Rudimentary uterine horn pregnancy. The 20th-century worldwide experience of 588 cases.

Objective: To investigate the outcomes of rudimentary uterine horn pregnancies and to identify trends and opportunities for improvement in patient care.

Study Design: During the period 1900-1999, 588 cases of rudimentary uterine horn pregnancy were identified using both manual and computerized searches of Index Medicus, Excerpta Medica and the Index-Catalogue of the Library of the Surgeon-General's Office of the United States Army as well as standard reference tracing. Nine characteristics of each case were evaluated: (1) fetal status at birth, (2) maternal survival, (3) neonatal survival, (4) gestational age at delivery, (5) whether the rudimentary horn ruptured, (6) communication status of the horn with the contralateral hemiuterus, (7) gravidity and parity, (8) side of the horn, and (9) order of the gestation.

Results: Newborn survival ranged from 0-13% by decade and trended upward. Eighty-five percent of pregnancies occupied noncommunicating horns. Thirty percent of gestations progressed to term or beyond. Fifty percent of pregnant uterine horns ruptured, with 80% of these events occurring before the third trimester. There was no trend in either the incidence or timing of uterine horn rupture during the century. Maternal mortality decreased from 6% to 23% during the first half of the century to < 0.5% currently. Twin pregnancies consisted of 5.3% of cases.

Conclusion: Neonatal survival has improved greatly for rudimentary horn pregnancies, and maternal mortality has decreased significantly. Such pregnancies are now identifiable early in gestation by obstetric imaging studies, and there can be guarded optimism that favorable trends in outcomes will continue into the 21st century.