II. History

  1. First described by Hippocrates in 5th century B.C.

III. Definition

  1. Bulbous digital deformity
  2. Watch-crystal deformity of Fingernail

IV. Pathophysiology

  1. Sign of Hypertrophic Osteoarthropathy (Acropachy)
  2. Thickening of nail bed's soft tissue (especially proximally)
    1. Typically affects all fingers
  3. Results from abnormal microvasculature with increased Blood Flow to the microvasculature

V. Signs: Schamroth's Window Test for Clubbing

  1. Oppose fingers of both hands
  2. Observe space formed between nail bases
    1. Normal: Diamond-Shaped "window" seen
    2. Clubbing:
      1. Window erased
      2. V-shaped gap at distal end of nail is wider

VI. Signs: Digital Index

  1. Use non-elastic string to measure digit circumference
  2. Measure circumference at 2 sites on all 10 digits
    1. Nailbed circumference (NB)
    2. Distal interphalangeal joint circumference (DIP)
  3. Calculate NB/DIP ratio
  4. Results suggestive of Digital Clubbing
    1. NB/DIP ratio exceeds 1 on all fingers or
    2. Sum of all ten NB/DIP ratios >10

VII. Signs: Lovibond Angle

  1. Line 1
    1. Draw a longitudinal line across the top of the distal digit soft tissue
  2. Line 2
    1. Draw a longitudinal line across the midpoint of the nail plate
  3. Angle
    1. Measure the angle at the intersection of the 2 lines (clockwise from proximal end of line 1)
  4. Interpretation
    1. Angle greater than 180 degrees is suggestive of Clubbing

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Related Studies

Ontology: Schamroth test (C0231676)

Concepts Diagnostic Procedure (T060)
SnomedCT 23405006
English Schamroth test, Schamroth test (procedure)
Spanish prueba de Schamroth (procedimiento), prueba de Schamroth

Ontology: Clubbing of nail (C0263538)

Concepts Sign or Symptom (T184)
ICD10 R68.3
SnomedCT 4373005, 201118006
English Clubbing of nails, Clubbing of nail, clubbing of nails, clubbing of fingernails, clubbing of fingernails (physical finding), clubbed nails, clubbing nail, club nails, clubbing nails, nail clubbing, Hippocratic nail (disorder), Club nail, Hippocratic nails, Increased curvature of nails, Hippocratic nail, Clubbing of nail (disorder), clubbed nail
Dutch trommelstoknagels
French Hippocratisme digital
German Auftreibung der Naegel
Italian Ippocratismo delle unghie
Portuguese Hipocratismo das unhas
Spanish Uñas de dedos en palillos de tambor, curvatura aumentada de la uña, uñas hipocráticas (trastorno), uñas hipocráticas
Japanese ばち状爪, バチジョウツメ, バチジョウソウ
Czech Nehty ve tvaru hodinových sklíček
Hungarian Óraüveg-köröm