Calot’s Triangle (CT)

Calot's triangle is a small (potential) triangular space at the porta hepatis of surgical importance as it is dissected during cholecystectomy. Its contents, the cystic artery and cystic duct must be identified before ligation and division to avoid intraoperative injury.

Borders

• Medial – common hepatic duct.
• Inferior – cystic duct.
• Superior – inferior surface of the liver.
  

The above differ from the original description of Calot’s triangle in 1891 – where the cystic artery is given as the superior border of the triangle. The modern definition gives a more consistent border (the cystic artery has considerable variation in its anatomical course and origin).

Contents

• Right hepatic artery
• Cystic artery
• Cystic lymph node (of Lund)
• Connective tissue
  
  
  
• Lymphatics
• Occasionally accessory hepatic ducts and arteries

Significance

• Cystic artery arises from Right Hepatic Artery in the Calot's triangle in 75%
• Cystic artery origin & course vary in 25% of population.
  
  
  

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ACTH stimulation test

IV/IM admin of cosyntropin (250 μg), with collection of serum & measurement of cortisol at baseline & 30–60 min post stimulation.

Supra-physiological dose stimulates the pituitary & releases cortisol from the adrenal cortex, as long as the adrenal cortex has a functional reserve.

Factors affecting ACTH stim test interpretation:

• Falsely negative or normal in mild disease or disease of recent onset.
• Most common- false-positive test is seen in recent use of corticosteroids
• Exogenous steroids lead to both baselines &adrenal responsiveness to cosyntropin.
• Propofol impairs adrenal steroidogenesis
• Midazolam, morphine, and fentanyl blunt the HPA axis, thereby interfering with corticosteroid metabolism.
• Metyrapone, etomidate, ketoconazole, megesterol, & mitotate interfere with cosyntropin function.
• Rifampin & phenytoin may increase cortisol metabolism.

In females, response to ACTH may be affected OCs which increase CBG levels.

• Salivary cortisol response can be useful as their measurement is a surrogate for serum free cortisol & are not affected by OCs
• Opioid receptors are present in the pituitary gland & hypothalamus, & opioids may impact HPA function.
• Nenke et al studied 17 pts treated with long-term opioids. Five of the 17 (29%) were found to have evidence of AI, with cortisol levels of <5 μg/dL.

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Diabetes and hemoglobin A1c

 

In patients ≥65 years of age treated with medication for type 2 diabetes, hemoglobin A1c values of 7%–8% have shown the greatest reduction in mortality in multiple studies. The specific hemoglobin A1c target between 7% and 8% should be based on shared decision-making and the overall condition of the patient at that specific age, with goals in the lower 7% range for those with good to excellent functional status. It is suggested that lower hemoglobin A1c values are associated with frequent hypoglycemia, which presents a greater risk than a higher hemoglobin A1c value alone. Hemoglobin A1c values over 9% are associated with greater mortality. Thus, while the risk of complications increases linearly with hemoglobin A1c, mortality has a U-shaped curve. Management of blood pressure and treatment with statins improves mortality in these patients as well and is important in addressing overall cardiovascular risk.

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Xanthogranulomatous pyelonephritis

 

Xanthogranulomatous pyelonephritis is an uncommon, severe, subacute, or chronic suppurative process characterized by destruction and replacement of the renal parenchyma by granulomatous tissue containing histocytes and foamy cells. It is most often associated with chronic obstruction and stones with ongoing infection. It is also referred to as a pseudotumor due to an enlarged kidney resembling a tumor and the ability of local invasion and destruction.

The etiology remains unknown. However, most of the cases result from chronic urinary obstruction and infection. The organisms most commonly associated with XGP are Escherichia coli, Proteus mirabilis, Pseudomonas, Enterococcus faecalis, and Klebsiella, etc. Urinary obstruction occurs as a result of calculus, most commonly, staghorn calculus (in almost 80% of patients), which serves as a nidus for infection resulting in the destruction of the renal parenchyma.

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Sister Mary Joseph’s Nodule

 

Defined as neoplastic lesion in the periumbilical region arising as a primary tumor or representing as a site of metastasis from visceral organ malignancies such as from the gastrointestinal tract and the reproductive organs. The overall incidence is 1-3% in general population with malignancies. The primary site of malignancy associated is significantly different in men and women. The most common primary site in men is the stomach followed by the colon and pancreas, whereas in women, the most common site is the ovary followed by endometrium, colorectal, and pancreas.

The prognosis of patients presenting with Sister Mary Joseph’s nodule is generally poor as it is a sign of advanced malignancy. Management of the disease should consider patient preference, the clinical state of the patient, and the etiology of the primary malignancy.

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Porcelain gallbladder (PGB)

Term porcelain gallbladder (PGB) is often used to describe calcification of the gallbladder wall. When infiltrated by extensive calcium deposits, the gallbladder wall can become fragile, brittle and bluish in appearance, resulting in a ‘porcelain’ appearance.

The true incidence of porcelain gallbladder is unknown, but it is reported to be 0.6-0.8%, with a male-to-female ratio of 1:5. Most porcelain gallbladders (90-95%) are associated with gallstone.  Mean age at diagnosis is 32 to 70 years.

Patients with porcelain gallbladder are usually asymptomatic, and the condition is usually found incidentally on plain abdominal radiographs, sonograms, or CT images.

Based on early studies which revealed a high association between porcelain gallbladder and gallbladder adenocarcinoma (22-30% of porcelain gallbladders developing gallbladder adenocarcinoma), cholecystectomy has been routinely performed when a porcelain gallbladder is identified.

