Rapid and radical amniodrainage in the treatment of severe twin-twin transfusion syndrome

Feasibility of continuous intra-uterine pressure measurements during amnioreduction in twin-to-twin transfusion syndrome therapy

INTRODUCTION

This work explores the feasibility of simultaneous and continuous intra-abdominal, intra-uterine, and arterial blood pressure measurements to examine the hemodynamic perturbation expected during therapeutic amnioreduction and to better understand the protective role of the placenta during that treatment.

METHODS

Patients with twin-to-twin transfusion syndrome were treated with fetoscopic laser ablation followed by amnioreduction. Intra-abdominal, intra-uterine, and mean arterial pressures were simultaneously recorded during amnioreduction performed in steps of 200 mL. Placental thickness and uterine dimensions were measured before and after amnioreduction by ultrasonography.

RESULTS

Useful pressure recordings were obtained between volume reduction steps and short hands-off periods in four studies. Median amnioreduction volume was 1400 mL corresponding to a median uterine volume reduction of 1121 mL. Mean intra-uterine pressure significantly fell from 24.8 to 13.6 mmHg (p = 0.011) and intra-abdominal pressure significantly decreased from 13.4 to 9.2 mmHg after amnioreduction (p = 0.015). Uterine pressure recordings revealed transient contractions (A, in mmHg) following individual amnioreduction steps, which increased with fractional amnioreduction (F, no dimension) (A = 17.23*F + 11.81; r = 0.50, p = 0.001).

DISCUSSION

Simultaneous and continuous measurement of intra-abdominal, intra-uterine, and arterial blood pressures during amnioreduction is feasible. The dynamics reveal transient uterine contractions reaching levels comparable to those seen during childbirth which seem to oppose impending maternal hypovolemia by placental steal at the expense of temporarily reducing placental perfusion pressure and underline the importance of uterine and placental interaction.

Thick Placenta in Pregnancy: A Review

Importance

A thickened placenta is easily identified on ultrasound and provides insight into maternal and fetal wellbeing as well as underlying structural and physiologic anomalies.

Objectives

The aim of this study was to review the literature to clarify what classifies a placenta as "thickened" and to review the associated incidence, maternal and fetal comorbidities, and management during pregnancy.

Evidence Acquisition

Electronic databases (PubMed and Web of Science) were searched from 2000 to 2020 in the English language. Studies were selected that examined associations between placental thickness, potential etiologies, and obstetric outcomes.

Results

There were 140 abstracts identified. After reviewing the articles, 60 were used in this review. Routine assessment of the placenta in the prenatal period is an easy and inexpensive way to assess the maternal and fetal patients. The criteria for a "thickened placenta" vary between studies based on gestational age, placental location, measurement technique, and maternal or fetal factors. Whereas most suggest thickness exceeding 4 cm is pathologic, a review had a threshold of 6 cm in the third trimester to classify placentomegaly. Several maternal and fetal conditions have been associated with a thickened placenta, such as obesity, parity, anemia, diabetes, preeclampsia, cardiac dysfunction, infection, assisted reproductive technology, multiple pregnancy, sacrococcygeal teratomas, and Beckwith-Wiedemann syndrome. A thickened placenta in pregnancy is associated with a higher incidence of adverse pregnancy outcomes and neonatal morbidity and mortality.

Conclusions

The literature is clear that early evaluation of the placenta using ultrasound should be a standard practice. A thickened placenta found on routine imaging should prompt a more thorough investigation to determine the etiology of the placentomegaly. At the time of this literature review, there are no recommendations regarding modality or frequency of antenatal surveillance in pregnancies complicated by a thickened placenta. However, serial ultrasounds and weekly antenatal testing in the third trimester should be considered.

Relevance

A thickened placenta has been associated with a variety of maternal and fetal conditions and increases the risk of adverse pregnancy outcomes and neonatal morbidity and mortality.

Understanding Sociodemographic Disparities in Maternal-Fetal Surgery Study Participation

BACKGROUND/PURPOSE

Although maternal-fetal surgery to treat fetal anomalies such as spina bifida continues to grow more common, potential health disparities in the field remain relatively unexamined. To address this gap, we identified maternal-fetal surgery studies with the highest level of evidence and analyzed the reporting of participant sociodemographic characteristics and representation of racial and ethnic groups.

