The roles of beta-human chorionic gonadotropin, creatinine and urea in vaginal washing fluid in the diagnosis of premature rupture of membranes

Objective

In this study, we aimed to test the roles and safety of urea, creatinine and beta-human chorionic gonadotropin for the diagnosis of premature rupture of membranes (PROM) by considering that fetus urine is significant for amnion formation, urea and creatinine concentrations being high in fetus urine and beta-human chorionic gonadotropin (beta-HCG) concentrations are high in amniotic fluid.

Methods

This study was conducted on 150 pregnant women who referred to the obstetrics and gynecology clinic. The study group consisted of 75 pregnant women between 27 and 42 weeks of gestation whose diagnosis of membrane rupture was confirmed and amniotic fluid came apparently. The control group consisted of 75 pregnant women between 27 and 42 weeks of gestation who did not have complaints of water break and vaginal discharge, and whose membrane rupture was ruled out. After administering 10 cc 0.9% NaCl to posterior fornix by sterile injector, a total of 6 cc washing fluid was collected. Urea, creatinine and human chorionic gonadotropin were examined on the same day on collected fluid and both groups were compared statistically.

Results

Beta-HCG, urea and creatinine values in vaginal washing fluid of the cases with premature rupture of membranes were statistically and significantly high compared to the control group (p<0.05). When designating cut-off value of beta-HCG in vaginal bleeding fluid as 50 mIU/dL, sensitivity, specificity, and positive and negative predictive values were 85.33%, 93.33%, 92.75% and 86.41%, respectively.

Conclusion

In our study, we obtained the most valuable data in premature rupture of membranes (PROM) by beta-HCG values in vaginal washing fluid. Similar results were obtained by other PROM diagnosis tests currently used such as insulin-like growth factor binding protein-1 (IGFBP-1), placental alpha microglobulin and prolactin in the vaginal fluid. When these tests are compared, it is seen that beta-HCG test in vaginal fluid is cheaper and easier, and thus it becomes more practicable

Keywords

Premature rupture of membranes, human chorionic gonadotropin

Introduction

Premature rupture of membranes (PROM) is a condition that fetal membranes rupture before labor and amniotic fluid discharges. If the rupture in membranes occurs before 37 weeks of gestation, it is defined as preterm premature rupture of membranes (PPROM). While PROM is seen in 10% of all pregnancies, 80% of the cases occur at term pregnancy.[1] Preterm premature rupture of membranes is seen in 3-5% of all pregnancies and it is the most common reason of preterm labor.[2] Fetal membranes are more solid in early pregnancy period in terms of rupture. As week of gestation increases, membranes get weaker and uterine contractions, fetal movements and increase of uterus tension facilitates the rupture of membranes.[3] Also, the decrease of collagen amount in membranes towards the term increase rupture risk. The most significant complication of PPROM is the preterm labor and associated prematurity.[4] It is essential to establish proper PROM diagnosis due to possible complications. The misdiagnosis of membrane rupture causes mistreatments such as labor induction and unnecessarily prolonged hospitalization. Today, there is no diagnosis method for PROM which is non-invasive and of gold standard. Observing direct fluid discharge from cervical os confirms PROM.[5] Amnion presence can be detected at a rate of 93% by nitrazine paper changing its color from yellow to dark blue when it is placed to vaginal posterior fornix , and many factors such as vaginitis, blood and semen increase false positivity of the test.[6] With quite high specificity and low sensitivity, the detection of fetal fibronectin in cervicovaginal secretions has been interpreted as the indicator of labor although there is no rupture of membranes.[7] Another diagnosis method is the determination of insulin-like growth factor binding protein-1 (IGFBP-1) and placental alpha microglobulin-1 protein in cervicovaginal fluids.[8,9] In a study performed, the sensitivity and specificity of immunochromatographic dipstick method used for the determination of IGFBP-1 in vaginal secretions for PROM diagnosis were found as 97%.[10] In a study including the determination of placental alpha-microglobulin-1 protein in cervicovaginal fluid as another immunochromatographic method, specificity was found 98.9% and sensitivity as 100%.[11]
Beta-human chorionic gonadotropin (HCG) exists in amniotic fluid as well as maternal blood and urine. In a study carried out by the measurement of beta-HCG level in vaginal fluid for PROM diagnosis at third trimester, sensitivity, specificity, and positive and negative predictive values were found as 100%, 96.5%, 88.9% and 100%, respectively. In the same study, it was emphasized that beta-HCG is a reliable test at second and third trimesters in PROM cases.[12] Urea and creatinine are two substances discharged from kidneys. By considering that a major part of amnion fluid consists of fetus urine, the studies have been performed to evaluate the roles of urea and creatinine levels in vaginal washing fluid for PROM diagnosis. In a study, sensitivity, specificity, and positive and negative predictive values were all found as 100% when creatinine and urea cut-off values were considered as 0.6 and 12, respectively.[13]
In this study, we aimed to test the roles and safety of urea, creatinine and beta-human chorionic gonadotropin for the diagnosis of PROM by considering that fetus urine is significant for amnion formation, urea and creatinine concentrations being high in fetus urine and beta-HCG concentrations are high in amniotic fluid.

