Related Experiment Video
Updated: Jul 2, 2026
Purification of HLA-G+ Extravillous Trophoblasts from Human Term Placental Tissues for Phenotyping and Functional Analysis
Published on: March 13, 2026
Blood test for placental site trophoblastic tumor and nontrophoblastic malignancy for evaluating patients with low
Laurence A Cole1, Sarah A Khanlian, Carolyn Y Muller
1USA hCG Reference Service, Department of Obstetrics and Gynecology, University of New Mexico, Albuquerque 87131-0001, USA. larry@hcglab.com
Objective:
To examine utility of measurement of proportions of free beta-subunit of human chorionic gonadotropin (hCG) in diagnosis of placental site trophoblastic tumor (PSTT) and nontrophoblastic neoplasm in patients with persistent low hCG levels and patients with history of gestational trophoblastic diseases.
Study Design:
The USA hCG Reference Service measured proportions of free beta-subunit in 128 cases, 45 with active invasive trophoblastic disease and 83 questionable cases with persistent low hCG levels, with or without history of gestational trophoblastic disease (GTD).
Results:
High proportions of free beta-subunit (> 30% of total hCG) were identified in 18 of 128 cases, all suspected of having PSTT or nontrophoblastic neoplasm, which was reported to referring physicians. Within 2 months of testing, hysterectomy or tumor biopsy led to histologic proof of PSTT in 13 of the 18 cases and biopsy led to proof of nontrophoblastic neoplasm in 5 of the 18 cases.
Conclusion:
We confirm use of proportion of free beta-subunit (> 30%) as a seemingly absolute test for identifying PSTT and nontrophoblastic neoplasms. It should be used to identify and diagnose these malignancies in women presenting with persistent low hCG levels outside of pregnancy and in secondary evaluation of patients with a history of GTDs.
