Background: Recently, ultrasound (US)-guided needle biopsy has been pr
oposed as an acceptable alternative to open biopsy in women with nonpa
lpable breast masses, This study evaluated the accuracy of US-guided n
eedle biopsy of nonpalpable breast masses performed by surgeons at the
time of the initial clinical examination. Methods: Ultrasound-guided
aspiration and/or core biopsy (US-GAB) was performed on 103 patients p
resenting with a nonpalpable, new, or increasing-size mass detected on
mammography. Study patients included those whose US was classified as
: fibroadenoma (FA) (n = 26), complex cyst (n = 32), indeterminate (co
mplex cyst versus solid; N = 24), or suspect (n = 21). Results: Of the
32 patients with diagnostic US of complex cyst, US-GAB confirmed 27 t
o be cysts. Twelve additional cysts were aspirated among the 24 indete
rminate lesions. Sixteen FA were diagnosed on US-GAB; 11 of these unde
rwent open biopsy and each was demonstrated to be a FA. Fibrocystic/be
nign-breast change (FBC) was diagnosed on 26 US-GAB; 15 of these under
went open biopsy, which demonstrated three FA and 12 FBC. Nine atypica
l lesions were diagnosed on US-GAB; six FBC, one papilloma, one FA, an
d one cancer were demonstrated on open biopsy. Seven cancers were diag
nosed on US-GAB and all were confirmed on open biopsy. There were six
insufficient specimens from US-GAB; four of these underwent open biops
y, which demonstrated two FA and two FBC. Conclusion: Ultrasound-guide
d aspiration and/or core biopsy performed by surgeons in conjunction w
ith the initial clinical examination can accurately diagnose nonpalpab
le, mammographically detected breast masses.