Promising blood test for ectopic pregnancy
Promising blood test for ectopic pregnancy
This article waslast modified
on 10 July 2017.
As many as two percent of pregnancies may be ectopic, the fertilized egg having implanted outside the womb. In 98% of cases the ectopic implantation is in one of the two fallopian tubes that carry eggs from the ovaries to the womb. Tubal pregnancy can cause abdominal pain and often vaginal spotting or bleeding. Most ectopic pregnancies are suspected between the sixth and tenth week of pregnancy. Early diagnosis is essential to prevent the developing placenta rupturing the fallopian tube and causing life-threatening shock.
Currently diagnosis depends on following changes in the serum concentration of human chorionic gonadotrophin (hCG) and, sometimes, progesterone. During early pregnancy blood hCG concentrations double every two to three days and indicate when a transvaginal ultrasound scan should be able to identify a pregnancy in the uterus. The hCG levels in ectopic pregnancies usually increase more slowly than normal, as do those with failing pregnancies where hCG levels may even fall. If tubal ectopic pregnancy is diagnosed, treatment is either by the intramuscular injection of methotrexate to stop placental growth or by abdominal key-hole surgery. However, it may take many days before a definite diagnosis can be made.
A hormone that stimulates the formation of new blood vessels to support an implanted fertilized egg, placental growth factor (PIGF), was investigated as a possible rapid diagnostic test for ectopic pregnancy by workers from the Centre for Reproductive Biology in the University of Edinburgh. Their hypothesis was that the PIGF production would be lower in tubal than in intrauterine pregnancy. The results of their small study were reported online on 3 November 2010 in the Journal of Clinical Endocrinology and Metabolism.
Blood samples were collected about the eighth week of pregnancy from 15 women undergoing elective surgical termination of normal pregnancy, 10 women having surgical treatment after a miscarriage and 15 having surgical management of tubal pregnancy. In fewer than half of each group it was also possible to obtain uncontaminated samples of trophoblast - the outer layer of tissue responsible for implantation of the fertilized ovum and formation of the placenta.
The researchers found that under the microscope PIGF was clearly localized to trophoblast tissue in samples from pregnancies in the uterus and miscarriages, but could not be identified in the tissue from tubal pregnancies. Blood PIGF was undetectable by a sensitive immunoassay in the 15 tubal pregnancies and was also undetectable in seven of the 10 miscarriages. The remaining three had detectable values that were at least five times lower than the lowest values in the 15 with intrauterine pregnancies. The authors comment that PIGF differentiated these three from the tubular pregnancies even though their hCG levels were similar, and recommend large-scale prospective studies of the clinical role of this commercially available test, alone or in combination with other markers.
Currently diagnosis depends on following changes in the serum concentration of human chorionic gonadotrophin (hCG) and, sometimes, progesterone. During early pregnancy blood hCG concentrations double every two to three days and indicate when a transvaginal ultrasound scan should be able to identify a pregnancy in the uterus. The hCG levels in ectopic pregnancies usually increase more slowly than normal, as do those with failing pregnancies where hCG levels may even fall. If tubal ectopic pregnancy is diagnosed, treatment is either by the intramuscular injection of methotrexate to stop placental growth or by abdominal key-hole surgery. However, it may take many days before a definite diagnosis can be made.
A hormone that stimulates the formation of new blood vessels to support an implanted fertilized egg, placental growth factor (PIGF), was investigated as a possible rapid diagnostic test for ectopic pregnancy by workers from the Centre for Reproductive Biology in the University of Edinburgh. Their hypothesis was that the PIGF production would be lower in tubal than in intrauterine pregnancy. The results of their small study were reported online on 3 November 2010 in the Journal of Clinical Endocrinology and Metabolism.
Blood samples were collected about the eighth week of pregnancy from 15 women undergoing elective surgical termination of normal pregnancy, 10 women having surgical treatment after a miscarriage and 15 having surgical management of tubal pregnancy. In fewer than half of each group it was also possible to obtain uncontaminated samples of trophoblast - the outer layer of tissue responsible for implantation of the fertilized ovum and formation of the placenta.
The researchers found that under the microscope PIGF was clearly localized to trophoblast tissue in samples from pregnancies in the uterus and miscarriages, but could not be identified in the tissue from tubal pregnancies. Blood PIGF was undetectable by a sensitive immunoassay in the 15 tubal pregnancies and was also undetectable in seven of the 10 miscarriages. The remaining three had detectable values that were at least five times lower than the lowest values in the 15 with intrauterine pregnancies. The authors comment that PIGF differentiated these three from the tubular pregnancies even though their hCG levels were similar, and recommend large-scale prospective studies of the clinical role of this commercially available test, alone or in combination with other markers.