This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
"Doughnut" sign is seen in 
Select and explain. 
A. Intussusception, B. Carcinoma colon, C. CHPS, D. Volvulus
C: CHPS
Answer: C: CHPS 
Explanation: .CONGENITAL HYPEROPHIC PYLORIC STENOSIS is hyperophy of musculature of pyloric antrum, especially the circular muscle fibres, causing primary failure of pylorus to relax. Duodenum is normal. Clinical features of congenital pyloric stenosis 1. Vomiting 2. VGP 3. Palpable mass 4. Constipation and dehydration Diagnosis is established by -- Clinical examination. -- U/S abdomen (very useful)--Doughnut sign. * Pyloric muscle 4 mm or more in thickness. * Length of pyloric canal > 1.8 cm. -- Barium meal shows obstruction. ref:SRB&;S manual of surgery,ed 3,pg no 752