The prediction, diagnosis and management of complications in monochorionic twin pregnancies: the OMMIT (Optimal Management of Monochorionic Twins) study

Ultrasonographic Diagnosis of Twin-to-Twin Transfusion Syndrome

INTRODUCTION

 Twin-twin transfusion syndrome (TTTS) is a typical complication of monochorionic twin pregnancies (MCTP). Placental vessels that communicate in the chorionic plate between donor and recipient, are responsible for the imbalance of blood flow. Circulatory imbalance causes hypovolemia in donor and hypervolemia in recipient fetus. In a typical case, recipient fetus develops polyhydramnios, weight gain, cardiomegaly and hydrops fetalis. In contrast, donor fetus develops oligohydramnios and fetal growth restriction.

AIM

 The objective of this review is to evaluate in detail the main diagnostic aspects and add other important data for diagnosis of TTTS.

SCIENTIFIC BASES

 The main diagnostic event for this condition is based on the ultrasonographic discovery of oligohydramnios-polyhydramnios sequence. Other useful elements for diagnosis, staging and prognosis are fetal urinary bladder visualization, urinary bladder volumen measurements, edema of subcutaneous and/or generalized tissue edema, Doppler flow velocity waves and cardiac evaluation.

CONCLUSION

 Considerations regarding diagnosis of TTTS make it possible to emphasize that role of physicians treating patients with MCTP is to identify ultrasound sequence of oligohydramnios-polyhydramnios. Other ultrasonographic fetal data as fetal urinary bladder visualization, urinary bladder volumen measurements, edema of subcutaneous and/or generalized tissue edema, Doppler flow velocity waves and cardiac evaluation; may help diagnosis, staging and prognosis of TTTS. It is their responsibility to accurately assess severity, therapeutic possibilities and prognosis.

KEY POINTS

· The role of physicians treating patients with MCTP, regarding diagnosis of TTTS, must be to identify ultrasound sequence of oligohydramnios-polyhydramnios.. · Other ultrasonographic fetal data may help diagnosis, staging, and prognosis of TTTS as follows: fetal urinary bladder visualization, urinary bladder volume measurements, edema of subcutaneous and/or generalized tissue edema, Doppler flow velocity waves, and cardiac evaluation.. · It is physicians' responsibility to accurately assess severity, therapeutic possibilities, and prognosis of patients with MCTP and diagnosis of TTTS..

Intestinal prolapse and exposure after peritoneal dialysis in low-birth-weight preterm infants with acute renal failure: a case report

BACKGROUND

The mortality rate of acute kidney injury (AKI) in low-birth-weight premature infants with acute renal failure is extremely high. Since small hemodialysis catheters do not exist, peritoneal dialysis (PD) is the most suitable dialysis method. At present, only a few studies have reported cases of PD in low-birth-weight newborns.

CASE DESCRIPTION

On September 8, 2021, a 10-day-old, low-birth-weight preterm infant, who presented with neonatal respiratory distress syndrome and acute renal failure, was admitted to the Second Affiliated Hospital of Kunming Medical University, China. The patient was the elder of twins and had experienced acute renal failure, hyperkalemia, and anuria following the onset of respiratory distress syndrome. During the initial PD catheterization operation, a double Tenckhoff adult PD catheter cut short by 2 cm was used, with the inner cuff placed in the skin. However, the surgical incision was relatively large, and PD fluid leakage occurred. Later, the incision tore, and the intestines prolapsed when the patient cried. The intestines were returned to the abdominal cavity in an emergency operation, and the PD catheter was placed again. This time, the inner Tenckhoff cuff was placed outside the skin, and PD fluid leakage did not reoccur. However, the patient also experienced a decrease in heart rate and blood pressure, as well as severe pneumonia and peritonitis. Following an active rescue, the patient recovered well.

CONCLUSIONS

The PD method effectively treats low-birth-weight preterm neonates with AKI. An adult Tenckhoff catheter was shortened by 2 cm and successfully used in the PD treatment of a low-birth-weight preterm infant. However, the catheter placement should be outside the skin, and the incision should be as small as possible to avoid leakage and incision tears.

