Synonyms: None.Prevalence: Rare.

Definition: Polyhydramnios asso­ciated with a small stomach.Etiology: Impaired swallowing.Pathogenesis: Anomaly of the mechanics, the patency, the neural or muscular control of swallowing and deglutition.Associated anomalies: Eso­pha­geal atresia, tracheo­eso­pha­geal fistula, agnathia-microstomia-syn­otia, goiter, dystrophic medullary calcifications, micrognathia.Differential diagnosis: See Table I.Prognosis: Function of the underlying disorder.Recurrence risk: Function of the underlying disorder.Management: Function of the underlying disorder.

MESH Esophageal-Atresia-diagnosis; Tracheoesophageal-Fistula-congenital, -diagnosis; Hydramnios-diagnosis, -complications, -therapy BDE 0365 MIM 18996 ICD9 750.3; 761.3 CDC 750.310

* Address correspondence to Marc Lacrampe, MD, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 21st and Garland Ave, Nashville, TN 37232-2675. Ph 615-322-0999 Fax 615-322-3764

Introduction

An absent or abnormally small fetal stomach is readily observed, because the stomach is routinely visualized when obtaining images for measurement of the abdominal perimeter. In addition, the amniotic fluid is always assessed and poly­hydramnios is easily determined. The combination of polyhydramnios and a small or absent stomach has long been recognized as a finding suggestive of tracheo­esophageal fistula and esophageal atresia^1-4. However, there are numerous other disorders that may affect either the structural or neuro­muscular components of the normal swallowing mechanism as shown in Table 1.

Many of these disorders conceivably may result in poly­hy­dramnios and small stomach. In the current study, we review the clinical outcome and pathologic findings in fetuses presenting with the combination of polyhydramnios and small stomach. We also reviewed the medical records of infants treated at our institution for tracheoesophageal fistula and esophageal atresia to assess for false negative prenatal ultrasound exams.

Material and methods

Eleven fetuses in the past 3 years were prospectively recognized as having polyhydramnios and a small or absent stomach. We defined a “small stomach” as a stomach no greater than the gallbladder. The medical records and ultrasound examinations of these fetuses were reviewed. The sonograms were evaluated for the amniotic fluid volume, presence and size of stomach, other anomalies and estimated gestational age. The medical records were examined for: sex, weight, and age of newborn; clinical and pathologic diagnoses; and current status of infant. In addition, medical records of all infants treated at our institution for tracheoesophageal fistula and eso­phageal atresia in the last 5 years were retrospectively reviewed for findings on prenatal ultrasound examination.

Results

The ultrasound findings, clinical outcome, and pathologic findings of the 11 prospectively identified cases are presented in Table 2. In 3 cases, serial ultrasound examinations were performed. In all cases, polyhydramnios with small or absent stomach was identified typically in early to middle third trimester (fig. 1)

Fig. 1: 1^st image: Typical appearance of small stomach with polyhydramnios in a fetus with cleft palate, microglossia and dystrophic medullary calcifications.

2^nd image: Tracheoesophageal fistula at 34 weeks. 

3^rd image: Normal stomach with slightly increased amniotic fluid at 29 weeks. 

4^th image: At 32 weeks  the stomach is too small and the polyhydramnios has markedly increased (not shown).

Polyhydramnios was identified earlier than the abnormal stomach in those cases where serial exams were performed. Several other abnormal findings were noted including cephalocele, multicystic kidney, club hand, goiter, hydrocephalus, triploidy and  agnathia-microstomia-synotia.

One of the fetuses was lost to follow-up, and the outcome is unknown. One pregnancy was terminated. The newborns ranged in age from 29 to 39 weeks and in weight from 1060 to 5190g. Eight of 10 were male. Of the remaining 9, 3 had tracheo­esophageal fistula and esophageal atresia. Four infants had neurologic and/ or oropharyngeal abnormalities including: dystrophic medullary calcification, ence­pha­lopathy, micro- gna­thia, microglossia, goiter, cleft palate and agnathia-microstomia-synotia. The other findings in these infants are noted in Table 2.

Table 2: History and findings in 11 cases of "small stomach and polyhydramnios".

Outcome

The clinical outcome of these 10 cases was generally poor. One pregnancy was terminated. One infant underwent surgical repair of tracheoesophageal fistula and esophageal atresia and is now well. Four infants died within 3 months of birth, and one is profoundly encephalopathic. The final three are now well.

