Pregnancy Outcomes in Patients With Prior Uterine Rupture or Dehiscence

Uterine rupture is a serious pregnancy complication associated with significant maternal and neonatal morbidity and mortality. For women with a history of uterine rupture, there is a risk of recurrence, ranging in the literature from 0-33%. Owing to this, some women with a prior uterine rupture are advised not to have more pregnancies. In 2014, we reported outcomes for 14 women (20 pregnancies) with a history of uterine rupture (clinically apparent, complete scar separation in labor or before labor) and 30 women (40 pregnancies) with a history of uterine dehiscence (incomplete uterine scar separation with intact serosa, sometimes referred to as a uterine window). In these 60 pregnancies, there was 0% severe morbidity and 6.7% of pregnancies had uterine dehiscence seen at the time of delivery. Subsequent to the 2014 publication, we have seen an increase in patients with a history of uterine rupture or dehiscence, and the objective of this Research Letter is to update our results with a larger sample size.

Dr. Fox was featured on “The Green Journal” discussing this topic. Listen in!



Frequency of spontaneous resolution of vasa previa with advancing gestational age

Vasa previa, defined as unprotected fetal vessels running through the membranes over the cervix, often ruptures when the membranes rupture, frequently leading to sudden fetal death. This used to be a feared condition among obstetricians, first because of its devastating consequences, but also because, until recently, it was rarely diagnosed prior to the rupture and hence was considered unpreventable. There are now several studies that have documented universally excellent outcomes when vasa previa is diagnosed prenatally, and planned cesarean delivery is undertaken before the membranes rupture. Risk factors for vasa previa include a second-trimester low lying placenta/placenta previa (regardless of resolution), pregnancies with bilobed or succenturiate-lobed placentas, pregnancies resulting from in vitro fertilization, and multifetal pregnancies. Based upon our prior publication from 2014 (Rebarber A, et al JUM) we have recommended targeted screening in pregnancies in which these risk factors are present. Most recently , our current publication (Klahr et al AJOG 2019) found an absence of risk factors in 6% of cases of vasa previa, so we routinely advocate the region over the cervix should also be examined carefully and judicious evaluation with Color Doppler is advised. Additonally, in our  most recent publication on this topic we noted that a proportion of cases diagnosed in early pregnancy will resolve prior to delivery.  Our findings mean that women with vasa previa diagnosed early in pregnancy may not necessarily need hospitalization and early delivery and serial evaluation is important to properly diagnose patients that require cesarean section and early intervention. More specifically, we found that 39% of vasa previas diagnosed patients in our population (at Carnegie Imaging for Women , NYC) resolved over the course of pregnancy. Earlier gestational age at diagnosis, vasa previa not covering the internal os, and not having a resolved placenta previa all are associated independently with an increased likelihood of vasa previa resolution.

We also proudly note that our paper was highlighted in the December 2019 American Journal of Obstetrics and Gynecology Editorial titled “Vasa previa: time to make a difference” providing evidence that standard screening for this condition should be implemented nationwide as we have done since 2005 in our ultrasound units. A unique opportunity exists to prevent perinatal mortality from this condition. Prenatal diagnosis accompanied by timely cesarean delivery will prevent deaths from vasa previa.

Association Between First-Trimester Subchorionic Hematomas and Pregnancy Loss in Singleton Pregnancies

Subchorionic hematomas, or subchorionic hemorrhages, are common ultrasound findings in early pregnancy.   However, their significance is uncertain.  Some believe they increase the risk of many pregnancy complications, including pregnancy loss / miscarriage.  In this study of almost 3000 women, we found that Subchorionic hematoma does not increase the risk of pregnancy loss prior to 20 weeks.  This information is reassuring as nearly 20% of women will have this finding on ultrasound.

Cervical Length, Cervical Dilation, and Gestational Age at Cerclage Placement and the Risk of Preterm Birth in Women Undergoing Ultrasound or Exam Indicated Shirodkar Cerclage

Certain high-risk women require cerclage placement in pregnancy to lower the risk of a pregnancy loss or preterm birth and we have previously published our vast experience with this procedure (  In this study we examined if there were any differences in cerclage outcomes, based on the cervical  length, cervical dilation, or gestational age at the time of the procedure.

Weight Gain and Pregnancy Outcomes in Underweight Women with Twin Gestations

We have previously shown the critical importance of adequate pregnancy weight gain for women with twin pregnancies  However, most data has been for women who enter pregnancy with a normal weight, as defined by the pre-pregnancy body mass index (BMI).  In this study, we found that women who enter pregnancy underweight should be recommended the same weight gain as women with normal pre-pregnancy weight.

The Association Between High-Normal Blood Pressure and the Development of Preeclampsia in Twin Pregnancies

Women with twin pregnancies are at increased risk of preeclampsia.  In this study we found that women  with twin pregnancies and blood pressure readings that were normal, but in the upper range of normal, are at significantly increased risk of developing preeclampsia and need to be monitored carefully.