Thanks to Public Domain Review for this:
From cabbage green to course meal, medieval manuscripts exhibit a spectrum of colours and consistencies when describing urine. Katherine Harvey examines the complex practices of uroscopy: how physicians could divine sexual history, disease, and impending death by studying the body’s liquid excretions.

Woodcut uroscopy chart pairing urine flasks with colour descriptions, printed at the private press of Ulrich Pinder, physician to the City of Nuremberg, 1506 — Source.
In the mid-thirteenth century, William of Rubruck, a Flemish Franciscan friar, travelled to the Mongol Empire. The main purpose of his visit was to undertake missionary work, but he also wrote a colourful account of his travels for King Louis IX of France, in which he described the region and its inhabitants. Among his many curious observations, he was astonished to find that the local physicians, who were generally skilled and knowledgeable, did not examine their patients’ urine.1
To the modern reader, this seems an odd detail to highlight, but William came from a world in which uroscopy — the examination of urine for the purpose of diagnosis and prognosis — was one of a doctor’s most valued skills. The link was so strong that the urine flask became the identifying symbol of the late medieval physician, who was often shown examining a sample. The symbol was used both to celebrate illustrious figures such as St Cosmas (the patron saint of medicine), and to punish charlatans like Roger Clerk of Wandsworth, who in 1382 was found guilty of selling useless “cures” to the poor, despite having no medical knowledge or training. He was led to the pillory on a saddleless horse, “a urinal being hung before him, and another urinal on his back”, in mockery of his malpractice. Satirists jeered at practitioners for their obsession with such unsavoury matter (Petrarch memorably claimed that the papal physicians were pale and emaciated because they “rummage around in sloshing chamber pots”), and comic images of monkey-physicians examining urine flasks are found in both manuscript marginalia and in early fourteenth-century stained glass at York Minster.2
Woodcut of a physician examining the “causes and signs” of disease, holding a urine flask up to the light, from a Spanish manuscript of Bartholomaeus Anglicus’ De proprietatibus rerum, ca. 1494 — Source.
Medical ring diagram with urine flasks from MS Savile 39, ca. 1387–1400 — Source.
Pages on interpreting the colour of urine from Sloane 1313, a Latin and French medical miscellany, ca. 1500–1600 — Source.
Manuscript detail from Sloane 7, a medical miscellany showing urine flasks with different layers of colour and particles, ca. 1400–25. The left is labelled “kyanos” (blue) in Greek and the right is labelled “inopos” (wine-coloured) — Source.
Detail from a French miniature depicting scenes of medical consultation, including a physician examining a urine flask (top right), ca. 1300–1325 — Source.
Woodcut uroscopy diagnostic chart, printed at the private press of Ulrich Pinder, physician to the City of Nuremberg, ca. 1506 — Source.
A skilled physician could identify a whole range of conditions based on a urine sample. According to Giles of Corbeil’s influential treatise, pure and unclotted blood in the urine indicated a problem with the kidneys, especially if it was accompanied by pain; “lividity coupled with minute, distinct particles consistently indicates respiratory trouble”, and gout was revealed by “tiny white flecks”.14 Urine was a particularly useful tool for diagnosing leprosy, because the immediate physiological cause was thought to be a malfunctioning liver — an organ which was central to the digestive process, and thus any problems would be visible in the urine. In 1456, when Richard Walsham, a monk of Norwich Cathedral Priory, was suspected of contracting leprosy, the Prior had several physicians examine his body and urine in order to confirm that he was not afflicted.15
Detail of a miniature depicting the bedridden John, Duke of Normandy, and physicians examining his urine, ca. 1380–1400 — Source.
