Introduction

Laryngeal/tracheal atresia or Congenital High Airway Obstruction Syndrome (CHAOS), esophageal atresia (EA) with tracheo-esophageal fistula (TEF) is a rare congenital anomaly resulting from absent recanalization of the upper airway and incomplete separation of the trachea and esophagus during embryonic development. The incidence of tracheal atresia is approximately 1 in 50,000 births [1]. Incidence of TEF is 1:2500 [2]. But the true incidence of CHAOS with or without TEF remains unknown [3]. Despite advancements in antenatal imaging, airway obstruction is often diagnosed postnatally following a critical presentation at birth. The classic ultrasound findings are dilated airways below the level of obstruction, hyperexpanded and hyperechoic lungs and flattened diaphragm, but CHAOS remains a frequently missed diagnosis [3]. CHAOS typically presents as a neonatal emergency with symptoms such as aphonia, severe respiratory distress, cyanosis, and hypotonia at birth. Postnatal diagnostic signs include failed attempts at intubation with no evidence of air entry during PPV. A visible air puffing in the neck strongly suggests atresia of both the respiratory tract and gastrointestinal tract. This case report details the clinical presentation, diagnostic challenges, and autopsy findings of a neonate born at 31 weeks of gestation with unanticipated CHAOS and EA with TEF without signs of polyhydramnios. An early antenatal observation of a small stomach may offer an additional clue in the absence of polyhydramnios and may warrant fetal radiology consultation, while recognizing that it remains an observational finding rather than a definitive diagnostic indicator (Table 1).

# | Title | Author | Year | Key features | Outcomes reported | How this differs from our case
1 | Congenital absence of trachea | Payne WA | 1900 | Isolated tracheal absence | Fatal shortly after birth | Our case involves combined laryngeal, tracheal, and esophageal anomalies
2 | Congenital tracheal obstruction with esophageal atresia | Ashley D | 1972 | Tracheal + esophageal obstruction | Poor survival | No laryngeal involvement in this case
3 | Tracheal atresia, proximal EA and distal TEF | Sankaran et al. | 1983 | TA + EA + TEF; polyhydramnios | Neonatal mortality reported | Our case lacked polyhydramnios
4 | Long-term survival in laryngeal atresia | Okada | 1998 | Laryngeal, intestinal, urethral anomalies | Long-term survival achieved | Additional systemic anomalies not present in our case
5 | Tracheal agenesis with bronchoesophageal fistulas | Demircan et al. | 2008 | TA + EA + BEF | Poor prognosis | No TEF; differs anatomically
6 | CHAOS syndrome | Mudaliar et al. | 2017 | CHAOS with hyperechoic lungs | Typically, fatal without intervention | Our case had small (hypoplastic) lungs
7 | CHAOS + EA + TEF + duodenal atresia | Kanamori et al. | 2017 | Multiple GI anomalies | Poor outcome | Additional duodenal atresia not seen in our case
8 | CHAOS survival with laryngeal atresia | Heriseanu et al. | 2023 | Isolated laryngeal atresia | Survival with intervention | Our case involves multi-level airway involvement
9 | Laryngeal atresia with H-type TEF | Soni et al. | 2024 | Laryngeal atresia + H-type TEF | Managed with airway intervention | Our case had type C TEF
10 | Tracheal agenesis with TEF | Wu et al. | 2024 | TA + TEF without EA | Poor survival overall | Our case includes esophageal atresia