Maternal-Fetal Conflicts in Anesthesia Practice.

Anesthesia clinicians often navigate a delicate balance between maternal and fetal safety. Interventions for at fetal well-being may introduce risks of harm to the mother and raise ethical dilemmas. Emergency procedures often focus on direct fetal safety, sidelining maternal physical and mental well-being. The clash between ethical principles, particularly nonmaleficence and beneficence, often arises, with maternal autonomy guiding decisions. Fetal surgery exemplifies risking maternal health for fetal benefit, whereas emergent cesarean deliveries pose physical and psychological challenges for both the mother and child.

Intracranial Parasitic Fetus in a Living Infant: A Case Study with Surgical Intervention and Prognosis Analysis.

BACKGROUND Fetus in fetu (FIF), or parasitic fetus, is a rare malformation that typically occurs in the retroperitoneum, but can be found in other unusual locations, such as the skull, sacrum, and mouth. The presence of a spine is necessary for diagnosis. CASE REPORT Intracranial FIFs were retrospectively studied. Abnormalities were detected in the fetal head during a 33-week prenatal examination; however, MRI could not provide more information, due to space occupation. A baby girl was born via cesarean delivery at 37 weeks, with a large head circumference. She had delays in motor skills and speech development, only able to say "mom". There was a large mass in the cerebral hemisphere, with a 13-cm maximum diameter, smooth boundary, and internal bone structure visible on head CT scan. Both ventricles and third ventricle had hydrops, with a fetal shape at a continuous level, along with apparent compression near the cerebral parenchyma. After performing preoperative examinations, laboratory tests, and surgical planning, craniotomy was performed on the FIF, under general anesthesia. Following complete mass resection, mouth, eye, arm, and hand shapes could be observed. The patient was unconscious after surgery and had seizures that were difficult to control. She died 12 days after surgery. Teratomas can be distinguished based on anatomy and imaging. Surgical resection is the only curative treatment and its prognosis is poor. CONCLUSIONS Intracranial FIF cases are rare and require early diagnosis and surgical treatment. Differentiating between FIF and teratoma is crucial, and monitoring alpha-fetoprotein levels after surgery can help detect recurrence.

In utero fetal organ transplantation.

Transplantation has generally been focused on end-stage organ disease in adults. Scientists from Japan are now focusing on in utero transplantation in fetuses with congenital anomalies.

Acute Fetal Metabolomic Changes in Twins Undergoing Fetoscopic Surgery for Twin-Twin Transfusion Syndrome.

Fetuses undergo major surgical stress as well as fluid shifts secondary to both twin-twin transfusion (TTTS) as well as the fetoscopic surgery for treatment of TTTS. While the pathophysiology of TTTS is understood, the acute metabolic changes that fetuses experience from fetoscopic surgery are not. We sought to evaluate the changes in recipient metabolomic profile secondary to TTTS surgery. Amniotic fluid was collected at the beginning and end of four TTTS surgical cases performed from 12/2022-2/2023. Samples were immediately processed and evaluated via NMR-based Metabolomics Facility protocol. In univariate analysis, 12 metabolites (glucose, lactate, and 10 key amino acids) showed statistically significant changes between the beginning and end of the surgery. Among these, 11 metabolites decreased at the end, while only lactate increased. Supervised oPLS-DA modeling revealed pyruvate and lactate as the two metabolites most impact on the variance between cases, and that 40% of metabolomic changes could be attributed directly to the timing that the sample was taken (i.e., if pre- or postoperatively). These results indicate significant metabolic changes in the recipient twin during fetoscopic surgery for TTTS. These findings of decreased glucose, increased lactate, and decreased amnio acids would indicate increased catabolism during surgery. This study raises questions regarding optimal maternal and fetal nutrition during surgery and if nutritional status could be optimized to further improve twin survival during fetoscopic surgery.

Anesthetic recommendations for maternal and fetal safety in nonobstetric surgery: a balancing act.

PURPOSE OF REVIEW: Nonobstetric surgery during pregnancy is associated with maternal and fetal risks. Several physiologic changes create unique challenges for anesthesiologists. This review highlights physiologic changes of pregnancy and presents clinical recommendations based on recent literature to guide anesthetic management for the pregnant patient undergoing nonobstetric surgery. RECENT FINDINGS: Nearly every anesthetic technique has been safely used in pregnant patients. Although it is difficult to eliminate confounding factors, exposure to anesthetics could endanger fetal brain development. Perioperative fetal monitoring decisions require an obstetric consult based on anticipated maternal and fetal concerns. Given the limitations of fasting guidelines, bedside gastric ultrasound is useful in assessing aspiration risk in pregnant patients. Although there is concern about appropriateness of sugammadex for neuromuscular blockade reversal due its binding to progesterone, preliminary literature supports its safety. SUMMARY: These recommendations will equip anesthesiologists to provide safe care for the pregnant patient and fetus undergoing nonobstetric surgery.

