STEP - GI Stuffs

What are 3 protective mechanisms that protect the airway during normal swallowing?

1) displacement of larynx superiorly & anteriorly under base of tongue 2) epiglottis tilts to block airway 3) adduction of vocal folds → glottis closed

An 8-month-old boy is brought to clinic due to abdominal distension. The patient has had excessive straining and irritability with bowel movements since birth. He had been exclusively breastfed, and his symptoms worsened after transitioning to pureed foods. Vital signs are normal. Abdominal examination shows distension with mild tenderness to palpation. Bowel sounds are present, and there is no hepatosplenomegaly. Barium enema shows a relatively narrow rectum and rectosigmoid area. The rest of the colon proximal to this segment is significantly dilated. Colorectal biopsy of which of the following areas is most likely to reveal the underlying cause of this patient's condition?

Absence of the submucosal (Meissner) and myenteric (Auerbach) plexuses in Hirschsprung disease causes the affected rectosigmoid region to become narrowed. The submucosa of the narrowed area is the most superficial layer where the absence of ganglion cells can be confirmed during biopsy procedures.

A 34-year-old man comes to the office due to epigastric pain. He has had the pain for several months and describes it as being worse at night and relieved by eating. The patient has no significant medical history and takes no medications. He does not use tobacco, alcohol, or recreational drugs. The patient immigrated to the United States from China 4 years ago. Vital signs are within normal limits. Physical examination shows mild epigastric tenderness to deep palpation. Laboratory testing demonstrates iron deficiency anemia and the presence of fecal occult blood. Upper gastrointestinal endoscopy reveals a 1-cm ulcer in the first portion of the duodenum. Additional test results are pending. In addition to proton pump inhibitor therapy, which of the following would be most appropriate to prevent ulcer recurrence based on this patient's most likely diagnosis?

Abx treatment Most duodenal peptic ulcers are caused by Helicobacter pylori infection. Treatment and prevention of disease recurrence focus on eradicating the infection with antibiotics (eg, tetracycline, metronidazole), typically in combination with PPI (eg, omeprazole) and, often, bismuth subsalicylate (quadruple therapy).

___________ typically occurs in children and young adults and is often initiated by obstruction of the lumen. The most common obstructing agents are fecaliths, hyperplastic lymphoid follicles (eg, following infection), tumors (eg, carcinoid), and nematodes.

Acute appendicitis Mucus accumulates in the lumen of the obstructed appendix, which causes ↑ pressure, appendiceal wall distension, and impaired venous outflow. The resulting ischemia and associated bacterial proliferation lead to inflammation of the appendiceal wall, causing edema, serosal erythema, and purulent exudate. Necrosis of the wall with rupture may follow, and inflammatory fluid and bacterial contents may spill into the peritoneal cavity, causing peritonitis.

Surface ectoderm gives rise to

Anterior pituitary (Rathke) Lens, cornea Inner ear sensory organs Olfactory epithelium Nasal/oral epithelial linings Glands: salivary, epidermis, sweat & mammary

Serology asso'd w/ Celiac Disease?

Anti-gliadin, anti-tTG, anti-endomysial

Neural tube (ectoderm) gives rise to

Brain, spinal cord Posterior pituitary, pineal gland Retina

A 58-year-old man comes to the office with upper abdominal pain, fatigue, and anorexia. He says his symptoms began about a month ago and seem to be getting worse. The patient has a history of cirrhosis due to chronic hepatitis C. Physical examination shows cachexia and worsening ascites. Imaging studies reveal a large mass in the right hepatic lobe consistent with unresectable hepatocellular cancer. The patient is scheduled to undergo percutaneous embolization of the artery supplying the tumor. Contrast material administration into which of the following structures is most likely to visually enhance the artery prior to embolization?

Celiac Trunk The celiac trunk is the first main branch of the abdominal aorta; it provides oxygenated blood to the spleen, stomach, liver, abdominal esophagus, and parts of the duodenum and pancreas. The proper hepatic artery branches off the common hepatic artery from the celiac trunk and provides arterial blood supply to the liver.

A 28-year-old man with vague abdominal pain, low-grade fever, and diarrhea is treated with antibiotics without significant improvement in his symptoms. Several weeks after symptom onset, the patient develops a skin lesion over the abdomen. His temperature is 37.8 C (100 F), blood pressure is 120/70 mm Hg, and pulse is 88/min. On physical examination, the abdomen is mildly distended and tender to palpation. Bowel contents appear to be draining to the surface of the skin in the right lower abdominal quadrant. This patient most likely suffers from which of the following conditions?

Crohn disease typically presents with prolonged diarrhea and abdominal pain. Diarrhea can be bloody if the colon is involved. Constitutional symptoms (eg, low-grade fever, fatigue), malabsorption, and weight loss are also common. Transmural inflammation of the bowel wall may result in the formation of fistulas and fibrotic strictures, causing bowel obstruction. Fistulas can form between 2 adjacent loops of bowel (enteroenteric fistula), between the bowel and another organ (eg, bladder, vagina), or between the bowel and skin of the abdominal wall (enterocutaneous fistula). Perianal fistulas and abscesses are also often seen.

A 46-year-old woman with a history of hiatal hernia and severe gastroesophageal reflux undergoes antireflux surgery. The reflux symptoms were refractory to medical therapy, so an endoscopic fundoplication procedure is performed. During surgery, the hiatal defect is repaired, and the gastric fundus is mobilized and wrapped around the lower esophagus to reinforce the lower esophageal sphincter. No esophageal or gastric injuries occurred, but a neural structure traversing the esophageal hiatus of the diaphragm was inadvertently injured. Which of the following is the most likely potential effect of this operative injury?

Delayed gastric emptying via the anterior & posterior vagal trunks passing through the esophageal hiatus & are vulnerable to injury during fundoplication. Injury to the trunks → delayed gastric emptying (gastroparesis), manifesting w/ abd pain, early satiety & postprandial emesis.

