Tarry stool

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Classification according to ICD-10
K92.1 Melena
ICD-10 online (WHO version 2019)

In medicine, black-colored stool is called tarry stool ( melena ) . The appearance of fresh blood in the stool is known as hematochezia .

The black discoloration of the stool is caused by the hematin content . Hematin is formed when hemoglobin comes into contact with stomach acid. The iron in the hemoglobin is oxidized and a color change occurs. The source of bleeding is therefore mostly in the upper digestive tract . However, if the intestinal transit is slow (longer than five hours), bleeding in the small and large intestines can lead to tarry stools if hematin is formed by bacterial decomposition of hemoglobin. Tar stools smell foul and are shiny.

A distinction must be made between tar stool and black stool when given iron. In this case the Haemoccult test is negative in contrast to the tarry stool.

Melaena spuria is the term used to describe the appearance of tarry stools caused by swallowing maternal blood in newborns or infants . This can occur during childbirth or through fissures in the mother's breast during breastfeeding .

Individual evidence

  1. ^ Julian A. Smith, Jane G. Fox, Alan C. Saunder, Ming Kon Yii: Hunt & Marshall's Clinical Problems in Surgery . Elsevier Health Sciences, 2nd edition, 2010, p. 271.
  2. ^ Friedrich Carl Sitzmann: Dual series pediatrics. Georg Thieme Verlag, 2007, ISBN 3-13-125333-9 .

See also