The November issue of Ultrasound in Obstetrics & Gynecology includes a study on a new approach for estimating the risk of miscarriage after chorionic villus sampling, a study on the trend in ventricle size during pregnancy and its use for prediction of ventriculoperitoneal shunt in fetal open neural tube defect, a study on ophthalmic artery Doppler in the prediction of pre-eclampsia at 35–37 weeks’ gestation, a study and accompanying video abstract on follow-up ultrasound in second-trimester low-positioned anterior and posterior placentae, and a study finding that transvaginal sonography accurately measures lesion-to-anal-verge distance in women with deep endometriosis of the rectosigmoid.
New approach for estimating risk of miscarriage after chorionic villus sampling
Calculating the procedure related-risk of miscarriage from chorionic villus sampling (CVS) by comparing the rate of miscarriage between women who had CVS and those who did not is likely to entail a risk of bias against CVS because several of the factors that lead to the need for CVS are also risk factors for miscarriage. To overcome this, Gil et al. used propensity score matching analysis to estimate the CVS-related risk of miscarriage, accounting for the effects of maternal and pregnancy characteristics that could have driven the decision to undergo CVS. It was found that, after accounting for these risk factors and confining the analysis to low-risk pregnancies, CVS seems to increase the risk of miscarriage by about three times above the patient’s background risk. Although this is a substantial increase in relative terms, in pregnancies without risk factors for miscarriage, the risk of miscarriage after CVS remains low and similar to, or slightly higher than, that in the general population.
This study is one of several in this issue of the Journal providing up-to-date information on current invasive diagnostic approaches.
Trend in ventricle size during pregnancy and its use for prediction of ventriculoperitoneal shunt in fetal open neural tube defect
The MOMS trial demonstrated a 50% reduction in the rate of ventriculoperitoneal shunt (VPS) placement in fetuses that had in-utero fetal repair of myelomeningocele compared with those that had postnatal repair, and those with preoperative ventricle size (VS) ≥15mm were more likely to have VPS placement. Donepudi et al. investigated the trend in VS during pregnancy and whether VS and change in VS, as assessed by ultrasound, were predictive of the need for VPS in pregnancy with an open neural tube defect. It was found that VS increased with advancing gestational age in all fetuses with an open neural tube defect, although in the in-utero fetal repair group this increase occurred immediately after fetal surgery and in the postnatal repair group it occurred after 30 weeks of gestation. In-utero surgery was associated with a decreased rate of VPS and was more predictive of need for VPS than was VS.
Ophthalmic artery Doppler in prediction of pre-eclampsia at 35–37 weeks’ gestation
The ophthalmic artery is an easily accessible vessel for Doppler assessment that provides information on the less accessible intracranial circulation. Sarno et al. examined the potential value of maternal ophthalmic artery Doppler in the prediction of subsequent development of pre-eclampsia and the variability between repeat measurements in the same eye and variability in measurements between the two eyes. It was found that the ratio of the second to first peak of systolic velocity of the ophthalmic artery at 35–37 weeks’ gestation can predict subsequent delivery with pre-eclampsia, especially if this occurs within 3 weeks after assessment. In the assessment of ophthalmic artery Doppler, it is necessary to use the average of one measurement from each eye to minimize variability of measurements.
Follow-up ultrasound in second-trimester low-positioned anterior and posterior placentae: prospective cohort study
To improve both maternal and fetal outcomes, it is important to diagnose low-positioned placentae during pregnancy. However, over 90% of women with placenta previa or a low-lying placenta in the second trimester will no longer have this condition in the third trimester. Jansen et al. assessed the accuracy of the distance between the placenta and the internal os of the cervix (IOD) in the second trimester for the prediction of third-trimester low-positioned placenta. It was found that low-lying placenta or placenta previa in the second trimester persists more often in the third trimester when the placenta is posteriorly located compared with when the placenta is located on the anterior side. With incorporation of a safety margin of 5mm and ensuring that all women with placenta previa undergo a follow-up scan, the authors recommend lowering the IOD cut-off value for follow-up in cases of an anterior low-positioned placenta from 20 to 5mm, which would decrease the number of unnecessary follow-up ultrasound examinations without missing any high-risk women. Watch the accompanying video abstract:
Transvaginal sonography accurately measures lesion-to-anal-verge distance in women with deep endometriosis of the rectosigmoid
In women undergoing surgery for rectosigmoid deep endometriosis (DE), low anastomotic height has been shown to confer increased fistula and anastomotic leakage rates. Aas-Eng et al. investigated whether presurgical transvaginal sonography (TVS) accurately predicts lesion-to-anal-verge distance (LAVD) in women with rectosigmoid DE, as compared with intraoperative measurement, and assessed the agreement between anastomotic height and LAVD measured using TVS. It was found that there is good agreement between LAVD measured using TVS and IOM in women with rectosigmoid DE. As a consequence, TVS could be useful for estimation of the height of the final surgical anastomosis in women undergoing full-thickness resection for rectosigmoid DE.
Coming up next month…
- A video abstract on the prevalence of negative sliding sign representing pouch of Douglas obliteration during pelvic transvaginal ultrasound for any indication. Read the Early View article.
- A series of papers on coarctation of the aorta.