Retroperitoneal ectopic pregnancy: successful expectant management in condition of early pregnancy failure

BACKGROUND: Retroperitoneal ectopic pregnancy (REP) refers to abnormal implantation of the fertilized egg in the retroperitoneal cavity. REP can be divided into pelvic and abdominal positions. Extremely rare, the incidence of REP is less than 1% of ectopic pregnancy (EP). Herein, we report the first case of paraaortic-located REP in association with successful expectant management, thus raising awareness among healthcare providers, particularly in low-resource settings. CASE PRESENTATION: A reproductive-age woman presented at our tertiary referral hospital because of amenorrhea and a positive pregnancy test. Based on serial serum β-hCG levels and imaging modalities including transabdominal ultrasound, transvaginal sonography, and magnetic resonance imaging (MRI), a REP of 7–9 weeks of gestational age adherent to abdominal paraaortic region was detected. Since the pregnancy was spontaneously arrested without clinical symptoms, expectant management was first indicated following careful evaluation. After a 1-month follow-up, the ectopic mass naturally degenerated without complications and her β-hCG concentration returned to a negative value. Therefore, the patient recovered completely and avoided unnecessary surgery as well as toxicity of medical treatment when using systemic methotrexate. CONCLUSIONS: In addition to transvaginal and transabdominal ultrasound, MRI is necessary for the diagnosis of nonviable REP. Alongside the great vessels in the abdominal cavity should be taken into consideration in all suspected cases relating to this rare entity. Expectant management may be carefully indicated in conditions of nonviable REP and unruptured REP, where applicable.