Research LetterDeclaring a gestation nonviable: when 99% certainty is not enough
Section snippets
Objective
The modern paradigm for diagnosing early pregnancy loss, including ectopic pregnancy, is to compare 2 human chorionic gonadotropin (hCG) values with those expected for a growing intrauterine pregnancy (IUP).1 Surveillance of women at risk has led to earlier diagnosis, successful medical management, and decreased morbidity and mortality.2 Confirmation of nonviability is imperative because the intervention for the diagnosis or treatment with uterine evacuation or methotrexate will terminate a
Study Design
The definition of a persistent pregnancy of unknown location included no definitive ultrasound evidence of intrauterine or extrauterine gestation and a plateau in hCG, defined as <30%, <50%, <75%, or <100% in 2, 3, 4, or 7 days, respectively.3 Here, 2 clinicians confirmed eligibility into the trial. Serial hCG levels from the participant were compared with levels used to assess the viability of a pregnancy.
Results
A participant was enrolled, randomized to expectant management, and later noted to have a viable gestation. A 33-year-old, G2 P1001, who conceived with use of clomiphene citrate and intrauterine insemination presented with abnormal serial hCG values of 7% in 2 days and 24% over 4 days: 86 at 4 0/7 weeks’ gestation, 92 at 4 2/7 weeks’ gestation, and 107 at 4 5/7 weeks’ gestation. All assays were performed in the same laboratory using the Roche E170 analyzer. A transvaginal ultrasound performed
Conclusion
Estimates of expected rise in hCG were generated from a normative sample of women at risk of pregnancy loss.4 Current clinical standards assessing viability of an early gestation are based on increases above the first percentile of hCG slopes for a growing IUP: >23% in 1 day and > 49% over 2 days (for values <1500 mIU/mL).4 Conversely, 99% of normal gestations will have at least this rise in hCG. Frequently, this is incorrectly interpreted as a threshold for viability.
The criteria used in this
References (6)
- et al.
Optimal treatment for women with a persisting pregnancy of unknown location, a randomized controlled trial: the ACT-or-NOT Trial
Contemp Clin Trials
(2018) ACOG Practice Bulletin no. 191 summary: tubal ectopic pregnancy
Obstet Gynecol
(2018)- et al.
Trends in the diagnosis and treatment of ectopic pregnancy in the United States
Obstet Gynecol
(2010)
Cited by (6)
Abnormal rate of human chorionic gonadotropin rise: a case series of patients with viable intrauterine pregnancies after embryo transfer
2021, F and S ReportsCitation Excerpt :A recently published study found that 99% of normal gestations will have a rise of at least 49% over 48 hours. The investigators clarify that this is not the threshold for viability (3). Our series highlights patients within this 1% of viable gestations who do not have the anticipated rate of rise of >49% over 2 days.
Expectant management versus systemic methotrexate in the management of persistent pregnancy of unknown location, a seven-year retrospective analysis
2024, Archives of Gynecology and Obstetricsβ -Human Chorionic Gonadotropin Dynamics in Early Gestational Events: A Practical and Updated Reappraisal
2024, Obstetrics and Gynecology InternationalEvaluation of a New Model for Human Chorionic Gonadotropin Rise in Pregnancies of Unknown Viability
2023, Obstetrics and GynecologyEffect of an Active vs Expectant Management Strategy on Successful Resolution of Pregnancy among Patients with a Persisting Pregnancy of Unknown Location: The ACT or NOT Randomized Clinical Trial
2021, JAMA - Journal of the American Medical Association
The authors report no conflict of interest.