Fetal Spina Bifida Repair in Obese Mothers: Is Maternal and Fetal Safety Compromised?

INTRODUCTION: The Management of Myelomeningocele Study (MOMS) eligibility criteria preclude in utero surgery for fetal spina bifida (fSB) when the maternal body mass index (BMI) is ≥35 kg/m2. Some centers still respect this criterion, while others, like ours, do not. This study aimed to assess whether maternal and fetal safety is compromised with higher maternal BMIs. METHODS: Data of 192 patients with open fSB repair at our center were retrospectively analyzed. According to their BMI, patients were divided into three groups: group 1 (BMI <30 kg/m2), group 2 (BMI 30-35 kg/m2), and group 3 (BMI >35 kg/m2). Subgroup analysis was performed to assess differences in maternal and fetal outcomes. Additionally, complications were divided into grades 1 to 5 according to their severity and outcome consequences and compared among groups. RESULTS: Out of 192 patients, 146 (76.0%) had a BMI <30 kg/m2, 28 (14.6%) had a BMI 30-35 kg/m2, and 18 (9.4%) had a BMI >35 kg/m2. Significant differences occurring more often in either group 2 or 3 compared to group 1 were maternal wound seroma (50% or 56% vs. 32%, p = 0.04), amniotic fluid leakage (14% or 6% vs. 2%, p = 0.01) as well as vaginal bleeding (11% or 35% vs. 9%, p = 0.01). On the contrary, duration of tocolysis with atosiban was shorter in patients with BMI >30 kg/m2 (4 or 5 vs. 6 days, p = 0.01). When comparing severity of maternal or fetal complications, grade 1 intervention-related complications occurred significantly more often in group 3 compared to group 1 or 2 (78% vs. 45% or 57%, p = 0.02). Gestational age at delivery was around 36 weeks in all groups without significant differences. CONCLUSION: This investigation did not identify clinically relevant maternal and/or fetal outcome problems related to BMIs >35 kg/m2. Additional studies are however needed to confirm our results.

Fetal cardiovascular changes during open and fetoscopic in-utero spina bifida closure.

OBJECTIVE: Fetoscopic closure of spina bifida using heated and humidified carbon dioxide gas (hhCO2) has been associated with lower maternal morbidity compared with open closure. Fetal cardiovascular changes during these surgical interventions are poorly defined. Our objective was to compare fetal bradycardia (defined as fetal heart rate (FHR) < 110 bpm for 10 min) and changes in umbilical artery (UA) Doppler parameters during open vs fetoscopic closure. METHODS: This was a prospective cohort study of 22 open and 46 fetoscopic consecutive in-utero closures conducted between 2019 and 2023. Both cohorts had similar preoperative counseling and clinical management. FHR and UA Doppler velocimetry were obtained systematically during preoperative assessment, every 5 min during the intraoperative period, and during the postoperative assessment. FHR, UA pulsatility index (PI) and UA end-diastolic flow (EDF) were segmented into hourly periods during surgery, and the lowest values were averaged for analysis. Umbilical vein maximum velocity was measured in the fetoscopic cohort. At each timepoint at which FHR was recorded, maternal heart rate and systolic and diastolic blood pressure were measured. RESULTS: Fetal bradycardia occurred in 4/22 (18.2%) cases of open closure and 21/46 (45.7%) cases of fetoscopic closure (P = 0.03). FHR decreased gradually in both cohorts after administration of general anesthesia and decreased further during surgery. FHR was significantly lower during hour 2 of surgery in the fetoscopic-repair cohort compared with the open-repair cohort. The change in FHR from baseline in the final stage of fetal surgery was significantly more pronounced in the fetoscopic-repair cohort compared with the open-repair cohort (mean, -32.4 (95% CI, -35.7 to -29.1) bpm vs -23.5 (95% CI, -28.1 to -18.8) bpm; P = 0.002). Abnormal UA-EDF (defined as absent or reversed EDF) occurred in 3/22 (13.6%) cases in the open-repair cohort and 23/46 (50.0%) cases in the fetoscopic-repair cohort (P = 0.004). There were no differences in UA-EDF or UA-PI between closure techniques at the individual stages of assessment. CONCLUSIONS: We observed a decrease in FHR and abnormalities in UA Doppler parameters during both open and fetoscopic spina bifida closure. Fetal bradycardia was more prominent during fetoscopic closure following hhCO2 insufflation, but FHR recovered after cessation of hhCO2. Changes in FHR and UA Doppler parameters during in-utero spina bifida closure were transient, no cases required emergency delivery and no fetoscopic closure was converted to open closure. These observations should inform algorithms for the perioperative management of fetal bradycardia associated with in-utero spina bifida closure. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

