Douglas Theodore Prehn (1901 – 1974) was an American urologist whose name is associated with a clinical sign for differentiating between testicular torsion and acute epididymitis

CAPT Douglas T. Prehn, MC, USN (Ret)

He was also granted a patent for a formula used to treat fungus infections of the skin.

  • Born on August 1, 1901 in Marathon, Wisconsin, USA
  • 1925 -Bachelor of Science (BS) degree, University of Wisconsin on the ‘toxicity of mercuric salicylate in rabbits’
  • 1927 – Doctor of Medicine (MD) from College of Physicians and Surgeons of Columbia University, New York; Intern at the Brooklyn Naval Hospital
  • 1929-1931 Served aboard USS Chaumont
  • 1935 – Division Medical Officer with USS J.D. Ford
  • 1940 – Urologist at the Naval Dispensary at the Naval Submarine Base in New London, Connecticut before assuming the position of chief of Urology at the Brooklyn Naval Hospital, New York
  • Chief of Urology at Camp Peary Hospital and Chelsea Naval Hospital in Massachusetts
  • 1953 – Retired from service
  • Died on June 30, 1974 in Washington, District of Columbia, USA
  • CAPT Prehn held the 2nd Nicaraguan Campaign Medal, Yangtze Service Medal, American Defense Service Medal, American Campaign Medal, Asiatic-Pacific Campaign Medal with two bronze stars. Navy Occupation Service Medal, and WWII Victory Medal.

Medical Eponyms
Prehn’s sign (1934)

Refers to the increase in pain with elevation of the scrotum seen with testicular torsion. In current practice, it is more commonly described as elevation of the scrotum not decreasing pain. It is a clinical sign which may help differentiate the presentation of acute epididymitis – where pain may be relieved with elevation – compared with testicular torsion.

It has been my experience in the treatment of hundreds of cases of acute epididymitis that when the scrotum is elevated with the Blockley bandage as suggested by Pelouze or the Bellevue suspensory bandage, immediate relief of the acute symptoms occurs, and frequently the patients get out of bed to walk about or resume their normal activities. Because of this experience I came upon a new sign which in both cases was the differential point and deciding factor in changing the diagnosis to torsion of the cord resulting in the necessary operative interference…

…In both cases reported acute epididymitis was ruled out by this positive sign; namely, elevation of the scrotum increased the pain and tenderness and did not give relief as it would in acute epididymitis

Prehn, 1934

Key Medical Contributions

1939: Patented a therapeutic agent for the treatment and prevention of mycotic and similar skin infections consisting of a composition containing Salicylic acid, menthol and camphor. [US2175780]

Major Publications



Eponymous terms



the person behind the name

Physician in training. German translator and lover of medical history.

BA MA (Oxon) MBChB (Edin) FACEM FFSEM. Emergency physician, Sir Charles Gairdner Hospital.  Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

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