Long-term outcome of kidney function after twin-twin transfusion syndrome treated by intrauterine laser coagulation.

Twin-twin transfusion syndrome (TTTS) is caused by unbalanced shunting of blood between monochorionic twins. It is well known that chronic hypotension and hypovolemia may cause renal insufficiency in the donor twin. The long-term outcome of kidney function after TTTS has not previously been delineated in the literature, however. The aim of this study was to evaluate the long-term outcome of kidney function in children after intrauterine laser treatment for severe TTTS. Eighteen surviving twin pairs after intrauterine laser treatment for TTTS were involved in the study. Their gestational age at birth was 29-39 weeks, their median birth weight was 2050 g, and their median age at evaluation was 3 years 1 month, range 1 year 9 months to 4 years 5 months. Serum creatinine, cystatin C, and beta 2-microglobulin, sodium, potassium, and phosphate excretion, and urine albumin and alpha-1-microglobulin were measured. Creatinine clearance was calculated by use of the Schwartz formula. The laboratory findings for all 36 children were within normal limits. There were no significant differences between donors and recipients. Despite severe alteration of renal function before the laser treatment (anuria-polyuria) no long-term impairment of renal function could be detected in any of the 18 twin pairs.