Expectant management of early pregnancies of unknown location: a prospective evaluation of methods to predict spontaneous resolution of pregnancy

Objective To assess prospectively the ability of two multiparameter diagnostic models and their individual components to predict the outcome of early pregnancies which could not be identified on transvaginal ultrasound scan.
Design Prospective observational study.
Setting Dedicated early pregnancy unit in an inner city teaching hospital.
Population Women with a positive urine pregnancy test and clinical suspicion of early pregnancy complications.
Methods A full medical history, clinical examination and transvaginal ultrasound scan were carried out at the initial visit. When the location of the pregnancy could not be ascertained by ultrasound, serum beta-human chorionic gonadotrophin ( β -hCG) and progesterone levels were measured. All women were managed expectantly until either a normal pregnancy was visualised on scan; the pregnancy resolved spontaneously or intervention was required due to a worsening of clinical symptoms or non-declining β -hCG levels.
Main outcome measures Spontaneous resolution of pregnancy (i.e. cessation of symptoms and decline in serum β -hCG level to < 20 iu/L) without need for any active intervention.
Results Of the 104 women recruited, 72 (69%) pregnancies resolved spontaneously. Both multiparameter diagnostic models identified resolving pregnancies with positive predictive values  ≥ 95%  . Their performances were not significantly better compared with individual progesterone levels which achieved a positive predictive value of 97% using a cutoff level of 20 nmol/L.
Conclusion Serum progesterone measurement alone is as accurate as more complex diagnostic models for the prediction of successful expectant management in pregnancies of unknown location.