"I don't have a telephone to the fetus": Clinicians' conceptions of fetal patienthood in maternal-fetal surgery counseling.

RATIONALE: Maternal fetal surgery (MFS) has developed rapidly since the 1960s and centers for fetal diagnosis and therapy (CFDT) have proliferated. As a result, CFDT clinicians have intervened with fetuses through pregnant bodies for decades, yet the patienthood status of the fetus and its implications for the pregnant person's autonomy have been relatively unexamined. OBJECTIVE: Our overall research aims were threefold: (1) to explore how clinicians train for and provide counseling for MFS; (2) to examine how clinicians assess fetal patienthood and its implications; and (3) to understand clinicians' professed needs and their recommendations for education and training for the provision of MFS counseling. This focuses on aim two. METHOD: In this qualitative study, conducted using in-depth interviews, we examined how 20 clinicians from 17 different sites understood fetal patienthood, how that affected their counseling of pregnant patients, and whether they drew on extant ethical frameworks for guidelines. RESULTS: We identified three major themes: 1) Clinicians entered fetal surgery consultations with assumptions about fetal patienthood (frequently informed by beliefs about fetal viability, maternal attachment, and disciplinary perspectives); 2) they consciously assessed their pregnant patients' connections to their fetus to inform or re-calibrate their own understandings of fetal patienthood; and 3) they used a threshold -based conceptualization whereby the fetus achieved patienthood after crossing a symbolic boundary, often related to the clinician's ability to intervene. CONCLUSIONS: Few clinicians invoked an extant ethical framework to determine fetal patienthood; most asserted that they did not view directive counseling toward MFS as appropriate, instead working diligently to protect pregnant patients' autonomy and rights to self-determination.

Hepatic arterial buffer response: activation in donor fetuses and the effect of laser ablation of intertwin anastomosis.

OBJECTIVES: Hepatic arterial buffer response (HABR) is an important defence mechanism for maintaining liver blood flow. It is suspected that HABR is active in monochorionic diamniotic twins (MCDA) with twin-to-twin transfusion syndrome (TTTS) where donor compensates a setting of volume depletion and the recipient an overload. The present study investigates whether in TTTS, HABR is active in donor and/or recipient individually and try to determine if the activation of HABR is a direct response to TTTS. METHODS: Hepatic artery (HA) peak systolic velocity (PSV) was measured in normal MCDA fetuses and TTTS. Correlation with relevant fetal Dopplers and characteristics were determined. Z-scores for HA-PSV (HAV-Z) were calculated and its association with TTTS in donors and recipients were determined as well as changes in HAV-Z after laser treatment. RESULTS: In this study 118 MCDA were included, 61.9 % normal and 38.1 % TTTS. Of the TTTS 22 required laser treatment. A total of 382 scans were performed in normal group and 155 in TTTS. Our data demonstrates that in donors HAV-Z was 2.4 Z-scores higher compared to normal fetuses (ß=2.429 95 % CI 1.887, 2.971; p<0.001) and after laser treatment HAV-Z reduced (ß=-1.829 95 % CI -2.593, -1.064; p<0.001). There was no significant difference between recipients and normal (ß=-0.092 95 % CI -0.633, 0.449; p=0.738). CONCLUSIONS: HABR is active in TTTS, promoting an increased hepatic blood flow in donors. The activation is direct response to TTTS as shown by the reduction in HAV-Z after laser. This finding provides important insights into the pathophysiology of TTTS.

Intrauterine Correction of Fetal Myelomeningocele Through Minihysterotomy.

