Maternal Laparotomy Research Articles

End-tidal concentration of sevoflurane for optimal surgical conditions in pregnant sheep: a pragmatic approach to a retrospective observational study.

The aim of this pragmatic approach to retrospective observational study was to identify the end-tidal concentration of sevoflurane which was associated with optimal surgical conditions (i.e., absence of any movement, coughing and straining) in 127 pregnant sheep. Optimal surgical conditions were observed in 90% of the ewes with an end-tidal concentration of sevoflurane of 2.4 Vol-% [95% CI: 2.2; 2.8] during minimal-mild nociceptive stimuli (placement of arterial catheter, bladder catheter, shaving), with 4.4 Vol-% [95% CI: 4.0; 5.2] during maternal laparotomy and hysterotomy and with 4.4 Vol-% [95% CI: 3.9; 5.8] during subsequent manipulation of the uterus and fetal surgery.

Should We Stitch-Close the Fetoscopic Percutaneous Access? A Case-Series of Laparotomy to Trans-Amniotic Membrane Suturing for Intrauterine Port Placement in Fetoscopic Surgery for Twins

Introduction: Maternal laparotomy-assisted fetoscopic surgery for in-utero myelomeningocele repair has shown that a trans-amniotic membrane suture during fetoscopic port placement can reduce postsurgical complications. Fetoscopic laser photocoagulation (FLP) for complex twins is typically performed percutaneously without a transmembrane stitch. However, in scenarios without a placental-free window, maternal laparotomy may be used for recipient sac access. Here, we present the outcomes of our series of laparotomy-assisted FLP cases, including a trans-amniotic membrane suturing of the fetoscopic port. Methods: Retrospective series of twin-twin transfusion syndrome or twin anemia-polycythemia sequence (TAPS) cases treated at 2 fetal centers that underwent maternal laparotomy to FLP from September 2017 to January 2023. We recorded preoperative and operative characteristics, as well as pregnancy and neonatal outcomes. Results: During the study period, 9 maternal laparotomy to FLP cases were performed. Two were excluded for prior percutaneous FLP in the pregnancy. The remaining seven utilized a maternal laparotomy to trans-amniotic membrane stitch with confirmation of proper suture placement under ultrasound guidance, and all surgeries were performed with a single 10 F Check-Flo® cannula. Mean gestational age (GA) at surgery was 19.1 weeks (range 16 weeks 4 days–23 weeks 3 days), with delivery occurring at a mean GA of 35.0 weeks (range 32 weeks 0 days–37 weeks 1 day), resulting in a mean latency of 15.8 weeks, significantly longer than what is reported in the literature and our own data (mean latency for percutaneous FLP 10.2, 95% CI 9.9–10.5). Furthermore, all cases underwent iatrogenic delivery before labor onset, with the lone delivery prior to 34 weeks due to concern for post-laser TAPS. Conclusion: This case series of laparotomy to FLP with trans-amniotic stitch, demonstrated no cases of spontaneous preterm birth and a longer-than-expected latency from surgery to delivery. Larger studies are warranted to investigate this approach.

Enhanced Recovery after Surgery in Open Fetal Spina Bifida Repair

Introduction: For open fetal spina bifida (fSB) repair, a maternal laparotomy is required. Hence, enhanced maternal recovery after surgery (ERAS) is paramount. A revision of our ERAS protocol was made, including changes in operative techniques and postoperative pain management. This study investigates eventual benefits. Methods: Our study included 111 women with open fSB repair at our center. The old protocol group (group 1) either received a transverse incision of the fascia with transection of the rectus abdominis muscle (RAM) or a longitudinal incision of the fascia without RAM transection, depending on placental location. The new protocol required longitudinal incisions in all patients (group 2). Postoperative pain management was changed from tramadol to oxycodone/naloxone. Outcomes of the two different protocol groups were analyzed and compared regarding the primary endpoint, the length of hospital stay (LOS) after fetal surgery, as well as regarding the following secondary endpoints: postoperative pain scores, day of first mobilization, removal of urinary catheter, bowel movement, and the occurrence of maternal and fetal complications. Results: Out of 111 women, 82 (73.9%) were in group 1 and 29 (26.1%) were in group 2. Women in group 2 showed a significantly shorter LOS (18 [14–23] days vs. 27 [18–39] days, p = 0.002), duration until mobilization (3 [2–3] days vs. 3 [3–4] days, p = 0.03), and removal of urinary catheter (day 3 [3–3] vs. day 4 [3–4], p = 0.004). Group 2 less often received morphine subcutaneously (0% vs. 35.4%, p < 0.001) or intravenously (0% vs. 17.1%, p = 0.02) but more often oxycodone (69.0% vs. 18.3%, p < 0.001). No significant differences were seen regarding pain scores, bowel movement, and maternal and/or fetal complications. Conclusion: The new ERAS protocol that combined changes in surgical technique and pain medication led to better outcomes while reducing LOS. Continuous revisions of current ERAS protocols are essential to improve patient care continuously.

