Antepartum hemorrhage of unknown origin--what is its clinical significance?

Antepartum hemorrhage of unknown origin is a common antenatal complication, accounting for more than half of the cases of antepartum hemorrhage. Few investigators had reported the importance of this condition and the proper management.

The present study reviewed retrospectively 718 cases with singleton pregnancies diagnosed as having antepartum hemorrhage of unknown origin after 24 weeks from 1991 to 1996 and compared their pregnancy outcomes with controls who delivered during the same period of time as the study cases. Clinical and ultrasound examinations were performed in all recruited cases to exclude accidental hemorrhage, placenta previa or lower genital tract bleeding.

Patients with antepartum hemorrhage of unknown origin ran a higher risk of spontaneous preterm labor (p<0.001). The birthweight, when adjusted for gestation, did not differ between the two groups. Labor induction rate and cesarean section rates were significantly higher in the antepartum hemorrhage group. The incidences of major antepartum complications and neonatal complications did not differ between the two groups. There were more babies with congenital abnormalities in the antepartum hemorrhage group (p<0.001) and perinatal mortality rate was also higher, though this difference was not statistically significant.

The main fetal risks associated with antepartum hemorrhage of unknown origin is preterm labor and its subsequent fetal complications. A small but significant proportion of these pregnancies might be associated with fetal congenital abnormalities. Routine induction at term for this group of patients is of questionable value as adverse fetal outcomes are mostly associated with those that delivered prematurely, or with babies with congenital malformations. When gross fetal abnormalities could be reasonably excluded, labor induction at term should only be contemplated in the presence of other obstetric indications.