More recent studies have cast some doubt on the association, and the risk of gallbladder cancer associated with calcification of the wall may be as low as 5-7%. There is no accepted follow-up interval, but the annual incidence of developing gallbladder cancer is likely to be <1% per year.

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Dupuytren’s contracture

Dupuytren’s contracture is predominantly a myo-fibroblastic disease that affects the palmar and digital fascia of the hand and results in contracture deformities. The most commonly affected digits are the fourth and fifth digits. It is a genetic disorder that often is inherited in an autosomal dominant fashion, but is most frequently seen with a multifactorial etiology. There are a number of factors that are believed to contribute to the development or worsening of this disease.

These include:

• Men are more likely to develop the condition than women.
• People of northern European (English, Irish, Scottish, French, and Dutch) and Scandinavian (Swedish, Norwegian, and Finnish) ancestry are more likely to develop the condition.
• Dupuytren's often runs in families.
• Drinking alcohol may be associated with Dupuytren's.
• Diabetes, HIV, Vascular disease, smoking and seizure disorders are more likely to have Dupuytren's.
• Incidence of the condition increases with age.
  
  
  
  
  
  
  
  
  
  

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Dual-energy x-ray absorptiometry (DEXA)

1. Uses x-rays at two energy levels to determine the bone mineral content.
2. Major role in diagnosis of osteoporosis, the assessment of patients' risk of fracture, and monitoring response to treatment.
3. T-score is a number of standard deviations between the patient’s mean BMD and the mean of the population compared with reference populations matched in gender and race.
4. Z-score is the number of standard deviations above or below the mean of age-matched controls.
5. DEXA could be used to measure bone density at many skeletal sites, two sites are typically measured: the first four vertebrae of the lumbar spine posteroanterior, and the proximal femur (“hip”), including the femoral neck and the trochanteric areas and total hip measurement. Femoral neck and lumbar spine are the gold standard for evaluating osteoporosis, with good accuracy and high precision.
6. All women 65 years and older and men 70 years and older should be screened for asymptomatic osteoporosis.

The World Health Organization (WHO) defines T-scores as:

• Greater than or equal to -1.0: normal
• Less than -1.0 to greater than -2.5: osteopenia
• Less than or equal to -2.5: osteoporosis
• Less than or equal to -2.5 plus fragility fracture: severe osteoporosis

Clinical risk factors included in WHO fracture algorithm

• Age
• Low body mass index
• Prior fracture after age 50
• Parental history of hip fracture
• Current smoking habit
• Current or past use of systemic corticosteroids
• Alcohol intake >2 units daily
• Rheumatoid arthritis 

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Splenectomy

 

• Patients who undergo splenectomy are at increased risk of infections secondary to encapsulated organisms: H Influenzae, Streptococcus pneumoniae & Neisseria meningitidis. 
• Vaccinations against these organisms are highly recommended in patients who have undergone splenectomy. 
• Careful attention must be paid to post-splenectomy patients presenting with febrile illnesses as they may require more aggressive, empiric antibiotic therapy.
• Palpation of spleen ---see below
  
  
  
  

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Niacin Deficiency

Distinctive dark red rash appears on the hands, feet, calves, neck, and face, and the tongue and mouth turn dark red.

Many people with niacin deficiency also have deficiencies of protein, riboflavin (a B vitamin), and vitamin B6.

Pellagra develops only if diet is deficient in niacin & tryptophan (body can convert tryptophan to niacin).

Affects the skin, digestive tract, & brain.

Also develops in:

Hartnup disease (absorption of tryptophan is impaired), & Carcinoid syndrome (tryptophan is not converted to niacin).

Alcoholism & isoniazid can lead to a deficiency of niacin.

The diagnosis of niacin deficiency is based on the diet history and symptoms. Measuring a by-product of niacin in urine can help establish the diagnosis, but this test is not always available. The diagnosis is confirmed if niacin relieves symptoms.

Treatment: Nicotinamide, unlike nicotinic acid, does not cause flushing, itching, burning, or tingling sensations.

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White Blood Cell Scan

 

Indium 111- tagged white blood cell scan is a type of imaging modality used to help identify regions of inflammation and thus infections when other imaging studies are equivocal or contraindicated.

The test is used for diagnostic purposes in the evaluation of prosthetic joint infections, osteomyelitis, vascular graft infections, intra-abdominal infections, abscesses, endocarditis, foot ulcers, infected implanted devices such as central venous catheters, fevers of unknown origin when there is a high probability of infection, and Inflammatory bowel disease.

Sensitivity 60 to 100% and specificity 69 to 92%.

White blood cells are obtained from a blood sample from a patient, are tagged with the radioisotope indium-111, and then re-injected intravenously into the patient. These labeled leukocytes localize to a region of inflammation visible on the whole body or regional nuclear imaging with bone scintigraphy.

Recommended dose for adults is 0.3 to 0.5 mCi

Prior IV antibiotics may produce false negative result.

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Pneumobilia vs Portal venous gas

 

Pneumobilia

Also known as aerobilia. Accumulation of gas in the biliary tree. Seen as linear branching gas within liver most prominent in central large caliber ducts as the flow of bile pushes gas toward the hilum. Gas within the biliary tree tends to be more central, whereas gas within the portal venous system tends to be peripheral (carried along by the blood). Also, biliary gas is anti-dependent, and typically fills the left lobe of the liver.

“Saber sign”: Supine radiographs often demonstrate a sword-shaped lucency in the right paraspinal region representing gas from the common duct and the left hepatic duct. Present in ~50% of patients with pneumobilia.

Portal venous gas

Peripheral small caliber branching gas (lucencies) projected in the liver or vessels coursing towards the Liver (away from the hilum).

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