Intra-amniotic sildenafil administration in rabbits: Safety, pharmacokinetics, organ distribution and histologic evaluation

BackgroundThe effectiveness of sildenafil in the management of pulmonary hypertension in congenital diaphragmatic hernia (CDH) has been reported but has not been systematically evaluated. Our studies have also demonstrated that intra-amniotic (IA) sildenafil administration improves pulmonary hypertension in CDH. MethodsWe evaluated the pharmacokinetics of sildenafil after IA administration in pregnant rabbits. Following maternal laparotomy, fetuses received IA injection of 0.8 mg of sildenafil. Maternal blood, amniotic fluid, and fetal tissues were collected at various time points. The concentrations of sildenafil and its major metabolite in samples were analyzed by liquid chromatography-mass spectrometry. To assess organ toxicity, 7 days after IA sildenafil administration, fetal organs were examined histologically. ResultsAfter IA dosing, sildenafil was absorbed quickly with an absorption half-life of 0.03–0.07 h into the fetal organs. All the organs showed a maximum concentration within 1 h and the disposition half-life ranged from 0.56 to 0.73 h. Most of the sildenafil was eliminated from both mothers and fetuses within 24 h after a single dose. There was no histological evidence of organ toxicity in the fetuses after a single dose of IA administration of sildenafil. ConclusionIA sildenafil is rapidly absorbed into the fetus, distributes into the mother, and is eliminated by the mother without accumulation or fetal organ toxicity. This study confirms the feasibility and the safety of IA administration of sildenafil and enables future applications in the treatment of CDH fetuses.

Effects of cumulative duration of repeated anaesthesia exposure on foetal brain development in the ovine model

ObjectiveAnaesthesia is required in 0.4–1% of pregnant women, and prolonged and repeated exposures to anaesthesia may be required. It is unknown whether these exposures may result in foetal neurotoxicity in humans. As sheep have a gestation comparable to that of humans, the objective of this study was to analyse the neurodevelopmental outcome of ovine foetuses that had been exposed in utero to repeated and prolonged anaesthesia. DesignRandomized controlled preclinical study. SettingAnaesthesia for non-obstetric surgery during pregnancy. AnimalsTwenty-four healthy pregnant Swifter ewes. InterventionsThe ewes were randomized to no anaesthesia exposure (control-group), single exposure (at gestational age 68–70 days), or repeated exposure (at gestational age 68–70 days and 96–98 days) to 2.5 h of sevoflurane anaesthesia and maternal laparotomy. All lambs were delivered at approximately term gestation (gestational age: 140–143 days). MeasurementsThe primary outcome was neuron density in the frontal cortex 24 h after birth for the control-group versus the repeated-exposure-group. Key secondary outcome was the time needed to achieve the milestone of standing. Secondary outcomes included other neurobehavioural assessments (e.g., motoric milestones) and histological parameters quantified in multiple brain regions (neuron density, total cell density, proliferation, inflammation, synaptogenesis, astrocytes and myelination). Main resultsNeuron density in the frontal cortex did not differ between groups (mean ± standard deviation: control-group: 403 ± 39, single-exposure group: 436 ± 23 and repeated-exposure-group: 403 ± 40 neurons/mm2, control-group versus repeated-exposure-group: p = 0.986, control-group versus single-exposure-group: p = 0.097). No significant difference was observed for the time needed to achieve the milestone of standing. Only very limited differences were observed for other histological outcome parameters and neurobehavioural assessments. ConclusionsThere is no evidence for foetal neuronal injury or neurobehavioural impairments after a cumulative duration of 5 h repetitive prenatal anaesthesia in sheep.

Minimally Invasive Bimanual Fetal Surgery-A Review.