Stomach CA that is not asso'd w/ H. pylori, but due to E-cadherin mut Signet ring cells (mucin) w/ peripheral nuclei Stomach wall is thicccccc w/ leathery appearance (linitis plastica) → early satiety

Diffuse gastric CA (adenocarcinoma > lymphoma > GI stromal > carcinoid tumors) Often asso'd w/ Virchow's node (Troisier sign of malignancy)

A 62-year-old man comes to the physician due to intermittent groin pain. The pain is most severe when the patient lifts heavy loads and after a long day at his job as a construction worker. Physical examination shows a right-sided groin bulge directly above the inguinal ligament. The bulge increases in size when he bears down. An ultrasound reveals that the mass originates medial to the inferior epigastric vessels. This patient's condition is most likely caused by which of the following?

Direct and indirect inguinal hernias are both located above the inguinal ligament. They can be differentiated by their side of origination in relation to the inferior epigastric vessels. Direct inguinal hernias originate medial to the inferior epigastric vessels in older men due to weakness of the transversalis fascia; passing only through the superficial inguinal ring w/ no direct route to the scrotum. Indirect inguinal hernias originate lateral to the inferior epigastric vessels.

An 18-year-old man is admitted to the hospital with cough, fever, and hypoxemia. Despite multiple intravenous antibiotics and frequent chest physiotherapy, the patient decompensates and is transferred to the intensive care unit for mechanical ventilation. Sputum cultures grow >100,000 colony-forming units of a non-lactose-fermenting gram-negative rod. After several days, the patient dies of overwhelming pneumonia complicated by respiratory failure. Since age 1, he had been hospitalized for recurrent episodes of multi-lobar pneumonia, sinusitis, and poor growth. On autopsy, both vas deferens are absent. Which of the following findings is also likely to be present on autopsy?

Distension & obstruction of pancreatic ducts The most common gastrointestinal disorder in patients with cystic fibrosis is pancreatic insufficiency. Mutations in the cystic fibrosis transmembrane conductance regulator gene lead to thick, viscous secretions in the lumens of the pancreas, resulting in obstruction, inflammation, and subsequent fibrosis. Clinical manifestations include steatorrhea, failure to thrive, and deficiency of fat-soluble vitamins.

Lymphatics for above the pectinate line?

Drain to internal iliac LN Above the pectinate line: internal hemorrhoids, adenocarcinoma Internal hemorrhoids receive visceral innervation and are NOT painful

Lymphatics for below the pectinate line?

Drain to the superficial inguinal LN Below the pectinate line: external hemorrhoids, anal fissures, squamous cell carcinoma Ext hemorrhoids receive somatic innervation (inferior rectal branch of pudendal n) → PAINFUL if thrombosed

A 16-year-old boy is brought to the emergency department due to severe retrosternal burning pain and odynophagia for the past 12 hours. The patient has had no fever, sore throat, nausea, vomiting, or abdominal pain. Medical history includes nodulocystic acne, for which he began taking oral doxycycline a week ago. Vital signs are within normal limits. Physical examination shows a normal oropharynx, clear lungs, normal heart sounds, and a nontender abdomen. Upper gastrointestinal endoscopy reveals a small, punched-out ulcer in the proximal esophagus and normal-appearing gastroduodenal mucosa. Doxycycline is presumed to be the culprit. This medication most likely led to this patient's current condition through which of the following mechanisms?

Drug induced direct mucosal injury Pill esophagitis occurs when caustic medications come in contact with the esophageal mucosa for a prolonged time, leading to direct mucosal injury. Common culprits include tetracyclines (eg, doxycycline), bisphosphonates (eg, alendronate), potassium chloride, and nonsteroidal anti-inflammatory drugs. This complication usually develops in locations where the esophageal lumen is compressed by other anatomic structures. Pill esophagitis causes odynophagia and retrosternal chest pain and is usually diagnosed by upper gastrointestinal endoscopy, which reveals discrete ulcerations at the location of medication-induced caustic injury. To avoid this complication, patients should remain upright after swallowing high-risk medications and consume plenty of water to facilitate rapid passage through the esophagus.

A 20-year-old man is evaluated in the clinic due to intermittent episodes of self-resolving jaundice. His symptoms are not provoked by any particular circumstances or events. The patient otherwise feels healthy and has no other symptoms. He does not use tobacco, alcohol, or illicit drugs. Complete blood count is within normal limits. Total protein 6.5 g/dL Albumin 4 g/dL Total bili: 2.8 mg/dL Direct bili: 2.0 mg/dL ALP, AST, ALT: normal Liver biopsy shows abundant pigment inclusions in the lysosomes of the otherwise normal hepatocytes. Electron spin resonance spectroscopy reveals that the pigment is composed of polymers of epinephrine metabolites. Which of the following is the most likely cause of this patient's jaundice?

Dubin-Johnson syndrome is a benign disorder characterized by defective hepatic excretion of bilirubin glucuronides across the canalicular membrane, resulting in direct hyperbilirubinemia and jaundice. Grossly, the liver appears black due to impaired excretion of epinephrine metabolites, which histologically appear as dense pigments within lysosomes.

A 1-day-old girl is evaluated in the nursery due to persistent vomiting and refusal to feed since early in the morning. The vomitus appears green-yellow. It does not contain blood. The infant appears dehydrated. Examination shows a distended abdomen. The remainder of the physical examination is unremarkable. After initial evaluation, the infant undergoes laparotomy. The full length of the duodenum is present. The proximal jejunum ends in a blind pouch. The distal jejunum and proximal ileum are absent. The distal ileum is present and winds around a thin vascular stalk. Which of the following embryologic processes is most likely responsible for this patient's condition?

