Table 1.

Hereditary hemorrhagic telangiectasia algorithm definitions

HHTA Group	Clinical findings	ICD-9-CM coding
A	Pulmonary AVM and at least 1 of the following: Epistaxis, brain AVM, peripheral AVM, or gastrointestinal angiodysplasia	[747.3 or 417.0] and [784.7, 747.81, 747.6, 537.82, 537.83, 569.84, or 569.85]
B	Brain AVM and gastrointestinal angiodysplasia	747.81 and [537.82, 537.83, 569.84, or 569.85]
C	Epistaxis (≥ 2 encounters) and at least 1 of the following: Gastrointestinal angiodysplasia, peripheral AVM, or other unspecified capillary diseases	784.7 and [537.82, 537.83, 569.84, 569.85, 747.6, or 448.9]

AVM = arteriovenous malformation; HHTA = hereditary hemorrhagic telangiectasia algorithm; ICD-9-CM = International Classification of Diseases, Ninth Revision-Clinical Modification.