How can I differentiate between internal and external haemorrhoids during a clinical examination?

Differentiating internal from external haemorrhoids during clinical examination involves inspection and digital examination of the anal region. Internal haemorrhoids originate above the dentate (pectinate) line and are covered by mucosa, making them generally painless and not visible externally unless prolapsed. They may present as swollen, prolapsed tissue within the anal canal that can sometimes be reduced manually. External haemorrhoids arise below the dentate line and are covered by anoderm and skin, often presenting as visible, tender lumps or swellings at the anal verge, which may be thrombosed and acutely painful.

During examination, internal haemorrhoids are typically identified by their location above the dentate line and may require a proctoscope or anoscope for visualization, especially if not prolapsed. Prolapsed internal haemorrhoids appear as bluish or purplish masses protruding from the anus but are usually less painful unless thrombosed or incarcerated. External haemorrhoids are visible on inspection as perianal lumps or swellings, often tender to touch, and may have a characteristic blue or dark discoloration if thrombosed.

Palpation can help differentiate: external haemorrhoids are palpable as tender, firm lumps at the anal margin, whereas internal haemorrhoids are softer and located higher within the anal canal. Digital rectal examination may reveal internal haemorrhoids as soft, compressible swellings inside the canal, while external haemorrhoids are outside the anal verge. Pain is a key clinical differentiator; external haemorrhoids are usually painful due to somatic innervation below the dentate line, whereas internal haemorrhoids are typically painless unless complicated.

In summary, the key clinical distinctions are the anatomical location relative to the dentate line, the presence or absence of pain, and whether the haemorrhoid is visible externally or only on internal examination. This differentiation guides management decisions, including the need for referral or intervention.

References: ¹; (Orkin et al., 1999)