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