Can maternal urinary and serum carbohydrate antigen 19-9 concentrations be utilized in the diagnosis of fetal hydronephrosis?

Fetal hydronephrosis (FH) is the most common fetal renal pathology encountered in daily obstetric practice. Urinary and serum carbohydrate antigen 19-9 (CA 19-9) concentrations are elevated in obstructive renal pathologies. Our aim was to assess maternal urinary and serum CA 19-9 concentrations in pregnancies with FH and compare results with controls. Twenty pregnancies with severe FH, 20 pregnancies with mild-moderate FH, and 20 healthy singleton pregnancies were included in this descriptive, case-control study. The diagnosis and classification of FH was based on the anterioposterior diameter of fetal renal pelvis. Maternal urinary and serum CA 19-9 concentrations were measured and compared between groups. Severe FH cases had significantly higher maternal urinary CA 19-9 concentrations compared to controls (median: 75 vs 24 U/mL; respectively; p=0.014). Concentrations of CA 19-9 did not differ between the mild-moderate FH group and control group. No statistically significant difference was found between the groups with respect to maternal serum CA 19-9 concentrations. Our results show that maternal urinary CA 19-9 concentration is significantly higher in pregnancies with severe FH. However, no difference was detected in serum CA 19-9 concentrations between pregnancies with severe FH, mild-moderate FH and controls. If the mechanisms of transplacental passage and maternal urinary excretion are clarified, maternal urinary CA 19-9 may be a potential marker for indicating fetal kidney damage.