Patulous Eustachian Tube Accompanied by Internal Carotid Artery Anomalies.

Patulous Eustachian tube is a physical disorder in which the normally closed Eustachian tube remains open intermittently. Internal carotid artery (ICA) anomalies accompanied by Eustachian tube anomalies have been described very rarely in the literature. To the best of our knowledge, the presented case is the second case in the literature. In this report, we present a rare case of ICA anomalies accompanied by a bilateral patulous Eustachian tube in a 51-year-old woman.

Further Delineation of the Proximal 16p11.2 Microdeletion Syndrome: Novel Findings Among 22 New Individuals.

The recurrent chromosome 16p11.2 BP4-BP5 microdeletion (MIM #611913) predisposes to a neurodevelopmental disorder with variable associated congenital anomalies and susceptibility to early-onset obesity. We identified 22 new individuals with proximal 16p11.2 deletions through retrospective data analysis at our institution and performed phenotyping through in-depth chart review. Our cohort exhibited a spectrum of neurodevelopmental abnormalities largely consistent with other publications, however they also were found to have a higher rate than expected of congenital anomalies, some of which have not yet been reported in association with 16p11.2 microdeletions to our knowledge. This series contributes to the body of data on this population, which we anticipate will continue to evolve along with increased uptake of genetic testing.

Minimally Invasive Surgery for Hirschsprung Disease: Current Practices and Future Directions.

Hirschsprung disease (HD) is a congenital disorder characterized by the absence of ganglion cells in the distal colon and rectum, leading to functional obstruction and severe constipation. Over the past decades, the surgical management of HD has significantly evolved, with minimally invasive surgery (MIS) techniques revolutionizing treatment approaches. This review explores recent innovations in MIS for HD, focusing on laparoscopic, transanal endorectal pull-through (TERPT), and robotic-assisted techniques. These approaches offer numerous advantages over traditional open procedures, including reduced surgical trauma, improved cosmesis, faster recovery times, and potentially lower complication rates. Laparoscopic surgery has become widely adopted, providing excellent visualization and precise dissection. TERPT has gained popularity for short-segment disease, offering a completely transanal approach with minimal scarring. Robotic-assisted surgery represents the cutting edge, enhancing surgical precision and dexterity. The review also examines emerging technologies and future directions, such as advanced imaging techniques, artificial intelligence applications, and potential developments in tissue engineering. While MIS techniques have shown promising outcomes, challenges remain in standardizing approaches, addressing long-segment disease, and optimizing long-term functional results. The future of HD surgery lies in personalized approaches that integrate genetic and molecular profiling with advanced surgical technologies. As the field continues to evolve, comprehensive long-term studies and efforts to improve access to specialized care will be crucial to further enhancing outcomes for patients with HD.

A rare case report: The value of fetal MRI to detect diprosopus twins.

Diprosopus is one of the rarest types of conjoined twins, caused by incomplete zygote separation in early pregnancy. It defines a condition with duplication of facial structures, monocephalic and 1 trunk. Early detection is difficult, but fetal MRI plays an important role in strengthening antenatal diagnosis of conjoined twin pregnancies and other major congenital abnormalities, complementing antenatal ultrasonography. A 28-year-old patient (G2P1A0) was referred from the regional general hospital for suspected malformations, including Dandy-Walker syndrome and a small mandible Antenatal 3-D ultrasound at 35 weeks revealed a single baby with macrosomia, hypoplasia of the vermis, and cleft lip with malformation of facial structures. A 3 Tesla MRI (Signa, GE Healthcare) revealed various developmental brain anomalies, including duplication of the frontotemporal lobes, corpus callosum agenesis, and small posterior fossa. The identification of 4 orbital structures raised suspicions of face duplication. This patient underwent a caesarean section and delivered a diprosopus twin baby. MRI emerged as an indispensable adjunct, complementing ultrasound in detecting congenital malformations. The success of this approach emphasizes collaborative efforts between clinicians and radiologists for accurate identification and management of complex fetal anomalies.

Knowledge and perception among adults of their congenital heart disease: A single center cross-sectional study.