Background: The aim of this review is to discuss experimental and clinical techniques and interventions of fetal surgery which have been performed minimally invasively by the means of a three-port approach for the fetoscope and instruments for the left and right hand of the surgeon (bimanual minimally invasive fetal surgery). Methods: a print and electronic literature search was performed; the titles and abstracts were screened and included reports were reviewed in a two-step approach. First, reports other than minimally invasive fetal surgery were excluded, then a full text review and analysis of the reported data was performed. Results: 17 reports were included. The heterogeneity of the included reports was high. Although reports on human fetoscopic surgical procedures can be found, most of them do not pick out bimanual fetal surgery as a central theme but rather address interventions applying a fetoscope with a working channel for a laser fiber, needle or flexible instrument. Most reports were on experimentation in animal models, the human application of minimally invasive fetoscopic bimanual surgery is rare and has at best been explored for the prenatal treatment of spina bifida. Some reported bimanual fetoscopic procedures were performed on the exteriorized uterus via a maternal laparotomy and can therefore not be classified as being truly minimally invasive. Discussion: our results demonstrate that minimally invasive fetoscopic bimanual surgery is rare, even in animal models, excluding many other techniques and procedures that are loosely termed ‘minimally invasive fetal surgery’ which we suggest to better label as ‘interventions’. Thus, more research on percutaneous minimally invasive bimanual fetoscopic surgery is warranted, with the aim to reduce the maternal, uterine and fetal trauma for correction of congenital malformations.

VP48.02: Factors precluding open fetal surgery for spina bifida repair in Mexico

To assess factors precluding open fetal surgery in pregnancies with prenatal diagnosis of open spina bifida (OSB). From October 2015 to January 2021, a prospective cohort of pregnancies with prenatal diagnosis of OSB selected for intrauterine OSB repair in our national referral fetal surgery centre at Queretaro, Mexico was constructed. All exclusion criteria for fetal surgery were analysed. During the study period, 236 OSB cases were evaluated, 75 (31.7%) underwent open fetal surgery and 161 fetuses were excluded. Within the population excluded for fetal surgery, 39.75% (64/161) were diagnosed or referred beyond 28 weeks of gestation, 35.40% (57/161) showed additional structural or chromosomal abnormalities, 13.66% (22/161) refused fetal intervention, 4.99% (8/161) did not show Chiari II Malformation, 1.24% (2/161) showed maternal medical contraindications for surgery, 1.24% (2/161) procedures were abandoned before performing maternal laparotomy due to anaphylactic shock, 1.24% (2/161) showed short cervical length (< 25mm), 1.24% (2/161) were twin pregnancies, and 1.24% (2/161) the diagnosis was not confirmed. In pregnancies complicated with OSB late prenatal diagnosis is the main factor precluding fetal surgery. This finding highlights the need to improve strategies to enhance access to advanced fetal evaluations in Mexico which will allow an accurate diagnosis and early referral to fetal surgery centres.

Fetal blood gases after in utero carbon dioxide insufflation for percutaneous fetoscopic spina bifida repair

Prenatal repair of open spina bifida via the percutaneous fetoscopic approach does not require maternal laparotomy, hysterotomy, or exteriorization of the uterus. This technique requires intrauterine partial CO2 insufflation. Limited data exist on the physiological effects of CO2 insufflation on human fetuses, with no data on open spina bifida repair performed using the entirely percutaneous fetoscopic surgical technique. Our aim was to examine the effects of intrauterine partial CO2 insufflation on fetal blood gases after percutaneous fetoscopic open spina bifida repair. This was a prospective study of patients who underwent percutaneous fetoscopic open spina bifida repair from February 2019 to July 2020. Fetal cordocentesis of the umbilical vein was performed in cases with favorable access to the umbilical cord. The umbilical vein cord blood samples were obtained under ultrasound guidance immediately at the conclusion of the open spina bifida repair. Simultaneous maternal arterial blood gas samples were also obtained. The results are reported as median (range). Of the 20 patients who underwent percutaneous fetoscopic open spina bifida repair during the study period, 7 patients (35%) underwent fetal blood sampling. The gestational age at the time of surgery was 27.4 (24.0-27.9) weeks and the operative time was 183 (156-251) minutes. The CO2 exposure time was 122 (57-146) minutes with maximum pressure of 13.5 (12.0-15.0) mm Hg. Fetal umbilical vein results were as follows: pH 7.35 (7.30-7.39), partial pressure of O2 56.2 (47.1-99.9) mm Hg, partial pressure of CO2 43.8 (36.2-53.0) mm Hg, HCO3 23.9 (20.1-25.6) mmol/L, and base excess -2.2 (-4.5 to -0.4) mmol/L. Simultaneous maternal arterial blood gas results were as follows: pH 7.37 (7.28-7.42), partial pressure of O2 187.5 (124.4-405.2) mm Hg, partial pressure of CO2 36.6 (30.7-46.0) mm Hg, HCO3 21.3 (18.0-22.8) mmol/L and base excess -3.2 (-5.9 to -1.8) mmol/L. Despite prolonged CO2insufflation of the uterus, fetal umbilical vein pH and base excess values did not approach those associated with potentially pathologic fetal acidemia.

