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NBME Surgery Form 2 - Answers & Explanations

Updated: Nov 16, 2019


1) Toxic thyroid adenoma • Focal patch of autonomously functioning thyroid tissue = “hot nodule”


2) Nerve conduction studies

• Confirmatory study for carpal tunnel syndrome (shows slowing in median nerve at wrist)

• EMG rules out other things such as polyneuropathy, plexopathy, radiculopathy, etc.


3) Loss of bicarbonate from the gastrointestinal tract • Drainage of pancreatic fluid can cause metabolic acidosis form loss of bicarbonate


4) CT scan of the abdomen and pelvis

• Acute abdominal pain in LLQ, fever, leukocytosis = acute diverticulitis

• CT is diagnostic

• Tx: NPO, IVF, Abx


5) Duodenal hematoma

• Contrast CT to confirm the diagnosis

• Hematoma may obstruct duodenal lumen → double bubble sign

• Diagnosis may be delayed as the retroperitoneal location prevents peritonitis


6) Urine output of 30-40 mL/h

• Adequate end-organ perfusion is best indicated by urine output of 0.5-1 mL/kg/h; average adult male weighs ~70kg (70 x 0.5 = 35 mL/h)

• HR, mental status, and cap refill may be affected by underlying disease processes (less reliable markers)


7) Pharyngoesophageal (Zenker) diverticulum

• Presents with dysphagia, obstruction, halitosis, and aspiration (leading to multiple episodes of pneumonia)

• Common in elder males


8) Esophagogastroduodenoscopy

• Dysphagia to solids, age >50, chronic smoker/drinker = concern for esophageal cancer

• Definitive diagnosis of esophageal cancer = esophageal endoscopy with biopsy

• Subsequent CT scan can be used for staging or if endoscopy is unrevealing


9) Laparotomy • perforated bowel → free air under diaphragm → laparotomy


10) Cholecystoduodenal fistula with an impacted gallstone

• Multiple dilated loops of small bowel = obstruction

• Gas within small bowel lumen and liver suggests communication (fistula) between enteric and biliary tracts

• Stone leaves through fistula to cause sxs


11) Distal pancreatectomy • Large (>4 cm) cystadenomas should be resected


12) Venous valvular insufficiency

• Ulcer on medial malleolus

• Post-thrombotic syndrome = development of chronic venous insufficiency following DVT


13) Repeat typing and crossmatching of the transfused blood • Crossmatching error - the patient is having an acute hemolytic reaction, most likely due to ABO incompatibility


14) Hypertension • Post-op HTN associated with cerebral hyperperfusion syndrome - manipulation of the carotid artery/sinuses lead to baroreceptor dysfunction


15) Massive hemothorax • Hypotension + flat neck veins + absent breath sounds after knife wound = hemothorax


16) Crohn disease • “string sign” on barium x-ray = thin luminal contrast, usually in terminal ileum from spasm and eventual fibrosis


17) Colonoscopy

• Age >50 with lower GI bleed → colonoscopy

• In all anorectal problems, cancer has to be ruled out first; once diagnosis has been confirmed, internal hemorrhoids are tx with rubber-band ligation, whereas external hemorrhoids require surgery


18) Surgical excision of the cyst • Choledochal cyst (cystic dilation of biliary tree) • U/S is best non-invasive test; ERCP for definitive diagnosis • Tx: surgical excision to relieve obstruction and biliary-enteric anastomosis

• Excision helps prevent malignant transformation (cholangiocarcinoma)


19) Hypovolemia

• Patient was down, laying on the floor for 48 hours (likely volume depleted)

• She hasn’t moved → muscle breakdown and rhabdo → lactic acidosis → compensatory hyperventilation

20) Intubation and hyperventilation • GCS <8 → Intubate • Hyperventilation → ↓ CO2 → vasoconstriction and ↓ ICP (CO2 is a potent vasodilator in the brain)



21) Herpes simplex conjunctivitis • Acute onset pain, conjunctival injection, vesicular lesions, visual blurring, discharge = HSV keratitis


22) Central retinal artery occlusion • Acute painless monocular vision loss with pallor of optic disc = CRAO

• Retinal vein occlusion → retinal hemorrhage and venous engorgement


23) Thyroidectomy • Follicular neoplasm with prior history of head/neck radiation - definitive treatment is total thyroidectomy


24) Bupivacaine • Amides (“i” before “caine" such as bup”i”vacaine) are intermediate/long acting • Esters (no ‘i’ before “caine” such as procaine and chloroprocaine) are short acting (tetracaine is a long-acting exception)


25) Surgical debridement

• Fournier’s gangrene = extensive tissue necrosis/infection of perineum in diabetics

• Tx: urgent surgical debridement


26) Tracheostomy • Recurrence of tumor → obstruction → difficult to maintain an endotracheal airway