Dx: intestinal atresia due to vascular occlusion Duodenal atresia: failure of the lumen to recanalize after epithelial proliferation in the first trimester Intestinal atresia of the midgut (eg, jejunum, ileum, proximal colon): vascular occlusion in utero. RF: underlying intestinal abnormality (eg, gastroschisis) or maternal use of vasoconstrictive drugs or substances (eg, nicotine). Compromised perfusion → ischemia of a bowel segment, with subsequent narrowing (stenosis) or obliteration (atresia) of the lumen. This patient most likely developed occlusion of the SMA → ischemia, necrosis, and resorption of the distal small bowel associated with the dorsal mesentery. The jejunum proximal to the ischemic segment ends in a blind pouch, and the ileum distal to the segment spirals around the ileocolic vessel that perfuses it (apple peel atresia).

An 80-year-old man comes to the office for evaluation of persistent dry mouth and difficulty chewing food. He has had no dry eyes or joint pains. The patient has no chronic medical conditions and takes no medications. On examination, there is decreased saliva production but no tenderness or swelling of the salivary glands. Extensive dental caries are present. Laboratory results show negative anti-Ro/SSA and anti-La/SSB antibodies. Which of the following age-related changes is most likely responsible for this patient's symptoms?

Elderly patients have decreased saliva production due to acinar atrophy and fatty infiltration of the salivary glands. Other age-related changes include oral mucosal atrophy; weakening of the muscles of mastication, tongue muscles, and pharyngeal constrictors; and a decreased sense of taste and smell. As a result, elderly patients are at increased risk of dysphagia, malnutrition, and pneumonia

A 23-year-old woman comes to the emergency department due to right wrist pain after a fall. The patient fell on her outstretched hand while walking across the floor at a gym where she exercises regularly. She has no significant medical history and takes no medications. The patient says she avoids eating high-fat or high-carbohydrate foods because she wants to avoid "getting bloated" and "gaining fat." Her last menstrual period was 7 months ago. She does not use tobacco, alcohol, or recreational drugs. Temperature is 35.9 C (96.6 F), blood pressure is 90/58 mm Hg, and pulse is 48/min. BMI is 18 kg/m2. Tenderness and swelling are present over the right distal radius. The parotid glands are enlarged and there are fine, soft hairs on her extremities. Urine pregnancy test is negative. X-ray reveals a nondisplaced fracture of the right distal radius and generalized radiolucency of the bone. Which of the following is the most likely underlying diagnosis?

FHA is a potential manifestation of anorexia nervosa (AN) ↓ BMI (<18.5 kg/m2) Restrictive eating patterns or purging behaviors Physiologic changes arising from chronic caloric deficits and associated clinical starvation (eg, bradycardia, osteoporosis, lanugo [ie, fine, downy body hair]) Distorted body image and abnormal fear of gaining weight BN: cycles of binge eating with purging (eg, vomiting, laxative abuse), and BMI is generally normal or near-normal. Electrolyte disorders are common, but manifestations of clinical starvation, seen in this patient (eg, FHA, lanugo, osteoporosis), are inconsistent with BN

Endoderm gives rise to

GI tract, liver, pancreas, lungs Thymus, parathyroid glands, thyroid follicular cells, parafollicular C-cells Middle ear Bladder, urethra

This hormone is produced primarily in the stomach in response to fasting; levels surge leading up to meals and fall after eating. It stimulates appetite and promotes weight gain.

Ghrelin Caloric restriction and falling fat stores → ↑ levels (along with ↓ leptin and insulin levels), which limits weight loss from dietary modification alone. However, patients who have undergone bariatric procedures that remove a portion of the stomach (eg, roux-en-Y gastric bypass, sleeve gastrectomy) can lose a significant number of the cells that release this hormone. This leads to lower ghrelin levels and less stimulation of appetite in response to fasting, promoting weight loss.

What HLA is asso'd w/ Celiac Disease?

HLA-DQ2 & DQ8 Northern Euro descent Dermatitis herpetiformis (IgA deposition) Intestinal T-cell lymphoma (type IV HSN, T-cell mediated attack) ↓ bone density

A 54-year-old man is evaluated in the clinic due to generalized weakness and lethargy for the past 5 years. He has no history of hypothyroidism or depression. The patient uses acetaminophen intermittently for joint pains that he attributes to "old age." He drinks alcohol occasionally but does not use tobacco or illicit drugs. His older brother died of liver cirrhosis. Laboratory tests show a serum ferritin level of 1800 μg/L. If this patient's disorder is hereditary, the genetic defect responsible for his condition most likely affects which of the following processes?

Hereditary hemochromatosis is most commonly caused by a missense mutation in the HFE gene, resulting in excessive intestinal iron absorption and organ damage (eg, cirrhosis, diabetes mellitus, cardiomyopathy, arthropathy) due to iron accumulation within parenchymal tissues. The HFE protein interacts with the transferrin receptor on the cell surface to facilitate endocytosis of the iron-transferrin complex. Once inside the cell, transferrin is degraded and the released iron is added to the labile iron pool. Mutation of the HFE protein leads to reduced iron uptake and causes enterocytes and hepatocytes to sense falsely low iron levels.

A 27-year-old woman, gravida 1 para 0, with gestational diabetes mellitus comes to the hospital at 38 weeks gestation for evaluation of abdominal pain. The patient is scheduled for an elective cesarean section at 39 weeks as a recent ultrasound revealed that the estimated fetal weight is 5200 g (11 lb 4 oz). Examination reveals that the patient is in active labor and the fetus is in breech presentation; an urgent cesarean section is performed. During the surgery, the rectus abdominus muscle is split vertically, but space appears to be limited. In anticipation of a large-for-gestational-age baby, a decision is made to transect the rectus abdominis muscle. If the rectus abdominis muscle is incised laterally, which of the following structures is at greatest risk of injury?

Horizontal transection of the rectus abdominis muscle must be performed with great caution as the inferior epigastric arteries enter this muscle at the level of the arcuate line. The inferior epigastric arteries below the arcuate line are susceptible to injury (eg, hematoma) due to lack of a supporting posterior rectus sheath.

