USMLE RX GI

Question 1

This patient’s presentation (jaundice, abdominal pain, and mildly elevated transaminases and alkaline phosphatase) after treatment with erythromycin for pneumonia is suggestive of ?

Answer 1

Acute cholestatic hepatitis secondary to macrolide toxicity.

Question 2

Macrolide toxicity can lead to ? painful jaundice and acute cholestatic hepatitis. A number of macrolides are inhibitors of the cytochrome P-450 system. (Azithromycin is the macrolide least likely to inhibit the cytochrome P-450 system.)

Answer 2

Painful jaundice and acute cholestatic hepatitis. A number of macrolides are inhibitors of the cytochrome P-450 system. (Azithromycin is the macrolide least likely to inhibit the cytochrome P-450 system.)

Question 3

Macrolides are contraindicated in patients with a history of ?

Answer 3

cholestatic jaundice or hepatic dysfunction associated with prior azithromycin use. These drugs should be discontinued immediately if symptoms of hepatitis occur.

Question 4

Glucose and galactose transporter that enables glucose and galactose absorption across the apical membrane of enterocytes?

Answer 4

SGLT1 ,

Question 5

SGLT1 achieves glucose and galactose absorption by coupling to the sodium gradient, created by ?

Answer 5

the basolateral sodium-potassium pump. Since SGLT1 is not involved in fructose absorption, inhibiting its function would not affecd

Question 6

patient presents with difficulty feeding, and coughing and choking while feeding. On exam, the patient also has an open space on the roof of the mouth that extends anteriorly to the lip. Together, these suggest
?

Answer 6

a cleft palate, a split in the roof of the mouth that leaves a hole between the nose and the mouth.

Question 7

Isolated cleft palate is not associated with genetic or chromosomal disorders, and therefore, patients with an isolated cleft palate typically have? . This orofacial defect makes it difficult to create the suction needed for proper feeding. As a result, children are at risk of ?

Answer 7

Normal facies,

choking and coughing, as well as aspiration and poor weight gain until the defect is repaired. Surgical correction is usually attempted between 9 and 12 months of age.

Question 8

Failure of the maxillary processes and medial nasal processes to fuse would lead to?

Answer 8

cleft lip

Question 9

55-year-old woman presents to the office with recent onset of diarrhea that “comes and goes”; she also experiences shortness of breath and “face redness” during these episodes ?

Answer 9

Malignant carcinoid syndrome

Question 10

Serotonin, which is also known as 5-hydroxytryptamine (5-HT), is often the amine that is released, but histamine, gastrin, or others may also be involved in this process. As in the patient described, intestinal carcinoid tumors are often asymptomatic until?

Answer 10

metastasis to the liver occurs. This is because the liver inactivates bioactive products secreted into the portal circulation. Following metastasis to the liver, however, the vasoactive substances exert their effects by leaving directly through the hepatic vein, thus escaping liver metabolism. Serotonin causes fibrosis in the tricuspid and pulmonary valves, gastrin can cause nausea and diarrhea, and histamine can cause flushing of the skin.

Question 11

This pregnant patient presents with jaundice, anorexia, fever, abdominal pain, nausea, vomiting, and malaise after consumption of river water. Results of her lab tests reveal high levels of alanine aminotransferase (ALT) and aspartate aminotransferase (ALT), which are indicative of liver damage. This is most consistent with a diagnosis of ?

Answer 11

Fulminant hepatitis. The most likely causative agent in this situation is hepatitis E virus.
Hepatitis E is a nonenveloped, single-stranded RNA hepevirus (recently reclassified from being a calicivirus) that resembles hepatitis A in its disease course, with nausea, vomiting, fever, anorexia, and jaundice.
spread by the fecal-oral route, is most commonly water-borne, and is associated with a high mortality rate in pregnant women

Question 12

A 20-year-old man comes to a clinic because of abdominal discomfort. The discomfort has progressively worsened. He denies nausea and vomiting, and has not traveled recently. He has no recent sick contacts. On further questioning, the patient admits to a week-long intravenous heroin binge the previous week?