946 Fetal blood gases after in utero carbon dioxide insufflation for percutaneous fetoscopic spina bifida repair

Prenatal repair of open spina bifida (OSB) via the percutaneous fetoscopic approach does not require maternal laparotomy, hysterotomy, or exteriorization of the uterus. This technique does require intrauterine carbon dioxide (CO2) insufflation for surgical manipulation of the fetus. There is limited data on the physiological effects of CO2 insufflation on human fetuses and no data using the entirely percutaneous fetoscopic surgical technique. Our aim was to examine the effects of CO2 insufflation on fetal blood gases after percutaneous fetoscopic OSB repair. Prospective study of patients that underwent percutaneous fetoscopic OSB repair from 2/2019 to 7/2020. Fetal cordocentesis of the umbilical vein was performed in cases with favorable access to the umbilical cord. The umbilical vein cord blood samples were obtained under ultrasound guidance immediately at the conclusion of the OSB repair. Simultaneous maternal arterial blood gas samples were also obtained. Results are reported as median (range). Of 20 patients who underwent percutaneous fetoscopic OSB repair, 7 patients (35%) underwent fetal blood sampling. Gestational age at time of surgery was 27.4 (24.0 – 27.9) weeks and operative time was 183 (156 – 251) minutes. The CO2 exposure time was 122 (57 – 146) minutes with maximum pressure of 13.5 (12.0 – 15.0) mmHg. Fetal umbilical vein results were: pH 7.346 (7.301 – 7.387), pO2 56.2 (47.1 – 99.9) mmHg, pCO2 43.8 (36.2 – 53.0) mmHg, HCO3 23.9 (20.1 – 25.6) mmol/l and base excess (BE) -2.2 (-4.5 – -0.4) mmol/l. The lowest fetal pH recorded was 7.301. Simultaneous maternal arterial blood gas results were: pH 7.370 (7.284 – 7.420), pO2 187.5 (124.4 – 405.2) mmHg, pCO2 36.6 (30.7 – 46.0) mmHg, HCO3 21.3 (18.0 – 22.8) mmol/l and BE -3.2 (-5.9 – -1.8) mmol/l. After prolonged CO2 insufflation of the uterus, the fetal umbilical vein pH remained within normal range, above levels associated with fetal acidosis.

