German researchers assessed perception thresholds for rectal distension and cutaneous referral of symptoms, while inflating one or two rectal balloons and the effect of both electro-acupuncture and placebo-acupuncture on rectal distensibility, perception and spatial summation. A tube with two barostat balloons was placed in the rectum of 12 healthy subjects and nine irritable bowel syndrome (IBS) patients with rectal symptoms. Volume-controlled stepwise distension of the distal balloon only or both balloons was performed first as a control, and thereafter with simultaneous placebo- or electro-acupuncture in dermatomes S3 and S4. A symptom questionnaire and an anatomic questionnaire were completed during each distension. Rectal elastance increased from 42.0 ± 19.6 log mmHg/ml during one-balloon distension to 59.6 ± 33.1 log mmHg/ml during two-balloon distension in healthy subjects, and from 48.8 ± 14.4 log mmHg/ml (one balloon) to 77.6 ± 24.2 log mmHg/ml in patients with IBS. Electro-acupuncture had no effect on rectal sensation, elastance and cutaneous referral when compared to placebo-acupuncture. However, acupuncture (both electro- and placebo-) increased volume thresholds for sensation compared to control experiments, while objective parameters like rectal tone and elastance were unaltered.