Amniotic Fluid Alpha-Fetoprotein Levels in the Differential Diagnosis of Cystic Hygroma

Abstract

In 7 second trimester pregnancies ultrasound (US) demonstrated cystic hygroma colli (CHC); amniocentesis was performed in 6 patients. In the 7th patient, because of oli-gohydramnios, the fluid for karyotype was aspirated from the CHC. Five pregnancies had been referred secondary to abnormalities on US and 2 others because of low maternal serum alpha-fetoprotein (MSAFP). Four karyotypes were abnormal (45, X; 47, XX+21; 47.XY+21; 46, XX/45, X), and 3 had normal karyotypes. Amniotic fluid alpha-fetoprotein (AFAFP) was normal in 4 pregnancies and low in 2 (0.09 MOM, 0.41 MOM). Of 2 pregnancies with trisomy 21 one had been referred for low MSAFP. In 2 pregnancies with normal karyotypes, US findings at early gestational age (14–17 weeks) of small, nonseptated, bilateral CHC disappeared during pregnancy; these women delivered normal, term babies. Most prenatally diagnosed CHC are not in fetuses with Turner syndrome. With a normal karyotype and CHC as the only finding on early US in utero, normal neonatal survival is possible. AFAFP is not elevated in pregnancies with CHC. If AFAFP is elevated with a positive acetylcholinesterase, such results may suggest that the CHC was inadvertently aspirated.

Increased Amniotic Fluid Alpha-Fetoprotein in Patients with Fetal Nuchal Edema

“…This may be explained by increased exudation of fetal serum through the edematous skin. Since previous studies [4] did document normal or low amniotic fluid AFP in pregnancies com plicated with cystic hygroma coli, our study seems to refute a possible etiologic association between nuchal edema and cystic hygromata.…”

“…Previous reports documented that a-feto protein (AFP) is grossly elevated in fluid aspi rated from cystic hygromata but amniotic fluid AFP is normal or low -the occasionally in-Results creased AFP has been generally attributed to in advertent aspiration of the cystic sacs [4], Our clinical impression has been, however, that AFP is commonly elevated in amniotic fluid samples obtained from pregnancies compli cated by fetal nuchal edema. We hypothesized that early in the second trimester, the edema tous area is covered only with a thin membrane and AFP may permeate from the enlarged and probably congested lymphatic system to amniotic fluid.…”

Second‐trimester maternal serum alpha‐fetoprotein screening of pregnancies characterized by first‐trimester isolated prominent fetal nuchal translucencies and normal karyotype

“…For those women who choose chorionic villus sampling (CVS) or amniocentesis at or before 12.9 weeks' gestation, clinical interpretation of amniotic fluid levels of alpha-fetoprotein (AFP) is not possible. Several authors have addressed the clinical value of AFP analyses (maternal serum and amniotic fluid) in the evaluation of second-trimester fetal cystic hygroma, with the consensus indicating that AFP determination adds little additional clinical information (Sorokin et al, 1989;Cohen et al, 1989;Oak et al, 1992), even in cases of spontaneous resolution of the cystic lesion (Baccichetti et al, 1990). However, amniotic fluid and maternal serum AFP (MSAFP) levels are occasionally elevated in cases of second-trimester cystic hygroma (Koske-Westphal and Muller-Holve, 1985;Lindfors et al, 1991) and may result from leakage or rupture of cystic lesions.…”