A 62-year-old man comes to the office for evaluation of abdominal swelling. Over the last few weeks his abdomen has become more distended with associated mild discomfort and decreased appetite. Past medical history includes multiple admissions for alcohol-induced pancreatitis. The patient currently drinks 1 pint of liquor daily and does not use tobacco or illicit drugs. Physical examination reveals mildly icteric sclera and multiple spider angiomas on the upper chest. The abdomen is distended and there is dullness to percussion that changes location when the patient lays on either side. Serum sodium is 130 mEq/dL and creatinine is 1.1 mg/dL. Which of the following would most likely be seen in this patient?

Hx of heavy EtOH use, abd swelling w/ shifting dullness, chronic liver disease & ascites (due to cirrhosis), ↑ sinusoidal blood flow resistance → portal HTN → ↑ vasodilatory factors (NO) Results in: ↓ SVR, blood pooling & ↓ BP → ↑ HR & CO (compensatory) ↓ renal perfusion → RAAS activation & ↑ ADH Aldosterone & ADH → ↑ renal resorption of Na & H2O Despite ↑ total-body vol, cirrhotic patients remain intravascularly depleted & continue to release hypovolemic hormones → chronic ↑ ADH secretion → HYPERVOLEMIC HYPONATREMIA ↑ ADH, ↓ urine Na, ↑ total body vol

A 26-year-old woman with anorexia nervosa is admitted to an eating disorder center for monitored refeeding and weight restoration. The patient reports a history of upper abdominal pain after eating and a frequent need to vomit to relieve symptoms. Blood pressure is 90/60 mm Hg and pulse is 50/min. BMI is 14.8 kg/m2. On physical examination, the patient is cachectic with a sunken, nontender abdomen. A progressively increasing oral refeeding plan is prescribed. On the fourth day, the patient experiences severe abdominal pain, nausea, and vomiting after a meal. CT scan of the abdomen with oral contrast reveals a marked lack of intraabdominal fat, a significantly dilated stomach, and an abrupt cutoff of oral contrast at the third segment of the duodenum. Compression by which of the following structures is most likely causing this patient's gastrointestinal symptoms?

In states of extreme weight loss (eg, severe anorexia nervosa) and/or hypercatabolism (eg, refeeding hypermetabolism), mesenteric fat is depleted. This collapses the angle between the superior mesenteric artery (SMA) and aorta (aortomesenteric angle), allowing the SMA to impinge on intervening structures. This may result in partial to complete compression of the

Stomach cancer that is asso'd w/ H. pylori, smoked foods, tobacco, chronic gastritis; what location is most common?

Intestinal gastric CA (adenocarcinoma > lymphoma > GI stromal tumor > carcinoid) Commonly located on the lesser curvature, looks like ulcer w/ raised margins Irregular tubular histology

If gastric CA mets hematogenously to ovaries...what is it called?

Kruckenberg tumor Biopsy: signet ring cells w/ mucin - this will be present BILATERALLY! (mucinous cystadenocarcinoma is unilateral) MAC: unilateral, pseudomyxoma peritonei (jelly belly), locular appearance SAC: bilateral

This hormone is produced primarily by fat cells in response to short-term food intake and long-term adequacy of fat stores. It acts on the hypothalamus to ↓ appetite (obesity blunts this action). During fasting states, ______ levels fall.

Leptin

_____________ classically causes painless hematochezia but can present with acute abdominal pain if inflamed, is an anatomic connection between the ileum and umbilicus resulting from incomplete obliteration of the vitelline duct. This congenital anomaly is a consisting of all 3 layers of the intestinal wall (mucosa, submucosa, and muscularis).

Meckel diverticulum

A 2-year-old girl is brought to the emergency department with intermittent pain in the abdomen that began several hours ago. The patient also had a bowel movement that appeared tinged with blood. Ultrasound shows an area along the ileum in which the proximal small intestine is telescoped into the distal small intestine. Reduction via enema is unsuccessful, and the patient undergoes laparotomy with resultant resection of the involved intestine. The pathologic finding at the lead point is shown in the exhibit. Which of the following is the most likely underlying diagnosis in this patient?

Meckel diverticulum is the most common pathologic lead point for intussusception (in kids), a condition in which a portion of the intestine telescopes into itself. Meckel diverticula frequently contain ectopic gastric mucosa, which can aid in diagnosis.

A 4-year-old girl is brought to the office after her parents noticed dark red blood on her toilet tissue after a bowel movement. She has had no abdominal pain, dysuria, or discomfort with defecation. The girl has no known medical conditions and takes no medications. Temperature is 36.7 C (98.1 F), blood pressure is 100/40 mm Hg, and pulse is 112/min. Examination shows a soft and nontender abdomen, and bowel sounds are present. Hemoglobin is 8 g/dL Platelet count is 215,000/mm3. Coagulation studies are normal. Sequential imaging using 99mTc-pertechnetate scintigraphy demonstrates focal radiotracer accumulation in the right lower quadrant. Which of the following embryologic processes most likely resulted in this patient's condition?

Meckel diverticulum results from incomplete obliteration (or persistence) of the vitelline duct and usually presents with painless lower gastrointestinal bleeding. 99mTc-pertechnetate localizes to heterotopic gastric mucosa that is often contained within a Meckel diverticulum, and uptake in the periumbilical area or right lower quadrant is diagnostic.

Hyperplasia of gastric mucosa (foveolar cells) → ↑ mucous production w/ protein loss & parietal cell atrophy → ↓ acid & IF production

Menetrier disease can be caused by CMV infx Precancerous (adenoCA), weight loss, anorexia, vomiting, epigastric pain, edema Achlorhydria & ↓ IF due to parietal cell loss foveolar cells are generally protective & line surface of stomach

________ stimulates smooth muscle contraction in the upper GIT & generally ↑ gastric motility. Although secretion appears to ↑ during fasting and ↓ following meals, it is produced primarily in the duodenal mucosa rather than the stomach.

