Outcomes of primary versus revisional robotically assisted laparoscopic Roux-en-Y gastric bypass: a multicenter analysis of ten-year experience.

BACKGROUND: Postoperative morbidity after laparoscopic bariatric surgery is considered higher for patients undergoing revisional versus primary procedures. The objective of this retrospective cohort study was to compare outcomes between patients undergoing primary versus revisional robotically assisted laparoscopic (RAL) Roux-en-Y gastric bypass (RYGB). METHODS: Data of all patients who underwent RAL primary and revisional RYGB between 2009 and 2019 at two accredited, high-volume bariatric surgery centers-the Memorial Hermann - Texas Medical Center, Houston, TX, and the Tower Health, Reading Hospital, Reading, PA, were analyzed. Primary outcomes were early (< 30 days) and overall postoperative complications. Secondary outcomes included intraoperative complications, operative times, conversions to laparotomy, length of hospital stay, early (< 30 days) postoperative readmissions and deaths. RESULTS: Data of 1072 patients were analyzed, including 806 primary and 266 revisional RAL RYGB procedures. Longer operative times (203 versus 154 min, P < 0.001), increased number of readmissions for oral intolerance (10.5% versus 6.7%, P = 0.046) and higher rate of gastrojejunal stricture (6.4% versus 2.7%, P = 0.013) were found in the revisional group. Gastrointestinal leak rates were 0.2% for the primary versus 1.1% for the revisional group (P = 0.101). Early (< 30 days) reoperations rates were 2.2% for the primary versus 1.1% for the revisional group (P = 0.318). There were no statistically significant differences between groups in overall and severe complication rates. CONCLUSION: Patients undergoing RAL primary and revisional RYGB had comparable overall outcomes, with a non-significant higher early complication rate in the revisional group. Despite the study being underpowered to detect differences in specific complication rates, the morbidity seen in the revisional RYGB group remains markedly below literature reports of revisional laparoscopic RYGB and might suggest a benefit of robotic assistance. Further prospective studies are needed to confirm these results.

Extracorporeal Membrane Oxygenation Rescue for Severe Aspiration Pneumonitis in Two Patients after Roux-en-y Gastric Bypass Procedure.

Roux-en-y gastric bypass (RYGB) is one of the most common weight loss surgical procedures performed in the United States. Early post-operative small bowel obstruction is a rare but potentially morbid, complication of RYGB. We report two patients who underwent RYGB and required subsequent treatment for a post-operative small bowel obstruction. Their post-operative course was complicated by severe aspiration pneumonitis leading to hypoxemic respiratory failure requiring rescue with femoral veno-venous extracorporeal membrane oxygenation (V-V ECMO). Both patients were successfully extubated, weaned off V-V ECMO support, and discharged to home. These cases highlight the potential role of V-V ECMO for patients who have undergone RYGB and develop severe aspiration pneumonitis. They also highlight the need for cautionary use of gastrografin in RYGB patients. Early engagement of a multidisciplinary team experienced with adult ECMO is vital for favorable patient outcomes.

Trocar site closure with a novel anchor-based (neoClose®) system versus standard suture closure: a prospective randomized controlled trial.

BACKGROUND: Patients with obesity have a higher risk of trocar site hernia. The objective of the present study was to compare a standard suture passer versus the neoClose® device for port site fascial closure in patients with obesity undergoing laparoscopic bariatric surgery. METHODS: This is a randomized, controlled trial with two parallel arms. Thirty five patients with BMI ≥ 35 kg/m2 and undergoing laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass were randomized to each group. Port site fascial closure for trocars ≥ 10 mm was performed with the neoClose® device in the study group and the standard suture passer in the control group. Primary outcomes were time required to complete closure and intensity of postoperative pain at the fascial closure sites. Secondary outcomes were intraabdominal needle depth and incidence of trocar site hernia. RESULTS: The use of the neoClose® device resulted in shorter closure times (20.2 vs 30.0 s, p = 0.0002), less pain (0.3 vs 0.9, p = 0.002) at port closure sites, and decreased needle depth (3.3 cm vs 5.2 cm, p < 0.0001) compared to the standard suture passer. There was no trocar site hernia at the one-year follow-up in either group. CONCLUSIONS: Use of the neoClose® device resulted in faster fascial closure times, decreased intraoperative needle depth, and decreased postoperative abdominal pain at 1 week as compared to the standard suture passer. These data need to be confirmed on larger cohorts of patients with longer follow-up.

