Physical examinations of the anus are sometimes used in North Africa to determine if a man has practiced receptive anal sex, and hence has broken laws against homosexuality.

Here is one such report from Tunisia in 2017

I was skeptical at first glance, but when I read the doctor's examination report:

Examen Medical :

  • L'absence de disparition des plis radiaire de la marge anale.

  • L'absence de douleur à l'écartement des deux fesses.

  • L'absence de lésions traumatiques de la marge anale.

  • Un toucher rectal indolore trouve un sphincter de tonus conservé.


  • Monsieur *** agé de 23 ans, ne présente pas de signes en faveur d'un coït anal récent. Toutefois un examen anal 20 jours après une supposée agression peut être normal en raison de la disparition rapide des lésions traumatiques anales en moins de 5 jours.

  • Il ne présente pas de signes en faveur de la sodoomie chronique.

  • Il ne présente pas de lésions traumatiques récentes.

Translation (Google translate + fixes):

Medical exam:

  • The absence of radial folds of the anal margin.

  • The absence of pain when spacing buttocks.

  • The absence of traumatic lesions of the anal margin.

  • A painless rectal examination finds a sphincter of a conserved tone.


  • Mr. *** aged 23, does not show signs in favor of a recent anal sex. However an anal examination 20 days after an alleged aggression might be normal due to the rapid disappearance of traumatic anal lesions in less than 5 days.

  • He does not show signs in favor of a chronic sodomy.

  • He does not present recent traumatic lesions.

It seems "scientific" and well argued but I'm no doctor.

My question is: has this "medical" exam technique been scientifically validated?

  • 3
    The distinction between "passive" and "active" homosexuals is dubious at best, as is the idea that all homosexuals have anal sex. It is not even necessarily true that all men who have anal sex are homosexual, leading some scientists to use the broader term "men who have sex with men". The only meaningful thing such a test could find would therefore be whether a man had recently or repeatedly been the receptive partner in anal sex.
    – IMSoP
    Commented Feb 17, 2019 at 0:12
  • 2
    @imsop Disregarding the unsubstantiated claims of your own, the medical exam quote doesn't say more than that. That quote focuses exclusively on what may be called "anal penetration". So, @ Akli, your title doesn't quite match the quotes. I suppose an answer can address that this test pinging positive might be used to infer homosexuality, but what it seems designed to discover is "chronic sodomy".
    – user11643
    Commented Feb 17, 2019 at 1:34
  • 3
    So do you want to know if this test accurately finds "chronic sodomy" or "homosexuality"? This is a rhetorical question, as I think just asking it shows the issues in scientifically proving a subjective self-identifying marker, that is, homosexuality. However, I'd not be surprised if these peoples define homosexuality as more of an act, such as sodomy, rather than a self-identifying marker.
    – user11643
    Commented Feb 17, 2019 at 1:38
  • 4
    I tried to avoid the above debate by editing to focus on the sexual act, rather than the sexuality behind it.
    – Oddthinking
    Commented Feb 17, 2019 at 4:29
  • 2
    @DanielRHicks That is indeed one of the many problems with the assumptions underlying these tests. Proponents will tie themselves in knots claiming contradictory things about the physical effects of consent, because what they are seeking to prove is a particular behaviour they disapprove of.
    – IMSoP
    Commented Feb 24, 2019 at 10:28

2 Answers 2


The scientific consensus is that examinations of the sort described are both ineffective and unethical.

I found an essay from PLOS medicine, titled Forced anal examinations to ascertain sexual orientation and sexual behavior: An abusive and medically unsound practice. (Cichowitz C, Rubenstein L, Beyrer C (2018) PLoS Med 15(3): e1002536. https://doi.org/10.1371/journal.pmed.1002536)

It summarises the evidence as follows:

The earliest recorded tests purported to detect homosexuality were described by a 19th century French forensic doctor who erroneously claimed that six criteria could be used to identify homosexuality on examination [9]. Despite being published in the 1800s and discredited by medical professionals then and now, the ideas put forth continue to inform states’ practices—namely that examination of the anal sphincter can correctly determine whether or not an individual has participated in consensual receptive anal intercourse [9]. More recently, in Egypt, physicians have attempted to determine this through electromyography, sonography, and manometry of the anal sphincter, pelvic floor, and rectum, respectively [9].


In 2016, an independent panel of forensic experts including doctors, psychologists, and psychiatrists issued a statement unequivocally refuting all claims that anal examination can identify sexual practices [12]. The statement discredited the most commonly cited reason for conducting exams—to determine anal sphincter tone. The panel highlighted the fact that there are no standardized ways of determining anal tone with digital rectal examination, that there are high levels of normal variability within the population, and that numerous conditions may affect anal tone, independent of any practiced behaviors.

The references are:

[9]: Long S. When Doctors Torture: The Anus and the State in Egypt and Beyond. Health Hum Rights. 2008 Mar 6;7:116–40.

[12]: International Forensic Expert Group. Statement on anal examinations in cases of alleged homosexuality. Torture. 2016;26(2):85–91.

