Pyloric Atresia

ICD 11 – LB13: Structural developmental anomalies of stomach
ICD 10 – Q40.0: Other congenital malformations of upper alimentary tract
 

Pyloric atresia, or congenital pyloric atresia (CPA) is a very rare congenital anomaly of the gastrointestinal tract where there is a blockage in the gastric outlet at the level of the pylorus.

CPA is extremely rare and causes 1% of all gastrointestinal obstructions. The incidence of CPA is 1:100,000 live births.(1)

CPA is classified into three types depending on the type of blockage. In type I, the most common type, which is reported in 57% of cases, there is a pyloric membrane or diaphragm which completely divides the stomach from the duodenum. Type II is characterized by pyloric tissue that has been replaced by a solid cord or tissue and comprises 34% of cases, and in type III, a gap is present between the stomach and the duodenum. This type of CPA is seen in 9% of cases.(2) 

The exact etiology of CPA is unknown, but in isolated CPA, it is thought to be the result of an arrest in embryological developmental or a consequence of vascular compromise in the upper gastrointestinal tract between five and seven weeks of gestation.(3, 4) CPA can be associated with epidermolysis bullosa (EB). In EB the integrity of the basement membrane of the gastrointestinal tract is affected which causes an inflammatory reaction. The normal process of wound healing is disturbed and the inflammatory reaction causes a massive fibrosis penetrating the deep layers of tissue and causing obstruction of the intestinal lumen. This particularly occurs at the level of the pylorus.(5) 

In 35% of cases, CPA is an isolated malformation, but it also may be seen in association with other structural or familial anomalies. 

In the literature, up to 40% of newborns with CPA are affected by epidermolysis bullosa (EB), a rare autosomal recessive genetic disease with a very poor, often lethal, prognosis. EB is a name given to a group of hereditary bullous skin disorders characterized by fragility of the skin and mucous membranes.(2, 6, 7) Type II and III CPA are more common in patients with EB compared to type I CPA.(8, 9) Prenatally, children with CPA and EB may have associated structural anomalies including nose and ear anomalies, ureteral stenosis, malposition of the first toe and arthrogryposis.(10, 11) CPA is also associated with hereditary multiple intestinal atresias (MIA), which has been reported in up to 25% of patients with CPA.(2, 12) In MIA, fetuses can have esophageal, duodenal, jejunal, ileal and anal atresias as well as duplication cysts.(2, 13) Other reported anomalies seen in CPA include cardiac defects, renal anomalies and aplasia cutis. Some fetuses with CPA have trisomy 21.(4, 14, 15)
 

If isolated, the recurrence risk for CPA is extremely low, although rare, a familial recurrence of isolated CPA has been reported.(16) In familial EB and in hereditary MIA the recurrence risk is 25%. If there is a chromosome abnormality, specific counseling is suggested. 

CPA is typically suspected during the third trimester when polyhydramnios and gastric dilatation are identified on a routine third trimester scan. Due to the obstruction caused by CPA, swallowed amniotic fluid will accumulate in the fetal stomach which results in gastric dilatation and the development of polyhydramnios. Nomograms for fetal stomach size throughout gestation are available.(17) Peristaltic movements from the stomach towards the pylorus can be visualized without dilatation of the pylorus or proximal duodenum (also see ‘Differential Diagnosis’). In addition to dilation of the stomach, a transiently dilated esophagus on either axial or sagittal sonographic views may be found. This dilated esophagus can be on transverse views of the chest at the level of the four chamber heart as a transient, extra hypoechoic area behind the heart and adjacent to the aorta. 

Once CPA is suspected, a thorough search for associated anomalies, including cardiac, renal, ear and face anomalies in addition to signs of arthrogryposis, is recommended. Sonographic markers associated with an increased risk for trisomy 21 can be evaluated, and the patient’s best a priori risk for aneuploidy by serum testing can be reviewed. 

In addition to signs of upper GI obstruction, fetuses with PA in association with EB may demonstrate other sonographic signs such as ‘snow flakes’ (echogenic particles) which swirl in the amniotic fluid during fetal movement, and are present in the fetal stomach and complete chorioamniotic membrane separation (see Powerpoint presentation).(6) A complete gastrointestinal assessment of the fetus should also be performed to detect other possible atresias associated with MIA. (See also the VISUOG chapters on Duodenal Obstruction, Jejunal-Ileal Atresia, Anal Atresia, and Intestinal Duplication Cyst). 

Gastric dilatation is also seen in fetuses with a duodenal stenosis or duodenal atresia. In contrast to fetuses with CPA, duodenal stenosis or atresia is characterized by the typical ‘double bubble’ appearance of a dilated stomach and proximal duodenum.(18) (See also the VISUOG chapter on Duodenal Obstruction). 

When pyloric atresia is suspected, a thorough search for associated anomalies is recommended as discussed in ‘Diagnosis’. Regular monitoring of the is recommended. The exact timing of follow-up scans should be based on the clinical presentation. The patient should be advised to report symptoms suggestive of severe polyhydramnios such as uterine overdistention, shortness of breath, an inability to lie flat, or uterine contractions. 

Overall survival rates in children with CPA vary between 40-89%.(2, 3, 19) When CPA is an isolated finding, the prognosis after surgery is excellent. If associated anomalies are suspected, the prognosis is dependent on the type of anomaly. If MIA is identified, the prognosis may be poor due to a multitude of gastrointestinal atresias. Neonatal death from sepsis is common in neonates with EB.(2) 

When CPA is suspected, a targeted anomaly scan for associated anomalies should be performed. Specific signs of EB should be excluded and the fetal abdomen evaluated for other bowel atresias which would suggest MIA. Invasive testing with amniocentesis for genetic testing as is locally available and genetic counseling can be considered. In EB, alpha-fetoprotein in the amniotic fluid is increased.(4) Consultation with a pediatric surgeon and neonatologist including a tour of the Neonatal intensive Care Unit (NICU) can be helpful for the parents. 

