Interrelationship of plasma and urinary luteinizing hormone preovulatory surge

The only reliable method of predicting spontaneous ovulation relies on the detection of the preovulatory luteinizing hormone (LH) surge in urine or plasma. The efficiency of the detection by means of plasma LH radioimmunoassay, urine LH radioimmunoassay or urine LH agglutination inhibition immunoassay were compared in 33 patients. The detection of the onset of LH surge was simultaneous in plasma and urine in only 11 cases. In two thirds of the patients, the urine LH surge onset is delayed by 3 to 21 h as compared with plasma LH surge onset. In some of these cases the oocyte would probably be missed if the laparoscopy had been scheduled according to urine data.