Ismar Isidor Boas (1858 – 1938) was a German gastroenterologist and is sometimes cited as the founder of modern gastroenterology.

In 1886, Boas was the first “specialist doctor for gastrointestinal diseases” to open a practice in Berlin, thus establishing gastroenterology as a medical specialty.

Boas pursued the idea of ​​a scientific society for the new field and a congress at which “the most important issues of digestive and metabolic pathology should be dealt with in the form of lectures and discussions”. The Deutsche Gesellschaft für Gastroenterologie (DGVS) was founded in 1913.

Boas is also remembered for his contribution to the detection of occult blood in the gastrointestinal tract and understanding its association with malignancy.

  • Born 28 March 1858 in the Prussian province of Posen
  • 1877 – Commenced medical studies at the Humboldt University of Berlin
  • 1881 – Obtained MD from the University of Halle-Wittenberg
  • 1882 – Passed state licensing examination in Leipzig and began practicing as a general practitioner in Breslau
  • 1888 – Established himself as a specialist in gastric diseases and founded a gastroenterology clinic in Freidrichstrasse, Berlin
  • 1895 – Founded the Archiv für Verdauungs-Krankheiten, Stoffwechselpathologie und Diätetik the first journal devoted to the subject of gastroenterology. This journal has since been retitled Digestion published by S. Karger.
  • 1901 – Became the first physician to demonstrate the abnormal conditions in which occult blood was present in the gastrointestinal tract using guaiac reagent.
  • 1913 – Founded the Deutsche Gesellschaft für Gastroenterologie (DGVS)
  • 1936 – Boas was a Jew and, fearing persecution, left Berlin for Vienna with the rise of Nazism
  • Died 15 March 1938 of an intentional barbital overdose as the Nazis invaded Vienna

Medical Eponyms
Boas sign and Boas point (1894)

Boas point: Point of tenderness to the left of the twelfth thoracic vertebra in individuals with gastric ulcer. Pressure-point tenderness located just to the left of the spine, close to the body of the twelfth dorsal vertebra. Boas reported 12th thoracic spinal tenderness in at least in one-third of cases of gastric ulcer.

Boas sign: Referred tenderness in gallbladder disease including biliary colic; acute and chronic cholecystitis. Posterior thoracic pressure point tenderness between the 10th and 12th thoracic vertebra on the right side. Extending laterally from a point 2-3 finger-breadths from the midline to the right, and out towards the posterior axillary line.

Boas first described the finding of referred tenderness in gallstone disease in 1894 in the third edition of Diagnostik und Therapie der Magenkrankheiten and expanded on his initial findings in MMW, 1902 and finally outlined Boas point in 1907 in Diseases of the stomach.

Least recognised as a symptom of cholelithiasis is tenderness over the posterior surface of the liver. When well marked it extends laterally from about an inch lateral to the spines of the vertebrae to the posterior axillary line, and vertically from the eleventh dorsal to the first lumbar spines. To demonstrate it the finger should be pressed against a point to the right side of the tenth dorsal spine; then against successive points in lines running horizontally outwards, opposite the other spinous processes, down to the first lumbar spine, first on one side, then on the other. It is then evident which side is the more tender. This symptom, if present during the acute attack, is also invariably present in the intervals; that is, if once present, it is always present, and is therefore of special diagnostic value in the latent stages. Occasionally it may be found years after the last attack of colic.

Boas sign 1902: 604

I consider the search for this tender area a necessary part of the examination of all patients who suffer from gall-stone disease, or in whom the existence of this disease is suspected. It is undoubtedly a sign of great value.

Moynihan 1905: 155
Boas sign 1894 acute cholecystitis
a. Boas point – gastric ulcer
b. Boas sign – gallbladder disease

Boas algesimeter (1891)

Instrument (dolorimeter) designed to determine the sensitiveness over the epigastrium, and assist in the diagnosis of gastric ulcer disease.

In order to measure the intensity of pain of a certain section of the gastro-intestinal tract, I have devised an instrument called the “algesimeter’. The apparatus consists of a hollow cylinder, which contains a spiral spring. A scale, showing whole, half, and quarter divisions, is attached to this cylinder, which indicates the degree of compression of the spiral spring, from 0.5 to 10 Kg. An indicator placed around the cylinder moves with the piston, so that when compression is exerted the amount of pressure upon the handle can be immediately read on the scale. In order to exactly cover the painful area, the apparatus is furnished with three different-sized removable plates, which can be easily attached to its lower end. 

A normal stomach presents a degree of tenderness on pressure varying from 5 – 10 Kg. The lowest values are obtained in gastric ulcer, in which they vary between 0.5 – 3 Kg. If the tolerance for pain is higher than these figures, we may, as a rule, exclude gastric ulcer.

Boas 1891: 82

Major Publications



Eponymous terms

Emergency Medicine Trainee based in Perth, Western Australia. Keen interest in ultrasound, rural health and water-based activities.

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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