Answer 12

Heroin and other opiates primarily function by stimulation of µ-receptors in the brain and gastrointestinal (GI) tract. μ-Receptor stimulation is responsible not only for the pleasure sensation derived from opiates, but also for the decreased bowel motility and constipation with which opiates are associated.

Question 13

Why is it important to minimize opiate use in patients with suspected small-bowel obstruction, ileus, or infectious diarrhea?

Answer 13

because these patients tolerate constipation and slowed GI motility poorly.

Question 14

The presence of both anti-HBs and anti-HBc without hepatitis B antigens suggests ?

Answer 14

prior infection with complete recovery

Question 15

The absence of current viral antigens in the serum (HBsAg negative, HBeAg negative) signifies? t

Answer 15

there is no current infection

Question 16

In a patient with chronic hepatitis B infection?

Answer 16

HBsAg and Anti-HBc IgG will be positive. The patient may also have HBeAg if he or she has high infectivity or Anti-HBe if low infectivity.

Question 17

This patient is presenting with abdominal pain and steatorrhea (fatty stools that are difficult to flush). In the context of chronic alcoholism, it is likely that this patient is having ?

Answer 17

pancreatic dysfunction secondary to chronic pancreatitis

Question 18

Octreotide is a somatostatin analog. By decreasing pancreatic fluid secretion, octreotide may allow the pancreas to rest and help in the management of? p

Answer 18

Pain in patients with chronic pancreatitis. Octreotide also inhibits growth hormone secretion and suppresses release of gastrin, cholecystokinin, secretin, and vasoactive intestinal peptide

Question 19

This patient presents with episodic abdominal pain, blood in his diaper, and a recent diarrheal illness. Taken together, these symptoms suggest a diagnosis of ?

Answer 19

small bowel intussusception after a recent GI infection. GI infections cause reactive hyperplasia of Peyer patches, which can then serve as the lead point for intussusception

Question 20

Peyer patches are gut lymphoid tissue, located primarily in the ileum. M cells in the Peyer patches take up antigens from the intestinal tract and present them to ?

Answer 20

B cells, which then secrete IgA antibodies.

Question 21

This patient presents with choking and coughing on feeding as well as limb defects. His coughing and choking on feeding suggests ?

Answer 21

infant likely has a tracheoesophageal fistula. The TEF causes the infant to choke as food enters the trachea. The most common type is a TEF with esophageal atresia, seen in ≥85% of cases

Question 22

In utero, this abnormality prevents the infant from swallowing amniotic fluid, which results in?

Answer 22

polyhydramnios (ie, excess amniotic fluid on ultrasound). Once the child is born, the blind-ended esophagus prevents swallowing, causing spillage of formula into the trachea with resultant choking and aspiration.The TEF also causes air to fill the stomach when the infant breathes. A large stomach air bubble would therefore be expected on this infant’s chest radiograph, like that shown in the image.

Question 23

TEFs may be isolated, but are also frequently associated with ?

Answer 23

VACTERL defects (Vertebral anomalies, Anal atresia, Cardiac defects, Tracheo-Esophageal fistula, Renal/gu anomalies, and Limb defects), as seen in this infant.

Question 24

A widened mediastinum is associated with?

Answer 24

aortic aneurysm, aortic dissection, mediastinal mass, or hilar lymphadenopathy

Question 25

This 4-week-old patient presents with projectile postprandial, nonbilious vomiting. His palmar crease, facial anomalies, and poor muscle tone also indicate?

Answer 25

Down syndrome. His age and symptoms suggest congenital pyloric stenosis in the context of Down syndrome

Question 26

Congenital pyloric stenosis, which occurs in 0.3% of infants with Down syndrome, is caused by ?

Answer 26

hypertrophy of the circular muscular layer of the pylorus, sometimes detectable on physical exam as a palpable epigastric mass (olive-sized lump).