Spina bifida is the most common congenital central nervous system anomaly, resulting in lifelong neurologic, urinary, motor, and bowel disability.1 Its most frequent form is myelomeningocele, characterized by spinal cord extrusion into a sac filled with cerebrospinal fluid.1 We report the case of a 28-year-old pregnant female with no comorbidities. At 16 weeks of pregnancy, fetal ultrasound presented ventriculomegaly, cerebellar herniation, and lumbar myelomeningocele. At 22 weeks, intrauterine surgical correction was performed (Video 1). A minihysterotomy spanning approximately 3 cm was performed. The defect was opened, and the neural placode was dissected and released. This was followed by the isolation of the peripheric dura, which was molded into a tube and closed with watertight suture. Finally, the minihysterotomy was sutured and the skin was closed. The pregnancy followed its course with no complications, and the child was born at term with the lesion closed and no necessity of intensive care. Recent studies have demonstrated that infants who undergo open in utero myelomeningocele repair have better neurologic outcomes than those who are treated after birth.1,2 However, maternal morbidity is nonnegligible with the classical open surgery.2 Peralta et al2 propose a modification of the classic 6.0- to 8.0-cm hysterotomy in which the same multilayer correction of the spinal defect is performed through a 2.5- to 3.5-cm hysterotomy. This modification, called minihysterotomy, has been successfully performed outside of its creation center and was associated with reduced risks of preterm delivery and maternal, fetal, and neonatal complications.2,3.

Percutaneous fetal endoscopic third ventriculostomy for severe isolated cerebral ventriculomegaly.

OBJECTIVE: To demonstrate the feasibility and preliminary results of percutaneous fetal endoscopic third ventriculostomy (ETV) in human fetuses (pfETV) with isolated progressive and/or severe bilateral cerebral ventriculomegaly (IPSBV). METHODS: The initial results of pfETV for IPSBV were described. Perioperative, perinatal and postnatal variables were described. The Ages and Stages Questionnaire (ASQ-3), 3rd edition (ASQ-3) was used for follow-up of all infants. RESULTS: Successful pfETV was performed in 10/11 (91%) fetuses, at a median gestational age (GA) of 28.7 weeks (25.3-30.7). There were no perioperative complications. After pfETV, 70% (7/10) of the fetuses had a decreased or stabilized lateral ventricle atria|lateral ventricle's atria. The median GA at delivery was 38.2 weeks (35.9-39.3). There were no perinatal complications. The postnatal ventriculoperitoneal shunt rate was 80% (8/10). Among neonates/infants who had prenatal stabilization or a decrease in the LVAs, 4 (4/7: 57.1%) had abnormal scores on the ASQ-3. Among neonates/infants that experienced prenatal increases in the LVAs, all of them (3/3: 100%) had abnormal scores on the ASQ-3. CONCLUSION: Percutaneous ETV is feasible in human fetuses with progressive and/or severe cerebral ventriculomegaly and seems to be a safe procedure for both the mother and the fetus.

Catheter ablation of atrioventricular nodal reentrant tachycardia, when AVNRT presented as a fetus or infant.

BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) does not commonly present during infancy. Although relative safety of catheter ablation of AVNRT has been demonstrated in pediatrics, this procedure is rarely indicated in children <15 kg. METHODS: Retrospective review of seven cases of AVNRT that presented in children younger than 1 year of age and required catheter ablation for definitive management. Electrophysiology (EP) study was planned with two or three catheters. Area of ablation determined by voltage mapping, propagation sinus wave collision and slow pathway potential location. Ablation performed with cryothermal energy. No fluoroscopy was used. RESULTS: Presentation ranged from 36 weeks of gestation to 11 months of age. Two presented in fetal life and two in the neonatal period. The median age of ablation was 20 months (range 17-31 months). The median weight at ablation was 11.4 kg (range 8.9-14.9 kg). Median follow-up time was 16 months. All had typical AVNRT. The median tachycardia cycle length was 216 ms. 100% successful rate using cryoablation. No complications. No recurrence of tachycardia during the follow-up period. CONCLUSION: Slow AV nodal pathway cryoablation may be safely performed, with good short and medium-term outcomes in patients under 15 kg.

Fetal neurosurgery.