INTRODUCTION AND OBJECTIVE: Congenital heart disease (CHD) is a complex condition requiring a multidisciplinary approach. It is crucial that adults with CHD (CHD) have adequate knowledge of their condition, enabling them to engage in their healthcare decisions and self-management. We aimed to investigate knowledge and perception among adults of their CHD. METHODS: Single-center, observational, cross-sectional study. A 25-item adapted survey of Leuven Questionnaire for CHD was used to assess four main domains: (1) disease and treatment, (2) endocarditis and preventive measures, (3) physical activity and (4) reproductive issues. RESULTS: 148 patients participated in the study. Patients had a significant lack of knowledge localizing their heart defect, recognizing drug side effects, acting in case of experiencing drug side effects, recognizing at least two symptoms of clinical deterioration, to adequately define endocarditis and most typical signs and risk factors, to acknowledge the hereditary nature of their CHD and risk of clinical deterioration during pregnancies. Patients with an education level ≥12th grade have higher knowledge in various items and, overall, the complexity of CHD was not associated with a better performance. CONCLUSION: This study highlights the existing knowledge gaps among adults with CHD. It underscores the need for tailored information and structured educational programs to improve management. By addressing these challenges, healthcare providers can enhance patient outcomes, improve quality of life, and promote long-term well-being for individuals with CHD.

Maternal and fetal risk factors for congenital anomalies of the kidney and urinary tract: a birth cohort study in urban China.

BACKGROUND: Congenital anomalies of the kidney and urinary tract (CAKUT) are among the most common causes of kidney diseases in children. Previous studies on CAKUT etiologies have been predominantly focused on non-modifiable genetic risk factors. The existing nongenetic studies are limited by lack of comprehensive investigation of potentially modifiable risk factors and the inability to distinguish among various phenotypes of CAKUT. Therefore, this study aimed to comprehensively evaluate both maternal and fetal risk factors of CAKUT, sorted by disease phenotype. METHODS: A prospective birth cohort study was conducted among 10,179 women who delivered a singleton live newborn in Lanzhou, China, between 2010 and 2012. Face-to-face interviews were conducted among the participants within 1-3 days after delivery using standard questionnaires to collect information on maternal demographics and characteristics. All newborns underwent postnatal renal ultrasonographic screening during their routine 1-month checkup. Clinical data, including birth outcomes and maternal complications, were confirmed by reviewing their medical records. Maternal and fetal risk factors were compared in children with and without CAKUT. Multivariable logistic regression analysis was performed to identify independent risk factors of CAKUT and their phenotypes, respectively. RESULTS: A total of 489 (4.8%) cases of CAKUT were identified. Logistic regression revealed that maternal overweight (pre-pregnancy), gestational diabetes, preterm birth, and low birth weight were independent risk factors for CAKUT. Maternal overweight increased the risk of vesicoureteral reflux (VUR, odds ratio (OR) = 1.441, 95% confidence interval (CI) 1.010-2.057) and posterior urethral valves (PUV, OR = 1.868, 95% CI 1.074-3.249). Gestational diabetes increased the risk of ureteropelvic junction obstruction (UPJO, OR = 1.269; 95% CI 1.044-1.543) and posterior urethral valves (OR = 1.794; 95% CI 1.302-2.474). Preterm birth increased the risk of ureteropelvic junction obstruction (OR = 1.056; 95% CI 1.004-1.111). CONCLUSIONS: Our study identified various risk factors associated with different CAKUT phenotypes, stressing the importance of separate analyses for each phenotype. Our findings may provide helpful guidance on developing targeted and effective CAKUT prevention programs in the future.

Four-Vessel Umbilical Cord: Supernumerary Right Umbilical Vein With No Associated Congenital Anomalies.

A four-vessel umbilical cord is a rare anomaly that can occur with abnormal persistence of the caudal portion of the vessel. Although supernumerary vessels can present as an isolated finding, they are known to be associated with multiple significant congenital anomalies. Ectopia cordis, pulmonary stenosis, cleft lip, cleft palate, situs inversus, tetralogy of Fallot, and gastroschisis are some anomalies associated with four-vessel cords. This is a case of a 22-year-old multigravida with a four-vessel umbilical cord initially found on sonography. The patient was sent to Maternal Fetal Medicine for evaluation. It was determined that the patient had a right supernumerary umbilical vein that did not require further workup. The patient presented to labor and delivery at 36 weeks and five days with regular contractions. After normal vaginal delivery without complications, the four-vessel-umbilical cord was visualized and confirmed by pathology. The patient and neonate both did well with no complications.

Associated Anomalies in Radial Ray Deficiency.

