Enlarged veins or varicose veins occur from the weakening of valves in the veins, causing blood to leak and flow backward and to accumulate in the veins, states Medicine News Today. Predisposing factors include obesity, standing for long periods of time, use of birth control and hormonal imbalance due to puberty, pregnancy and menopause, notes WebMD.
The veins have one-way valves that keep blood flowing from the legs to the heart, explains WebMD. If these veins malfunction, pressure builds up due to the collection of blood in the legs, making the veins become large, twisted and weak.
The veins may lose elasticity with aging, allowing blood to flow backward, causing the vein to enlarge and become varicose, reports Mayo Clinic. These veins may appear blue as they contain deoxygenated blood. During pregnancy, the volume of the blood in the body may increase, but the flow of blood from the legs to the pelvis may decrease, causing enlarged veins. This condition may worsen during late pregnancy but typically improves within three months after delivery.
Enlarged veins run in families, the condition is more common in women than men, and overweight people have a high risk of having varicose veins, says Medicine News Today. During diagnosis, the doctor may want to know about the symptoms, whether a close relative has or had varicose veins and if the patient is pregnant. Tests include a Doppler test and color duplex ultrasound scan.