3434 The Study of Fetal Tracheal Occlusion to Treat Congenital Diaphragmatic Hernia in the EXTEND Model

OBJECTIVES/SPECIFIC AIMS: The goal of this project is to study fetal pulmonary vasculature in a CDH animal model, to understand how FETO affects developing vasculature, and to develop a modifiable fetal tracheal occlusive therapeutic device that avoids previously seen sequelae of FETO, like alveolar distension, decreased surfactant production, and decreased Type II Pneumocytes. The primary outcome is lung volume/kilogram. The secondary outcomes are contrast-enhanced ultrasound perfusion metrics (Time to Peak, Mean Transit Time, Wash-in Rate, Wash-in Perfusion Index), pulmonary vascular density, Lung Injury Histology Scores, and Lung Compliance upon ventilation. METHODS/STUDY POPULATION: Congenital diaphragmatic hernias will be modeled by surgical hernia creation via maternal laparotomy and hysterotomy at gestational age 72 - 74 days. The ewe will undergo a second laparotomy at 105 - 115 days gestational age. After a second hysterotomy is made, the fetus will be removed from the amniotic sac, though placental circulation will be maintained (EXIT Procedure). The animal is cannulated via the umbilical vein and arteries onto the pumpless ECMO circuit. The balloon and pressure sensor complex is placed into the trachea via direct laryngoscopy, and the fetus aseptically sealed into the Biobag. The wires of the tracheal occlusive device (balloon catheter and pressure sensor) will egress via the port of the Biobag. The fetus remains in the Biobag for fourteen days, with the tracheal occlusive device in place for ten days, followed by a four day recovery period. Daily contrast-enhanced ultrasounds and pulmonary artery dopplers are performed. Upon study completion, the fetus is intubated and placed on a conventional ventilator. A full necropsy is then performed, with perfusion fixation of the lungs via the pulmonary artery. RESULTS/ANTICIPATED RESULTS: Hypothesis 1: Modifiable Tracheal Occlusion will have statistically different effects on developing lung parenchyma, surfactant production, and abundance of Type II Pneumocytes Hypothesis 2: Modifiable Tracheal Occlusion will have lower levels of pulmonary hypertension than negative control animals, as measured by contrast-enhanced ultrasound (pulmonary artery velocity and washout time). DISCUSSION/SIGNIFICANCE OF IMPACT: This project will provide insight into the development of pulmonary hypertension in the CDH fetus. It will provide insight into the physiology of FETO, a novel therapy for congenital diaphragmatic hernias, and will demonstrate the utility of the EXTEND System for fetal treatments that are not possible in the maternal uterus.

Fetal Surgery for Myelomeningocele: A Systematic Review and Meta-Analysis of Outcomes in Fetoscopic versus Open Repair

Background/Objectives: The Management of Myelomeningocele (MMC) Study (MOMS) showed that prenatal repair of MMC resulted in improved neurological outcomes but was associated with high rates of obstetrical complications. This study compares outcomes of open and fetoscopic MMC repair. Data Sources: PubMed and Embase studies reporting outcomes of fetal MMC repair published since the completion of the MOMS. Results: We analyzed 11 studies and found no difference in mortality or the rate of shunt placement for hydrocephalus. Percutaneous fetoscopic repair was associated with higher rates of premature rupture of membranes (91 vs. 36%, p < 0.01) and preterm birth (96 vs. 81%, p = 0.04) compared to open repair, whereas fetoscopic repair via maternal laparotomy reduced preterm birth. The rate of dehiscence and leakage from the MMC repair site was higher after both types of fetoscopic surgery (30 vs. 7%, p < 0.01), while the rate of uterine dehiscence was higher after open repair (11 vs. 0%, p < 0.01). Discussion: Fetoscopic repair is a promising alternative to open fetal MMC repair with a lower risk of uterine dehiscence; however, fetoscopic techniques should be optimized to overcome the high rate of dehiscence and leakage at the MMC repair site. A fetoscopic approach via maternal laparotomy reduces the risk of preterm birth.

Prenatal interventions for congenital diaphragmatic hernia for improving outcomes.

Prenatal interventions for congenital diaphragmatic hernia for improving outcomes.

Computer‐assisted navigation applied to fetal cardiac intervention

Prenatal cardiac interventions (PCI) for human fetal aortic valve (AoV) stenosis can reduce left ventricular hypoplasia and restore ventricular growth and function. However, 'freehand' needle delivery from the maternal skin through the uterine wall, fetal chest and ventricular apex to cross the fetal AoV remains technically challenging and time intensive, and is the rate-limiting step in the procedure. We developed a computer-assisted navigation (CANav) system that tracks the position and orientation of a two-dimensional (2D) ultrasound image relative to the trajectory of an electromagnetic (EM) embedded needle and stylet. We tested the CANav system in vitro using a water bath phantom, then in vivo using adult rats and pregnant (fetal) sheep. The CANav system accurately tracked the delivered needle position in both in vitro phantom and adult rat model experiments. We performed 22 PCI attempts with or without CANav in a fetal sheep model. Maternal laparotomy was required to adjust the fetal position in 50% of the procedures. The time required to deliver the needle from the skin into the left ventricle (LV) using CANav was 2.9 +/- 1.7 (range 2-7) min (n = 14) vs. 5.5 +/- 4.3 (range 1-12) min (n = 8) without CANav (p < 0.05). The time needed to cross the aortic valve once the needle was within the LV was similar with and without CANav (p = 0.19). CANav reduces the PCI time required to accurately deliver a needle to the fetal heart. Adaptations of this technical approach may be relevant to other congenital cardiac conditions and ultrasound-guided medical procedures.