Among fetal surgical procedures, neurosurgery stands out due to the number of cases and the possibility of developing new procedures that can be performed in the fetal period. To perform fetal neurosurgical procedures, there is a need for specialized centers that have experts in the diagnosis of fetal pathologies and a highly complex obstetrics service with specialized maternal-fetal teams associated with a pediatric neurosurgery center with expertise in the diverse pathologies of the fetus and the central nervous system that offers multidisciplinary follow-up during postnatal life. Services that do not have these characteristics should refer their patients to these centers to obtain better treatment results. It is essential that the fetal neurosurgical procedure be performed by a pediatric neurosurgeon with extensive experience, as he will be responsible for monitoring these patients in the postnatal period and for several years. The objective of this manuscript is to demonstrate the diagnostic and treatment possibilities, in the fetal period, of some neurosurgical diseases such as hydrocephalus, tumors, occipital encephalocele, and myelomeningocele.

Prenatal Spina Bifida Repair: Defendable Trespassing of MOMS Criteria Results in Commendable Personalized Medicine.

INTRODUCTION: We hypothesize that after publication of the quintessence of the MOMS trial, eligibility criteria for prenatal spina bifida (SB) repair may be modified if a tenable argumentation underlies this decision. METHODS: Our first 154 fetal surgery patients were analyzed with particular focus on how many, which, and why the original eligibility criteria, set forth by the MOMS Trial Protocol, were disobeyed, and what the eventually detectable, negative and positive impacts of these deviations on outcomes were. RESULTS: A total of 152 patients (2 missing consent) were included (100%). In 69 patients (45.4%), a total of 89 eligibility criteria were disobeyed. In 54 (35.6%) cases, the following maternal criteria were concerned: gestational age at operation of >25+6 weeks in 17 (11.2%), uterine pathologies in 13 (8.6%) women, preoperative BMI ≥35 kg/m2 in 12 (7.9%), previous hysterotomy in 7 (4.6%), previous prematurity in 3 (2%), HIV/hepatitis B in 2 (1.3%), psychosocial issues in 2 (1.3%), and placenta praevia in 1 (0.7%). In 32 (21.1%) cases, fetal criteria were disobeyed 34 times: Fetal anomaly unrelated to SB in 19 (12.5%), no/minimal evidence of hindbrain herniation in 13 (8.6%), and severe kyphosis in 2 (1.3%). We could not identify cases where non-observation of criteria led to clear-cut maternal and/or fetal disadvantages. CONCLUSION: This study shows that MOMS trial eligibility criteria for prenatal SB repair should be modified or even abandoned with adequate medical and ethical argumentation, and with written parental informed consent after non-directive, full disclosure counseling. This clear-cut change of paradigm is a necessity as it leads toward personalized medicine, allowing more fetuses to benefit from fetal surgery than would have benefitted with the former, published, MOMS criteria in place.

Postnatal Myelomeningocele Repair in the United States: Rates and Disparities Before and After the Management of Myelomeningocele Study Trial.

BACKGROUND AND OBJECTIVES: Evolving technologies have influenced the practice of myelomeningocele repair (MMCr), including mandatory folic acid fortification, advances in prenatal diagnosis, and the 2011 Management of Myelomeningocele Study (MOMS) trial demonstrating benefits of fetal over postnatal MMCr in select individuals. Postnatal MMCr continues to be performed, especially for those with limitations in prenatal diagnosis, health care access, anatomy, or personal preference. A comprehensive, updated national perspective on the trajectory of postnatal MMCr volumes and patient disparities is absent. We characterize national trends in postnatal MMCr rates before and after the MOMS trial publication (2000-2010 vs 2011-2019) and examine whether historical disparities persist. METHODS: This retrospective, cross-sectional analysis queried Nationwide Inpatient Sample data for postnatal MMCr admissions. Annual and race/ethnicity-specific rates were calculated using national birth registry data. Time series analysis assessed for trends relative to the year 2011. Patient, admission, and outcome characteristics were compared between pre-MOMS and post-MOMS cohorts. RESULTS: Between 2000 and 2019, 12 426 postnatal MMCr operations were estimated nationwide. After 2011, there was a gradual, incremental decline in the annual rate of postnatal MMCr. Post-MOMS admissions were increasingly associated with Medicaid insurance and the lowest income quartiles, as well as increased risk indices, length of stay, and hospital charges. By 2019, race/ethnicity-adjusted rates seemed to converge. The mortality rate remained low in both eras, and there was a lower rate of same-admission shunting post-MOMS. CONCLUSION: National rates of postnatal MMCr gradually declined in the post-MOMS era. Medicaid and low-income patients comprise an increasing majority of MMCr patients post-MOMS, whereas historical race/ethnicity-specific disparities are improving. Now more than ever, we must address disparities in the care of MMC patients before and after birth.