The IFEG statement is another summary.

It introduces context very similar to that quoted in the question:

Medical personnel are called upon to conduct a digital examination of the anus using a gloved and lubricated finger of the examiner as well as visual inspection of the anal area and sometime the insertion of tubes of varying sizes. The examination is performed with the presumption that there are characteristic signs that correlate with consensual anal intercourse, namely laxity of the anal sphincter. In some cases, examiners claim that the appearance of the anus and the degree of laxity are signs of "chronic anal intercourse" or "habitual anal penetration."

It states unequivocally that:

There are no scientific studies that provide any basis for the validity of forcibly conduct- ed anal examinations in the detection of consensual anal intercourse.

It details five problems:

  1. Lack of standardised measurement and baseline data
  2. Normal variability in anal sphincter tone
  3. Lack of standardised procedure
  4. The potential for involuntary reaction of the inner sphincter and voluntary tensing of the outer sphincter
  5. A wide variety of causes for decreased anal sphincter pressure, listing the following examples

mechanical trauma, increasing age, haemorrhoids, chronic constipation, irritable bowel syndrome, neurologic conditions such as pudendal neuropathy from constant straining, cauda equine syndrome, diabetic neuropathy, multiple sclerosis, Amyotrophic Lateral Sclerosis (ALS), Parkinson’s Disease, Guillain-Barre syndrome, iatrogenic causes (caused by physicians) such as surgical sphincterotomy for the treatment of anal fissures and other anal/rectal surgeries, benign prostatic hypertrophy, and side effects from medications.

The other reference is a long essay by Scott Long, which provides more primary sources.

The "19th Century Frenchman" referenced elsewhere is Auguste Ambroise Tardieu, who wrote a treatise called Etude médico-légale sur les attentats aux moeurs ("Forensic Study of Assaults against Decency") in 1857.

In it, he proposes six signs of "passive pederasty" (what we would now call receptive anal sex), clearly similar to those used in the Tunisian report. In Scott Long's translation, they are:

  • excessive development of the buttocks
  • funnel-shaped deformation of the anus
  • relaxation of the sphincter
  • the effacement of the folds, the crests, and the wattles at the circumference of the anus
  • extreme dilation of the anal orifice
  • ulcerations, hemorrhoids, fistules

Long does not cite specific refutations of this work, but quotes private correspondence with an expert:

Dr. Robert Nye, a historian of sexology, wrote to me, "The famous six 'signs' of passive sodomy were questioned and disregarded by the very next generation of forensic doctors and sexologists."

  • If I may add one more factor, people suffering from haemorrhoids are sometimes recommended to stretch their sphincter on a regular basis, to ease dejection. So, you have haemorrhoids and a relaxed sphincter... how is a "doctor" to tell apart medical condition and treatment vs. results of intercourse? Besides, the whole premise is ridiculous. It's nobody's business whether you have receptive anal sex in the first place. +1 for the well-sourced answer.
    – DevSolar
    Commented Feb 25, 2019 at 8:13
  • And of course the very exam techniques of inserting objects into the rectum could well bring about similar signs as actual anal intercourse.
    – jwenting
    Commented Feb 26, 2019 at 6:27

It depends

The available analysis (e.g. Human Rights Watch report, IRCT, though limited references to primary sources) state that, in essence,

  1. "The normal variability in anal sphincter tone and anatomical appearance makes it difficult for digital anal examinations to distinguish normal anal tone from that which may be clinically significant."
  2. A decreased anal sphincter tone is not a reliable sign of consensual anal intercourse; both in the sense that there may be regular anal intercourse without such effects, and that such effects can be caused by various other factors.

Thus concluding that "There are no scientific studies that provide any basis for the validity of forcibly conducted anal examinations in the detection of consensual anal intercourse."

However, in some cases (notably, if the anal sex was very recent and/or traumatic), it's possible to detect and verify it, which is commonly done in police forensics in e.g. rape test kit analysis. There may be clear signs of traumatic penetration by someone or something, and if you recover a semen sample from a patients rectum, then you can reliably assert that anal intercourse occurred and can run DNA tests to determine the active partner. So sometimes an anal test can prove beyond all reasonable doubt that such an event ocurred (which gets used in rape convictions) but that doesn't imply that there exists a procedure that reliably detects regular consensual anal intercourse in all cases.

Of course, detecting anal intercourse also doesn't necessarily answer the title question (if a person is homosexual), but it usually does answer the actual legal question asked by acts like https://en.wikipedia.org/wiki/Buggery_Act_1533 .

  • 2
    Given the context of the question - a procedure often performed by force to criminalise alleged behaviour - I think the bold "it depends" here is dubious. Yes, it's possible that physical examinations form evidence in rape cases (although you haven't provided any references for that) but such a broad interpretation of the question risks legitimising a practise which is universally condemned by human rights and medical ethics groups.
    – IMSoP
    Commented Feb 24, 2019 at 17:44

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