Amnion Nodosum

Gross appearance:

(1) granules on the fetal surface less than 5 mm in diameter, best seen under oblique light

(2) present in the amnion (move with the amnion)

(3) absent from the umbilical cord

(4) can be scraped off the amnion

Histologic features of the granules:

(1) fetal squamous cells

(2) sebum, keratin and hair

(3) proteinaceous debris

Associations:

(1) congenital anomalies (renal agenesis, sirenomelia, other)

(2) pulmonary immaturity

(3) oligohydramnios (especially in the first trimester)