Risk factors and clinical features of ovarian pregnancy: a case-control study.

OBJECTIVE

To identify risk factors for ovarian pregnancy (OP) and compare clinical features between OP and tubal pregnancy (TP) patients.

DESIGN

Case-control study.

SETTING

University hospital.

PARTICIPANTS

A case-control study was conducted from January 2005 to May 2014. Women diagnosed with OP were recruited as the case group (n=71), 145 women with TP and 146 with intrauterine pregnancy (IUP) were matched as controls at a ratio of 1:2:2. Women who refused interviews or provided incomplete information were excluded.

RESULTS

OP risk was lower than TP risk in women with serological evidence of Chlamydia trachomatis infection (adjusted OR1 0.17, 95% CI 0.06 to 0.52), previous adnexal surgery (adjusted OR1 0.25, 95% CI 0.07 to 0.95), and current levonorgestrel emergency contraceptive use (adjusted OR1 0.24, 95% CI 0.07 to 0.78). In vitro fertilisation-embryo transfer (IVF-ET) carried a higher risk of OP (adjusted OR1 12.18, 95% CI 2.23 to 66.58) than natural conception. When Controlled by IUP women, current users of intrauterine devices (IUDs) carried a higher risk of OP than non-users of any contraceptives (adjusted OR2 9.60, 95% CI 1.76 to 42.20). β-Human chorionic gonadotropin (hCG) levels on the day of surgery were higher in OP patients than in TP patients (p<0.01). Women with OP were less likely to initially present with vaginal bleeding than those with TP (p=0.02). Moreover, shock (p=0.02), rupture (p<0.01), haemoperitoneum (p<0.01) and emergency laparotomy (p<0.01) were more common in the OP group than in the TP group.

CONCLUSIONS

IVF-ET and IUD use may be risk factors for OP, and OP patients tend to have high β-hCG levels and a poor clinical outcome (shock, rupture, haemoperitoneum and need for emergency laparotomy). Our findings may contribute to the prevention and early diagnosis of OP.