Question 27

Forceful, postprandial, nonbilious vomiting in the first 2 months of life suggests ?

Answer 27

pyloric stenosis.

Question 28

double-bubble” sign is consistent with?

Answer 28

duodenal atresia.

Question 29

technetium-99m pertechnetate scan is utilized to diagnose?

Answer 29

Meckel diverticulum

Question 30

A corkscrew appearance of the duodenum is evidence of ?

Answer 30

malrotation.

Question 31

Narrowing of the rectum is typically seen with?

Answer 31

Hirschsprung disease.

Question 32

The thickened pylorus is often detectable with ultrasonography. This anomaly results in obstruction of the gastric outlet, causing episodes of nonbilious, forceful vomiting beginning in the first 2 weeks of life. Vomiting can lead to?

Answer 32

dehydration and a hypokalemic, hypochloremic metabolic alkalosis. Treatment involves surgical release of the hypertrophied muscle (pyloromyotomy).

Question 33

misoprostol should not be used to treat NSAID-induced ulcers in women who are pregnant or trying to conceive. Moreover, use of misoprostol during pregnancy is associated with ?

Answer 33

Because it is an abortifacient, birth defects.Misoprostol is a prostaglandin-1 analog used to prevent NSAID-induced peptic ulcers. It increases the production and secretion of gastric mucus and also decreases the production of acid.

Question 34

This patient has a history of an inflammatory injury (tennis elbow). Treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) for pain relief would put this patient at greater risk for development of an NSAID-induced ulcer, given the fact that she also has ?

Answer 34

underlying peptic ulcer disease. misoprostol is also an abortifacient because it inhibits uterine implantation of the blastocyst and may cause birth defects

Question 35

The woman presents with vomiting, flushing, and tachycardia after alcohol consumption, which is a presentation that is highly suggestive of ?

Answer 35

disulfiram-like reaction. These reactions occur when a medication inhibits alcohol metabolism in the liver, leading to an accumulation of acetaldehyde. Since this patient has type 2 diabetes mellitus and is compliant with her medications, chlorpropamide is the likely culprit.

Question 36

Medications that are known to cause disulfiram-like reactions include ?

Answer 36

Sorry Pals, Can’t Go Mingle.

Sulfonylureas (first generation), Procarbazine, certain Cephalosporins, Griseofulvin, and Metronidazole

Question 37

This patient presents with symptoms of chest discomfort that are worse after eating, and exacerbated by lying in a supine position. She also has a bitter taste in the mouth and hoarseness. Together, these symptoms are consistent with?

Answer 37

severe, long-standing gastroesophageal reflux disease (GERD). A normal ECG suggests the patient’s symptoms are non-cardiac.

Question 38

Long-standing untreated GERD can lead to?

Answer 38

Barrett esophagus, which is characterized by metaplasia of squamous esophageal epithelium into intestinal columnar epithelium.

Question 39

Patients with Barrett esophagus are at a higher risk of developing?

Answer 39

esophageal adenocarcinoma. PPIs can be used to reduce symptoms, and patients should undergo surveillance with EGDs to monitor for development of esophageal adenocarcinoma.

Question 40

This patient presents with nausea, bloating, and increased gastric retention, with no evidence of mechanical bowel obstruction. She has also had an elevated HbA1c and gastric retention of 35% at 4 hours. Together these symptoms support a diagnosis of ?

Answer 40

gastroparesis.

Question 41

The patient’s high HbA1c is evidence of poorly controlled diabetes, a common cause of?

Answer 41

delayed gastric emptying. Metoclopramide, a promotility agent, is first-line therapy for this condition. Other drugs that are also effective for gastroparesis include domperidone and erythromycin.

Question 42

Omeprazole is a proton pump inhibitor used to treat ?

Answer 42

acid reflux.

Question 43

Vagotomy is an effective treatment for ?

Answer 43

reducing acid secretion, but it would not address this patient’s gastric retention.