METHODS

We conducted a systematic review of the scientific literature using biomedical databases. We selected randomized control trials (RCTs) and cohort studies with comparison groups published in English from 1990 to May 5, 2020. We included studies from across the globe that examined the efficacy of fetal surgery for twin-twin transfusion syndrome (TTTS), obstructive uropathy, congenital diaphragmatic hernia (CDH), myelomeningocele (MMC), thoracic lesions, cardiac malformations, or sacrococcygeal teratoma. We determined the frequency of reporting of age, gravidity/parity, race, ethnicity, education level, language spoken, insurance, income level, and relationship status. We identified whether sociodemographic factors were used as inclusion or exclusion criteria. We calculated the racial and ethnic group representation for studies in the USA using the participation-to-prevalence ratio (PPR).

RESULTS

We included 112 studies (10 RCTs, 102 cohort) published from 1990-1999 (8%), 2000-2009 (30%), and 2010-2020 (62%). Most studies were conducted in the USA (47%) or Europe (38%). The median sample size was 58. TTTS was the most common disease group (37% of studies), followed by MMC (23%), and CDH (21%). The most frequently reported sociodemographic variables were maternal age (33%) and gravidity/parity (20%). Race and/or ethnicity was only reported in 12% of studies. Less than 10% of studies reported any other sociodemographic variables. Sociodemographic variables were used as exclusion criteria in 13% of studies. Among studies conducted in the USA, White persons were consistently overrepresented relative to their prevalence in the US disease populations (PPR 1.32-2.11), while Black or African-American, Hispanic or Latino, Asian, American-Indian or Alaska-Native, and Native-Hawaiian or other Pacific Islander persons were consistently underrepresented (PPR 0-0.60).

CONCLUSIONS

Sociodemographic reporting quality in maternal-fetal surgery studies is poor and inhibits examination of potential health disparities. Participants enrolled in studies in the USA do not adequately represent the racial and ethnic diversity of the population across disease groups.

Aspiration in injections: should we continue or abandon the practice?

Aspiration during any kind of injection is meant to ensure that the needle tip is at the desired location during this blind procedure. While aspiration appears to be a simple procedure, it has generated a lot of controversy concerning the perceived benefits and indications. Advocates and opponents of aspiration both make logically sound claims. However, due to scarcity of available data, there is no evidence that this procedure is truly beneficial or unwarranted. Keeping in view the huge number of injections given worldwide, it is important that we draw attention to key questions regarding aspiration that, up till now, remain unanswered. In this review, we have attempted to gather and present literature on aspiration both from published and non-published sources in order to provide not only an exhaustive review of the subject, but also a starting point for further studies on more specific areas requiring clarification. A literature review was conducted using the US National Institute of Health’s PubMed service (including Medline), Google Scholar and Scopus. Guidelines provided by the World Health Organization, Safe Injection Global Network, International Council of Nursing, Center for Disease Control, US Federal Drug Agency, UK National Health Services, British Medical Association, Europe Nursing and Midwifery Council, Public Health Agency Canada, Pakistan Medical Association and International Organization of Standardization recommendations 7886 parts 1-4 for sterile hypodermics were reviewed for relevant information. In addition, curricula of several medical/nursing schools from India, Nigeria and Pakistan, the US pharmacopeia Data from the WHO Program for International Drug Monitoring network in regard to adverse events as a result of not aspirating prior to injection delivery were reviewed. Curricula of selected major medical/nursing schools in India, Nigeria and Pakistan, national therapeutic formularies, product inserts of most commonly used drugs and other possible sources of information regarding aspiration and injections were consulted as well.

Polyhydramnios: Causes, Diagnosis and Therapy

Polyhydramnios is defined as a pathological increase of amniotic fluid volume in pregnancy and is associated with increased perinatal morbidity and mortality. Common causes of polyhydramnios include gestational diabetes, fetal anomalies with disturbed fetal swallowing of amniotic fluid, fetal infections and other, rarer causes. The diagnosis is obtained by ultrasound. The prognosis of polyhydramnios depends on its cause and severity. Typical symptoms of polyhydramnios include maternal dyspnea, preterm labor, premature rupture of membranes (PPROM), abnormal fetal presentation, cord prolapse and postpartum hemorrhage. Due to its common etiology with gestational diabetes, polyhydramnios is often associated with fetal macrosomia. To prevent the above complications, there are two methods of prenatal treatment: amnioreduction and pharmacological treatment with non-steroidal anti-inflammatory drugs (NSAIDs). However, prenatal administration of NSAIDs to reduce amniotic fluid volumes has not been approved in Germany. In addition to conventional management, experimental therapies which would alter fetal diuresis are being considered.

