to wait with permanent implantation of the stimulator until family completion. Diagnostic ultrasound provides an, non-invasive, opportunity to study various aspects of uterine activity. The purpose of this pilot study was to assess the influence of SNS on endometrial waves of the nonpregnant uterus by ultrasound recordings.

Six patients with an implanted SNS were included. Ultrasound recordings were performed with the stimulator turned off and in three stimulation frequencies. Uterine activity is described as wave frequency and wave direction.

All three premenopausal patients showed endometrial activity with the stimulator turned off. This activity was maintained with the stimulator turned on in two patients, but disappeared in one patient. All three postmenopausal patients had no endometrial activity with the stimulator turned off. In one patient there was activity with the stimulator turned on at a frequency of 21 Hz.

We have shown some effect of SNS on uterine activity. In premenopausal women we discovered that SNS seems to exhibit no effect or an inhibitory effect rather than an excitatory effect on uterine activity. Based on the preliminary results of this study, we can not recommend any guidelines for SNS usage during conception and pregnancy. A larger study in premenopausal women with SNS is needed to investigate the significance of these changes.