Question 44

This patient presents with failure to pass meconium and abdominal distention. His examination also includes prominent epicanthal folds, flat face, and downward slanting eyes, and a cardiac murmur that is likely a ventricular septal defect (holosystolic murmur best heard at the left sternal border). These findings strongly suggest ? .

Answer 44

Down syndrome

Question 45

his inability to pass meconium is combined with an empty rectum. Overall, the total clinical picture is strongly suggestive of?

Answer 45

Hirschsprung disease, or congenital megacolon.Hirschsprung disease is caused by failure of neural crest cell migration into the bowel wall during embryogenesis. It is characterized by the absence of ganglion cells in the large bowel, typically in the rectum and the adjacent segment of the distal colon that is immediately proximal to the rectum.

Question 46

Patient presents with bloody diarrhea after eating undercooked ground beef. Given her fever, tachycardia, petechiae (a sign of thrombocytopenia), elevated creatinine (which is concerning for renal failure), elevated WBC count, and decreased hemoglobin (which is concerning for anemia), without coagulopathy, this child is likely suffering from?

Answer 46

Hemolytic-uremic syndrome

Question 47

HUS is most commonly associated with infection?

Answer 47

with Shigella dysentariae and Escherichia coli O157:H7– both express shiga-toxin

Question 48

E. coli O157:H7 (EHEC) and Shigella are two foodborne pathogens that can lead to hemolytic-uremic syndrome (HUS). These bacteria secrete protein toxins that enter intestinal cells and inhibit?

Answer 48

protein synthesis by binding ribosomes. Some of the more common manifestations are bloody diarrhea, acute renal failure, and thrombocytopenia.

Question 49

An otherwise healthy adolescent patient presents with vague abdominal pain, mild scleral icterus, and normal AST and ALT levels with direct (conjugated) hyperbilirubinemia. These findings indicate that the patient might have?

Answer 49

Dubin-Johnson syndrome.

Question 50

Dubin-Johnson syndrome is an autosomal recessive, benign disorder in which patients have?

Answer 50

conjugated hyperbilirubinemia due to impaired excretion of conjugated bilirubin and a grossly black liver. A similar disorder, Rotor syndrome, may also present with conjugated hyperbilirubinemia due to impaired hepatic uptake and excretion, but it is milder in presentation, and patients do not have a grossly black liver. Because this patient has vague abdominal pain, the most likely diagnosis is Dubin-Johnson syndrome.

Question 51

This patient presents with decreased libido and worsened heartburn. He reports that he was been taking larger than usual doses of his medication to help with his esophageal reflux (referred to by the patient as heartburn)?

Answer 51

Medications such as cimetidine are possible options for treating esophageal reflux. Cimetidine is an H2-antagonist and is associated with headache, confusion, thrombocytopenia, inhibition of the cytochrome P-450 system, and antiandrogen effects. Increased prolactin release results in gynecomastia, erectile dysfunction, and decreased libido in men.

Question 52

A 45-year-old woman with a history of cholelithiasis presents with generalized, cramping abdominal pain. She noticed the pain 2 days ago on waking and says that it has been getting progressively worse. She has been nauseous, but has had no bouts of emesis.?

Answer 52

small bowel obstruction patients with subacute onset of crampy abdominal pain in the setting of constipation. The diagnosis is made on plain abdominal films that show air-fluid levels.

Question 53

1. Diminished pulses, sunken eyes, and poor skin turgor are signs of ?.
2. The image portrays motile, comma-shaped organisms, which are not lactose-fermenters but are oxidase-positive. This clinical picture strongly suggests that the causative organism is ?.

Answer 53

1. severe dehydration, supporting the patient’s history of severe watery diarrhea
2. Vibrio cholerae

Question 54

Vibrio cholerae causes a secretory diarrhea by ? It is a motile, comma-shaped organism that does not ferment lactose and is oxidase-positive.

Answer 54

irreversibly activating Gs. Gs-α subunit continuously activates adenylyl cyclase, which increases cAMP levels and overactivates protein kinase A (PKA)