Motilin

Mesoderm gives rise to

Muscle (all), bone, kidney/ureters, adrenal cortex, spleen, HSC CT, bone, cartilage Serosal linings CV system & lymphatics Internal genitalia

Below pectinate line

Nerves: somatic innervation Artery: Inferior rectal (internal pudendal) Veins: Inferior rectal Lymph: superficial inguinal LN

Above pectinate line

Nerves: visceral innervation Artery: Superior rectal (IMA) Veins: Superior rectal Lymph: Internal iliac LN

Neural crest (ectoderm) gives rise to

Neural ganglia, adrenal glands Schwann cells, pia/arachnoid matter Aorticopulmonary septum, endocardial cushions Skull bones Melanocytes

Researchers studying neural crest cell migration in a human fetus observe normal activity beginning at the 8th week of embryogenesis with interruption during the 12th week, when migration is typically completed. Which of the following structures is most likely to lack innervation as a result of this disruption?

Normally, neural crest cells start migrating to the intestinal wall in early embryogenesis and give rise to ganglion cells of the submucosal (Meissner) and myenteric (Auerbach) plexus of the bowel wall. These parasympathetic ganglia are responsible for intestinal peristalsis. Neural crest cells enter the developing foregut mesenchyme and then migrate caudally along the entire length of the bowel; they are present in the wall of proximal colon by the 8th week of gestation and in the rectum by the 12th week. The arrest of migration of neural crest cells causes Hirschsprung disease, in which a distal segment of colon lacks ganglion cells. Because neural crest cells migrate caudally, the rectum is always involved. The absence of parasympathetic ganglia in the colonic wall causes the affected segment to be narrowed because it cannot relax. The passage of intestinal contents through this area is difficult, and compensatory dilation of the proximal colon occurs.

A 62-year-old man comes to the office due to gnawing epigastric pain radiating to the back, which started 3 months ago and has become increasingly intense. He has also experienced a 10-kg (22-lb) weight loss and yellowing of the eyes. The patient has smoked 4 or 5 cigarettes a day for most of his life. Vital signs are within normal limits. The patient appears cachectic. Examination shows scleral icterus. The abdomen is tender to deep palpation. Abdominal CT scan shows a mass in the body of the pancreas. This patient's abdominal lesion most likely originated from which of the following?

Pancreatic duct epithelium This patient's abdominal lesion most likely originated from which of the following Pancreatic ductal adenocarcinoma is the most common pancreatic malignancy and typically presents with epigastric pain, weight loss, jaundice (more common if in the pancreatic head), or back pain (more common if in the pancreatic body/tail). It appears radiographically as an ill-defined hypoattenuating lesion within the pancreatic parenchyma. It is characterized microscopically by haphazardly arranged pleomorphic glandular cells surrounded by dense stromal fibrosis (eg, desmoplasia).

A 45-year-old man comes to the office due to fatigue, lack of sexual desire, and inability to maintain an erection. A year ago, he was advised to lose weight with diet and exercise due to mildly elevated fasting glucose levels. The patient has smoked a pack of cigarettes daily for the past 20 years and drinks an alcoholic beverage 3-4 times per month. Blood pressure is 110/70 mm Hg and pulse is 65/min. Oxygen saturation is 99% on room air. BMI is 29 kg/m2. Skin examination shows increased pigmentation over the knuckles and face. The liver is palpable 3-4 cm below the right costal margin. The remainder of the examination reveals small testes. Which of the following is most likely contributing to the development of the patient's symptoms?

Patient is experiencing hypogonadism (↓ libido, erectile dysfunction, testicular atrophy), hyperpigmentation of skin, ↑ glucose/DM & hepatomegaly → point towards hereditary hemochromatosis Hereditary hemochromatosis can cause secondary hypogonadism due to deposition of iron in the pituitary gland, resulting in decreased gonadotropin secretion. Patients who develop secondary hypogonadism are also at risk for deficiencies in other pituitary hormones (eg, central hypothyroidism).

A 62-year-old woman comes to the office for diarrhea. She has had 4 or 5 watery, brown stools every day for the past 6 months. Although most episodes occur during the day, she wakes up at least once a night to defecate. There is no associated hematochezia, melena, vomiting, or unexpected weight loss. Medical history is significant for type 2 diabetes mellitus and hypertension. She takes lisinopril, insulin, and metformin. She has no recent travel or new medications. Family history is unremarkable. She does not drink alcohol. Temperature is 37.4 C (99.3 F), blood pressure is 125/80 mm Hg, and pulse is 80/min. The abdomen is nontender and nondistended. Complete blood count, serum chemistries, and stool studies are normal. Which of the following is the most likely cause of this patient's diarrhea?

Prolonged hyperglycemia in diabetes mellitus can injure the parasympathetic and sympathetic nervous system, resulting in diabetic autonomic neuropathy. This can lead to disordered small-bowel and colonic motility and increased intestinal secretions, resulting in secretory-like diarrhea (eg, fasting bowel movements).

_________ is a nonabsorbable antibiotic that alters GI flora to ↓ intestinal production and absorption of ammonia.

Rifaximin Rifaximin is also sometimes used for traveler's diarrhea, as it inhibits bacterial RNA synthesis through binding with DNA-dependent RNA polymerase. It's generally used in addition to lactulose, which is catabolized by intestinal bacterial flora to short-chain fatty acids, lowering the colonic pH and ↑ conversion of ammonia to ammonium.

A 54-year-old man comes to the emergency department after vomiting blood. He has also had melena, fatigue, and lethargy over the last 24 hours. The patient emigrated from sub-Saharan Africa 20 years ago and occasionally returns to visit friends and family. Temperature is 37.5 C (99.5 F), blood pressure is 90/60 mm Hg, and pulse is 115/min. Abdominal palpation reveals an enlarged liver and a spleen tip below the level of the umbilicus. Laboratory results are as follows: Complete blood count Hemoglobin 5.2 g/dL Platelets 75,000/mm3 Leukocytes 8,000/mm3 Neutrophils 79% Eosinophils 15% Lymphocytes 6% Upper endoscopy reveals bleeding esophageal varices. Which of the following is the most likely underlying cause of this patient's symptoms?

