Influence of Aspirin on Haemostatic Parameters.

In recent years faecal blood loss due to ingestion of acetyl salicylic acid (ASA) has been demonstrated by various authors, both by chemical methods such as the benzidine reaction, and by physical methods with erythrocytes labelled with radioactive substances. Stubbe (1958) reported occult faecal blood loss in 70 per cent. and Alvarez and Summerskill (1958) in 50 per cent. of patients and healthy volunteers taking ASA. Scott, Porter, Lewis, and Dixon (1961), reporting a 70 per cent. incidence of faecal blood loss with ASA, found no indication as to the actual site of bleeding and no correlation between dyspepsia and blood loss. Stubbe (1958) time and again found normal values for the bleeding time and assumed a local irritant action of ASA on the gastric mucosa to be responsible for the faecal blood loss. Entericcoated ASA tablets, at least those commercially available, provide "no protection of the gastric mucosa" as faecal blood loss was reported in about 32 per cent. of cases by Scott and others (1961) and in 65 per cent. of cases by Stubbe (1958) and also by Lange (1957). Also Pierson, Holt, Watson, and Keating (1961) found that enteric-coated ASA induced the same rate of bleeding as non-coated ASA; according to these authors the intestinal mucosa is also susceptible to ASA irritation. With a special experimental coating of ASA tablets, faecal blood loss was reduced to a minimum (Stubb6, Pietersen, and van Heulen, 1962). In addition to the 50 to 70 per cent incidence of faecal blood loss presumably due to gastric irritation, there are incidental reports of manifest bleeding during medication with ASA after tooth-extraction (Smith and MacKinnon, 1951), post-biopsy bleeding and epistaxis (Frick, 1956), haematuria, bleeding gums, menorrhagia (Wising, 1952), and after tonsillectomy (Neivert, 1945). Here, factors other than