Is there a role for fetoscopic laser ablation therapy in Type-2 vasa previa?

Fetoscopic Laser Ablation of Type II Vasa Previa: A Cost Benefit Analysis

OBJECTIVE

 We aimed to compare costs of two strategies for third-trimester type II vasa previa management: (1) fetoscopic laser ablation surgery (FLS) referral and (2) standard management (SM).

STUDY DESIGN

 A decision analytic model and cost-benefit analysis from a health care perspective were performed. The population included patients with type II vasa previa at approximately 32 weeks. SM entailed 32-week antepartum admission and cesarean at approximately 35 weeks. FLS referral included consultation and possible laser surgery at 32 weeks for willing/eligible candidates. Successful laser surgery allowed the possibility of term vaginal delivery. Outcomes included antepartum admission, preterm birth, cesarean, neonatal transfusion, and death. Sensitivity analyses were performed.

RESULTS

 In base case analysis, FLS referral was cost saving compared with SM (total cost per patient $65,717.10 vs. 71,628.16). FLS referrals yielded fewer antepartum admissions, cesareans, premature births, neonatal transfusions, and deaths. Eligible referred patients choosing FLS incurred a total cost of $41,702.46, a >40% decrease compared with SM. FLS referral was cost saving in all one-way sensitivity analyses except when antepartum admission costs were low. In threshold analyses, FLS referral was cost saving unless laser surgery cost was >$39,892 (2.75x expected cost), antepartum admission cost for monitoring of vasa previa or ruptured membranes was <$7,455, <11% patients were eligible for laser surgery, and when <12% of eligible patients chose laser surgery. In two-way sensitivity analysis, FLS referral was cost saving except at very high laser surgery costs and extremely low antepartum admission costs.

CONCLUSION

 Referral for FLS for type II vasa previa was cost saving and improved outcomes compared with SM, despite upfront costs, fetoscopy-related risks, and many patients being ineligible or not opting for surgery after referral.

KEY POINTS

· Vasa previa rupture may lead to fetal exsanguination and death.. · Late preterm cesarean is common practice for prenatally diagnosed vasa previa.. · Successful fetoscopic laser ablation for type II vasa previa has been described.. · Laser ablation of vasa previa allows for a safe-term vaginal delivery.. · Referral for laser surgery is cost saving and is associated with improved outcomes..

Vasa previa in singleton pregnancies: diagnosis and clinical management based on an international expert consensus

BACKGROUND

There are limited data to guide the diagnosis and management of vasa previa. Currently, what is known is largely based on case reports or series and cohort studies.

OBJECTIVE

This study aimed to systematically collect and classify expert opinions and achieve consensus on the diagnosis and clinical management of vasa previa using focus group discussions and a Delphi technique.

STUDY DESIGN

A 4-round focus group discussion and a 3-round Delphi survey of an international panel of experts on vasa previa were conducted. Experts were selected on the basis of their publication record on vasa previa. First, we convened a focus group discussion panel of 20 experts and agreed on which issues were unresolved in the diagnosis and management of vasa previa. A 3-round anonymous electronic survey was then sent to the full expert panel. Survey questions were presented on the diagnosis and management of vasa previa, which the experts were asked to rate on a 5-point Likert scale (from "strongly disagree"=1 to "strongly agree"=5). Consensus was defined as a median score of 5. Following responses to each round, any statements that had median scores of ≤3 were deemed to have had no consensus and were excluded. Statements with a median score of 4 were revised and re-presented to the experts in the next round. Consensus and nonconsensus statements were then aggregated.

