Multiple pregnancy must be distinguished from the following conditions.

A. Singleton Pregnancy

Inaccurate dates may give a false impression of the duration of the pregnancy, and the fetus may be larger than expected.

B. Polyhydramnios

Either single or multiple pregnancy may be associated with excessive accumulation of fluid.

C. Hydatidiform Mole

Although usually easily distinguished from multiple gestation, this complication must be considered in diagnosis early in pregnancy.

D. Abdominal Tumors Complicating Pregnancy

Fibroid tumors of the uterus, when present in great numbers, are readily identified. Ovarian tumors are generally single, discrete, and harder to diagnose. A distended bladder or full rectum may elevate the pregnant uterus.

E. Complicated Twin Pregnancy

If one dizygotic twin dies early in pregnancy and the other lives, the dead fetus may become flattened and mummified (fetus papyraceous;). Its portion of a fused placenta will be pale and atrophic, but remnants of 2 sacs and 2 cords may be found. If one twin dies in late pregnancy, considerable enlargement of the uterus persists, although the findings on palpation may be unusual and only one fetal heartbeat will be heard. Ultrasonography can confirm the diagnosis. The living fetus generally presents first.