This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'Most common organ involved in retroperitoneal fibrosis is - \nSelect and explain. \nA. Aorta, B. Ureter, C. Inferior vena cava, D. Sympathetic nerve plexus', 'role': 'user'}, {'content': "Answer: B \nExplanation: The most important clinical aspect of retroperitoneal fibrosis is that the fibrotic process frequently entraps and constricts the ureters thereby causing obstructive uropathy.\nRetroperitoneal fibrosis -\n\nIt is a nonspecific, nonsuppurative inflammation of fibro-adipose tissue of unknown cause that produces symptoms by the gradual compression of tubular structures in retroperitoneal space.\n\nAetiology of retroperitoneal fibrosis - \n\nAbout 2/3rd cases are primary idiopathic, are also known as Ormond's disease\n\nSecondary Retroperitoneal fibrosis\n\na variety of inflammatory conditions - chronic pancreatitis, histoplasmosis, tuberculosis, or actinomycosis.\ndrugs\nmethysergide (most imp.)\nβ blockers\nhydralazine\nα methyldopa\nEtacapone (used in the t/t of Parkinson's ds.) -\nmalignancies (prostate, non-Hodgkin's lymphoma, sarcoma, characinoid & gastric cancer).\nantoimmune disorders (ankylosing spondylitis, SLE\xa0PAN etc.)\n\nSymptoms of retroperitoneal fibrosis \xa0-\n\nIt is more common in men between 40-60 yrs of age\nEarly symptoms are nonspecific and vague. These are\nPain → Dull noncolicky and insidious in onset.\nAnorexia, nausea\nGeneral malaise, diarrhea\n\nLater on, symptoms result from compression of tubular retroperitoneal structures. The major structure involved are-\n\nUreter - Most commonly involved\nAorta\nInferior venacava\n\n\nSymptoms due to the involvement of ureter (usually b/1 involvement)\nDysuria\nFrequency of urination\nChills and fever occur with secondary infection of a hydronephrotic kidney.\nHematuria can occur.\n\nDiagnosis \n\nThe diagnosis of retroperitoneal fibrosis usually can be made accurately by intravenous pyelography if uremia is not present.\nThe characteristic finding on pyelogram are\n\n\nHydronephrosis with a dilated tortuous upper ureter.\nMedial deviation of the ureter\nExtrinsic ureteral compression\n\nNote: In a retroperitoneal tumor, ureter is laterally deviated while in retroperitoneal fibrosis ureter medially deviates.\n\nCurrently, the imaging procedure of choice is the CT scan.\nBut if renal function is compromised contrast agents are not given and then MRI is the procedure of choice.\n\nT/T of Retroperitoneal fibrosis \nCorticosteroids, with or without surgery, are the mainstay of medical therapy.\nSurgical treatment is required in patients who present with moderate or massive hydronephrosis. It consists primarily of ureterolysis (freeing the ureter from adhesions and surrounding tissue) or ureteral stenting..\nAlso, know\n\nPartial or complete ureteral obstruction occurs in 75 to 85% of patients.\nMost common site of urethral obstruction is lower third of the ureter.", 'role': 'assistant'}]