Factors affecting technical success of fetal aortic valve dilation

We have reported previously that valve dilation enhances growth of cardiac structures and may prevent hypoplastic left heart syndrome (HLHS) in fetuses with critical aortic stenosis. We aimed to investigate maternal/fetal factors which may affect the technical success of fetal valvuloplasty, and to describe perinatal complications of the procedure. This was a descriptive series of 22 fetuses diagnosed with critical aortic stenosis developing into HLHS which underwent intervention by valvuloplasty. Initially this was attempted using a percutaneous approach; reassessment after our first five attempts, only one of which was successful, led to the introduction of the option of laparotomy. Technical success was defined as balloon inflation across the aortic annulus and a broader jet through the aortic valve as assessed by Doppler. Data collected included body mass index, demographic variables, ultrasound findings and postprocedure interventions. Technical success increased significantly if maternal laparotomy was an option (83.3% vs. 20.0%, P = 0.017). Laparotomy was performed in 66.6% (12/18) of cases. There was a learning curve that showed an increase in success rate and decrease in need for laparotomy over the 3-year study period. Neither the need for laparotomy nor the chances of technical success were predictable by gestational age, body mass index or placental location. Tocolysis was limited to perioperative prophylaxis; one woman experienced wound infection and fluid overload. Postoperatively, three fetuses died and two delivered prematurely, 2 and 7 weeks after intervention. Fetal aortic valvuloplasty can be performed with technical success, with low fetal loss rate and few maternal complications. While the need for laparotomy cannot be predicted, having it available as an option improves the technical success rate.

In‐utero intervention for hypoplastic left heart syndrome — a perinatologist's perspective

.Today,whenHLHSisdiagnosedinthenewborn,or suspected by prenatal ultrasound studies, surgicalinterventions typically take one of two directions – eitherthe multistaged reconstruction pioneered by Norwood toenable single ventricle survival or cardiac transplantation.Compassionate care, although increasingly controversial,remains an option in some centers. Although increasingsurvival rates following both multi-staged surgery ortransplant are being reported, the nature of theseinterventions is such that these children remain at lifelongrisk for cardiac and neurologic morbidity.Consideration of HLHS as a candidate for

Foetal surgery and cleft lip and palate: current status and new perspectives

Now-a-days, high-resolution ultrasound allows an accurate and relatively early diagnosis of congenital malformations. In a limited number of such conditions foetal surgery may be lifesaving. However, premature labour has been the major drawback for open foetal surgery. Recently, improvement of video-endoscopic technology has boosted the development of operative techniques for feto-endoscopic surgery, which has been demonstrated to be less invasive than the open approach. Main clinical application of fetoscopic procedures today is the treatment of feto-foetal transfusion syndrome. Although still in development, feto-endoscopic surgery seems to offer new hope for surgical foetal therapy not only in cases of life threatening conditions. Experimental intrauterine correction of cleft lip and palate (CLP) has been lately performed using the feto-endoscopic approach. This procedure offers two major advantages: first, scarless foetal wound healing and bone healing without callus formation, which would also allow a better/normal maxillary growth, and second, significant decrease of foetal and maternal morbidity. Herein, we report the current status of experimental and clinical foetal surgery and propose possible directions for continuing research to make intrauterine procedures safer. Furthermore, we discuss current knowledge and new perspectives of experimental foetal cleft lip and palate repair, which in the future may lead to such excellent results in the operative treatment of clefts, that less or no secondary corrections and therapies, such as orthodontic, dental, logopedic, etc. would be needed. Only if these conditions can be fulfilled, will we be able to improve substantially our therapy for the human foetus with a cleft lip and palate. In spite of all efforts, however, it must be considered that it may not ever be possible to find the optimal treatment method for this or other craniofacial malformations.

Evolution of a percutaneous fetoscopic access system for single-port tracheal occlusion