Schistosomiasis, a parasitic blood fluke infection, is common in rural portions of sub-Saharan Africa. Initial infection is often asymptomatic, but some patients develop chronic hepatosplenic (eg, portal hypertension, hepatosplenomegaly, esophageal varices) or urinary (eg, bladder cancer) complications years or decades later. The presence of eosinophilia is an important diagnostic clue. Exposure to Schistosoma occurs when humans swim in freshwater contaminated by infected snails → migrate to the liver, where they mature to adult worms. Adult worms then spread through the portal circulation & release eggs into host tissue that are excreted in the feces or urine. Patients frequently have anemia from intestinal/variceal bleeding, thrombocytopenia from splenic trapping of platelets, and eosinophilia in response to adult worms.

An 87-year-old woman comes to the office to discuss treatment for colon cancer, which was recently diagnosed by colonoscopy. CT scan was negative for metastatic disease. The patient has no other medical conditions, and family history is unremarkable. She does not drink alcohol. Vital signs are normal. A chemotherapy regimen containing a medication that is primarily metabolized by the liver is chosen for therapy. Because of the patient's age, the physician is considering adjusting the dose to prevent adverse effects. Which of the following parameters is likely to be the most similar between this patient and a healthy 40-year-old individual?

Serum aminotransferase levels are unchanged Effects of aging on liver: 1. ↓ liver size & mass 2. ↓ hepatic perfusion 3. ↓ regenerative capacity 4. ↓ P450 system 5. ↓ protein synthesis 6. ↑ hepatocyte size 7. ↑ polyploidy 8. Accumulation of lipofuscin

Fibrosis and focal lymphocytic infiltration into the salivary glands are seen in __________, an autoimmune disease impacting exocrine glands (eg, salivary, lacrimal, vaginal). Although patients often have dry mouth, they also typically have dry eyes and positive anti-Ro/SSA and/or anti-La/SSB antibodies

Sjögren syndrome

A 35-year-old man comes to the emergency department due to persistent abdominal pain. Yesterday, during a soccer game, he collided with another player while running at full speed. The patient had abdominal pain at the time but did not seek care until this morning when the pain seemed to worsen. It is suspected that he has an injury involving an organ that is supplied by an artery of the foregut although the organ itself is not a foregut derivative. Which of the following organs is most likely to be injured in this patient?

Spleen Organ damage from blunt abdominal trauma (eg, collision while running at full speed) most commonly involves the spleen and liver and less commonly the kidneys. The spleen is an intraperitoneal organ derived from the mesoderm of the dorsal mesentery. However, the spleen is unique in that its blood supply originates from a foregut derivative (the splenic artery from the celiac trunk). Venous return from the spleen courses through the splenic vein to the portal circulation rather than to the systemic circulation.

What stain do we use to scan for fecal fat?

Sudan Stain

A 45-year-old woman comes to the office due to several months of episodic right upper quadrant abdominal pain associated with nausea. The pain is often brought on by fatty meals and subsides in 1-2 hours. The patient has no fever, vomiting, diarrhea, melena, or bright red blood per rectum. Her BMI is 31.2 kg/m2. Physical examination is unremarkable. A cholecystokinin stimulation test is performed and shows slow and incomplete gallbladder emptying. This patient is most likely to have which of the following pathologic findings?

The gallbladder functions to actively absorb water from bile. Gallbladder hypomotility causes the bile to become concentrated, promoting precipitation and accumulation of particulate material. This forms a viscous biliary sludge that can cause transient bile duct obstruction (biliary colic) and promote cholesterol gallstone formation.

71-year-old man comes to the emergency department due to several episodes of bright red blood per rectum. His recent colonoscopy revealed numerous colonic diverticula. Laboratory studies on admission are notable for a hemoglobin of 8.2 g/dL with an unremarkable coagulation profile. An abdominal angiogram shows active bleeding from the sigmoid colon. Catheter embolization is planned via the femoral artery. During the procedure, the arterial catheter is most likely to proceed in which of the following orders?

The hindgut encompasses the distal one-third of the transverse colon, the descending colon, the sigmoid colon, and the rectum. These structures receive their main arterial blood supply from the inferior mesenteric artery.

A 47-year-old morbidly obese woman comes to the physician seeking advice regarding weight loss. She has tried diet and exercise a number of times without success. Her other medical problems include type 2 diabetes mellitus and obstructive sleep apnea. Her body mass index is 43 kg/m2. After a discussion about available surgical options, she expresses interest in the adjustable gastric band, an inflatable silicone device that is placed around the cardiac part of the stomach. In order to encircle the stomach, the band must pass through which of the following structures?

The lesser omentum is a double layer of peritoneum that extends from the liver to the lesser curvature of the stomach and the beginning of the duodenum. It is divided into the hepatogastric and hepatoduodenal ligaments.

A 23-year-old man comes to the physician due to a 2-month history of fatigue, malaise, and abdominal discomfort. He is found to have tender hepatomegaly with elevated liver function tests. The patient has never been vaccinated against hepatitis. He has had no raw or uncooked foods recently and recalls no ill contacts. There is no history of blood transfusion. The patient is a graduate student who immigrated to the United States 2 years ago and has not traveled outside the country since. He smokes 2 packs of cigarettes a day and consumes 1 or 2 bottles of beer on weekends. The patient does not use illicit drugs. He has had several episodes of unprotected sex with different female partners within the past year. Which of the following is most likely to be present in this patient?