The Association between Intertwin Difference in First Trimester Crown-Rump Length, Nuchal Translucency, and Birth Weight Discordance in Twin Pregnancies: A Retrospective Cohort Study

Background. Discordant birth weight in twins is linked to poor outcomes and predicting this discrepancy may lead to enhanced screening and surveillance. Our purpose was to quantify the relationship between intertwin nuchal translucency (NT) and crown-rump length (CRL) discordance with birth weight discrepancies ≥ 20%. Methods. We conducted a retrospective cohort study of 887 live twin births delivering at a Canadian tertiary care center over a 7-year period who opted for integrated prenatal screening. Categorical data are presented as numbers and percentages, and continuous data are expressed as means and standard deviations. Chi-square tests, Fisher’s Exact tests, or $T$ -test were performed as appropriate. We then used published data and receiver operating curves to determine the optimal thresholds for predicting birth weight discordance based on first trimester intertwin NT differences. These values were used in multivariate logistic regression models accounting for known confounders. Results. Roughly 16% of twin pairs exhibited ≥ 20% difference in birth weight. Twin pairs with a CRL discordance greater than 10% have nearly a 4 times greater likelihood of having a birth weight discordance greater than 20% (OR 3.71, CI 2.24-6.14) while controlling for chorionicity, maternal age, gestational age at delivery, maternal body mass index (BMI), and parity. In these models, intertwin NT discordance ≥ 20% (OR 1.16, CI 0.77-1.77) and NT discordance ≥ 14% (OR 1.08, CI 0.73-1.60) were not statistically significant predictors of twin birth weight differences. However, when evaluating the effect of the larger intertwin NT value corresponding to the 95th percentile, an NT difference ≥ 0.9 mm was predictive of birth weight discordance ≥ 20% (OR 2.53, CI 1.21-5.29). Conclusion. Although intertwin CRL and NT discordance measured via ultrasound between 11-14 weeks gestation are related to birth weight discordance, there is uncertainty as to whether twin birth weight differences are related to adverse pregnancy outcomes in this population.

Management of Complicated Monochorionic Twin Gestations: An Evidence-Based Protocol

Importance

Monochorionic (MC) twins are hemodynamically connected by vascular anastomoses within the single shared placenta. The transfer of fluid or blood from one fetus to the other may result in development of pathologic complications, such as twin-twin transfusion syndrome, twin anemia polycythemia sequence, selective intrauterine growth restriction, and twin reversed arterial perfusion sequence. Monoamniotic gestations, which comprise a small fraction of MC pregnancies, can also present with unique challenges, particularly antepartum umbilical cord entanglement. All these complications carry a high risk of fetal morbidity and mortality if not recognized and managed in a timely fashion.

Objective

The purpose of this article is to review evidence-based management of complicated MC twin gestations and propose a standardized approach to surveillance.

Evidence Acquisition

Monochorionic gestations account for the majority of complications that occur in twin pregnancies; however, there is unclear evidence on the appropriate surveillance for and management of specific complications associated with these pregnancies.

Results

This article summarizes management for each specific type of MC complication in a structured and clear manner.

Conclusions

Early pregnancy ultrasound, ideally between 10 and 13 weeks' gestation, is critical for the diagnosis and characterization of twin pregnancies. To improve outcomes for MC twins, appropriate fetal surveillance should be initiated at 16 weeks' gestation and continued until delivery.

The Use of Sequential Integrated Screening to Stratify Risk in Monochorionic-Diamniotic Twin Pregnancies

OBJECTIVE

This study aimed to identify differences in sequential integrated screening and early ultrasound markers in monochorionic/diamniotic (MC/DA) pregnancies complicated by twin-to-twin transfusion syndrome (TTTS) and unequal placental sharing (UPS).

STUDY DESIGN

Retrospective cohort study of MC/DA pregnancies evaluated between January 2012 and July 2017 at the University of California San Francisco. MC/DA pregnancies with ultrasound surveillance up to 26 weeks who participated in the California Prenatal Screening Program (CPSP) were included. Pregnancies with structural or genetic anomalies were excluded. UPS was defined as an intertwin growth discordance ≥20%. Intertwin nuchal translucency (NT) discordance was calculated by the absolute value of the difference of the NT of cotwins. Kruskal-Wallis or ANOVA testing was performed where appropriate, and negative binomial regression models were chosen to test for differences in mean biomarker levels by outcome group.

RESULTS

A total of 191 MC/DA pregnancies were included; 85 were affected by TTTS, 35 by UPS, and 71 controls. Significant differences in intertwin NT discordance in pregnancies complicated by TTTS and UPS compared with controls (p = 0.007) were found. TTTS cases had a mean NT discordance greater than two times that of controls (p = 0.04), while UPS cases had a value more than three times greater (p = 0.003). There was a statistically significant difference in mean second trimester human chorionic gonadotropin (hCG) between the cohorts (p = 0.0002) with TTTS cases having a mean second trimester hCG value 1.5 greater than both controls (p < 0.001) and UPS cases (p = 0.001). Analysis showed a significant difference in mean second trimester inhibin between the three cohorts (p = 0.029). Pregnancies complicated by UPS had a mean second trimester inhibin 1.5 times greater than controls (p = 0.010).