Methods

This study was conducted on 165 pregnant women who referred to Obstetrics and Gynecology Clinic of İzmir Tepecik Training and Research Hospital between April 2009 and October 2009. Fifteen patients were excluded from the study due to vaginal bleeding, vaginitis, amniotic fluid with meconium and maternal urine mixing with amniotic fluid. Seventy-five patients between 27 and 42 weeks of gestation whose diagnoses of membrane rupture were confirmed by IGFBP-1 measurement in vaginal fluid, nitrazine test and ultrasonography and whose amniotic fluid discharged clearly were included in the study group (Group 1), and 75 patients between 27 and 42 weeks of gestation who had no complaints for water break and vaginal discharge, whose membrane rupture was ruled out were included in the control group (Group 2). All patients underwent vaginal examination by sterile speculum after the anamnesis procedure. The samples were collected as a total of 6 cc washing fluid after administering 10 cc 0.9% NaCl to posterior fornix by sterile injector, and they were examined in the same day. Same researcher collected the samples and carried out the ultrasonography in order to eliminate the difference between observers. Demographic data of the patients included in the study were recorded before collecting samples. Statistical Package for the Social Sciences (SPSS) for Windows 17.0 (SPSS Inc., Chicago, IL, USA) was used for statistical analysis. In intergroup comparisons, independent samples t test was used for the analysis of data with normal distribution. The results were evaluated within 95% confidence interval and according to p<0.05 significancy level.

Results

Our study included 150 cases and their ages were ranging between 19 and 42. No statistical difference was found when both groups were compared in terms of age, parity and the week of gestation (Table 1).
Beta-HCG values in vaginal washing fluid of Group 1 cases were statistically and significantly higher than the values of Group 2 (Table 1). When designating cut-off value of beta-HCG as 50 mIU/dL, sensitivity, specificity, and positive and negative predictive values were 85.33%, 93.33%, 92.75% and 86.41%, respectively.
Urea and creatinine values in vaginal washing fluid of Group 1 cases were statistically and significantly higher than the values of Group 2 (Table 1). When we designated cut-off value of urea as 10 mg/dL, sensitivity, specificity, and positive and negative predictive values were 26.66%, 100%, 100% and 57.69%, respectively; when we designated cut-off value of creatinine as 0.3 mg/dL, sensitivity, specificity, and positive and negative predictive values were 46.66%, 94.66%, 89.74% and 63.96%, respectively (Tables 3 and 4).