The main modes of transmission of HBV are sexual and percutaneous. Vertical (mother-to-child) transmission is common in high-prevalence areas. This unvaccinated patient with tender hepatomegaly and liver function abnormalities most likely has acute HBV infection. Serum hepatitis B surface antigen (HBsAg) would be present. Anti-HBsAg immunoglobulin G (IgG) appears after either successful HBV vaccination or HBsAg clearance and remains detectable for life (indicator of non-infectivity and immunity). Because this patient is symptomatic, he has not cleared the virus and would likely not yet have anti-HBsAg IgG

A 65-year-old man with a history of hypertension, type 2 diabetes mellitus, and tobacco smoking comes to the office reporting mild back pain. Abdominal examination reveals a bruit, but no pulsatile mass is palpated. Femoral and pedal pulses are symmetric. The patient is sent for ultrasound and is found to have a large infrarenal abdominal aortic aneurysm. Open aneurysm repair is performed. During the procedure, the inferior mesenteric artery is ligated, the diseased portion of the aorta is dissected, and a graft is placed from below the renal arteries to the bifurcation of the aorta. Collateral circulation from which of the following vessels is most likely responsible for preventing ischemia of the descending colon?

The superior mesenteric artery and inferior mesenteric artery are the 2 main vessels supplying the small and large intestines. They are connected by a pair of anastomoses: the marginal artery of Drummond, which is the principal anastomosis, and the inconsistently present arc of Riolan (mesenteric meandering artery).

A 67-year-old man comes to the office due to dark urine, pale-appearing stools, and progressive yellowing of his eyes over the last few weeks. He also reports unintentional weight loss, but has had no night sweats, abdominal pain, bloody stools, or vomiting. He has no chronic medical conditions and takes no medication. Vital signs are within normal limits. Scleral icterus is present. The neck is supple. No lymphadenopathy or skin abnormalities are present. There is no hepatosplenomegaly. Laboratory results are as follows: Total Bilirubin: 7.2 mg/dL ALP: 398 U/L CT scan of the abdomen reveals a pancreatic mass compressing the common bile duct and the pancreatic duct. This patient's disease process is most likely caused by a mutation affecting which of the following genes?

The vast majority (>85%) of obstructing pancreatic masses are due to pancreatic ductal adenocarcinoma. The major genomic abnormality in pancreatic ductal adenocarcinoma is KRAS-activating mutation (oncogene), which allows tumor cells to grow and divide without input from the cellular milieu due to aberrant activity that relays a continuous growth signal to the nucleus. Because KRAS mutations are one of the earliest oncogenic mutations in pancreatic adenocarcinoma, tests for KRAS abnormalities are being developed to help with early detection. Many colorectal cancers and non-small cell lung cancers also have KRAS-activating mutations.

A 3-year-old boy is brought to the emergency department by his parents after he develops acute abdominal pain and vomiting. Examination shows diffuse tenderness to palpation, and abdominal imaging reveals a foreign body lodged within the intestine, causing a small bowel obstruction. Laparotomy is performed to remove the foreign body; during the procedure, an incidental cyst is discovered. The cyst is connected by a fibrous band to the ileum and the umbilicus. The embryologic defect underlying the formation of this patient's cyst is also associated with which of the following?

The vitelline (omphalomesenteric) duct normally obliterates during early embryologic development. Incomplete obliteration can result in a spectrum of anomalies, including vitelline duct cyst (ie, cyst connected by fibrous bands to the ileum and umbilicus) and Meckel diverticulum.

A 3-week-old-girl in the neonatal intensive care unit develops abdominal distension, vomiting, and blood-streaked stools. She had previously tolerated formula feeds and had normal stool and urine output. She was born at 27 weeks gestation to an 18-year-old-mother. The pregnancy was complicated by premature rupture of membranes and preterm delivery. Abdominal x-ray shows thin curvilinear areas of lucency that parallel the bowel wall lumen. Which of the following is the most likely diagnosis?

This infant has pneumatosis intestinalis (ie, air in the bowel wall), which can be seen on abdominal x-ray as thin curvilinear areas of lucency that parallel the lumen. Infants w/ abdominal distension and bloody stools → NEC It occurs predominantly in preterm infants secondary to gastrointestinal and immunologic immaturity. Impaired mucosal barrier function allows the bacteria to invade the bowel wall, causing inflammation and ischemic necrosis of the terminal ileum and colon.

A 47-year-old man comes to the office due to dysphagia. The patient says that it feels like food has been getting stuck in his throat over the last month. He has changed his diet to accommodate his symptoms and now consumes only liquid foods. The patient has a long history of postprandial heartburn that sometimes awakens him from sleep. He has treated his heartburn with over-the-counter antacids but usually only has partial relief. A thoracic CT image near the level of the aortic arch is done. This patient's symptoms are most likely related to pathology involving which of the following structures?

This patient's prolonged history of heartburn is suggestive of GERD, a condition that affects the esophagus. Dysphagia (ie, difficulty swallowing) is common in patients with longstanding GERD and can be caused by impaired peristalsis, esophageal inflammation/stricture, or malignancy. In the thorax, the esophagus courses between the trachea and vertebral bodies and is typically collapsed with no visible lumen.

A 58-year-old man comes to the emergency department with a 1-day history of fever, headache, and vomiting. He underwent kidney transplantation last year. His temperature is 39.4 C (103 F), blood pressure is 130/80 mm Hg, pulse is 98/min, and respirations are 16/min. Neck stiffness is present on physical examination. Cerebrospinal fluid (CSF) results are as follows: Glucose 40 mg/dL Protein 80 mg/dL Leukocytes 900/mm3 Neutrophils 80% Gram-positive rods with tumbling motility at room temperature are seen on CSF microscopy. How was this patient's infection most likely transmitted?

This patient, who is likely taking immunosuppressants given his kidney transplantation, has fever, headache, neck stiffness, and cerebrospinal fluid (CSF) findings suggestive of bacterial meningitis. There is CSF pleocytosis (elevated leukocyte count) with left shift, ↑ protein, and low-normal glucose (low CSF glucose is seen in most though not all bacterial meningitis cases); and bacteria are seen on CSF microscopy. Listeriosis is most commonly transmitted through food ingestions and can cause meningitis in immunocompromised adults. Listeria is a gram-positive rod with tumbling motility. It grows well in cold temperatures and can therefore contaminate refrigerated food.