Safety of robotic assisted laparoscopic recurrent paraesophageal hernia repair: insights from a large single institution experience.

BACKGROUND: Laparoscopic repair of recurrent as opposed to primary paraesophageal hernias (PEHs) are historically associated with increased peri-operative complication rates, worsened outcomes, and increased conversion rates. The robotic platform may aid surgeons in these complex revision procedures. The aim of this study was to compare the outcomes of patients undergoing robotic assisted laparoscopic (RAL) repair of recurrent as opposed to primary PEHs. METHODS: Patients undergoing RAL primary and recurrent PEH repairs from 2009 to 2017 at a single institution were reviewed. Demographics, use of mesh, estimated blood loss, intra-operative complications, conversion rates, operative time, rates of esophageal/gastric injury, hospital length of stay, re-admission/re-operation rates, recurrence, dysphagia, gas bloat, and pre- and post-operative proton pump inhibitor (PPI) use were analyzed. Analysis was accomplished using Chi-square test/Fischer's exact test for categorical variables and the Mann-Whitney U test for continuous variables. RESULTS: There were 298 patients who underwent RAL PEH repairs (247 primary, 51 recurrent). They were followed for a median (interquartile range) of 120 (44, 470) days. There were no significant differences in baseline demographics between groups. Patients in the recurrent PEH group had longer operative times, increased use of mesh, and increased length of hospital stay. They were also less likely to undergo fundoplication. There were no significant differences in estimated blood loss, incidence of intra-operative complications, re-admission rates, incidence of post-operative dysphagia and gas bloat, and incidence of post-operative PPI use. There were no conversions to open operative intervention or gastric/esophageal injury/leaks. CONCLUSIONS: Although repair of recurrent PEHs are historically associated with worse outcomes, in this series, RAL recurrent PEH repairs have similar peri-operative and post-operative outcomes as compared to primary PEH repairs. Whether this is secondary to the potential advantages afforded by the robotic platform deserves further study.

Correction to: Trocar site closure with a novel anchor-based (neoClose®) system versus standard suture closure: a prospective randomized controlled trial.

After careful review, the authors have noticed the following mistakes in the article entitled "Trocar site closure with a novel anchor based (neoClose®) system versus standard suture closure: A prospective randomized controlled trial": - Correct closure times are 19.9 seconds (SD 9.9) for the study group and 31.0 seconds (SD 20.1) for the control group (initial incorrect values were 20.2 seconds (SD 10.1) and 30 seconds (SD 19.1) respectively). The new correct P-value is <0.0001 (initial incorrect P-value was 0.0002). - Correct maximal needle depth values are 3.2 cm (SD 0.93) for the study group and 4.9 cm (SD 1.97) for the control group (initial incorrect values were 3.3 cm (SD 0.9) and 5.2 cm (SD 1.6) respectively). P-value remains unchanged at <0.0001. For these two outcomes, some values of control group patients were mistakenly included in the study group. These errors only marginally affected the mean and standard deviation values. Statistical significance of the results was not affected and the conclusions of the study remain unchanged.

Frequency of Clinically Significant Findings in the Surgical Pathology Specimen Following Laparoscopic Sleeve Gastrectomy and Concordance with Preoperative Endoscopy: Insights from a Large Single-Center Experience.

