Purpose: To determine whether bladder pain syndrome/interstitial cystitis (BPS/IC) has the characteristics of a functional somatic syndrome (FSS).

Materials and methods: There is no accepted definition of an FSS. Consequently, this paper reviewed the literature for common FSS characteristics and for reports that BPS/IC has these characteristics.

Results: Eleven articles met inclusion and exclusion criteria and yielded 18 FSS characteristics. BPS/IC patients manifest all but two: the exceptions were normal light microscopic anatomy (after hydrodistention under anesthesia, some BPS/IC bladders have Hunner's lesions and most have petechial hemorrhages) and normal laboratory tests (many BPS/IC patients have hematuria). Petechial hemorrhages and hematuria are probably related and may appear during naturally-occurring bladder distention. Without such distention, then, the 90% of BPS/IC patients without a Hunner's lesion have all the characteristics of an FSS. Comparisons in the opposite direction were consistent: several additional features of BPS/IC were found in FSSs.

Conclusions: This systematic but untested method is consistent with but does not test the hypothesis that BPS/IC in some patients might best be understood as an FSS. Like most conditions, BPS/IC is probably heterogeneous; hence only a proportion of BPS/IC cases are likely to be manifestations of an FSS. This hypothesis has several implications. Explorations of processes that connect the FSSs might contribute to understanding the pathogenesis of BPS/IC. Patients with FSSs are at risk for BPS/IC and may benefit from future preventive strategies. Therapies that are useful in FSSs also may be useful in some cases of BPS/IC.