Hematocolpos as a cause of back pain in premenarchal adolescents.

Persistent low back pain in children demands thorough investigation. An unusual cause of such discomfort is hematocolpos secondary to imperforate hymen in premenarchal girls. Experience with four patients whose initial primary symptom was low back pain has been documented. All had large pelvic masses with greater than 400 ml of old blood being drained at hymenotomy in all patients. Irritation of the sacral plexus or nerve roots is postulated as a mechanism for the referred back pain. Hematocolpos should be included in the differential diagnosis of prepubertal girls who have low back pain.