INTRODUCTION: Endoscopy prior to bariatric surgery is not always performed, and in sleeve gastrectomy (SG), the surgical specimen is not always sent for pathological examination. There is limited data on the frequency of clinically significant findings in SG specimens or correlation with preoperative endoscopy. METHODS: We reviewed 426 consecutive SG patients to determine the concordance of preoperative endoscopy findings in patients with clinically significant postoperative pathology. RESULTS: Preoperative endoscopy was performed on 397 patients (93.2%). Three hundred seventy-three patients had preoperative endoscopy and surgical pathology results available. Then, 20/373 (5.4%) patients had potentially significant postoperative pathology, including intestinal metaplasia, autoimmune metaplastic atrophic gastritis (AMAG), gastrointestinal stromal tumors, and/or gastric cancer. The overall incidence of AMAG in the entire cohort was 2.3%. Preoperative gastric biopsies (to include gastric body) identified AMAG in nearly 1/2 of patients. Patients with clinically significant postoperative pathology results had a median [interquartile range] of 3 [3-5] tissue blocks examined as compared to 3 [1-3] for the remainder of the cohort (p < 0.001). CONCLUSION: This is one of the largest studies describing clinically significant postoperative pathology after SG. AMAG, in particular, is of particular importance as it is associated with a 3-fivefold increase in risk for gastric cancer. The incidence of significant postoperative pathology in this population is small but potentially clinically significant and requires validation in larger studies. We recommend wider sampling in preoperative endoscopy (body and antrum), especially in patients being planned for gastric bypass, consideration for routine pathological examination of SG surgical specimens, with careful gross examination and targeted sampling.

Bouveret syndrome: current management strategies.

Bouveret syndrome is a rare complication of cholelithiasis that usually presents with signs and symptoms of gastric outlet obstruction. Given the relative rarity of this condition, there are no standardized guidelines for the management of this condition. In this paper, we review the diagnosis and management options (endoscopic, laparoscopic, and open approaches) of patients with Bouveret syndrome, including a report of one case to illustrate some of the endoscopic and surgical principles of management.

A randomized trial comparing reflux symptoms in sleeve gastrectomy patients with or without hiatal hernia repair.

BACKGROUND: The effect of laparoscopic sleeve gastrectomy (SG) on reflux symptoms is unclear. Many surgeons offer SG only to patients with minor or no reflux symptoms, fearing that patients with severe reflux symptoms will experience worsening of their condition after SG. Many also advocate crural repair at the time of SG to prevent de novo or worsening reflux symptoms. These decisions are made without suitable data to form such conclusions. OBJECTIVE: To determine the effect of SG with or without hiatal hernia repair on reflux symptoms. SETTING: University of Texas Health Sciences Center in Houston. METHODS: The Gastrointestinal Symptom Rating Scale (GSRS) was administered to 100 consecutive, preoperative SG patients who were then randomly assigned into a crural repair group or nonrepair group in a parallel design. The patients were subsequently followed-up every 3 months for 1 year. We compared reflux symptoms of the 2 groups on the basis of demographic characteristics, body mass index, weight loss, presence and size of hiatal hernia, and GSRS for 12 months. RESULTS: At 1 year, with 78% follow-up, the data demonstrated a significant decrease in the GSRS for both groups (P<.001); however, there was no difference between the groups (P = .35). Age, starting body mass index, percent excessive weight loss, and hiatal hernia size did not correlate with change in the GSRS score. The only variable that affected outcome was the preoperative GSRS. At 12 months, 38% of patients with a preoperative GSRS score less than the median score of the study population experienced worsening of their symptoms compared with only 2% of patients who had a preoperative GSRS score greater than the median. Overall, 19% experienced worsening reflux (5% de novo), 14% had no change, and 66% reported an improvement in symptoms. CONCLUSION: These data suggest that a crural repair at the time of SG does not significantly reduce reflux symptoms compared with SG alone. Preoperative patients with significant reflux symptoms experienced a more significant improvement in symptoms after surgery compared with those who did not report significant reflux symptoms before surgery. The high incidence of reflux after SG observed in the current literature may be a result of a specific patient subpopulation who undergoes SG because of surgeon bias rather than an inherent property of SG itself or the presence of a hiatal hernia.

