- A dictionary of medical eponyms

Throckmorton's sign

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Also known as the John Thomas sign. Synonym: position of the penis in relation to unilateral disease. Throckmorton's sign is a slang term used jokingly by medical students and residents. A positive "Throckmorton" sign is when the patient's penis lies to or points to the side of the body wherein lies the abnormality on a plain X-ray of the Pelvis. For example, a broken right hip with a shadow of the penis pointing to the right has a positive "throckmorten". If there is no abnormality, a jovial Radiologist might tell the referring Physician; "He's Throckmorten to the right so you might want to check over there.”

We thank Kris Rowney, Mike Michaels, George Broughton and Roger Blauvelt for information submitted.

We also thank John Howe for solving (probably) the problem of the identity of John Thomas: John Thomas is a well known British euphemism for the penis. So it is likely that John Thomas was not a real person but a polite if jokey name for the male member.


  • A. E. Baogaert:
    Genital asymmetry in men. Human Reproduction, Oxford, 1997, 12: 68-72.
  • R. H. Chang, F. K. Hsu, S. T. Chan, et al:
    Scrotal asymmetry and handedness.
    Journal of Anatomy, London, 1960, 94: 543-548.
  • Merlin C. Thomas, Brett D. Lyons, Robert J. Walker:
    John Thomas sign: common distraction or useful pointer?
    Letter. The Medical Journal of Australia, Sydney, 1998, 169: 670

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