Persistent pelvic pain, not only affecting the pelvic area

Persistent pelvic pain (PPP) can lead to far-reaching physical, psychological, and even economic burden for the patient and for society. Some of PPP can be traced back to existence of endometriosis, a condition in which endometrium cells which line the uterus, are found outside of it.

In a Swedish study published last year, researchers explored whether patients with PPP, with or without confirmed endometriosis, suffered sensitization as compared to healthy controls (Grundström et al. 2019).

What QST was performed?

Thermal quantitative sensory testing (QST) was conducted using Medoc’s TSA-II. Heat and cold pain thresholds were performed on the lower back, the midline abdomen, the lower abdomen, and the lower leg as a reference site. Additional measures were pressure pain thresholds, quality of life (SF-36), and depression and anxiety questionnaires (HADS).

Widespread sensitization in persistent pelvic pain

In total 97 women participated in the study. Of those, 37 suffered from PPP, among them 13 with biopsy proven endometriosis.

Women with PPP, irrespective of endometriosis confirmatory biopsy, has significantly lower pain thresholds on all tested sites, including the dominant lower leg.

There was also a statistically significant negative correlation between pain duration and pain thresholds in PPP patients; the longer the pain was present, the lower the pain thresholds.

Pain thresholds and quality of life

Interestingly, in PPP patients heat and cold pain threshold were significantly correlated to the bodily pain dimension in the SF-36, while the cold pain threshold was significantly correlated to the depression subscale of the HADS.

These findings link self-reported pain and pain duration to measurable thermal thresholds, suggesting the value and usability of QST in clinical pain management.