Discussion

Preterm premature rupture of membranes is one of the most common reasons for fetal morbidity and mortality. Therefore, establishing correct diagnosis of PPROM is essential to prevent possible complications and to decrease hospitalization period in case of misdiagnosis. Fluid drainage from cervical os is observed during speculum examination in the most of the patients referring to hospital with vaginal discharge complaint. Remaining patient group which includes the patients who have no fluid discharge during the examination is the group difficult to establish PROM diagnosis. Since methods such as fern test and nitrazine (pH) test which have been used widely so far are not sufficiently reliable and there is no method defined as a non-invasive golden standard yet, new tests have been researched such as insulin-like growth factor binding protein-1 (IGFBP-1), alpha-fetoprotein, prolactin, fibronectin, beta-HCG and placental alpha microglobulin-1. In addition to these tests, the presence of urea, creatinine, AST and ALT in the vaginal washing fluid which were proved to exist in amniotic fluid have become the subjects of new researches in PROM diagnosis. In our study, we also researched the role of beta-HCG, urea and creatinine values in vaginal washing fluid for PROM diagnosis.
A major part of amniotic fluid includes fetal urine at second and third trimesters. Urea and creatinine filtered out of fetal kidneys pass to the amniotic fluid through urine. Beta-HCG is a substance produced by trophoblastic tissue, exists at various concentrations in maternal blood, urine and amniotic fluid, and easy to detect.[14] Presence of these three substances in vaginal secretions at low concentrations and the increase of vaginal concentration after amniotic drainage at PROM mean that it would be useful to use these substances in the diagnosis of PROM. In our study, beta-HCG values in vaginal washing fluid of Group 1 cases were statistically and significantly higher than the values of Group 2 (Table 1). Similarly, urea and creatinine values in vaginal washing fluid of Group 1 were statistically and significantly higher than the values of Group 2 (p=0.001 and p<0.001, respectively).
In the study of Cooper et al., when cut-off value of beta-HCG in vaginal washing fluid for PROM diagnosis was designated as 50 mIU/dL, sensitivity, specificity, and negative and positive predictive values were found as 96%, 79%, 95% and 84%, respectively.[14] In our study, When designating cut-off value of beta-HCG in vaginal bleeding fluid as 50 mIU/dL, sensitivity, specificity, positive and negative predictive values were 85.33%, 93.33%, 92.75% and 86.41%, respectively.
In the study carried out by Kafalı and Öksüzler, the authors designated urea cut-off value in the vaginal washing fluid as 12 mg/dL and creatinine cut-off value as 0.6 mg/dL and they found sensitivity, specificity and negative and positive predictive values as 100%.[13] In our study, we found completely different results. When we designated cut-off value of urea in vaginal bleeding fluid as 10 mg/dL, sensitivity, specificity, and negative and positive predictive values were 26.66%, 100%, 100% and 57.69%, respectively. When we designated cut-off value of creatinine as 0.3 mg/dL, sensitivity, specificity, and negative and positive predictive values were 46.66%, 94.66%, 89.74% and 63.96%, respectively.

Conclusion

In our study, we obtained the most valuable data in PROM by beta-HCG values in vaginal washing fluid. We found that we can use beta-HCG for the diagnosis of PROM when we designated the cut-off value of beta-HCG as 50 mIU/dL. Similar results were also reached by IGFBP-1 in vaginal fluid, placental alpha microglobulin-1 and prolactin tests which have been currently used as other PROM diagnosis tests.[15-17] When these tests are compared, it is seen that beta-HCG test in vaginal fluid is cheaper and easier, and thus it becomes more practicable.
Conflicts of Interest: No conflicts declared.