Twin-Twin Transfusion Syndrome Modeling

The twin-twin transfusion syndrome (TTTS) is a severe complication occurring in monochorionic twins, and untreated, causes high rates of mortality and morbidity. In TTTS, five consecutive stages of increasing severity can be distinguished: first, the oligopolyhydramnios sequence; second, anuria in the donor twin; third, abnormal flow waves in either twin; fourth, a hydropic recipient, and finally the fifth stage, fetal demise of either twin. Recently, we developed a mathematical model of the Stages I-IV. In this report, we investigated the influence of amnioreduction and laser therapy at two different gestational ages on the resolution of TTTS Stage III. Simulations were performed for two gestational ages, at 22 and 28 weeks; that is, at the onset of a stuck donor twin and when TTTS has progressed to an anuric donor with abnormal umbilical flow waves and a hydropic recipient, respectively. Results indicate abnormal umbilical flow waves in the donor to resolve rapidly after both amnioreduction and laser therapy. TTTS and abnormal umbilical flows in the donor, however, return after amnioreduction. Laser therapy, leading to cessation of fetofetal transfusion, produces complete resolution of TTTS sequelae, however, with increased vascular stiffness in the donor. Amnioreduction and laser therapy both produce rapid resolution of abnormal umbilical flows in a mathematical model of TTTS. Laser ablation of all anastomoses, however, completely ceases the fetofetal transfusion, so that no TTTS redevelops. In the donor, vascular stiffness remains increased after laser, suggesting increased pulse wave velocities can be measured clinically.

Polyhydramnios: An Update

Maternal, fetal or placental pathologies may result in an excessive amount of amniotic fluid (AF) volume. Therefore, the surveillance of the AF volume, predominantly by ultrasound, has become an important instrument for the assessment of fetal well-being. An excessive accumulation of amniotic fluid, as a consequence of a disturbed balance between production, fetal resorption and secretion, is defined as polyhydramnios. Its degree correlates significantly with fetal morbidity and mortality. Therefore, polyhydramnios is an important clinical pattern in perinatal medicine. Approximately 20 percent of the fetuses with severe polyhydramnios show a congenital anomaly, whereas 50 percent of all cases are considered to be idiopathic, mostly with mild patterns. Furthermore, the likelihood of aneuploidy varies from 0.4 to 10 percent. Early detection, provides a correct diagnosis and allows a individual therapy. A referral to a tertiary center is advised in case of severe polyhydramnios and unknown etiology.

In this review, current diagnostic as well as therapeutical aspects are discussed.

Hypothesis: The Placental ‘Steal’ Phenomenon – A Possible Hazard of Amnioreduction

The twin-twin transfusion syndrome (TTTS) complicates approximately 15% of monochorionic twin pregnancies. Severe TTTS is associated with poor neonatal outcome and a relatively high rate of neurological abnormalities. Some studies have suggested this outcome to be more severe in cases treated by amnioreduction. In this paper we present a hypothesis that radical amnioreduction performed after 24 weeks of gestation might cause a shift of blood from the fetus into the placenta. This could explain some of the severe neurological outcomes, such as hypoxic ischemic brain damage, seen in these cases.

Simulation of therapy in a model of a nonhydropic and hydropic recipient in twin-twin transfusion syndrome

OBJECTIVE

This study was undertaken to model the sequence of events that occurs after amnioreduction, laser therapy, and digoxin administration in twin-twin transfusion syndrome (TTTS) with and without a hydropic recipient twin.

STUDY DESIGN

We added amnioreduction, laser therapy, and digoxin administration to our mathematical TTTS model and simulated combinations of these therapies.

RESULTS

With a nonhydropic recipient, simulated amnioreduction delays the onset of hydrops. Conversely, with a hydropic recipient, amnioreduction aggravates the degree of hydrops. Furthermore, amnioreduction increases the transplacental fluid flow and may temporarily cause a hydropic donor. Laser therapy terminates the cause of recipient hydrops. Digoxin reduces the degree of recipient hydrops, but increases arteriovenous fetofetal transfusion.

