Foregut (esophagus) – related to failure of embryologic recanalization of the gut (3-10 weeks gestation).
Midgut/Hindgut (jejunum/ileum) – related to intra-uterine ischemia/vascular accidents.
Midgut/Hindgut – also can be result of Ý or exaggerated reabsorption of the vitelline duct (10th week 3rd trimester gestation).
(2) Intestinal Malrotation
(3) Duplication
and Cysts
Related to malformations either during the division of the forget into GI and Pulmonary structures, during the recanalization period or later during the solid organogenesis.
(4) Ano-rectal Malformations
Occur during the period of division of the cloaca or joining of the proctodeum with the forming hindgut.
(5) Abnormal Neural Innervation
Result of abnormalities in the normal proximal to distal descent of these cells.
Clinical Presentation: Timing
(1) Prenatal
, anomalies diagnosed by sonography (18-24 weeks gestation)
Esophageal Atresia
Gastroduodenal Stenosis
Duplications
Cysts
Hydramnios
Amniotic fluid filled sacs caused by obstruction (atresia, etc). If the obstruction perforates it will become calcified and will appear as such on the ultrasound. Increased risk of premature delivery and associated low birth weight.
Distal Hindgut (colon) Obstruction – may be diagnosed later in infancy.
(4) Infancy
to Adulthood
Malrotation Defects
Duplications
Cysts and Hamartomas
Distal Hindgut (colon) Obstruction – may be diagnosed earlier in neonatal period.
Signs and Symptoms / Diagnosis of Congenital GI Obstruction:
Bilious Vomiting – is either due to sepsis or GI obstruction
Abdominal Distention
Obstipation – no bowel movements
Maternal Hydramnios
Therapy Goals:
Restoration of intestinal patency and function
excision of extra-luminal obstruction (duplication, etc.)
excision of stenosis/atresia with reanastomosis
excision of abnormally innervated intestine with reanastomosis
creation of missing anal orifice
Separation of abnormally associated GI/respiratory tracts and/or GI/urinary systems – note: if have 1 anomaly, 10% chance of another anomaly elsewhere! Associated anomalies pneumonic: VACTRL (Vertebral, Atresia, Cardiac, Tracheoesophageal fistula (TEF), Renal (duplicated collecting system, missing kidney, etc.), Limb).
Prenatal Therapy
Fetal surgery is not indicated for congenital GI obstruction at the present time. Low postnatal mortality and morbidity rates preclude a significant benefit of prenatal intervention.
Prognosis
Isolated GI tract congenital anomalies have an excellent prognosis. However, the prognosis can be limited by:
Severity of associated defects
Severity of primary defect
Any delay in diagnosis or appropriate therapy with development of secondary complications (infectious, respiratory, metabolic)
Specific Malformations
Tracheoesophageal Malformations
Aberrant separation of dorsal foregut and ventral trachea.
VACTRL associated problems.
Ý
incidence of prematurity.
85% have esophageal atresia with distal TEF (baby coughs and sputters).
Occurs on 19+ gestational day. Incidence: 1:3 – 5000 live births.
Gastric Malformations
Almost never happens. "I’ve seen one in twenty-eight years of doing surgery."
Duodenal Malformations
Duodenal atresia due to failure of gut recanalization.
On ultrasound see "double-bubble", air trapped around atresia.
Occurs on 19+ gestational day. Incidence 1:4 – 10,000 live births.
Intestinal Malformations
Intestinal atresia and stenosis, most common cause of newborn intestinal obstruction.
Mostly due to ischemia of bowel
Þ disables GI neurons Þ no peristalsis Þ need to remove these sections of gut.
Associated with duodenal atresia (30%), and jejunal/ileal atresia (<12%).
Occurs on 3rd gestational week and/or past 10th gestational week.
Incidence 1:3000 livebirths.
Probably a familial genetic problem if baby has >3 atresias
Christmas Tree
Syndrome – missing all proximal small bowel and superior mesenteric artery. Distal gut ends up looping in a circle around inferior mesenteric artery.
Colonic Malformations
very rare.
Malrotation Anomalies
Occur within 10 days – 1st trimester.
Incidence 1:10,000 live births.
Increased with congenital diaphragm or abdominal wall defects.
Valvulus – Mesentery twists the wrong way (clockwise).
GI Duplication / Cysts
3rd gestational week.
1:10,000 live births.
Mesenteric cyst can’t be removed because of this will compromise the blood supply to the gut.
These problems can also impinge on the bowel.
Ano-rectal Malformations
Mostly associated with urogenital problems: in girls can have a blind intestine ending in the vagina, in boys intestine can connect to bladder or urethra.
Hirschsprung’s Disease
Absent neurons in distal colon cause tonic contractions.
Get constipation and can’t get proper nutrition. Have to remove damaged region of intestine.