RESULTS

A total of 68 international experts were invited to participate in the study, of which 57 participated. Experts were from 13 countries on 5 continents and have contributed to >80% of published cohort studies on vasa previa, as well as national and international society guidelines. Completion rates were 84%, 93%, and 91% for the first, second, and third rounds, respectively, and 71% completed all 3 rounds. The panel reached a consensus on 26 statements regarding the diagnosis and key points of management of vasa previa, including the following: (1) although there is no agreement on the distance between the fetal vessels and the cervical internal os to define vasa previa, the definition should not be limited to a 2-cm distance; (2) all pregnancies should be screened for vasa previa with routine examination for placental cord insertion and a color Doppler sweep of the region over the cervix at the second-trimester anatomy scan; (3) when a low-lying placenta or placenta previa is found in the second trimester, a transvaginal ultrasound with Doppler should be performed at approximately 32 weeks to rule out vasa previa; (4) outpatient management of asymptomatic patients without risk factors for preterm birth is reasonable; (5) asymptomatic patients with vasa previa should be delivered by scheduled cesarean delivery between 35 and 37 weeks of gestation; and (6) there was no agreement on routine hospitalization, avoidance of intercourse, or use of 3-dimensional ultrasound for diagnosis of vasa previa.

CONCLUSION

Through focus group discussion and a Delphi process, an international expert panel reached consensus on the definition, screening, clinical management, and timing of delivery in vasa previa, which could inform the development of new clinical guidelines.

Prenatal diagnosis and postnatal outcome of Type-III vasa previa: systematic review of literature

OBJECTIVE

Type-III vasa previa (VP) is a rare form of VP, not necessarily associated with other placental or vascular anomalies, in which aberrant vessels run from the placenta to the amniotic membranes, near the internal cervical os, before returning to the placenta. Early diagnosis of Type-III VP is important but technically challenging. The objective of this study was to gather the current available evidence on the perinatal diagnosis and outcome of Type-III VP.

METHODS

A systematic review of the literature on the perinatal diagnosis of atypical Type-III VP was carried out in PubMed, MEDLINE and EMBASE accordingto PRISMA guidelines from inception to March 2023. Data extraction and tabulation were performed by two operators and checked by a third senior author. The quality of the included studies was evaluated using the National Institutes of Health tool for the quality assessment of case-series studies. Our local ultrasound database was searched for previously unreported recent cases. Characteristics of prenatally and postnatally diagnosed Type-III VP, including clinical features and perinatal outcomes, were summarized using descriptive statistics.

RESULTS

Eighteen cases of Type-III VP were included, of which 16 were diagnosed prenatally (14 cases were retrieved from 10 publications and two were unpublished cases from our center) and two were diagnosed postnatally (retrieved from two publications). All prenatal cases were diagnosed on transvaginal ultrasound at a mean gestational age of 29 weeks (median, 31 weeks; range, 19-38 weeks). Conception was achieved with in-vitro fertilization in 4/16 (25.0%) cases. There were no prenatal symptoms in 15/18 (83.3%) cases, while in two (11.1%) cases there was vaginal bleeding and in one (5.6%) preterm labor occurred. In 15/18 (83.3%) cases, at least one placental abnormality was observed, including low-lying insertion (9/17), succenturiate or accessory lobe (1/17), velamentous cord insertion (3/18) and marginal insertion (9/18). All prenatally diagnosed cases were liveborn and were delivered by Cesarean section before rupture of membranes at a median gestational age of 35 weeks (range, 32-38 weeks) without neonatal complications. Emergency Cesarean section was performed in 2/16 (12.5%) cases with a prenatal diagnosis and 1/2 (50.0%) cases with a postnatal diagnosis (P = 0.179). Among those with data available, an Apgar score of ≤ 7 was observed in the prenatally vs postnatally diagnosed group in 5/13 vs 1/1 cases, respectively, at the 1-min evaluation and 3/13 vs 1/1 cases, respectively, at the 5-min evaluation.

CONCLUSIONS

The prenatal diagnosis of Type-III VP is challenging, with few cases reported in the literature; however, it is crucial for minimizing the risk of adverse outcome by enabling early-term elective Cesarean delivery prior to rupture of membranes. Given that clinical manifestations and risk factors are non-specific, and that Type-III VP cannot be excluded when there is a normal cord insertion or a singular placental mass, systematic screening by transvaginal ultrasound in the general pregnant population is recommended, particularly in those with a low-lying or morphologically abnormal placenta and those who conceived using assisted reproductive technology. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Vasa Previa