Abdominal testicular vessel distribution in human fetuses - basis for fowler-Stephens surgery.

PURPOSE: To analyze the histology and distribution of abdominal testicular vessels in human fetuses Patients and Methods: We studied 19 fetuses (34 testes) ranging in age from 12 to 19 weeks post-conception. The fetuses were evaluated regarding crown-rump length (CRL), total length (TL) and body weight immediately before dissection. Each testis was dissected and embedded in paraffin, from which 5 µm thick sections were obtained and stained with Masson's trichrome and Anti-CD31 antibody to quantify the vessels. The stereological analysis was carried out with the Image Pro and Image J programs, using a grid to determine volumetric densities (Vv). Means were statistically compared using the unpaired T-test (p<0.05). RESULTS: The fetuses presented mean weight of 222.5g, mean CRL of 15.3 cm and mean TL of 23.2 cm. All testes were in the abdominal position. The mean percentage of vessels (Vv) in the upper portion of the testis was 7.6% (4.6 to 15%) and in the lower portion the mean was 5.11% (2.3 to 9.8%), with a significant difference (p=0.0001). In the analysis between the upper portion of the right and left testes (p=0.99) and in the analysis of the lower portion of the right and left testes (p=0.83), we did not observe significant differences. CONCLUSION: The upper portion of the abdominal testis in human fetuses had a higher concentration of vessels than the lower portion. These results suggest that manipulation of the lower end of the testis during Fowler-Stephens surgery should be avoided in order to preserve the collateral circulation.

Laparoscopy-assisted percutaneous correction of abdominal wall defects in the umbilical region in a cadaveric model of bovine fetus.

Abdominal wall defects in calves are commonly diagnosed and treated via laparotomy. This technique has witnessed several advancements in the management of these disorders. This study aimed to create a study model and evaluate the feasibility of video-assisted percutaneous correction of abdominal wall defects in bovine fetuses (corpses) compared with the conventional technique. Sixteen bovine fetuses from pregnant cows slaughtered in slaughterhouses were included in this study. The fetuses were categorized into the control group (CG, n = 8), which was subjected to umbilical abdominorrhaphy via laparotomy, and the video-surgical group (VG, n = 8), which received video-assisted percutaneous sutures with two lateral accesses on the right flank. An abdominal wall defect was created in the VG group to generate a study model, which was corrected using the laparoscopic technique. The procedures were performed in two steps. The first step consisted of creating an abdominal wall defect in the umbilical region by laparoscopic approach in an iatrogenic manner (Step 1: E1). The second stage consisted of conventional abdominorrhaphy of the umbilical region wall defect in the CG group and video-assisted percutaneous suturing of the edges of the iatrogenic abdominal wall defect in the VG group, until reversal of the laparoscopic accesses (Step 2: E2). Step 1 showed no statistically significant difference between the two groups. However, a significant statistical difference (p < 0.0001) was observed between the two groups in step 2. The surgical time of step 2 was longer in the CG group (33.10 ± 0.43 minutes) than that in the VG group (10.13 ± 0.68 minutes, p < 0.0001), and the total surgical time was also longer in the CG group (38.48 ± 0.35 minutes) than that in the VG group (15.86 ± 0.67 minutes). The proposed laparoscopic technique allowed the creation of a study model for video-assisted percutaneous suturing with two portals and reduced the surgical time compared with the conventional technique. However, this method needs to be studied further in live animals.

The value and limitations of using predetermined criteria in decision making for maternal-fetal interventions.

Maternal-fetal interventions-such as prenatal fetal myelomeningocele (MMC) repair-are at the forefront of clinical innovation within maternal-fetal medicine, pediatric surgery, and neonatology. Many centers determine eligibility for innovative procedures using pre-determined inclusion and exclusion criteria based on seminal studies, for example, the "Management of Myelomeningocele Study" for prenatal MMC repair. What if a person's clinical presentation does not conform to predetermined criteria for maternal-fetal intervention? Does changing criteria on a case-by-case basis (i.e., ad hoc) constitute an innovation in practice and flexible personalized care or transgression of commonly held standards with potential negative consequences? We outline principle-based, bioethically justified answers to these questions using fetal MMC repair as an example. We pay special attention to the historical origins of inclusion and exclusion criteria, risks and benefits to the pregnant person and the fetus, and team dynamics. We include recommendations for maternal-fetal centers facing these questions.