Interplay of glucagon-like peptide-1 and transforming growth factor-beta signaling in insulin-positive differentiation of AR42J cells.

The differentiation of pancreatic exocrine AR42J cells into insulin-expressing endocrine cells has served as an important model for both endogenous in vivo beta-cell differentiation as well as potential application to beta-cell engineering of progenitor cells. Exogenous activin, possibly working through intracellular smad 2 and/or smad 3, as well as exogenous exendin-4 (a long-acting glucagon-like peptide-1 agonist) have both been shown to induce insulin-positive/endocrine differentiation in AR42J cells. In this study, we present evidence of significant interplay and interdependence of these two pathways as well as potential synergy between the pathways. In particular, insulin-positive differentiation seems to entail an exendin-4-induced drop in smad 2 and elevation in smad 3 in RNA levels. The latter appears to be dependent on endogenous transforming growth factor (TGF)-beta isoform release by the AR42J cells and may serve as a mechanism to promote beta-cell maturation. The drop in smad 2 may mediate early endocrine commitment. The coapplication of exogenous exendin-4 and, specifically, low-dose exogenous TGF-beta1 led to a dramatic 20-fold increase in insulin mRNA levels, supporting a novel synergistic and codependent relationship between exendin-4 signaling and TGF-beta isoform signaling.

Defective sonic hedgehog signaling in esophageal atresia with tracheoesophageal fistula.

BACKGROUND: The pathogenesis of esophageal atresia and tracheoesophageal fistula (EA/TEF) remains unknown. We have found previously that an initial esophageal atresia, followed by an abnormal (absent) branching pattern of the middle branch of a trifurcation of the lung/tracheal bud, leads to the neonatal finding of TEF. Mice null mutant for hedgehog signaling can experience the development of EA/TEF, but the mechanism for this development is also unknown. Given that EA/TEF in humans appears not to be due to genetic defects, a hedgehog mutation cause seems very unlikely. However, defective hedgehog signaling that is caused by environmental effects in the human embryo likely could be implicated. We studied a teratogen-induced model of EA/TEF to determine the mechanism by which defective hedgehog signaling may lead to EA/TEF. METHODS: We injected Adriamycin into pregnant rats to induce EA/TEF in rat embryos. We first quantified sonic hedgehog (Shh) signaling pathway molecule expression using real-time, semiquantitative reverse-transcriptase polymerase chain reaction for Shh, Shh receptors (patched and smoothened), and downstream intracellular targets of those receptors (Gli family members). On the basis of these findings, we then developed an in vitro culture system for the day-12 embryonic TEF and manipulated Shh signaling using either exogenous Shh or Shh inhibitors. RESULTS: By reverse transcriptase-polymerase chain reaction, a unique difference between the fistula tract and control tissues was that Gli-2 (downstream signaling molecule of Shh) messenger RNA levels were much lower in the fistula tract than in the adjacent esophagus (P =.002). Surprisingly, in the culture experiments, the fistula tract was induced to branch by exogenous Shh. Such branching of the fistula was unexpected and further supports the presumed respiratory origin of the fistula tract because the normal lung, but not normal esophagus, branched in response to Shh. The Shh inhibitor had no effect, which indicated that defective signaling, rather than hyperfunctioning Shh, is critical to the nonbranching phenotype of the fistula tract in TEF. CONCLUSIONS: The recapitulation of respiratory developmental morphogenesis by the fistula tract of TEF in the presence of exogenous Shh, together with the quantitative reduction in normal, endogenous levels of Gli-2, strongly suggests that 1 mechanism for the formation of the fistula tract is the lack of proper Shh signaling because of Gli-2 deficiency, with subsequent straight, nonbranching caudal growth of the fistula tract. This deficiency can be rescued by excess exogenous Shh, thus reestablishing respiratory morphogenesis.