CONCLUSION

Our study shows that there are unique differences in early ultrasound and sequential integrated serum markers between MC/DA gestations complicated by TTTS and UPS versus those unaffected.

KEY POINTS

· Differences exist in sequential integrated screening markers in monochorionic-diamniotic twin pregnancies.. · Early risk stratification of monochorionic-diamniotic twin pregnancies may be possible.. · Sequential integrated screening testing can provide useful information to clinicians when evaluating monochorionic-diamnitoic twin pregnancies..

Twin-twin transfusion syndrome is associated with alterations in the metabolic profile of maternal plasma in early gestation: a pilot study

OBJECTIVE

Twin-twin transfusion syndrome (TTTS) causes perinatal mortality and morbidity in monochorionic twins. The early recognition of and interventional therapy for TTTS is associated with a more favorable overall prognosis. However, the prediction by the use of ultrasound in the first trimester has relatively poor sensitivity and specificity. This study aimed to identify metabolic biomarkers to aid in ultrasound screening of TTTS.

METHODS

Maternal plasma was prospectively collected between 11 and 15 weeks of gestation in apparently uncomplicated monochorionic-diamniotic twin pregnancies. This cohort was divided into: (i) patients who were subsequently diagnosed with TTTS by using ultrasound; (ii) uncomplicated matched controls. Metabolome was profiled by using gas chromatography-mass spectrometry.

RESULTS

The levels of fatty acids, organic acids, oxaloacetic acid, and beta-alanine were significantly lower in the TTTS maternal plasma at 11-15 weeks of gestation, and methionine and glycine were also higher (p < 0.05, FDR<0.12). Generally, in TTTS pregnancies, the metabolisms of amino acid, carbohydrate, cofactors, vitamins, and purine were "down-regulated"; whereas bile secretion and pyrimidine metabolism were "upregulated."

CONCLUSIONS

The metabolomics scanning of early gestation maternal plasma may identify those pregnancies that subsequently develop TTTS; in particular, downregulated fatty acid levels may be biologically plausible to be implicated in the pathogenesis of TTTS.

Associated factors with neonatal near miss in twin pregnancies in a public referral maternity unit in Brazil

Objective

The aim was to analyze the factors associated with neonatal near miss (NNM) in twin pregnancies in a public referral maternity unit in Brazil.

Material and Methods

This retrospective, cross-sectional study included 697 twin newborns. Cases of fetal and neonatal deaths were excluded. Neonates were divided into those meeting NNM criteria (5 min Apgar score <7, birth weight <1,500 g, gestational age at delivery <32 weeks, use of mechanical ventilation or congenital malformation, transfer before 28 days of life) and those who did not. In the bivariate analysis, the chi-square and Fisher's exact tests were used. Variables with a p-value ≤0.20 were subjected to the multiple analyses, which followed the Poisson regression model.

Results

The cohort consisted of 130 (18.7%) neonates meeting NNM criteria and 567 (81.3%) with no NNM criteria after multiple analyses, the following variables were associated with NNM: no previous pregnancy, prevalence ratio (PR): 1.38 [95% confidence interval (CI), 1.03-1.85]; >3 previous pregnancies, PR: 1.93 (95% CI, 1.38-2.69); premature rupture of membranes, PR: 1.50 (95% CI, 1.70-2.12); intrauterine growth restriction, PR: 2.28 (95% CI, 1.53-3.33); premature labor, PR: 1.63 (95% CI, 1.13-2.35); resuscitation in the delivery room, PR: 1.80 (95% CI, 1.24-2.62); and transfusion of blood products, PR: 4.44 (95% CI, 3.14-6.28).

Conclusion

The study findings indicate that having had 0 or >3 previous pregnancies, premature rupture of the membranes, intrauterine growth restriction, resuscitation in the delivery room, premature labor, and transfusion of blood products were associated with NNM in twin pregnancies.

