Gestational sac volume in missed abortion and anembryonic pregnancy compared to normal pregnancy.

PURPOSE

To compare gestational sac (GS) volume (GSV) between normal pregnancies and missed abortions and anembryonic pregnancies and to determine at what gestational age differences in GS volume become evident. METHODS.: GSV in missed abortion and anembryonic pregnancy were measured using three-dimensional ultrasound and the results were compared with GSV in normal pregnancies. Pregnancies between 6 and 12(+6) gestational weeks of age according to last menstrual period were included in normal pregnancies, missed abortions, and anembryonic pregnancies.

RESULTS

There were 141 normal pregnancies and 82 missed or anembryonic abortions. GSV was significantly larger in normal pregnancies than in missed or anembryonic abortion: 27.51 + or - 25.25 cm(3) and 8.04 + or - 10.54 cm(3), respectively (p < 0.001). When stratified by weeks, statistically significant differences were found beginning at 7 weeks, while GSV measurements were not significantly different between the normal and abnormal pregnancies from 6 to 6(+6) weeks.

CONCLUSION

GSV in missed abortion and anembryonic pregnancies is significantly smaller than in normal pregnancies, starting at 7 weeks of gestational age. This finding may be helpful in the diagnosis of missed abortion or anembryonic pregnancies in selected cases.