Radial ray deficiency (RRD) may be isolated, without other congenital anomalies or co-occurring with other, non-RRD, congenital anomalies. The prevalence and the types of co-occurring anomalies are variable in the reported studies. The aim of this study was to obtain the prevalence and the types of co-occurring congenital anomalies among cases with RRD in a geographically well-characterized population of 387,067 consecutive births in northeastern France from 1979 to 2007 including live births, stillbirths and terminations of pregnancy. During the study period 83 cases with RRD were ascertained (prevalence of 2.14 per 10,000 births), 63 cases (75.9%) had co-occurring anomalies. Cases with co-occurring anomalies were divided into chromosomal anomalies (18 cases, 22%), syndromic conditions (syndromes and associations, 23 cases, 28%), and multiple congenital anomalies (MCA) (22 cases, 26%). Trisomies 18 and autosomal deletions were the most common chromosomal abnormalities. Thrombocytopenia absent radii syndrome, VACTERL association, Fanconi anemia, Roberts syndrome, and Holt-Oram syndrome were the most common syndromic conditions. Anomalies in the musculoskeletal, the cardiovascular, the urinary, and the orofacial system were the most common co-occurring anomalies in cases with MCA. As cases with RRD have often co-occurring congenital anomalies, a multidisciplinary checkup of these cases is recommended.

Histomorphometric and developmental analysis of human fetal caecum and appendix with its embryological significance.

PURPOSE: The variable positions of the appendix can mislead surgeons and physicians to a wrong diagnosis. When appendicitis happens in subhepatic caecum, it can be misdiagnosed and can lead to severe complications during surgical procedures. Therefore, this study aimed to understand the histomorphometric development of the appendix and caecum and to identify when lymphoid follicles appear in the appendix during fetal life. METHODS: The study was conducted on a total of 50 fetuses. The caecum and appendix were carefully dissected. Their position and various measurements were observed. Afterwards, the appendix was taken out for histological processing. All three layers, mucosa, submucosa, and muscularis externa were measured using Image Analyzer Software Image Pro Premiere 9.1, and the appearance of lymphoid follicles was also examined. Results were analyzed using SPSS statistical software. RESULTS: During the 1st, 2nd, and 3rd trimesters the most common caecum type was type 1: as a lengthy tube, type 3: The lateral wall expanded more, thus it has an asymmetric saccule, and type 4: adult-like caecum. The caecum was mostly situated in the right lumbar region in the 2nd and 3rd trimesters. In the 1st trimester, it was subhepatic in position. The most common position of the appendix was 11 o'clock in 1st and 3rd trimesters. 2nd trimester's most common position of the appendix was 12 o'clock. The thickness of the mucosa, submucosa, and the muscularis externa increases as the trimester increases. The lymphoid follicles have appeared during the 2nd trimester. CONCLUSION: The knowledge from this study will be useful in the diagnosis and treatment of malformations, pathology, and anomalies of the caecum and appendix due to congenital causes.

Polymelia and concurrent intestinal duplication and cloacal atresia in a broiler chick: case report and literature review.

Congenital malformations are a highly diverse group of conditions reported in both humans and animals, characterized by defects in morphogenesis observed at birth. Although most cases are idiopathic, genetic and environmental factors may be involved. The frequency of such conditions varies with species, geographic regions, and the specific malformation involved. In polymelia, supernumerary limbs are attached to different parts of the body. Gastrointestinal duplications are described less frequently and can be associated with polymelia. Cloacal atresia is among the least-reported malformations in avian species, described only once in a kiwi. Here we describe a case with these 3 malformations in a single broiler chick (Gallus gallus domesticus) and provide a literature review about the occurrence of these malformations in birds. The 3-d-old chick also had an unidentified structure projecting from the pygostyle region. We performed clinical, radiographic, and postmortem examinations. The intestinal duplication was identified only during the postmortem evaluation. Detailed descriptions of avian congenital malformations are scarce. Although similar cases have been reported, we retrieved no cases of concurrent polymelia, intestinal duplication, and cloacal atresia in broiler chickens in our literature search, suggesting that the simultaneous occurrence of these conditions has not been reported previously in this species.

Preclinical Detection of Early Glomerular Injury in Children with Kidney Diseases-Independently of Usual Markers of Kidney Impairment and Inflammation.