Background/Purpose: Prenatal tracheal occlusion currently is being assessed as a treatment modality for congenital diaphragmatic hernia (CDH). The development of a totally percutaneous fetoscopic access system would help avoid the need for maternal laparotomy and reduce the morbidity rate of fetal surgical procedures for the mother. Laparoscopic radial expansion sheaths and Seldinger technique–based vascular catheters both have been advocated as means of achieving amniotic cavity access. The authors have investigated these 2 systems in an attempt to develop a reliable method for achieving safe percutaneous fetoscopic access and present the first successful attempt to deploy an intratracheal balloon using an entirely percutaneous approach through a single port in an ovine model. Methods: A number of prototype systems were evaluated sequentially over a 3-year period in an ovine model: (1) the radially expanding InnerDyne step port system, (2) a new rigid cannula with a bulbous/sharp end preloaded onto the radially expanding InnerDyne port, (3) a conical removable addition to the rigid cannula in 2, (4) a modified bulbous/sharp ended cannula incorporating a circumferential protective insert, (5) a rigid split sheath with the radially expanding port placed through the lumen of the split sheath, (6) a flexible introducer and dilator with the split sheath (used in the Seldinger placement of central lines), and (7) a 2-needle approach using a superelastic shape-memory alloy Nickel-Titanium wire with the flexible dilator and sheath, incorporating a side perfusion port. For balloon tracheal occlusion, live anaesthetized time-mated pregnant ewes were used at 110 days' gestation. Tracheobronchoscopy was achieved using a 3-mm 0° telescope, and the cutaneotracheal tract was secured by a 3.3-mm sheath incorporating a side-perfusion port. The rigid telescope was replaced by a flexible choledochoscope preloaded with a silicone balloon. The balloon was deployed 2 cm above the carina proximal to the right upper lobe bronchus. Results: The many problems encountered in the evolution of the preferred system related mainly to separation and tenting of the chorioamniotic membranes in the ovine uterus and inconsistent access to the fetal parts of interest. Each resulted in significant modifications to our approach. Furthermore, the use of rigid access devices commonly caused fetal injury. Successful access to the intrauterine cavity and cannulation of the trachea was achieved consistently with minimal trauma, irrespective of fetal position by method 7. Multiple port placement allowed visualization of the entry of all components of the system confirming minimal chorioamniotic membrane separation and tenting. Single port tracheal occlusion was undertaken first on 6 cadavers before being performed successfully on 3 live anaesthetized ewes. Fetoscopic access and cannulation of the trachea was achieved consistently in all live animals irrespective of fetal position. Conclusions: This modified Seldinger technique using the unique properties of the memory-shaped alloy wire for initial uterine access offers a safe method for the percutaneous placement of fetoscopic ports in the ovine model for prenatal intervention. Successful placement of a tracheal balloon entirely through a single percutaneously placed port represents a further advance in prenatal therapy for CDH. J Pediatr Surg 38:45-50. Copyright 2003, Elsevier Science (USA). All rights reserved.

Placental Expression of Insulin-Like Growth Factor Receptor-1 and Insulin Receptor in the Growth-Restricted Fetal Rat

The type 1 insulin-like growth factor receptor (IGF-R1), which resembles the insulin receptor (INS-R), is expressed abundantly in the placenta. The regulation of fetal growth by IGFs and insulin might reflect their actions on the placenta. This study compared the placental expression of IGF-R1 and INS-R in growth-restricted and normal pregnancies. Fetal growth restriction was produced in Sprague-Dawley rats by bilateral ligation of the uterine artery on day 19 (term = 21.5 days). Fetuses were delivered by hysterotomy on day 20, and placental samples were frozen. Fetuses that had been subjected to a sham operation of maternal laparotomy without uterine artery manipulation were studied as matched controls. IGF-R1 and INS-R message was assessed by reverse transcription and polymerase chain reaction amplification of extracted placental RNA. The receptors also were assessed by Western blotting of extracted placental protein. Measurements for the growth-restricted group were expressed as a multiple of that of the matched sham litter. Placental IGF-R1 messenger RNA (mRNA) level was significantly lower in the growth-restricted fetuses (0.66 x sham [0.47-0.93], P <.05), but INS-R mRNA was not different (0.89 x sham [0.63-1.3], P >.5). IGF-R1 protein transcript was similarly reduced in the growth-restricted fetuses (0.78 x sham [0.69-0.88], P <.005), but the INS-R protein transcript was not (0.98 x sham [0.69-1.4], P >.8). Birth weights were significantly less in the growth-restricted group (3.06 +/- 0.07 versus 3.29 +/- 0.06 g, P =.016); placental weights were not (0.54 +/- 0.02 versus 0.54 +/- 0.02 g, P =.90). The placenta responds to decreased nutrient delivery with decreased expression of IGF-R1. This would reduce the growth-promoting effects of insulin-like growth factors, which include augmentation of placental lactogen production and glucose and amino acid transport. INS-R was unaffected, which suggests that placental response to insulin is less important than its response to insulin-like growth factors in growth restriction.

