Embryological congenital anomalies



Embryological congenital anomalies

Heart

1. Total Anomalous Pulmonary Venous Return (TAPVR): blood from pulmonary veins goes into SVC. Causes mixing of deoxygenated and oxygenated blood. Atrial septal defect leading to shunt of blood from R. atrium to L. atrium.

2. Atrial Septal Defects: from either excessive resorption of septum primum leading to a large oval foramen or from absence of septum secundum. Leads to L. to R. shunting of blood.

3. Common atrium: absence of both septum primum and secundum leading to only one atrium.

4. Ventricular Septal defect: most common and can be fixed. Part of interventricular septum (usually membranous portion) fails to grow. Allows blood from L. ventricle to go into both aorta and pulmonary arteries.

5. Patent Ductus Arteriosus: ductus arteriosus fails to close and form ligamentum arteriosum. Blood from higher pressured aorta back flows into pulmonary arteries.

6. Persistent Truncus arteriosus: failure of conotruncal cushions to separate aorta and pulmonary arteries. Single outflow trunk causing mixing of blood leading to cyanosis.

7. Transposition of Great Arteries: R. ventricle connected to aorta and L. ventricle connected to pulmonary artery. 2 independent circulations. Also have patent ductus arteriosus.

8. Teratology of Fallot:

a. pulmonary stenosis

b. membraneous IV septal defect

c. overriding aorta; part of aorta is over R. ventricle

d. hypertrophy of R. ventricle

Limb development

1. Amelia: absence of an extremity

2. Meromelia: absence of part of an extremity

3. Phocomelia: no long bone in limbs

4. Syndactyly: webbed or fused digits because apoptosis fails to occur

5. Polydactyly: extra digits

6. Lobster claw: abnormal cleft between 2nd and 4th metacarpals

7. club foot deformations: abnormal rotation of extremities

GI Tract

1. Cleft palate: failure of palates to fuse

2. Cleft lip: failure of maxillary and nasal prominence to fuse

3. Tracheoesophageal fistula: improper division leading to open communication between trachea and esophagus

4. Esophageal atresia: esophagus ends in blind pouch. Usually accompanied by tracheoesophageal fistula. Associated with polyhydramnios

5. Polyhydramnios: fetus is unable to swallow amniotic fluid because of GI tract blockage. Fluid accumulates in amniotic sac.

6. Pyloric stenosis: muscle layer in pyloric region hypertrophies, causing narrowing of pyloric lumen.

7. Diaphragmatic Hernia: abdominal contents herniate into pleural cavity because of failure of pleuroperitoneal membrane to fuse. Most found on left side. Abdominal contents compress lung buds causing pulmonary hypoplasia.

8. Annular Pancreas: ventral bud fuses dorsally and ventrally with dorsal bud, forming a ring of pancreatic tissue around duodenum.

9. Ectopic pancreas: pancreatic tissue appearing in GI tract

10. Duodenal atresia: no recanalization of duodenum causing a back up in stomach and polyhydramnios

11. Choledochal Cyst: localized cystic dilation of biliary tree

12. Biliary atresia: some aspect of biliary tree is obliterated as a result of incomplete recanalization. Leads to jaundice and liver failure

13. Volvulus: twisting of intestines causing loss of blood supply and bowel obstruction

14. Omphalocele: intestinal midgut loop fails to return to abdominal cavity. Defect in midline

15. Gastroschisis: hole in abdominal cavity lateral to midline with intestines protruding without membranous structure covering it.

16. Meckel’s diverticulum: remnant of vitelline duct persists and forms outpouching from ileum and connects to umbilicus via vitelline ligament.

17. Vitelline fistula: vitelline duct remains open with direct connection between bowels and anterior surface. Fecal discharge at umbilicus occurs

18. Imperforate anus: anal membrane fails to perforate. No meconium passed

19. Bowel atresia: blind gut pouch

20. Persistent cloaca: common tube for anorectal and urogenital septum

21. Rectovaginal fistula: incomplete separation between rectum and vagina. Allows stool to come out of vagina.

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