β-human chorionic gonadotropin assay in vaginal washing fluid for the accurate diagnosis of premature rupture of membranes during late pregnancy

Abstract

Objective: To determine whether the measurement of beta-human chorionic gonadotropin (β-hCG) levels in vaginal fluid is useful for the diagnosis of premature rupture of membranes (PROM). Material and Methods: A total of 92 pregnant women between 24and 40 weeks gestation participated in this study. The patients with fluid leaking from the vagina were designated Group 1, the patients with no fluid leaking from the vagina were Group 2, and those with a suspicion of fluid leaking from the vagina were classified as Group 3. Irrigating the posterior vaginal fornix with 5 mL sterile saline was used to measure β-hCG levels of the patients. Receiver operator curve (ROC) analysis was used to determine the cut-off value for a positive diagnosis. Results:The β-hCG levels of vaginal fluid were measured as 20.5±25.0 mIU/mL, 254.6±346.8 mIU/mL, and 74.3±100.8 mIU/mL in Group 1, Group 2, and Group 3, respectively. Vaginal β-hCG level was higher statistically significantly in Group 2 than Group 1 and 3 (p<0.001). 100 mIU/mL was accepted as a cut-off value by using the receiver operating characteristic curve. According to 100 mIU/mL, sensitivity, specificity, positive predictive and negative predictive values were calculated as 71.2, 100, 100, and 65.1%, respectively. Conclusion:The study showed that the measurement of β-hCG level in vaginal washing fluid is an efficient and easy diagnostic test for predicting the amount of fluid leaking from the vagina. However, due to the low negative predictive value of the test, it would not be convenient in daily practice. (J Turkish-German Gynecol Assoc 2013; 14: 201-4) Key words: Beta-human chorionic gonadotropin, premature rupture of membranes, diagnosis Received: 01 June, 2013 Accepted: 19 September, 2013 Amaç: Erken membran rüptürünün tanısı için vajinal sıvıda beta-human koryonik gonadotropin (β-hCG) seviyesinin ölçümünün yararlı olup olmadığını belirlemek. Gereç ve Yöntemler:Gebeliğin 24-40. haftaları arasında olan toplam 92 gebe bu çalışmaya dahil edildi. Vajinadan sıvı geldiği görülen hastalar Grup 1, vajinadan sıvı gelmeyenler Grup 2 and şüpheli sıvı gelişi olan hastalar Grup 3 olarak sınıflandırıldı. Hastaların vajinal sıvıdaki β-hCG seviyelerinin ölçümü için posterior vajinal fornixin 5 mL salin ile elde edilen yıkantı suyu kullanıldı. Receiver operator curve (ROC) analizi yapılarak doğru tanı için gereken eşik seviye belirlendi. Bulgular:Vajinal sıvıda β-hCG seviyesi Grup 1 için, 20.5±25.0 mIU/mL, Grup 2 için 254.6±346.8 mIU/mL, Grup 3 için 74.3±100.8 mIU/mL olarak ölçüldü. Vajinal β-hCG seviyesi Grup 2 de Grup 1 ve 3'ten istatistiksel olarak daha yüksek bulundu (p<0.001). ROC analizi eğrisi kullanılarak eşik seviye 100 mIU/mL olarak kabul edildi. 100 mIU/mL eşik degree göre; sensitivite, spesifite, pozitif ve negatif prediktif değerler sırasıyla %71.2, %100, %100 ve %65.1 olarak hesaplandı. Sonuç:

Qualitative Determination of Human Chorionic Gonadotropin in Vaginal Washings for the Early Diagnosis of Premature Rupture of Fetal Membranes

“…These results were better than the NPV of another study that used a bigger cut-off point (100 mUI/mL). 4 Likelihood ratio is the ratio between the probability of a result at a diagnosis test in people with a disease and the probability of getting the same result in healthy people. So, for the β-hCG-10 test, the LRþ of 1.37 is the chance to find a positive result in people with PROM (true positive), and it is similar to finding a positive result in healthy people (false positive).…”

“…16 In our review, the major cutoff point studied was of 100 mUI/mL, and it provided a sensibility of 71.2%, a specificity of 100%, a PPV of 100%, and an NPV of 65.1%; even though there was a high specificity with this cut-off point, it showed lower sensibility. 4 A cut-off point of 39.8 mUI/mL was also studied, and all parameters were higher than 90%, so the literature suggests that this is a good value to be considered. 16 Researchers had who used a cut-off point 25 mUI/mL also achieved sensibility and specificity rates higher than than 90%, which suggest this can be an appropriate value.…”

“…2 Current studies emphasize research on biochemical agents found at high levels in the amniotic fluid: prolactin, α-fetoprotein, insulin-like growth factor, fetal fibronectin, urea, lactate, placental alpha microglobulin-1, diamine oxidase, human chorionic gonadotropin (hCG), and creatine. [2][3][4]8,9,[11][12][13][14] Most of these tests are not popular because they have high costs and complexity. 2 Out of all biochemical markers studied, we highlight the hCG β subunit (β-hCG).…”

“…However, there is little information about the level of β-hCG in the vaginal fluid and its fluctuation between the three pregnancy trimesters. 4,8,10 Quantitative analysis of the β-hCG is expensive and takes time, but the qualitative analysis is simple, fast, inexpensive, and can be used in the diagnosis of PROM. Therefore, it is possible that the pregnancy test over the threshold to the β-hCG level in the vaginal discharge in a normal pregnancy.…”

“…2,3 Infection is the most common complication of PROM, and the incidence of this damage is more frequent the longer is the latency period of delay in the diagnosis. 4 Moreover, other complications include prolonged and preterm labor, cord accident, neonatal sepsis, respiratory distress syndrome, and increase in perinatal mortality especially associated with prematurity. 1,5,6 The best method to confirm PROM is a visible leakage of amniotic fluid from the cervix, although this method is associated with 12-30% of false negative results.…”