A rapid test strip can accurately identify embryonic or fetal tissue in vaginal blood at the bedside, say authors of a paper published in Obstetrics and Gynecology.
The strip, called the ROM Plus test, can detect alpha-fetoprotein (AFP) and insulin-like growth factor–binding protein 1 (IGFBP-1) to identify the presence of the tissue, researchers say.
A positive test could help diagnose miscarriage and rule out ectopic pregnancy.
The ROM Plus test was originally created for diagnosing rupture of amniotic membranes and has been approved by the Food and Drug Administration. This study describes an off-label use of the test.
Lead author Michelle Volovsky, MD, of the department of obstetrics and gynecology at Maimonides Medical Center in Brooklyn, N.Y., said that in the current legal climate for abortion care, the test could have an additional use for women having vaginal bleeding.
“This test could be used as evidence to confirm that a miscarriage has occurred, and hence, a D&C (dilation and curettage) procedure in that case is not an induced abortion of a viable pregnancy,” Dr. Volovsky said.
Women in study
Three groups of reproductive-age women (totaling 90) were included in the study.
One was a negative control group consisting of nonpregnant women undergoing D&C or experiencing vaginal bleeding (n = 23). The positive control group of women had confirmed intrauterine pregnancy undergoing D&C (n = 31), and the third group was a study group of pregnant women with first-trimester bleeding (n = 36). Twelve women in the study group had confirmed ectopic pregnancies.
High sensitivity and specificity
Overall, 47 women had confirmed embryonic or fetal tissue in vaginal or uterine blood samples. The test strip was accurately positive in 45 of those 47 cases for a test sensitivity of 95.7%. The other 43 had confirmed absence of embryonic or fetal tissue in their vaginal or uterine blood samples.
The test had high specificity as well. “In the absence of embryonic or fetal tissue, such as vaginal blood sampled in cases of ectopic pregnancy, threatened or complete miscarriage, or nonpregnant individuals, the test strip had a specificity of 97.7% for obtaining a negative result,” the authors wrote.
The researchers noted that the high sensitivity and specificity were seen as all tests were performed in real-time, common clinical scenarios encountered in a high-volume, urban ob.gyn. unit.
First-trimester bleeding can be common
First-trimester bleeding occurs in 20%-40% of pregnancies and results in almost 500,000 emergency department visits in the United States every year, the authors wrote.
The most common causes include threatened miscarriage, but more serious etiologies include ectopic pregnancy.
Because criteria often are not met for ectopic pregnancy, many women are told they have a pregnancy of unknown location, which can lead to extensive and expensive follow-up.
“The current study was designed to offer a simple diagnostic alternative that does not require the use of an automated laboratory analyzer,” the authors wrote.
The test could be used by patients with confirmed intrauterine pregnancies at home – a highly desirable feature for people hesitant to come into medical offices or who live in remote areas, they noted.