Serum Human Chorionic Gonadotropin (β- hCG) Clearance Curves in Women with Successfully Expectantly Managed Tubal Ectopic Pregnancies: A Retrospective Cohort Study

Abstract

Objective: To establish clearance curves for serum β -hCG in women with successfully expectantly managed tubal ectopic pregnancies.

Design: Retrospective cohort study. Non- viable tubal ectopic pregnancy was diagnosed on transvaginal ultrasound. If initial serum β hCG was less than 5000 IU/L and patients were asymptomatic, expectant management was offered. Patients underwent serial β hCG measurements until serum β hCG was less than 20 IU/l, or the urine pregnancy test was negative.

Setting: Early Pregnancy and Gynaecology Assessment Unit, Kings College Hospital, London (December 1998 to July 2006).

Patients: We included 161 women with diagnosed non-viable tubal ectopic pregnancy who underwent successful expectant management.

Main outcome measure: Serum β hCG level.

Results: Mean initial serum β- hCG was 488 IU/L (41 - 4883) and median serum β hCG clearance time was 19 days (5 - 82). The average half-life of β hCG clearance was 82.5 hours (±SD 50.2) in patients with steadily declining serum β- hCG levels compared to 106.7 hours (±SD 72.0) in patients with primarily plateauing β-hCG levels in the declining phase. However, these differences were not significant (p>0.05).

Conclusion: We identified a median follow-up of 19 days until serum β hCG clearance in women with tubal ectopic pregnancy and successful expectant management. Although non- significant, women with initially plateauing serum β hCG showed a longer follow-up time until clearance compared to women with steadily declining β hCG levels. This information may serve as a guideline enabling clinicians to predict the length of follow-up for women with tubal ectopic pregnancy and expectant management.

Fig 1. Ultrasound image of a right tubal ectopic pregnancy at 6⁺² weeks gestation.

A gestation sac is seen adjacent to the right ovary.

Fig 2. Ultrasound image of a left tubal ectopic at 6+1 weeks gestation.

A hyperechoic mass is seen adjacent to the left ovary.

Fig 3. β hCG clearance curves in women with an ectopic pregnancy managed successfully expectantly in whom the β hCG declined steadily from the initial measurement.

Fig 4. β hCG clearance curves in women with an ectopic pregnancy managed successfully expectantly in whom the β hCG plateaued before declining.