Glomerular kidney diseases typically begin insidiously and can progress to end stage kidney failure. Early onset of therapy can slow down disease progression. Early diagnosis is required to ensure such timely therapy. The goal of our study was to evaluate protein biomarkers (BMs) for common nephropathies that have been described for children with Alport syndrome. Nineteen candidate BMs were determined by commercial ELISA in children with congenital anomalies of the kidneys and urogenital tract, inflammatory kidney injury, or diabetes mellitus. It is particularly essential to search for kidney disease BMs in children because they are a crucial target group that likely exhibits early disease stages and in which misleading diseases unrelated to the kidney are rare. Only minor differences in blood between affected individuals and controls were found. However, in urine, several biomarker candidates alone or in combination seemed to be promising indicators of renal injury in early disease stages. The BMs of highest sensitivity and specificity were collagen type XIII, hyaluronan-binding protein 2, and complement C4-binding protein. These proteins are unrelated to inflammation markers or to risk factors for and signs of renal failure. In conclusion, our study evaluated several strong candidates for screening for early stages of kidney diseases and can help to establish early nephroprotective regimens.

Genetics of anomalies of the kidney and urinary tract with congenital heart disease: A review.

Congenital anomalies of the kidney and urinary tract (CAKUT) and congenital heart disease (CHD) are the most common congenital defects and constitute a major cause of morbidity in children. Anomalies of both systems may be isolated or associated with congenital anomalies of other organ systems. Various reports support the co-occurrence of CAKUT and CHD, although the prevalence can vary. Cardiovascular anomalies occur in 11.2% to 34% of patients with CAKUT, and CAKUT occur in 5.3% to 35.8% of those with CHD. The co-occurrence of genetic factors in both CAKUT and CHD would raise common etiologies including genetics, genetic-environmental interactions, or shared molecular mechanisms and pathways such as NODAL, NOTCH, BMP, WNT, and VEGF. Studies in animal models and humans have indicated a genetic etiology for CHD and CAKUT with hundreds of genes recognized and thousands of entries, found in a catalog of human genetic disorders. There are over 80 CAKUT genes and over 100 CHD genes available for clinical testing. For example, the HNFIB gene accounts for 5% to 31% of reported cases of CAKUT. In view of the association between CAKUT and CHD, a thorough cardiac examination should be performed in patients with CAKUT, and a similar evaluation for CAKUT in the presence of CHD. This will allow early diagnosis and therapeutic intervention to improve the long- term outcome of patients affected, and test for at-risk family members. We present here evidence for an association of anomalies involving the two organ systems, and discuss possible etiologies of targeted genes, their functions, biological processes and interactions on embryogenesis.

Association between Congenital Anomalies and Late-Onset Bacterial Infections in Neonates Admitted to Neonatal Intensive Care Units in Australia and New Zealand: A Population-Based Cohort Study.

INTRODUCTION: Compromised neonatal intensive care unit neonates are at risk of acquiring late-onset infections (late-onset sepsis [LOS]). Neonates born with congenital anomalies (CAs) could have an additional LOS risk. METHODS: Utilising the population-based Australian and New Zealand Neonatal Network data from 2007 to 2017, bacterial LOS rates were determined in very preterm (VPT, <32 week), moderately preterm (MPT, 32-36 weeks), and term (FT, 37-41 weeks) neonates with or without CA. Stratified by major surgery, the association between CA and bacterial LOS was evaluated. RESULTS: Of 102,808 neonates, 37.7%, 32.8%, and 29.6% were born VPT, MPT, and FT, respectively. Among these, 3.4% VPT, 7.5% MPT, and 16.2% FT neonates had CA. VPT neonates had the highest LOS rate (11.1%), compared to MPT (1.8%) and FT (1.8%) neonates. LOS rates were higher in CA neonates than those without (8.2% versus 5.1% adjusted relative risk [aRR] 1.67, 95% confidence interval [CI]: 1.45-1.92). Neonates with surgery had a higher LOS rate (14.2%) than neonates without surgery (4.4%, p < 0.001). Among the neonates without surgery, CA neonates had consistently higher LOS rates than those without CA (VPT 14.3% vs. 9.6% [aRR 1.32, 95% CI: 1.11-1.57]; MPT 4% vs. 0.9% [aRR 4.45, 95% CI: 3.23-6.14]; and FT 2% vs. 0.7% [aRR 2.87, 95% CI: 1.97-4.18]). For the neonates with surgery, CAs were not associated with additional LOS risks. CONCLUSION: Overall, we reported higher rates of LOS in neonates with CA compared to those without CA. Regardless of gestation, CA was associated with an increased LOS risk among non-surgical neonates. Optimisation of infection prevention strategies for CA neonates should be explored. Future studies are needed to evaluate if the infection risk is caused by CA or associated complications.

Risk of Hearing Loss in Neonates and Toddlers with in Utero Exposure to SARS-CoV-2.

