Water balance of Dermatophagoides pteronyssinus (Acari: Pyroglyphidae) maintained by brief daily spells of elevated air humidity

OBJECTIVES: To review the urological abnormalities in conjoined twins, a rare congenital abnormality arising from an incomplete separation of a pair of monozygotic twins, and who can be joined from the head to the pelvis with varying degrees of union. PATIENTS AND METHODS: The records and urological anomalies of conjoined twins presenting from 1985 to 1995 were reviewed retrospectively and the management and surgical reconstruction described. RESULTS: Seven of 11 sets of conjoined twins underwent surgical exploration. Complex urological problems occurred in all twins with omphalo-ischiopagus. The urological anomalies were: Set 1; both twins had one lateral crossed fused renal ectopia with uncrossed ureters draining into a single bladder with one urethra. They had one set of genitalia. Each twin received one crossed fused ectopic kidney, half the bladder and genitalia, with one retaining the urethra and one a vesicostomy. Set 2; these twins had four kidneys (two lateral and two central that were fused), four ureters (two of which crossed) and these drained into two sagittal bladders that emptied by one urethra associated with a single set of external genitalia containing three corpora cavernosa. At separation, the crossed ureters were re-routed, each received a bladder and the genitalia were split. Set 3; there were four kidneys with two crossed ureters draining into two collateral bladders, there was a partial duplication of the urethra and a single hypospadiac penis. After separation, each had kidneys draining into a bladder, one received the urethra and external genitalia, and one a urostomy. CONCLUSION: Complex urological problems occur in conjoined twins, although restricted to those with pelvic fusion (ischiopagus). Assessment and treatment needs to be individualised and overseen by a surgeon with experience in complex urology.