Placental Alpha-Microglobulin-1 as a Marker of Membrane Rupture

Preterm babyPremature rupture of membranes (PROM) is spontaneous rupture of fetal membranes before the onset of uterine contractions. Preterm PROM, which is PROM before 37 weeks is a major cause of preterm birth.

Previously, we have blogged about the cervicovaginal markers IGFBP1 and AFP to diagnose PROM. In recent years, a number of studies have reported on the utility of cervicovaginal placental alpha-microglobulin-1 (PAMG-1) as a marker of Rupture of Membranes.

PAMG-1 is present in blood, amniotic fluid (AF), and cervicovaginal fluid of pregnant women. The concentration of PAMG-1 in AF (2,000–25,000 ng/mL) is several thousand times higher than that in cervico-vaginal discharge when the fetal membranes are intact (0.05–0.2 ng/mL). The high concentration of PAMG-1 in AF makes it potentially a good marker to detect the presence of AF in the vaginal canal.

In one of the largest studies, Lee et al examined 184 women with symptoms or signs of PROM. 159 were later confirmed to have PROM. In this population, PAMG-1 demonstrated a sensitivity of 98.7%, specificity of 87.5%, positive predictive value of 98%, and a negative predictive value of 91.3%. In contrast, Nitrazine in the same patients demonstrated a sensitivity of 88.1%, specificity of 87.5%, positive predictive value of 97.9%, and a negative predictive value of 52.5%. This performance is supported by several other studies as well.

Diagnostic Utility of PAMG-1

Reference

n

sensitivity

specificity

+PV

-PV

Lee et al. 2007 Obstet Gynecol

184

98.7%

87.5%

98.1%

91.3%

Cousins et al.2005 Am J Perinatol

203

98.9%

100%

100%

99.1%

Ng et al. 2013 BioMed Res Intern

211

95.7%

100%

100%

75%

Abdelazim et al. 2013 J Obstet Gyneacol Res

150

97.3%

98.7%

   

In summary, PAMG-1 appears to be a viable method to detect PROM in cervicovaginal fluid and appears to be superior to conventional methods.

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