Monitoring the pregnancy for development of polyhydramnios is advised and parents should be informed about the risks of polyhydramnios, which include premature labor and delivery and fetal malposition. Occasionally, if a patient becomes very uncomfortable due to uterine distention from polyhydramnios, amniotic fluid drainage may be required for temporary relief of symptoms. Ideally, these pregnancies should be delivered at term with cesarean delivery reserved for the usual indications. Management of the pregnancy and delivery should take place in a specialized facility which can care for a baby with surgical needs. 

Diagnosis in the neonate is confirmed by abdominal X-ray, a Barium swallow or endoscopy of the upper gastrointestinal tract.(19) Surgical correction is done when the neonate is stable for surgery. Neonates may spend weeks in the hospital.

If the diagnosis is not made prenatally, neonates and children present with nonbilious vomiting, feeding intolerance and distension of the upper abdomen. Some will present at a later age with failure to thrive.(19)

1.    Yoshizato T, Satoh S, Taguchi T, Suita S, Nakano H. Intermittent 'double bubble' sign in a case of congenital pyloric atresia. Fetal Diagn Ther. 2002;17(6):334-8.
2.    Al-Salem AH, Abdulla MR, Kothari MR, Naga MI. Congenital pyloric atresia, presentation, management, and outcome: a report of 20 cases. J Pediatr Surg. 2014;49(7):1078-82.
3.    Al-Salem AH. Congenital pyloric atresia and associated anomalies. Pediatr Surg Int. 2007;23(6):559-63.
4.    Chen CP, Sheu JC, Lin SP, Lin CJ, Chan YJ, Wang W. Sonographic findings in a case of congenital pyloric diaphragm. Ultrasound Obstet Gynecol. 2002;19(5):528-9.
5.    Maman E, Maor E, Kachko L, Carmi R. Epidermolysis bullosa, pyloric atresia, aplasia cutis congenita: histopathological delineation of an autosomal recessive disease. Am J Med Genet. 1998;78(2):127-33.
6.    Dural O, Acar DK, Ekiz A, Aslan H, Polat I, Yildirim G, et al. Prenatal ultrasound findings and a new ultrasonographic sign of epidermolysis bullosa with congenital pyloric atresia: a report of three cases. J Med Ultrason (2001). 2014;41(4):495-8.
7.    De Jenlis Sicot B, Deruelle P, Kacet N, Vaillant C, Subtil D. Prenatal findings in epidermolysis bullosa with pyloric atresia in a family not known to be at risk. Ultrasound Obstet Gynecol. 2005;25(6):607-9.
8.    Shaw DW, Fine JD, Piacquadio DJ, Greenberg MJ, Wang-Rodriguez J, Eichenfield LF. Gastric outlet obstruction and epidermolysis bullosa. J Am Acad Dermatol. 1997;36(2 Pt 2):304-10.
9.    Fine JD, Eady RA, Bauer EA, Bauer JW, Bruckner-Tuderman L, Heagerty A, et al. The classification of inherited epidermolysis bullosa (EB): Report of the Third International Consensus Meeting on Diagnosis and Classification of EB. J Am Acad Dermatol. 2008;58(6):931-50.
10.    Achiron R, Hamiel-Pinchas O, Engelberg S, Barkai G, Reichman B, Mashiach S. Aplasia cutis congenita associated with epidermolysis bullosa and pyloric atresia: the diagnostic role of prenatal ultrasonography. Prenat Diagn. 1992;12(9):765-71.
11.    Lepinard C, Descamps P, Meneguzzi G, Blanchet-Bardon C, Germain DP, Larget-Piet L, et al. Prenatal diagnosis of pyloric atresia-junctional epidermolysis bullosa syndrome in a fetus not known to be at risk. Prenat Diagn. 2000;20(1):70-5.
12.    Samuels ME, Majewski J, Alirezaie N, Fernandez I, Casals F, Patey N, et al. Exome sequencing identifies mutations in the gene TTC7A in French-Canadian cases with hereditary multiple intestinal atresia. J Med Genet. 2013;50(5):324-9.
13.    Snyder CL, Mancini ML, Kennedy AP, Amoury RA. Multiple gastrointestinal atresias with cystic dilatation of the biliary duct. Pediatr Surg Int. 2000;16(3):211-3.
14.    Patel SB, Milstein JM, Schwartz MZ, Wood BP. Radiological case of the month. Congenital pyloric atresia in Down syndrome. Am J Dis Child. 1993;147(3):307-8.
15.    Matsuo Y, Nukina S, Hasegawa K, Yoshida N, Doi Y, Sawada T, et al. Combined esophageal and pyloric atresia without tracheoesophageal fistula in Down's syndrome. Acta Paediatr Jpn. 1988;30(5):632-4.
16.    Saka R, Yamamoto D, Kuroda S, Ibuka S, Kodama T, Hasegawa T. Prenatally diagnosed congenital pyloric atresia in consecutive three siblings: a case report. Surg Case Rep. 2021;7(1):9.
17.    Sase M, Asada H, Okuda M, Kato H. Fetal gastric size in normal and abnormal pregnancies. Ultrasound Obstet Gynecol. 2002;19(5):467-70.
18.    Traubici J. The double bubble sign. Radiology. 2001;220(2):463-4.
19.    Kansra M, Raman VS, Kishore K, Khanna S, Puri B, Sharma A. Congenital pyloric atresia - nine new cases: Single-center experience of the long-term follow-up and the lessons learnt over a decade. J Pediatr Surg. 2018;53(11):2112-6.

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