Urine predicted the end of life, but it could also be used to track its conception through fertility testing. The Trotula, an influential compendium of women’s medicine, recommended that both husband and wife should urinate in a pot of bran: if, after ten days, either pot was stinking and full of worms, that indicated which spouse was infertile.18 According to The Dome of Uryne (a widely circulated Middle English compendium of uroscopic texts), it was possible to know whether a woman had conceived immediately after intercourse: if her urine was clear, then she was pregnant, and if it was thick, she was not. A few months on, the sex of the child could be determined by the cloudiness of the mother’s urine, whilst lead-coloured urine suggested a miscarriage.19 But not all physicians were willing to pronounce on such matters. A wise one would refuse to do so if he suspected that a female patient was intending to procure an abortion.20
Urine could be used to uncover an individual’s sexual history. The water of a “constant virgin” would be “wan and extremely calm”, and passed in a slow, delicate fashion because the passages of the womb and vulva were narrow. (It was evidently common to conflate the urinary passage and vagina.) On the other hand, “Thick urine of a woman declares her to be corrupt”. Men’s urine could be equally revealing, as seed in the bottom of the flask proved that the provider recently had sex.21 In the mid-twelfth century, shortly after taking his third wife, Ralph, Count of Vermandois, became seriously ill, and his doctor told him to abstain from marital relations. But when the physician examined the count’s urine, he realised that his advice had been ignored, and correctly predicted that Ralph would be dead within three days.22
Count Ralph’s unfortunate demise highlighted another potential problem with uroscopy: patients who ignored or mistrusted their doctors. Some went so far as to test the skills of their chosen practitioner. Although Arabic medical authorities such as Rhazes and Avicenna — both of whom were widely read and highly respected in the medieval West — recommended it, European physicians rarely smelt or tasted urine for medical reasons.23 Even so, they might be well-advised to give it a discreet sniff, since cynical patients sometimes provided samples of white wine or other yellowish liquids.24 In one extreme case from around the year 1000, the duke of Bavaria began his consultation with the famous monk-physician Notker by sending him a urine sample provided not by the duke, but by a pregnant servant girl. On examining it, Notker fell to his knees, praising God and declaring: “Within the week, the Lord will perform an unheard-of miracle: the duke will give birth to a son!” Shortly afterwards, the maid produced a baby boy, and the duke sent his messengers back to Notker with a sample of his own.25
Illumination of the Perisan physician Rhazes (Abu Bakr Mohammad Ibn Zakariya al-Razi) practising uroscopy, from a manuscript of Gerard of Cremona’s Recueil des traités de médecine, ca. 1250–1260 — Source.
In theory, patients could also fall victim to urine-related trickery, as happens in a humorous tale from The Decameron in which Calandrino’s friends team up with a doctor to convince him he is pregnant.26 But for the most part, the demand and trust in uroscopy was high, because it seemed to offer objective and certain diagnosis for a relatively small cost. In 1315, when Jaume II of Aragon closed a street in Barcelona’s Jewish quarter, he exempted the physician Vidal Rouen, because “many people have to show him the urines of sick people and to ask him for advice for them”.27 Other towns in the region appointed municipal physicians for this purpose: Abraham des Castlar, employed in this capacity by Castelló d’Empúries in 1316, agreed to “look at and assess all the urines brought to me by the citizens”.28
Indeed, the demand for uroscopy was too high to be satisfied by university-trained physicians (who were both rare and expensive), and many patients turned to less qualified practitioners. In mid-fifteenth century Essex, John Crophill worked as both a bailiff and a healer. Seemingly self-taught, and certainly not university educated, his commonplace book includes two texts on urine (alongside others on subjects such as blood-letting and astrology), plus a list of patients whose urine he had examined, and to whom he had provided cures.29 Across the Channel, Jacoba Felice, an unlicensed female practitioner who appeared before the Parisian medical authorities in 1322, offered similar services. Several of her mostly female clientele recalled her “continually examining their urine in the manner of physicians and doctors”, and reported that she had cured them when male physicians had failed to do so.30 Eighteen years earlier, when Gueraula de Codines faced a similar hearing in Barcelona, she asserted that “she could diagnosis a patient’s illness from his urine”, having been taught to do so by “a certain foreign doctor”. Clearly her legal travails did not deter patients, since three years later, she was back in court, claiming that many people consulted her, and that her uroscopy skills were especially in demand.31