Middle Cerebral Artery Doppler Velocimetry for the Diagnosis of Twin Anemia Polycythemia Sequence: A Systematic Review

Twin anemia polycythemia sequence (TAPS) is a rare complication of monochorionic diamniotic (MCDA) twins. Middle cerebral artery peak systolic velocity (MCA-PSV) measurements are used to screen for TAPS while fetal or neonatal hemoglobin levels are required for definitive diagnosis. We sought to perform a systematic review of the efficacy of MCA-PSV in diagnosing TAPS. Search criteria were developed using relevant terms to query the Pubmed, Embase, and SCOPUS electronic databases. Publications reporting diagnostic characteristics of MCA-PSV measurements (i.e., sensitivity, specificity or receiver operator curves) were included. Each article was assessed for bias using the Quality Assessment of Diagnostic Accuracy Studies II (QUADAS II) tool. Results were assessed for uniformity to determine whether meta-analysis was feasible. Data were presented in tabular form. Among publications, five met the inclusion criteria. QUADAS II analysis revealed that four of the publications were highly likely to have bias in multiple areas. Meta-analysis was precluded by non-uniformity between definitions of TAPS by MCA-PSV and neonatal or fetal hemoglobin levels. High-quality prospective studies with consistent definitions and ultrasound surveillance protocols are still required to determine the efficacy of MCA-PSV in diagnosing TAPS. Other ultrasound findings (e.g., placenta echogenicity discordance) may augment Doppler studies.

Dispelling Myths about Antenatal TAPS: A Call for Action for Routine MCA-PSV Doppler Screening in the United States

In the United States, routine middle cerebral artery peak systolic velocity (MCA-PSV) Doppler screening for the detection of antenatal twin anemia-polycythemia sequence (TAPS) is not recommended. The current and only national clinical guideline from the highly-influential Society for Maternal-Fetal Medicine states that, “There is no evidence that monitoring for TAPS with MCA PSV Doppler at any time, including > 26 weeks, improves outcomes, so that this additional screening cannot be recommended at this time.” We argue this recommendation has disproportionate influence on patients and the care they are offered and receive. We use current evidence to highlight and dispel pervasive myths surrounding antenatal TAPS and the value of routine MCA-PSV screening. An ethical framework that illustrates the importance of giving patients the opportunity for routine screening is presented. Findings demonstrate that: (1) both spontaneous and post-laser TAPS is a serious, potentially life-threatening complication, (2) treatment for TAPS is effective and includes expectant management, intrauterine transfusion (IUT), or surgery, (3) and routine MCA-PSV, which has satisfactory diagnostic accuracy, is currently the only way to provide early detection of TAPS. We conclude that routine TAPS screening is a medically proven valuable resource that should be offered to patients in need and to the clinicians who are trying to act toward their benefit.

MicroRNA changes in maternal serum from pregnancies complicated by twin-twin transfusion syndrome: A discovery study

Objective

MicroRNAs (miRNAs) are used as biomarkers in cardiovascular disease and cancer. miRNAs are involved in placental development but have not previously been investigated in twin‐twin transfusion syndrome (TTTS). Our aim is to explore the miRNA profile of TTTS pregnancies.

Method

Initial miRNA profiling was performed using a reverse transcription polymerase chain reaction (RT‐PCR) panel on maternal serum samples taken from five women prior to fetoscopic laser ablation for TTTS and compared with serum samples from five women with uncomplicated monochorionic diamniotic twin pregnancies. Validation RT‐PCR was performed in an additional cohort of eight TTTS pregnancies and eight uncomplicated pregnancies.

Results

Median gestational age at sampling in the TTTS and control groups was 20⁺⁰ weeks (interquartile range [IQR], 19⁺⁴‐20⁺⁰) and 20⁺² weeks (IQR, 20⁺⁰‐20⁺²), respectively. All samples passed quality control. One control sample was excluded as a biological outlier. Thirty‐one of 752 miRNAs were significantly different: 17 were upregulated and 14 downregulated in the TTTS group, although they did not remain significant following Benjamini‐Hochberg correction for multiple testing. The six miRNAs chosen for validation demonstrated no significant difference.

Conclusion

This is the first study to investigate miRNA changes in TTTS pregnancies. We did not demonstrate a statistically significant difference in miRNAs in TTTS pregnancies, but further investigation is required.

First-trimester ultrasound measurements and maternal serum biomarkers as prognostic factors in monochorionic twins: a cohort study

BACKGROUND

Monochorionic twin pregnancies are at high risk of adverse outcomes, but it is not possible to predict which pregnancies will develop complications. The aim of the study was to evaluate, in monochorionic twin pregnancies, whether first-trimester ultrasound (nuchal translucency [NT], crown-rump length [CRL]), and maternal serum biomarkers (alpha-fetoprotein [AFP], soluble fms-like tyrosine kinase-1 [sFlt-1] and placental growth factor [PlGF]), are prognostic factors for fetal adverse outcome composite, twin-twin transfusion syndrome (TTTS), growth restriction, and intrauterine fetal death (IUFD).

