External haemorrhoids

External haemorrhoids

A thrombosed external haemorrhoid relates anatomically to the veins of the superficial or external haemorrhoidal plexus and is commonly termed a perianal haematoma. It presents as a sudden onset, olive-shaped, painful blue subcutaneous swell ing at the anal margin and is usually consequent upon straining at stool, coughing or lifting a heavy weight. The thrombosis is usually situated in a lateral region of the anal margin. If the patient presents within the first 48 hours, the clot may be ev acuated under local anaesthesia. Untreated it may resolve, suppurate, fibrose and give rise to a cutaneous tag, burst and the clot extrude ( Figure 80.26 ) or continue bleeding. In the majority of cases, resolution or fibrosis occurs. John T empleton Bowen , 1857–1941, Professor of Dermatology , Harvard University Medical School, Boston, MA, USA, described this intradermal precancer ous skin lesion in 1912. Sir James Paget , 1814–1899, surgeon, St Bartholomew’s Hospital, London, UK, described this disease in 1874. - - - -

Figure 80.26 A thrombosed external haemorrhoid that has sponta

neously ruptured. Most of the underlying blood clot has extruded. There is also a mucosal prolapse, which is separate from the cuta

neous lesion.