The impact of advances in developmental biology on the management of neonatal surgical anomalies.

While advances in the clinical management of various congenital anomalies in pediatric surgery have led to new and exciting therapeutic modalities, our understanding of the mechanisms responsible for these defects lags far behind. In a new era of developmental biology, the prospect of unlocking some of these mysteries has become a real possibility. Advances in gene sequencing has allowed us to create new phenotypes that closely mimic those seen in patients, and has created a setting where we are now better able to understand and develop new therapeutic interventions. Here we discuss the implications of some of the molecular mechanisms underlying various congenital anomalies encountered in pediatric surgery, and how continued research will impact the future of these disease processes.

Extracellular control of pancreatic differentiation.

Our understanding of basic mechanisms of differentiation has evolved rapidly in the last two decades. Spurred by advances in molecular biology and other research technologies, these advances have become of heightened importance with the recent advent of the possibility of engineering different types of stem cells into needed cell and tissue sources. As pediatric surgeons, we have the potential to play a key role in interfacing between the basic science necessary to understand differentiation processes, and its application at the bedside. In this brief article, we outline our in-depth analysis of mechanisms of basic differentiation of pancreatic precursor cells in an effort to better understand ways in which we can engineer a stem cell pool to form mature pancreatic cells.

Past, present, and future: Critical analysis of use of gastric bands in obese patients.

Adjustable gastric banding (AGB) is quickly becoming the most popular bariatric operation performed in the United States and Canada. Patients are particularly fond of the simplicity of the tool, the relatively low morbidity of the surgery, the quick recovery, and overall results. The gastric band has evolved over its 35-year history into a very successful adjustable tool used to restrict food consumption and limit caloric intake. The percent of excessive weight loss after banding can range from 30%-60% and depends on the time out from surgery. Along with weight loss, there is good resolution of the co-morbid conditions that are associated with excess weight and improvements in quality of life demonstrated after banding. Nutrition and follow up are extremely important after banding to ensure good compliance and adequate weight loss. Failure to follow the postoperative diet, exercise regiment, or mechanical failure of the band can lead to failure to lose adequate weight. While there are particular early and late complications associated with this surgery, the safety profile of the AGB is very appealing when compared to other bariatric operations. As we continue to reduce the morbidity of the procedure, the simple adjustable band concept has a lot of potential to remain a primary technique of maintaining long term weight loss. In conclusion, AGB has and continues to play an important role in the treatment of morbid obesity. It offers reasonably good weight loss results with very little morbidity, and the future of the adjustable band is bright.

Bone morphogenetic protein expression patterns in human esophageal atresia with tracheoesophageal fistula.

The organogenesis of esophageal atresia with tracheoesophageal fistula (EA/TEF) remains unknown. The fistula tract appears to develop from a non-branching trifurcation of the embryonic lung bud. The non-branching growth of the fistula differs from the other lung buds and suggests a deficiency in bone morphogenetic protein (BMP) signaling, since BMPs are critical to proper lung development and branching. With IRB approval, portions of newborn human proximal esophageal pouch and distal fistula samples were recovered at the time of surgical repair of EA/TEF. The tissues were processed for immunohistochemistry. Commercially available fetal tissues were used as controls. In control tissues, BMP ligands (BMP 2, 4, and 7) were all present in the esophagus but absent in the trachea. BMPRIA was absent in both tissues. BMPRIB was detected in trachea but not in esophagus and BMPRII was detected in esophagus but not in trachea. In the EA/TEF specimens, all BMP ligands were present in the proximal esophageal pouch but absent in the fistula tract. BMPRIA and BMPRIB were not detected in either tissue. However, BMPRII was found in both fistula tract and proximal pouch. The submucosa of the fistula appears to maintain a mixed (identical neither to lung, esophagus, or trachea) BMP signaling pattern, providing one mechanism which could potentially explain the esophageal dismotility and lack of lung branching seen in the fistula/distal esophagus.