Retrospective review of esophageal atresias

The charts of 32 infants treated at our institution for tracheo­eso­pha­geal fistula and esophageal atresia in the past 5 years were reviewed retrospectively. This group included the 3 fetuses prospectively diagnosed. The remainder of these infants were transferred to us and we had not performed pre­natal ultrasound examinations. Thus, there were no false negative examinations for tracheoeso­pha­geal fistula and esophageal atresia in fetuses examined and delivered at our institution  in the past 5 years (see Discussion).

Discussion

Swallowing is regulated by a complex mechanism and may begin as early as twelve weeks gestational age¹. The mechanism in infants differs from that in adults because suckling is the initiating event in newborns. Normal swallowing requires a proper bony support and musculature, and innervation of the tongue, palate, oropharynx, larynx, and esophagus. Neural control via cranial nerves VII, IX, X, XII and brainstem centers in the medulla is critically important. Disruption of any of the above components may result in dysphagia⁵.

Amniotic fluid volume is determined by the rate of production and reabsorption of amniotic fluid. Reabsorption occurs primarily by fetal swallowing and absorption from the gastrointestinal tract. Assuming that production of fluid is normal, then impairment of gastrointestinal absorption will lead to polyhydramnios. If the fetal stomach appears absent or small, then the site of impairment is most likely in the foregut proximal to the stomach.

Previous reports in the literature have focused on tracheoeso­phageal fistula and esophageal atresia as the source of this impairment; however, as suggested in Table 1, there are numerous other potential causes. In reviewing the outcome of cases with poly­hydramnios and small stomach, we would thus expect to find a spectrum of these causes. Our cases indeed demonstrated not only tracheoesophageal fistula and esophageal atresia but oro­pharyngeal and brainstem abnormalities, all potential sources of dysphagia. Other anomalies, particularly genitourinary and cardiac, are associated with tracheo­esophageal fistula and esophageal atresia, and several were found in our cases as expected⁶.

There was a strong sexual predilection in our group (M8:F2), in contradiction to the usual slight male pre­do­mi­nan­ce in other series⁷.

The outcome of our group was poor, with 50% mortality. This outcome is much worse than that reported in the literature for tracheoesophageal fistula and esophageal atresia, where the survival rate is now 90-95%⁸. This discrepancy is most likely due to the associated anomalies encountered in our group, particularly cardiac and neurologic dysfunction which resulted in death. This stresses the importance of performing a thorough examination to detect associated anomalies. The retrospective review of infants treated for tracheoesophageal fistula and esophageal atresia revealed that there were no false negative prenatal exams; however, we cannot exclude that infants with negative exams may have been delivered elsewhere with tracheoesophageal fistula and esophageal atresia and not referred back to us.

Conclusion

In the present study we examine the association between poly­hy­dramnios and the small or absent stomach and review the differential diagnosis of conditions that may present with these findings. Aside from tracheo­eso­phageal fistula and esophageal atresia, other causes for this finding were identified which included oropharyngeal or brainstem abnormality. Additional anomalies were present, including: cephalocele, multicystic kidney, hypoplastic left heart, imperforate anus, absent radius, and trisomy 18-Klinefelter mosaicism. We conclude that poly­hy­dramnios associated with a small or absent stomach is not pathognomic of tracheoesopha­geal fistula and esophageal atresia but may also be seen with numerous other disorders affecting the swallowing mechanism. In addition, this combination of findings is ominous and has poor outcome with high morbidity and mortality.

References

1. Pretorius DH, Drose JA, Dennis MA, et al: Tracheoesophageal fistula in utero: twenty-two cases.  J Ultrasound Med 6:509-513, 1987

2. Rahmani MR, Zalev AH:  Antenatal detection of esophageal atresia with distal tracheoseophaegeal fistula. JCU 14:143-145, 1986

3. Weinberg B, Diakoumakis EE:  Three complex cases of foregut  atresias prenatal sonographic diagnosis with radiologic correlation. JCU 13:481-484, 1985

4. Pretorius DH, Meier PR, Johnson ML:  Diagnosis of esophageal atresia in utero.  J Ultrasound Med 2:475-476, 1983

5. Weiss MH:  Dysphagia in infants and children. Otolaryngol Clin North Am 21:4:727-735, 1988

6. McGahan JP, Leeba JM, Lindfors KK: Prenatal sonographic diagnosis of VATER association. J Clin Ultrasound 16:588-591, 1988

7. Ozimek CD, Grimson RC, Aylsworth AS: An epidemiologic study of tracheoesophageal fistula and esophageal atresia in North Carolina.  Teratology 25: 53-54, 1982

8. Martin LW, Alexander F: Esophageal atresia. Surg Clin North Am 21:4:727-735, 1988