Rib notching is seen in all EXCEPT-

Ans. is 'c' ie IVC obstruction CAUSES OF RIB NOTCHINGRib notching Inferior surface* Rib notching - Superior surfaceArterial* A) Connective tissue diseasesCoarctation of the aorta* Rheumatoid arthritisrib signs are unusual before 10 yrs of age** SLEAffects 4th to 8th ribs bilaterally, not the upper two ribs** SclerodermaU/L and right sided ribs are affected if the coarctation is proximal to the left subclavian artery* Sjogren's syndrome * B) MetabolicAortic thrombosis* HyperparathyroidismSubclavian obstruction* C) Miscellaneousmost commonly post Blalock operation for fallot's Petrology** Neurofibromatosis* Restrictive lung diseaseunilateral upper three or four ribs on the operation side* Poliomyelitisare affected.* Marfan's syndromePulmonary oligaemia* Osteogenesis imperfectaVenous* ProgeriaChronic superior vena caval obstruction or IVC obstruction*ArteriovenousPulmonary arteriovenous malformation*Chest wall arteriovenous malformationNeurogenicNeurofibromatosis*Though IVC obstruction is mentioned as a cause of inf. rib notching, in Sutton & Grainger it is a very rare cause.