Vasa previa refers to unprotected fetal vessels running through the membranes over the cervix. Until recently, this condition was associated with an exceedingly high perinatal mortality rate attributable to fetal exsanguination when the membranes ruptured. However, ultrasonography has made it possible to diagnose the condition prenatally, allowing cesarean delivery before labor or rupture of the membranes. Several recent studies have indicated excellent outcomes with prenatally diagnosed vasa previa. However, outcomes continue to be dismal when vasa previa is undiagnosed before labor. Risk factors for vasa previa include second-trimester placenta previa and low-lying placentas, velamentous cord insertion, placentas with accessory lobes, in vitro fertilization, and multifetal gestations. Recognition of individuals who are at risk and screening them will greatly decrease the mortality rate from this condition. Because of the relative rarity of vasa previa, there are no randomized controlled trials to guide management. Therefore, recommendations on the diagnosis and management of vasa previa are based largely on cohort studies and expert opinion. This Clinical Expert Series review addresses the epidemiology, pathophysiology, natural history, diagnosis and management of vasa previa, as well as innovative treatments for the condition.

The Characteristics and Obstetric Outcomes of Type II Vasa Previa: Systematic Review and Meta-Analysis

Vasa previa is a rare fetal life-threatening obstetric disease classified into types I and II. This study aimed to examine the characteristics and obstetric outcomes of type II vasa previa. A systematic review was performed, and 20 studies (1998-2022) were identified. The results from six studies showed that type II vasa previa accounted for 21.3% of vasa previa cases. The characteristics and obstetric outcomes (rate of assisted reproductive technology (ART), antenatal diagnosis, emergent cesarean delivery, maternal transfusion, gestational age at delivery, and neonatal mortality) were compared between type I and II vasa previa, and all outcomes of interest were similar. The association between ART and abnormal placenta (bilobed placenta or succenturiate lobe) was examined in three studies, and the results were as follows: (i) increased rate of succenturiate lobes (ART versus non-ART pregnancy; OR (odds ratio) 6.97, 95% confidence interval (CI) 2.45-19.78); (ii) similar rate of abnormal placenta (cleavage-stage versus blastocyst embryo transfer); (iii) increased rate of abnormal placenta (frozen versus fresh embryo transfer; OR 2.97, 95%CI 1.10-7.96). Although the outcomes of type II vasa previa appear to be similar to those of type I vasa previa, the current evidence is insufficient for a robust conclusion.

Fetoscopic Laser Ablation Therapy for Type II Vasa Previa

BACKGROUND

In type II vasa previa, fetoscopic laser ablation has the potential to avoid prolonged hospitalization, elective prematurity, and cesarean delivery associated with traditional conservative management.

OBJECTIVE

To assess the feasibility and to report perinatal outcomes of type II vasa previa patients treated via fetoscopic laser ablation.

STUDY DESIGN

This is a retrospective descriptive study of all women with vasa previa treated with laser at our center between 2006 and 2019. After 2010, laser ablation of vasa previa was only offered after 31 gestational weeks. Continuous variables are expressed as means ± SD.

RESULTS

33 patients were evaluated for laser ablation of suspected vasa previa. Fifteen were not candidates (7 had type I vasa previa and 8 had no vasa previa), and the 18 remaining had type II vasa previa. Ten (56%) elected to undergo in utero laser ablation of the vasa previa vessel(s), which was successful in all patients. The mean gestational age (GA) at the time of the procedure was 28.8 ± 5.4 weeks, and the total operative time was 48.1 ± 21.3 min; there were no perioperative complications. The number of vessels lasered were distributed as follows: 1 (2 cases), 2 (5 cases), and 3 (3 cases). All patients except for 1 were subsequently managed as outpatients. The mean GA at delivery was 35.5 ± 3.2 weeks, and vaginal delivery occurred in 5 cases. The 5 patients with singletons who underwent laser ablation for primary diagnosis of type II vasa previa after the protocol change in 2010 had the following outcomes: mean GA of surgery was 32.5 ± 0.8 weeks, mean GA at delivery was 38.1 ± 1.4 weeks, vaginal delivery occurred in all cases, mean birth weight was 2,965 ± 596 g, and none were admitted to the neonatal intensive care unit.

CONCLUSION

This cohort represents the largest number of vasa previa cases treated via in utero laser reported to date. Laser occlusion of type II vasa previa was technically achievable in all cases and resulted in favorable outcomes.