Reliability of adnexal mass mobility in distinguishing possible ectopic pregnancy from corpus luteum cysts.

OBJECTIVE

The purpose of this study was to evaluate the utility of paraovarian pelvic mass mobility as an indicator of mass identity, corpus luteum versus other, in ruling out ectopic pregnancy.

METHODS

This was a retrospective study of all pelvic sonographic examinations on patients with first-trimester complications seen over an 18-month period at a large urban emergency department. All pregnant patients with signs or symptoms of concern for ectopic pregnancy were scanned to evaluate for intrauterine pregnancy. Masses suggestive of either a corpus luteum or an ectopic pregnancy were separated from the ovary with abdominal palpation and endovaginal transducer movement. The ultrasound director and assistant director reviewed videos of all scans. Results of mass separation and outcome were recorded. Independent movement of a mass and ovary was defined as movement of the mass away from the ovary, sliding past the ovary or rotation past the ovary. Statistical analysis included descriptive statistics, inter-rater reliability, the Fisher exact test, and sensitivity, specificity, and negative and positive predictive values.

RESULTS

A total of 78 patient scans fit the criteria, and in 27 of them, the mass separated from the ovary. Twenty-three patients had ectopic pregnancy as the final diagnosis, and in 2 of these, no independent mass movement occurred. Lack of independent movement of the mass and ovary was significantly more common in patients without a final diagnosis of ectopic pregnancy (P < .0001). The negative predictive value was 96.1%.

CONCLUSIONS

Lack of independent movement of an adjacent mass and ovary was strongly associated with absence of ectopic pregnancy.