METHODS

A cohort study of 177 monochorionic diamniotic twin pregnancies. Independent prognostic ability of each factor was assessed by multivariable logistic regression, adjusting for standard prognostic factors. Factors were analysed as continuous data; thus, the reported ORs relate to either 1% change in NT or CRL inter-twin percentage discordance or one unit of measure in each serum biomarker.

RESULTS

The odds of the fetal adverse outcome composite were significantly associated with increased NT inter-twin percentage discordance (adjusted OR 1.03 [95% CI 1.01, 1.06]) and CRL inter-twin percentage discordance (adjusted OR 1.17 [95% CI 1.07, 1.29]). TTTS was significantly associated with increased NT discordance (adjusted OR 1.06 [95% CI 1.03, 1.10]) and decreased PlGF (adjusted OR 0.42 [95% CI 0.19, 0.93]). Antenatal growth restriction was significantly associated with increased CRL discordance (adjusted OR 1.20 [95% CI 1.08, 1.34]). Single and double IUFD were associated with decreased PlGF (adjusted OR 0.34 [95% CI 0.12, 0.98]) and (adjusted OR 0.18 [95%CI 0.05, 0.58]) respectively.

CONCLUSIONS

This study has identified potential individual prognostic factors in the first trimester (fetal biometric and maternal serum biomarkers) that show promise but require further robust evaluation in a larger, prospective series of MC twin pregnancies, so that their usefulness both individually and in combination can be defined.

TRIAL REGISTRATION

ISRCTN 13114861 (retrospectively registered).

Early prognostic factors of outcomes in monochorionic twin pregnancy: systematic review and meta-analysis

BACKGROUND

Monochorionic twin pregnancies are high-risk, however at present, no screening test is available to predict which monochorionic twin pregnancy will develop complications.

OBJECTIVE

We sought to assess ability of first-trimester pregnancy-related factors (ultrasound measurements, maternal characteristics, biomarkers) to predict complications in monochorionic twin pregnancies.

DATA SOURCES

Data sources were MEDLINE, Embase, ISI Web of Science, CINAHL, the Cochrane Central Registration of Controlled Trials and Research Registers, and Google Scholar, from inception to May 12, 2017. Gray literature and bibliographies of articles were checked.

STUDY ELIGIBILITY CRITERIA

Studies that reported ultrasound measurements, maternal characteristics, or potential biomarkers, measured in the first trimester in monochorionic-diamniotic twin pregnancies, where the potential prognostic ability between the variable and twin-twin transfusion syndrome, growth restriction, or intrauterine fetal death could be assessed, were included.

STUDY APPRAISAL AND SYNTHESIS METHODS

Quality assessment was evaluated using the Strengthening the Reporting of Observational Studies in Epidemiology checklist by 2 reviewers independently. For meta-analysis, odds ratios using a random effects model, or standardized mean difference were calculated. If a moderate association was found, the prognostic ability was evaluated by calculating the sensitivity and specificity. Risk of heterogeneity was reported as I² and publication bias was visually assessed by funnel plots and quantitatively by Egger test.

RESULTS

In all, 48 studies were eligible for inclusion. Twenty meta-analyses could be performed. A moderate association was demonstrated in 3 meta-analyses, between: nuchal translucency >95th centile in one/both fetuses and twin-twin transfusion syndrome (odds ratio, 2.29 [95% confidence interval, 1.05-4.96], I² = 6.6%, 4 studies, 615 pregnancies); crown-rump length discordance ≥10% and twin-twin transfusion syndrome (odds ratio, 2.43 [95% confidence interval, 1.13-5.21], I² = 14.1%, 3 studies, 708 pregnancies); and maternal ethnicity and twin-twin transfusion syndrome (odds ratio, 2.12 [95% confidence interval, 1.17-3.83], I² = 0.0%, 5 studies, 467 pregnancies), but none demonstrated a prognostic ability for any outcome under investigation.

CONCLUSION

It is not currently possible to predict adverse outcomes in monochorionic twin pregnancies. We have revealed a lack of research investigating first-trimester biomarkers in monochorionic twin pregnancies. Different assessment methods and definitions of each variable and outcome were an issue and this highlights the need for a large cohort study to evaluate these factors.