Surgery 7 Flashcards by Maggie Musso

Nasopharyngeal carcinoma is associated with the reactivation of ___ and occurs most commonly in those from what parts of the world?

EBV; Asia (particularly southern China), parts of Africa and the Middle East

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Presentation of nasopharyngeal cancer?

Nasal congestion with epistaxis, headache, cranial nerve palsies, and/or serous otitis media (eustachian tube obstruction) due to obstruction of the nasopharynx and invasion of adjacent tissues; early metastatic spread to the cervical lymph nodes may cause a non-tender neck mass

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Aflatoxin B1 is a mycotoxin that often contaminates agricultural products and is associated with an increased risk of ___.

Hepatocellular carcinoma

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Causes of colonic ischemia?

Non-occlusive, “watershed” ischemia (usually)
Underlying atherosclerotic disease
State of low blood flow (eg, hypovolemia)

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Presentation of colonic ischemia?

Moderate abdominal pain and tenderness (usually lateralizes to the affected side)
Hematochezia, diarrhea
Leukocytosis, lactic acidosis

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Dx colonic ischemia?

CT scan - colonic wall thickening, fat stranding
Endoscopy - edematous and friable mucosa, cyanotic mucosa, hemorrhagic ulcerations, with a sharp transition from affected to unaffected mucosa

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Management of colonic ischemia?

IV fluids and bowel rest
ABX with enteric coverage
Colonic resection if necrosis develops

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Discuss the pathogenesis of symptomatic hyponatremia.

Low serum tonicity results in the influx of water into brain cells, leading to swelling and cerebral edema

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How long does it take to normalize brain volume?

~48 hours

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What is the difference between acute and chronic hyponatremia?

Acute - present for <48 hours, poorly tolerated, high risk for brain herniation

Chronic - present for 48+ hours, better tolerated

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Management of symptomatic hyponatremia?

Acute, serum sodium <130, any symptoms of elevated ICP: hypertonic 3% saline boluses to rapidly correct serum sodium

Chronic, serum sodium <120, severe symptoms (seizure) or concurrent intracranial pathology (eg, masses, hemorrhagic stroke): hypertonic saline

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Why can you manage acute hyponatremia with hypertonic 3% saline boluses?

Because neural adaptations have no occurred, patients are at relatively low risk of osmotic demyelination syndrome

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What is the goal of hypertonic saline infusion?

Raise serum sodium levels by 4-6 mEq/L over a period of hours

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Maximum rate of correction to prevent ODS?

8 mEq/L in 24 hours

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Presentation - nausea, weakness, confusion, hyponatremia, hyperkalemia, severe hypotension

Acute adrenal insufficiency

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Management of acute adrenal insufficiency?

Rapid administration of hydrocortisone or dexamethasone

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What is the cause of gallstone ileus?

Results from a SBO due to a gallstone that has passed through a biliary-enteric fistula. As the stone advances, it may cause “tumbling” obstruction before ultimately causing complete obstruction

Dx gallstone ileus?

Abdominal CT scan - gallbladder wall thickening, pneumobilia, obstructing stone

Rx gallstone ileus?

Removal of the stone and either simultaneous or delayed cholecystectomy

How do uric acid stones form and what are some risk factors?

Excess urinary excretion of uric acid and low urine pH can lead to supersaturation of urine and the formation of uric acid stones. Acidic urine factors formation of uric acid (insoluble) over urate (soluble)

Risk factors:

Increased uric acid excretion: gout, myeloproliferative disorders
Increased urine concentration: hot, arid climates; dehydration
Low urine pH: chronic diarrhea (GI bicarbonate loss), metabolic syndrome/DM

Rx uric acid stones?

Alkalization of the urine with potassium citrate

Clinical characteristics of uric acid kidney stones?

Radiolucent stones (not visible on X-ray)
Uric acid crystals on urine microscopy
Urine pH usually <5.5

How do calcium oxalate kidney stones develop?

Malabsorption of fat -> increased binding of calcium by fat in the intestinal lumen -> decreased calcium available to form insoluble oxalate complexes -> increased intestinal absorption of oxalate -> renal clearance of excess oxalate

How do struvite stones develop?

Hydrolysis of urea to ammonia -> alkalinizes the urine -> precipitation of magnesium ammonium phosphate (struvite) crystals

Recurrent UTI with urease-producing organisms

What is the difference between superficial and deep wound dehiscences?

Superficial - separations of the skin and subQ tissue with intact rectus fascia; typically develop within the first post-op week due to abnormal subQ fluid build-up, can be managed with careful dressing changes Deep - involve the rectus fascia, result in evisceration, require emergency surgery

Trace mineral deficiency presenting with thyroid dysfunction, cardiomyopathy, and/or immune dysfunction?

Selenium

Trace mineral deficiency presenting with impaired glucose control in diabetes?

Chromium

Trace mineral deficiency presenting with microcytic anemia?

Iron

Trace mineral deficiency presenting with brittle hair, skin depigmentation, neurologic dysfunction, sideroblastic anemia, and/or osteoporosis?

Copper

Trace mineral deficiency presenting with alopecia, pustular skin rash (perioral, extremities), hypogonadism, impaired wound healing, impaired taste, and/or immune dysfunction?

Zinc

Where is zinc mostly absorbed?

Duodenum and jejunum

Who is at risk for trace mineral deficiency?

Malabsorption, bowel resection, gastric bypass, poor nutritional intake, parenteral nutrition (especially with comorbid diarrhea and malabsorption)

DDx - mediastinal mass - anterior, middle, posterior

Anterior - thymoma, retrosternal thyroid, teratoma, lymphoma Middle - bronchogenic cyst, tracheal tumor, pericardial cyst, lymphoma, lymph node enlargement, aortic aneurysm of the arch Posterior - neurogenic tumor (meningocele, enteric cysts, lymphoma, diaphragmatic hernia, esophageal tumor, aortic aneurysm), esophageal leiomyoma

Best imaging choice for middle mediastinal mass?

CT scan (may be seen on CXR)

Best imaging choice for posterior mediastinal masses?

MRI

Testicular germ cell tumors are common in young men and manifest primarily with a painless testicular mass. However, a minority of patients may have symptoms of metastatic disease - how does this present?

Low back pain (retroperitoneal lymphadenopathy) and dyspnea/cough (pulmonary nodules)

Presentation - fever, irritability, limited function/refusal to bear weight, and bony tenderness/swelling in a child

Osteomyelitis

Most common cause (pathogenesis and bug) of osteomyelitis in children?

Hematogenous spread, S. aureus

Diagnose osteomyelitis?

Gold standard - biopsy and culture of the infected bone Radiographs may be normal initially or reveal periosteal elevation (due to subcortical purulence) or cortical thickening Inflammation on MRI usually confirms the Dx

Presentation - chronic hip or referred knee pain, limp, afebrile, limited ROM of the hip without soft-tissue swelling

Avascular necrosis of the femoral head (Legg-Calve-Perthes disease)

Presentation - obese adolescent boys, chronic dull hip or referred knee pain, limp, afebrile, limited internal rotation of the hip on exam

Slipped capital femoral epiphysis (with displacement of the proximal femoral physis on imaging)

Presentation - localized pain and swelling of the leg, presents over weeks to months, often worse at night

Ewing sarcoma