Faulty bone morphogenetic protein signaling in esophageal atresia with tracheoesophageal fistula.

BACKGROUND: The organogenesis of esophageal atresia with tracheoesophageal fistula remains unclear. We have previously demonstrated that the fistula tract develops from a trifurcation of the embryonic lung bud and displays pulmonary lineage traits. Unlike the lung, the fistula grows without branching. Bone morphogenetic proteins (BMPs) are known to be important in lung branching. We studied possible BMP signaling defects as a potential cause for the absence of branching in the fistula tract. METHODS: Adriamycin was administered to pregnant rats on days 6-9 of gestation to induce tracheoesophageal fistula. Microdissection was performed at E13 and E17 isolating the foregut. Tissues were analyzed using immunohistochemistry for BMP ligand (BMP2, BMP4, BMP7) and receptor (BMPRIA, BMPRIB, BMPRII) expression. RESULTS: Immunohistochemistry revealed the presence of all 3 BMP ligands at E13, localized specifically to the esophageal mucosa but absent in the fistula and lung. At E17, the ligands were again present in the esophageal mucosa, and additionally in the fistula tract mucosa, but remained absent in the lung. At E17, all of the BMP receptors were also localized to the luminal surface of esophagus and fistula. However, in the lung epithelium, only BMPRII was found, whereas BMPRIA and BMPRIB remained absent. CONCLUSIONS: The normal expression pattern of BMP4 was increased at the branch tips and low between branches. Among other results, we show here a constant expression level of BMP ligands throughout the entire epithelium of the fistula tract. This diffuse expression suggests defective BMP signaling in the fistula tract and explains its nonbranching phenotype.

Pancreatic differentiation.

Over the last decade, with the advent of new techniques and technologies in modern molecular biology, our understanding of the underlying mechanisms responsible for organ differentiation has developed rapidly. Despite this, our knowledge of these signaling pathways is still far from complete. Some of these advances, such as the creation of transgenic mouse models, have given us new tools to help us understand the interactions of the various transcription factors that are responsible for the creation of various cell types from a single cell type during embryogenesis. This knowledge then gives rise to the concept of creating new ways to manipulate stem cells in order to correct the deficiencies present in various disease processes. Here, we present work that focuses specifically on pancreatic development. The ultimate goal of our research in studying the mechanisms of the basic differentiation of pancreatic precursor cells is to gain the knowledge necessary to be able to engineer stem cells specifically into beta-cells in the treatment of diabetes.

Synergistic endocrine induction by GLP-1 and TGF-beta in the developing pancreas.

OBJECTIVES: Glucagon-like peptide-1 (GLP-1) is known to stimulate glucose-dependent insulin production and secretion by pancreatic beta-cells. Preliminary evidence suggests that GLP-1 may also influence endocrine differentiation from pancreatic progenitor cells. Additionally, TGF-beta signaling can also control endocrine differentiation by both inhibiting proliferation and enhancing differentiation of endocrine progenitor cells to become mature beta-cells. Here we document synergy of these two signaling pathways in the differentiation of endocrine cells in the developing pancreas. METHODS: Embryonic pancreas was harvested from mice at day 11.5 and cultured for six days with GLP-1 agonist, exendin-4, and/or TGF-beta1 ligand. Also, a pan-neutralizing TGF-beta isoform antibody was used alone or with exendin-4 to study TGF-beta inhibition in this system. Pancreatic cultures were processed for immunohistochemistry. RESULTS: Exogenous TGF-beta1 and exendin-4 each individually enhanced both insulin and glucagon differentiation dose-dependently. However, when combined there was an additive effect to a 4.5-fold increase in insulin-positive differentiation. We also saw suppression of amylase-positive differentiation. Surprisingly, TGF-beta pan-neutralizing antibody also gave an augmentation of endocrine differentiation by 1.5 to 2-fold, but no synergistic effect was seen with exendin-4. CONCLUSION: We conclude that TGF-beta isoforms have a specific synergistic role with GLP-1 pathway signaling in early pancreatic development, toward endocrine differentiation and away from acinar differentiation.