• Tracheostomy would be below the lesion → maintain airway


27) Radionuclide scan with thallium and dipyridamole • Pharmacologic stress test (dipyridamole thallium scanning - DTS); dilates coronary arteries without increasing HR or BP


28) Cyclo-oxygenase inhibition with increased norepinephrine release

• Indomethacin is an NSAID that inhibits PGE2 synthesis via COX inhibition

• Increased arterial tension is the natural way that the PDA closes


29) Ruptured diaphragm • Traumatic disruption of hemidiaphragm → gas occupying the lower third of the left hemithorax


30) Ceftriaxone and vancomycin therapy • No spleen → susceptible to encapsulated organisms


31) Collapse of the right middle lobe of the lung from decreased inspiratory effort

• Hasn’t been out of bed yet, POD#1, egophany (consolidated or collapsed) → atelectasis


32) Intraductal papilloma • Most common cause of nipple discharge (serous or bloody)

• Mammillary duct ectasia = mass + green/brown discharge


33) Reintubation and mechanical ventilation • Elevated PCO2 = hypoventilation • Oxygenation is adequate (do not need to increase FiO2)


34) Choledocholithiasis

• Cholangiography/imaging was not performed, suggesting a retained stone in bile duct

• Normal AST/ALT rule out cirrhosis

• No weight loss/painless jaundice rule out pancreatic cancer


35) Rupture of the thoracic aorta

• “hidden injury” - asymptomatic until hematoma contained by the adventitia expands

• 1st rib break, presence of wide mediastinum, severe deceleration injury should all raise suspicion


36) Secondary hyperparathyroidism • Hypocalcemia → ↑ PTH secretion → ↑ ALP

• CKD → ↑ creatinine and ↑ phosphate


37) Cholecystitis • Risk factors: female, fat (BMI >30), fertile, forty


38) Mitral valve prolapse

• Mid-systolic click = MVP

• MVP syndrome is associated with nonspecific sxs (palpitations, dyspnea, dizziness, panic/anxiety attacks, numbness/tingling, etc.)


39) Torn meniscus

• Medial joint line tenderness with effusion = Meniscal; pain when getting up from a

low position is a classic presentation

• Medial joint line tenderness without effusion = MCL


40) Increased serum tumor necrosis factor concentration • Cachectic (weight loss, muscle atrophy, fatigue) is mediated by cytokines TNF, IFN-Ɣ,

IL-1, and IL-6. Appetite is usually suppressed (via hypothalamus) and BMR is increased → ↑ lipolysis, hypotriglyceridemia.


41) Basal cell carcinoma • Upper lip, pearly surface, telangiectasia = basal cell carcinoma

• Lower lip = squamous cell carcinoma


42) Prednisone therapy and temporal artery biopsy immediately • Requires immediate prednisone therapy to prevent blindness and bx to confirm dx


43) Apocrine glands • Hidradenitis Suppurativa = inflammation of apocrine sweat glands


44) Observation • Primary spontaneous pneumothorax


45) Exploratory celiotomy • Atherosclerosis, lactic acidosis and leukocytosis = acute mesenteric ischemia

• Celiotomy (laparotomy) is needed to resect dead bowel


46) Retrograde urethrography

High-riding prostate + blood at urethral meatus = urethral injury

• Suspected urethral injury should be evaluated with retrograde urethrogram

• IV pyelogram is useful for suspected ureter injuries; Cystoscopy is useful for

suspected bladder injuries (should rule out urethral injury first, as cystoscope must go through urethra and could exacerbate existing injuries)


47) Cancel the operation • Respect the patients decision and determine rationale for refusal


48) Varicocele • “ropy mass” = “bag of worms” • Stasis of venous blood → ↑ temp → damage to sperm


49) Exploratory operation • Torsion of ovarian cyst • Tx: surgical uncoiling and possible oophoropexy to fixate ovary (prevent recurrence)

• Drainage is contraindicated as it increases risk of spread/seeding


50) Insulinoma

• Whipple triad: low blood glucose, sxs of hypoglycemia, resolution of sxs with normalization of blood glucose

• Tx: surgical resection




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5 Comments


#2 " EMG rules out other things such as polyneuropathy, plexopathy, radiculopathy, etc. " EMG is not used to evaluate nerves, since it evaluates MUSCLES. Therefore it is useful (Highly Sensitive) in Myasthenia Gravis AND Lambert-Eaton

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46) Retrograde urethrography

"Cystoscopy is useful for suspected bladder injuries (should rule out urethral injury first, as cystoscope must go through urethra and could exacerbate existing injuries)". Think you meant Cystogram. Cystoscopy on the other hand is used in the presence of suspected bladder neoplasia

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Number27 could be better explained why it is the correct answer and not others such as Echo

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For #33 patient is in ARDS. PaFIO2 ratio is 150. You must intubate

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sadly your explanation for 24 is poor. Lidocaine and Prilocaine are both Amides

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