References

1. Mercer BM. Preterm premature rupture of the membranes. Obstet Gynecol 2003;101:178-93.
2. Aagaard-Tillery KM, Nuthalapaty FS, Ramsey PS, Ramin KD. Preterm premature rupture of membranes: perspectives surrounding controversies in management. Am J Perinatol 2005;22:287-97.
3. Garite TJ. Management of premature rupture of membranes. Clin Perinatol 2001;28:837-47.
4. Meis PJ, Goldenberg RL, Mercer BM, Iams JD, Moawad AH, Miodovnik M, et al. The preterm prediction study: risk factors for indicated preterm births. Maternal-Fetal Medicine Units Network of the National Institute of Child Health and Human Development. Am J Obstet Gynecol 1998;178:562-7.
5. Gibbs RS, Karlan BY, Haney AF, Nygaard I. Erken Membran Rüptürü. Danforth’s Obstetrik ve Jinekoloji. 10. Baskı. Ankara: Güneş Tıp Kitabevleri; 2010: p. 186-976.
6. Davidson KM. Detection of premature rupture of the membranes. Clin Obstet Gynecol 1991;34:715-22.
7. Abbott DS, Radford SK, Seed PT, Tribe RM, Shennan AH. Evaluation of a quantitative fetal fibronectin test for spontaneous preterm birth in symptomatic women. Am J Obstet Gynecol 2013;208:122.e1-6.
8. Akercan F, Cirpan T, Kazandi M, Terek MC, Mgoyi L, Ozkinay E. The value of the insulin-like growth factor binding protein-1 in the cervical-vaginal secretion detected by immunochromatographic dipstick test in the prediction of delivery in women with clinically unconfirmed preterm premature rupture of membranes. Eur J Obstet Gynecol Reprod Biol 2005;121:159-63.
9. Lee SE, Park JS, Norwitz ER, Kim KW, Park HS, Jun JK. Measurement of placental alpha-microglobulin-1 in cervicovaginal discharge to diagnose rupture of membranes. Obstet Gynecol 2007;109:634-40.
10. Erdemoglu E, Mungan T. Significance of detecting insulin-like growth factor binding protein-1 in cervicovaginal secretions: comparison with nitrazine test and amniotic fluid volume assessment. Acta Obstet Gynecol Scand 2004;83:622-6.
11. Cousins LM, Smok DP, Lovett SM, Poeltler DM. AmniSure placental alpha microglobulin-1 rapid immunoassay versus standard diagnostic methods for detection of rupture of membranes. Am J Perinatol 2005;22:317-20.
12. Anai T, Tanaka Y, Hirota Y, Miyakawa I. Vaginal fluid hCG levels for detecting premature rupture of membranes. Obstet Gynecol 1997;89:261-4.
13. Kafali H, Oksüzler C. Vaginal fluid urea and creatinine in diagnosis of premature rupture of membranes. Arch Gynecol Obstet 2007;275:157-60.
14. Cooper AL, Vermillion ST, Soper DE. Qualitative human chorionicgonadotropin testing of cervicovaginal washings for the detection of preterm premature rupture of membranes. Am J Obstet Gynecol 2004;191:593-7
15. Abdelazim IA, Makhlouf HH. Placental alpha microglobulin-1 (AmniSure® test) for detection of premature rupture of fetal membranes. Arch Gynecol Obstet 2012;285:985-9.
16. Tagore S, Kwek K. Comparative analysis of insulin-like growth factor binding protein-1 (IGFBP-1), placental alpha-microglobulin-1 (PAMG-1) and nitrazine test to diagnose premature rupture of membranes in pregnancy. J Perinat Med 2010;38:609-12.
17. Kariman N, Hedayati M, Alavi Majd Sh. The diagnostic power of cervico-vaginal fluid prolactin in the diagnosis of premature rupture of membranes. Iran Red Crescent Med J 2012;14:541-8.

	File/Dsecription
	Table 1. The demographic data of the patients and their beta-HCG, urea and creatinine values in vaginal bleeding.
	Table 2. The distribution of patients to the groups when B-HCG level is considered as 50 IU.
	Table 3. The distribution of patients to the groups when urea level is considered as 10 mg/dL.
	Table 4. The distribution of patients to the groups when creatinine level is considered as 0.3 mg/dL.