Cross-talk between bone morphogenetic protein and transforming growth factor-beta signaling is essential for exendin-4-induced insulin-positive differentiation of AR42J cells.

A key goal of cellular engineering is to manipulate progenitor cells to become beta-cells, allowing cell replacement therapy to cure diabetes mellitus. As a paradigm for cell engineering, we have studied the molecular mechanisms by which AR42J cells become beta-cells. Bone morphogenetic proteins (BMPs), implicated in a myriad of developmental pathways, have not been well studied in insulin-positive differentiation. We found that the canonical intracellular mediators of BMP signaling, Smad-1 and Smad-8, were significantly elevated in AR42J cells undergoing insulin-positive differentiation in response to exendin-4 treatment, suggesting a role for BMP signaling in beta-cell formation. Similarly, endogenous BMP-2 ligand and ALK-1 receptor (activin receptor-like kinase-1; known to activate Smads 1 and 8) mRNAs were specifically up-regulated in exendin-4-treated AR42J cells. Surprisingly, Smad-1 and Smad-8 levels were suppressed by the addition of BMP-soluble receptor inhibition of BMP ligand binding to its receptor. Here, insulin-positive differentiation was also ablated. BMP-2 ligand antisense also strongly inhibited Smad-1 and Smad-8 expression, again with the abolition of insulin-positive differentiation. These results demonstrate a previously unrecognized key role for BMP signaling in mediating insulin-positive differentiation through the intracellular Smad signaling pathway. In short, BMP signaling may represent a novel downstream target of exendin-4 (glucagon-like peptide 1) signaling and potentially serve as an upstream regulator of transforming growth factor-beta isoform signaling to differentiate the acinar-like AR42J cells into insulin-secreting cells.

Aberrant fibroblast growth factor receptor 2 signalling in esophageal atresia with tracheoesophageal fistula.

BACKGROUND: Although the pathogenesis of esophageal atresia with tracheoesophageal fistula (EA/TEF) remains unknown, it has been shown that despite its esophageal appearance, the fistula tract originates from respiratory epithelium. The authors now hypothesize that defects in fibroblast growth factor (FGF) signaling contribute to the esophaguslike phenotype of the fistula tract. FGF2R is critical to normal lung morphogenesis and occurs in 2 isoforms (FGF2RIIIb and FGF2RIIIc), each with different ligand-binding specificity. To characterize FGF signaling in the developing EA/TEF, the authors analyzed levels of FGF2R splice variants in experimental EA/TEF. METHODS: The standard Adriamycin-induced EA/TEF model in rats was used. Individual foregut components from Adriamycin-treated and control embryos were processed for real-time, fluorescence-activated semiquantitative reverse transcriptase polymerase chain reaction on gestational days 12.5 and 13.5. RESULTS: Both fistula tract and Adriamycin-treated or normal esophagus showed significantly lower levels of FGF2RIIIb than either Adriamycin-treated lung buds (E12.5, P =.02; E13.5, P <.005) or normal lung buds (E12.5, P <.005; E13.5, P <.01). At E13.5, the fistula tract had lower levels of FGF2RIIIc than either treated (P <.01) or normal lung (P <.05). CONCLUSIONS: Levels of FGF2R in the developing fistula tract resemble that of distal esophagus rather than developing lung. This defect in FGF2RIIIb signaling may account for the nonbranching, esophaguslike phenotype of the fistula, despite its respiratory origin.