In eight women with ovarian failure, we induced histologically normal endometrial function during a preparatory cycle consisting of sequential administration of estrogen and progesterone. During a subsequent cycle, endometrial stimulation was synchronized with surrogate-embryo transfer performed on days 16 to 21. Among the eight women, two pregnancies were established by embryo transfer on days 18 and 19. In both women, ovarian tissue was absent, and these patients therefore serve as an in vivo model for the isolated effects of estrogen and progesterone on implantation and maintenance of pregnancy. Treatment with exogenous estrogen was mandatory up to the 11th week of gestation, and treatment with progesterone until the 18th to 22nd weeks. We conclude that it is biologically feasible to simulate the essential hormonal and endometrial milieu of a fertile menstrual cycle and early gestation solely by the administration of estrogen and progesterone. Days 18 to 19 of the cycle are recommended for successful embryo implantation with this treatment program.

Objective To determine the relationship between amnionicity and number of yolk sacs before 11 weeks of gestation. Methods

A 25-year-old woman, gravida 4 para 3, presented at our antenatal clinic complaining of abdominal pain at 27 weeks of gestation. The patient's obstetric history consisted of two normal term deliveries. In her third pregnancy holoprosencephaly was diagnosed and at 26 weeks of gestation feticide was performed followed by hysterotomy due to placenta previa. The uterine incision was low transverse.Ultrasound examination demonstrated a single fetus in breech presentation with an estimated weight of 1030 g and decreased amniotic fluid volume. The cervical length was 35 mm. Midway between the internal os and the uterine fundus, we observed dehiscence of the scar measuring 50 × 26 mm, with a large herniated amniotic sac extending into the maternal abdominal cavity ( Figure 1, Videoclip S1). The extrauterine amniotic sac measured 100 × 45 mm and contained most of the amniotic fluid as well as a fetal arm and shoulder. These findings were also demonstrated on three-dimensional (3D) ultrasound (Figure 2, Videoclip S2). Following broad perinatal consultation we presented to the patient the benefits and potential risks of immediate delivery compared with expectant management. As she was asymptomatic at this point, expectant management was chosen, with the understanding that any change for the worse would necessitate immediate intervention. She was assigned a dedicated midwife and was followed without intervention. Betamethasone for lung maturation and magnesium sulfate for tocolysis were administered and instructions were issued for complete bed rest. Tocolytic treatment was discontinued after 1 day and the following 2.5 weeks were uneventful. Serial ultrasound examinations demonstrated the fetal arm and a loop of cord moving repeatedly in and out of the uterine cavity and the herniated amniotic sac (Figure 3). Seventeen days later, on follow-up ultrasound examination, the herniated amniotic sac had disappeared and severe oligohydramnios was observed. The arm was located outside the uterine cavity. Premature rupture of the membranes was diagnosed and an