When semen is ejaculated ,it is thick and gel like. This is to help it adhere to the neck of the womb(cervix). The semen eventually liquefies within 15-20 minutes, setting free the sperm and enabling them to swim up the genital tract .
A viscous semen with delayed liquefaction may affect your fertility as it may indicate infection of the testis, seminal vesicles( a pair of tube-like glands,behind the urinary bladder) and the prostate gland, (a walnut-sized gland located between the bladder and the penis). Both the seminal vesicles and prostate gland contribute and secretes most of the seminal fluid that nourishes and protects sperm .
Most of the time, the infection of these organs is due to sexually transmitted diseases such as Mycoplasma, Chlamydia and Gonococcus. Early treatment of the infection is important to correct the abnormality of the semen. Anti-inflamatory medications and diuretics (pills that help rid your body of salt (sodium) and water) are also helpful .