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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