OBJECTIVE: Given the prevalence of neonatal hearing loss (HL) associated with intrauterine viral exposures, the goal of this study is to provide information on neonatal HL in the context of the COVID-19 pandemic. METHODS: Data were drawn from the COVID-19 Mother Baby Outcomes (COMBO) Initiative. 1007 participants completed the newborn hearing screen as part of routine clinical care (COMBO-EHR cohort) and 555 completed the National Survey of Children's Health (NSCH) at 2 and/or 3 years of age for research purposes (COMBO-RSCH cohort). Maternal SARS-CoV-2 infection status during pregnancy was determined through electronic health records and maternal-reported questionnaires. RESULTS: In adjusted multivariate logistic regression models covarying for newborn age at assessment, mode of delivery, and gestational age at delivery, there was no significant association between intrauterine SARS-CoV-2 exposure and newborn hearing screening failure (OR = 1.05, 95% CI = 0.39-2.42, p = 0.91) in the COMBO-EHR cohort. In the COMBO-RSCH cohort, there were similar non-significant associations between intrauterine exposure to SARS-CoV-2 and maternal-reported concern for HL on the NSCH (OR = 1.19 [95% CI = 0.30-4.24], p = 0.79). CONCLUSION: There is no association between intrauterine exposure to SARS-CoV-2 and failed hearing screen in neonates. Similarly, based on the NSCH, there is no association between intrauterine exposure to SARS-CoV-2 and maternal-reported concern for hearing in toddlers. These results offer reassurance given the widespread nature of this pandemic with tens of millions of fetuses having a history of intrauterine exposure. LEVEL OF EVIDENCE: Level 4 Laryngoscope, 2024.

A Cadaveric Case Report of an Incomplete Double Ureter Associated With Testicular Arterial Variations.

This case report details anatomical variations in a cadaveric donor during the dissection laboratory. This case shows a possible association between an incomplete double ureter, arching testicular arteries, and an accessory testicular artery. This case describes these variations and briefly discusses ways to classify them. We aim to document these anomalies, discuss possible embryological reasons for their association, and shed light on their clinical significance. This case report contributes to the limited literature and highlights the importance of reporting these anomalies when encountered during autopsies or pedagogical cadaveric dissection.

Assessment of Parental Risk Factors Involved in Orofacial Clefts in Hail, Saudi Arabia: A Retrospective Cohort Study.

Background Orofacial clefts are congenital anomalies affecting the development of the oral and facial structures, influenced by genetic and environmental factors. The prevalence of orofacial clefts varies globally, necessitating region-specific studies to understand contributing factors. Orofacial clefts are among the most common congenital defects affecting the head and neck, underscoring the importance of investigating paternal and maternal influences on their development to enhance awareness and understanding of potential contributing factors. Therefore, this research aimed to investigate parental risk factors contributing to the development of orofacial clefts.  Methods A retrospective cohort study was conducted at the Oral and Maxillofacial Department of King Khaled Hospital, Hail, Saudi Arabia, involving 40 parents of children born between 2019 and 2023 with orofacial clefts. Data collection included interviewer-administered questionnaires with parents addressing demographic information, pregnancy details, parental medical history, and postoperative outcomes. Statistical analysis utilized descriptive statistics, chi-square tests, Fisher's exact test, and linear regression, with significance defined as p<0.05. Results The study had a gender distribution of 19 males (47.5%) and 21 females (52.5%) among orofacial cleft cases (p<0.75), with cleft palate (13 cases, 32.5%) and cleft lip (11 cases, 27.5%) being the most prevalent anomalies (p<0.05). Maternal supplementation rates were high, with 34 mothers (85%, p<0.05) taking folic acid and 36 mothers (90%, p<0.05) taking iron, yet orofacial clefts incidence persisted. Paternal risk factors such as tobacco use were reported by 19 fathers (47.5%, p<0.05), and familial history of orofacial clefts was noted in nine cases (22.5%, p<0.05). Postoperative outcomes indicated varying levels of functional recovery and satisfaction. Conclusion This study explored the complex origins of orofacial clefts, emphasizing genetic and environmental influences. The findings suggest a potential paternal risk factor. The study highlights the need for further investigation into genetic mechanisms and the development of effective prevention strategies.

Multiple congenital anomalies in two fetuses with glutathione-synthetase deficit (GSS).

