The Perthes test is a clinical test for assessing the patency of the deep femoral vein prior to varicose vein surgery. It is named after German surgeon Georg Perthes

Georg Perthes

Georg Clemens Perthes was a German surgeon and X-ray diagnostic pioneer who was born in Moers, Germany.-Biography:...

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The limb is elevated and an elastic bandage is applied firmly from the toes to the upper 1/3 of the thigh to obliterate the superficial veins only. With the bandage applied the patient is asked to walk for 5 minutes. If deep system is competent, the blood will go through and back to the heart.
If the deep system is incompetent, the patient will feel pain in the leg.

This test is sometimes referred to as the Delbet-Mocquot test, named after French physicians Pierre Delbet

Pierre Delbet

Pierre Delbet was a French surgeon who was born in La Ferté-Gaucher. In 1889 he received his medical doctorate, and in 1909 became a professor of clinical surgery in Paris. In 1921 he became a member of the Académie de Médecine....

 and Pierre Mocquot.

Modified Perthes test

The test in done by applying a tourniquet at the level of the sapheno-femoral junction to occlude the superficial pathway, and then the patient is asked to move in situ. If the deep veins are occluded, the dilated veins increase in prominence and pain occurs.

This is a better test as it does not depend on patient's pain threshold.