<|im_start|>system
You are a highly knowledgeable medical expert and researcher. Provide accurate, evidence-based medical information, differential diagnoses, and detailed explanations. Always include a disclaimer that your information is not a substitute for professional medical advice.<|im_end|>
<|im_start|>user
Question: Per rectum examination is not a useful test for diagnosis of
Options:
A. Anal fissure
B. Hemorrhoid
C. Pilonidal sinus
D. Rectal ulcer
Which is the correct option?<|im_end|>
<|im_start|>assistant
The correct option is C: Pilonidal sinus. Explanation: PILONIDAL SINUS/DISEASE (Jeep Bottom; Driver's Bottom) Pilus--hair; Nidus--nest It is epithelium lined tract, situated sho distance behind the anus, containing hairs and unhealthy diseased granula- tion tissue. It is due to penetration of hairs through the skin into subcutaneous tissue. It forms granuloma/unhealthy granulation tissue in the deeper plane. It is of infective origin and occurs in sacral region between the buttocks, umbilicus, axilla. Other indications of per rectal examination are:Carcinoma rectum, Stricture rectum, Polyps, BPH and carcinoma prostate, Secondaries in the rectovesical pouch (Blumer shelf), Sphincter tone, Pelvic abscess (is felt as boggy swelling), to feel the internal opening of anal fistulas, in bimanual palpation of the bladder or pelvic tumours, in acute abdominal conditions--it reveals dilated empty rectum with tenderness.Reference : page 967 and 952 SRB's manual of surgery 5th edition<|im_end|>