Glutathione synthetase deficiency is a rare inborn metabolic disease usually caused by biallelic variants in GSS. Clinical severity varies from isolated hemolytic anemia, sometimes associated with chronic metabolic acidosis and 5-oxoprolinuria, to severe neurological phenotypes with neonatal lethality. Here we report on two fetal siblings from two pregnancies with glutathione synthetase deficiency exhibiting similar multiple congenital anomalies associating phocomelia, cleft palate, intra-uterine growth retardation, genito-urinary malformations, and congenital heart defect. Genome sequencing showed that both fetuses were compound heterozygous for two GSS variants: the previously reported pathogenic missense substitution NM_000178.4 c.800G>A p.(Arg267Gln), and a 2.4 kb intragenic deletion NC_000020.11:g.34944530_34946833del. RNA-seq on brain tissue revealed the out-of-frame deletion of the exon 3 and an almost monoallelic expression of the missense variant (88%), suggesting degradation of the deletion-harboring allele by nonsense-mediated mRNA decay. 5-oxoproline (pyroglutamic acid) levels in amniotic fluid were elevated, suggesting an alteration of the gamma-glutamyl cycle, and corroborating the pathogenicity of the two GSS variants. Only one case of glutathione synthetase deficiency with limb malformations has previously been reported, in a newborn homozygous for the c.800G>A variant. Thus, our data allow us to discuss a potential phenotypic extension of glutathione synthetase deficiency, with a possible involvement of the c.800G>A variant.

Unusual Developmental Vascular Anomalies: Insights From a Chest Physician's Perspective.

This case report discusses three developmental vascular anomalies (DVAs) observed in adults and highlights the challenges related to the diagnosis and management. Even though detected at early ages, diagnostic difficulties are observed in the adult age due to the scarcity and diverse clinical features. These cases illustrate the necessity of a multidisciplinary approach involving clinicians and radiologists for precise and prompt diagnosis in adults, where misdiagnosis and delays in intervention are frequent. The cases comprised a 17-year-old female with an absent right pulmonary artery and mitral stenosis, a 46-year-old female with chronic obstructive pulmonary disease (COPD), with an absent left pulmonary artery, and a 60-year-old female with bronchial asthma and tuberculosis exhibiting a rare DVA. This discussion highlights the importance of intensified clinical suspicion and thorough evaluation for the cases of unexplained respiratory symptoms and abnormal image findings in patients, which can further provide the medical community with valuable insights.

Multidisciplinary Management of a Pediatric Patient With Congenital Anomalies Syndrome Without an Identified Genetic Mutation.

Congenital anomalies syndrome without an identified genetic mutation often presents significant challenges in pediatric care, requiring coordinated efforts across multiple specialties. This case reports a 10-year-old female patient with complex medical conditions, which exemplifies the intricate nature of managing children, necessitating long-term follow-up and comprehensive care. This case report aims to provide an in-depth analysis of her medical journey, including various interventions like tracheostomy and G-tube placement, and management strategies employed to address her congenital anomalies and associated health issues.

Enhancing the Classification of Congenital Heart Defects for Outcome Association Studies in Birth Defects Registries.

INTRODUCTION: Traditional strategies for grouping congenital heart defects (CHDs) using birth defect registry data do not adequately address differences in expected clinical consequences between different combinations of CHDs. We report a lesion-specific classification system for birth defect registry-based outcome studies. METHODS: For Core Cardiac Lesion Outcome Classifications (C-CLOC) groups, common CHDs expected to have reasonable clinical homogeneity were defined. Criteria based on combinations of Centers for Disease and Control-modified British Pediatric Association (BPA) codes were defined for each C-CLOC group. To demonstrate proof of concept and retention of reasonable case counts within C-CLOC groups, Texas Birth Defect Registry data (1999-2017 deliveries) were used to compare case counts and neonatal mortality between traditional vs. C-CLOC classification approaches. RESULTS: C-CLOC defined 59 CHD groups among 62,262 infants with CHDs. Classifying cases into the single, mutually exclusive C-CLOC group reflecting the highest complexity CHD present reduced case counts among lower complexity lesions (e.g., 86.5% of cases with a common atrium BPA code were reclassified to a higher complexity group for a co-occurring CHD). As expected, C-CLOC groups had retained larger sample sizes (i.e., representing presumably better-powered analytic groups) compared to cases with only one CHD code and no occurring CHDs. DISCUSSION: This new CHD classification system for investigators using birth defect registry data, C-CLOC, is expected to balance clinical outcome homogeneity in analytic groups while maintaining sufficiently large case counts within categories, thus improving power for CHD-specific outcome association comparisons. Future outcome studies utilizing C-CLOC-based classifications are planned.