CONCLUSION

Laser therapy is superior in TTTS with a hydropic recipient, because simulated amnioreduction aggravates the recipient's cardiovascular status. Digoxin benefits a hydropic recipient but slightly worsens the donor's condition. Therefore, TTTS presenting with a hydropic recipient prior to fetal viability (approximately 26 weeks) may be best treated with laser therapy, whereas more advanced gestations may be offered digoxin administration plus amnioreduction, to delay the progression of TTTS.

Procedure-related complications of rapid amniodrainage in the treatment of polyhydramnios

OBJECTIVE

To investigate the procedure-related complications of rapid amniodrainage in the treatment of polyhydramnios.

METHODS

We followed prospectively all patients with polyhydramnios treated with rapid amniodrainage under continuous ultrasound guidance using a vacuum wound-drainage system from 1995 to 2002 in the fetal medicine unit of a university teaching hospital. We recorded: maternal age, type of pregnancy (singleton/twin), cause of polyhydramnios, gestational age at amniocentesis, volume of amniotic fluid drained, duration of the procedure, other intrauterine procedures in addition to the amniodrainage, and procedure-related complications including placental abruption, premature rupture of membranes (PROM), chorioamnionitis, fetal bradycardia and preterm delivery within 48 h of amniodrainage.

RESULTS

Seventy-four consecutive women had 134 rapid amniodrainage procedures during the study period. Four procedures were excluded because the women were already in labor at the time of amniodrainage and they delivered within 48 h of the procedure. The final database therefore consisted of 70 patients with 130 procedures. Sixty-two percent (80/130) of the procedures were performed for the treatment of twin-twin transfusion syndrome (TTTS). There were altogether four procedure-related complications (3.1%; 95% CI, 1.0-8.0%). Three of them occurred in the TTTS group (3/80 procedures, 3.8%; 95% CI, 1.0-11.0%): one case each of placental abruption, PROM and fetal bradycardia. One PROM occurred in the non-TTTS group (1/50 procedures, 2.0%; 95% CI, 0-11.0%). In both cases of PROM the women presented in labor.

CONCLUSIONS

Rapid amniodrainage using a vacuum wound-drainage system is safe and efficient to treat severe polyhydramnios, with a 3.1% complication rate.

Does amniotic fluid volume affect fetofetal transfusion in monochorionic twin pregnancies? Modelling two possible mechanisms

Clinical evidence suggests that increased amniotic fluid volume due to polyhydramnios increases placental vascular resistance. We have sought to model the possible effects of an increased amniotic fluid volume on the net fetofetal transfusion in monochorionic twin pregnancies. We wanted to compare these effects with the results of previous simulations, which aimed to explain why the twin-twin transfusion syndrome (TTTS) placentas more often include bidirectional arteriovenous (AV) rather than AV plus arterioarterial (AA) anastomoses. We extended our mathematical model of TTTS by simulating two different mechanisms that increase the placental vascular resistance as a consequence of polyhydramnios. First, there is an increase in the placental capillary resistance and hence in deep AV and opposite AV (denoted as VA) resistances due to polyhydramnios. Second, there is an increase in the resistance of chorionic veins due to polyhydramnios, assuming that these veins act as Starling resistors. We then simulated the effects of polyhydramnios on different placental anastomotic patterns. The results were as follows. In the first mechanism (polyhydramnios affects AV-VA resistances), an increased amniotic fluid volume hardly affected bidirectional AV, but slightly decreased fetofetal transfusion in AV plus AA anastomoses. However, for these effects to change the natural development of the pregnancy, polyhydramnios needed to persist for approximately 4 weeks, and by comparing the effects of polyhydramnios with the effects of amnioreduction, amnioreduction was more beneficial for normalizing the donor amniotic fluid volume. Therefore, these beneficial effects due to polyhydramnios have no practical clinical significance. In the second mechanism (Starling resistor for chorionic veins), polyhydramnios slightly increased fetofetal transfusion and hence slightly increased TTTS severity in bidirectional AV and AV plus VV, but did not affect AV plus AA anastomoses. In conclusion, we hypothesize that the simulated effects of polyhydramnios are not the primary cause of the fact that TTTS placentas more often include bidirectional AV than AV plus AA anastomoses. Rather, the more likely explanation is the previously identified larger range of AA than VA anastomotic diameters that adequately compensate for the effects of the AV.