BAPS Prize—1999: Lung growth induced by prenatal tracheal occlusion and its modifying factors: A study in the rat model of congenital diaphragmatic hernia

Background/Purpose: Prenatal tracheal occlusion (TO) has been shown to accelerate lung growth in animal models and models of pulmonary hypoplasia. However, these models may not mimic early events in human congenital diaphragmatic hernia (CDH). The authors previously have developed a model of TO in the rat. The purpose of this study was to apply this technique to characterize TO-induced lung growth in the early onset nitrofen-induced model of CDH, and to address the clinically important questions of the effect of timing of TO and maternal infusion of terbutaline on TO-induced lung growth. Methods: Left-sided CDH was induced in the fetuses of time-dated pregnant Sprague-Dawley rats by feeding 100 mg of nitrofen on day 9 of gestation. TO was performed via maternal laparotomy and hysterotomy at 19 days' gestation. At harvest (21.5 days' gestation), lungs from nitrofen-exposed fetuses without CDH (non-CDH), with CDH (CDH), and with CDH and TO (CDH-TO) were compared by analysis of wet and dry weight, DNA and protein content, and stereologic morphometry. A second study was performed to assess relative lung growth achieved by equal intervals of TO after “early” (19 days) versus “late” (20 days) gestational TO. Finally, the effect of maternal infusion of terbutaline, a commonly used tocolytic for fetal surgery, on TO-induced lung growth was analyzed. Results: Analysis of lung growth showed consistent and significant lung growth in CDH-TO lungs. Lung growth after TO was proliferative and characterized by an increase in parenchymal volume as manifest by increased total saccular number and surface area and radial saccular count. Although visceral reduction was partially achieved, herniated liver was reduced incompletely. The majority of lung growth occurred during the latter half of the TO period. Early gestational age at TO and maternal terbutaline administration adversely influenced lung growth in CDH-TO fetuses. Conclusions: Prenatal TO induces dramatic lung growth in the early onset, nitrofen-induced rat model of CDH. TO is more effective later in gestation presumably because of the advanced stage of lung development and lung fluid production. This effect could be counterbalanced by the use of β-mimetic tocolytic, which inhibits fetal lung fluid production late in gestation. Multiple factors including fetal lung fluid production and absorption, pharmacologic agents, space-occupying herniated viscera, and timing and duration of TO may be important clinical variables. The development of the rat model should facilitate further studies into the cellular and molecular mechanisms responsible for TO-induced lung growth. J Pediatr Surg 36:251-259. Copyright © 2001 by W.B. Saunders Company.

Tracheal Ligation Increases Mitogen-Activated Protein Kinase Activity and Attenuates Surfactant Protein B mRNA in Fetal Sheep Lungs

Background.Tracheal ligation has been shown to accelerate fetal pulmonary growth in normal and hypoplastic lungs. Our aim was to study the effects of tracheal ligation on established molecular markers of growth and differentiation [mitogen-activated protein (MAP) kinase] and maturity [surfactant protein B (SPB) and fatty acid synthase (FAS)].Materials and methods.Tracheal ligation was performed on four 100-day-gestation fetal sheep, with four age-matched fetuses undergoing maternal laparotomy and hysterotomy as control. Lungs from surviving fetuses (n= 2 in each group) were harvested after 4 days and frozen in liquid nitrogen. Protein lysates were prepared, and MAP kinase enzymatic assays [extracellular signal regulated protein kinase (ERK)-1 and -2] and Western blots were performed. Total RNA was isolated, and a fetal sheep lung cDNA library was created. The sheep SPB and FAS genes were cloned and sequenced. Northern blots were performed with the new clones, normalizing to β-actin.Results.Tracheal ligation lungs contained a larger volume of fluid (40 ml) compared with age-matched controls (8 ml). MAP kinase enzymatic ERK-1 activity was increased and SPB mRNA expression was reduced in fetal lungs after tracheal ligation. Neither ERK-2 enzymatic activities and FAS mRNA nor ERK protein levels were affected by tracheal ligation, by Western blot analysis.Conclusion.Tracheal ligation-induced fetal lung growth may be mediated in part via the MAP kinase pathway. Expression of SPB mRNA is attenuated by tracheal ligation, whereas FAS, one of the key enzymes that synthesizes the lipid portion of surfactant, is not affected.