A 14-year-old boy is brought to the physician by his mother due to chronic diarrhea and failure to gain weight appropriately. He has a history of recurrent respiratory infections, and prior sputum cultures have been positive for Pseudomonas aeruginosa. His younger brother died from a severe respiratory infection at age 9. Which of the following agents is most likely to improve this patient's condition in the long term?

This young patient has a history of recurrent respiratory infections caused by Pseudomonas aeruginosa, chronic diarrhea, and FTT. These findings, along with a family history of early sibling death from pulmonary infection, suggest a diagnosis of cystic fibrosis. Steatorrhea and failure to thrive occur as a result of malabsorption due to obstructive fibrosis and progressive insufficiency of the exocrine pancreas. Pancreatic lipase supplementation is likely to improve this patient's condition by enhancing macronutrient and vitamin absorption.

The most common gastrointestinal abnormality associated with __________ is duodenal atresia.

Trisomy 21 ↑ nuchal translucency on US ↓ maternal serum α-FP Duodenal atresia: failure of duodenal lumen to recanalize → intestinal obstruction → double bubble sign, bilious emesis Trisomy 21 also at risk for imperforate anus & tracheoesophageal fistula

Asso'd w/ PAS (+) foamy MO in lamina propria of SI & mesenteric nodes Cardiac sx, Arthralgias & Neuro sx are common w/ diarrhea & steatorrhea later in the course Commonly seen in older men

Whipple Disease caused by Tropheryma whipplei Intracellular gram (+) organism; rod bacilli (sickle) Look for triad of CAN

The ___________ provide parasympathetic innervation to the bowel and bladder, and their impairment in cauda equina syndrome can cause constipation and difficulty urinating. Other signs of cauda equina syndrome include radicular low back pain and leg weakness (sciatic nerve) as well as saddle anesthesia (pudendal, ilioinguinal nerves).

pelvic splanchnic nerves (S2-S4)

A 45-year-old woman diagnosed with Crohn disease 3 years ago comes to the office due to recurrent right upper quadrant abdominal pain. The pain is graded 5/10 in intensity, is characterized as dull, and occasionally radiates to the right shoulder. It typically occurs after eating fatty meals and is associated with nausea. The patient has no fever, vomiting, melena, or hematochezia. She currently takes infliximab for Crohn disease and atorvastatin for hyperlipidemia. Vital signs and abdominal examination are normal. Abdominal ultrasonography reveals multiple mobile calculi within the gallbladder. Which of the following processes is most likely responsible for the development of gallstones in this patient?

↑ bile acid wasting Patients with Crohn disease affecting the terminal ileum (most common site of involvement) are prone to developing gallstones. The terminal ileum is a typical location of activity in Crohn disease. When the mucosa of the terminal ileum is inflamed, bile acids are lost in the feces. As a result, a lesser amount of bile acid is present in the bile, so the ratio of cholesterol/bile acids increases. Supersaturation of the bile with cholesterol then leads to formation of gallstones.

A 43-year-old woman comes to the office with a 1-month history of dull abdominal pain that occurs mainly after eating. The pain is localized to the right upper quadrant and is especially severe after fatty meals. Physical examination is unremarkable. Ultrasound of the abdomen reveals several mobile echogenic foci within the gallbladder lumen. Which of the following sets of conditions is most likely present within this patient's gallbladder? What are the levels for cholesterol, bile acids & phosphatidylcholine?

↑ cholesterol concentrations → ↑ likelihood of cholesterol precipitation and gallstone formation. ↑ levels of bile salts and phosphatidylcholine → ↑ cholesterol solubility and ↓ risk of gallstones ↑ cholesterol & ↓ bile acids & phosphatidylcholine levels

This patient's recurrent epigastric pain after eating fat- and protein-rich meals strongly suggests biliary colic from underlying gallstones and/or biliary sludge. Most commonly, gallstones are cholesterol based, often developing in persons older than age 40. Elevated ____________ exposure significantly ↑↑ the risk because it stimulates cholesterol-rich bile secretion. When bile becomes supersaturated with cholesterol, microscopic crystal formation creates a thick slurry (biliary sludge), with further aggregation producing gallstones. On detecting fat- and protein-rich chyme, I-cells lining the duodenum and jejunum release ________ , causing the gallbladder to contract. This contraction may force gallstones and sludge against the gallbladder outlet; the resulting occlusion ↑↑ intragallbladder pressure, → pain that is typically felt in the right subcostal or epigastric region.

↑ estrogen exposure CCK (Cholecystokinin); as CCK levels wane, the gallstones and sludge fall back, relieving pressure (ie, a postprandial waxing-waning pain pattern). CCK also ↑ pancreatic enzyme secretion and relaxes the sphincter of Oddi, thereby orchestrating fatty and amino acid absorption.

A 35-year-old woman comes to the office due to malaise and generalized weakness. The patient has type 1 diabetes mellitus and hypothyroidism for which she takes insulin and levothyroxine. She eats a balanced diabetic diet and exercises 5 times per week. Physical examination shows mild conjunctival pallor. Laboratory results are as follows: Hemoglobin 10 g/dL Mean corpuscular volume 118 µm3 Folate, serum9 ng/mL (normal: 2.5-20) Vitamin B12, serum60 pg/mL (normal: 200-800) Which of the following changes are most likely to be present in this patient? Serum gastrin = ? Gastric pH = ? Gastric parietal cell mass = ?

↑ pH, ↑ gastrin, ↓ parietal cell mass (collectively) Pernicious anemia is an autoimmune disease characterized by CD4+ cell-mediated destruction of parietal cells. Because these cells normally produce hydrochloric acid, patients with pernicious anemia have elevated gastric pH, which upregulates gastrin secretion. Decreased parietal cell secretion of intrinsic factor also results in vitamin B12 deficiency (eg, megaloblastic anemia).

A 33-year-old man with a 2-year history of Crohn ileocolitis comes to the clinic with left-sided flank pain that started in the morning. The pain is 8 on a scale of 0-10 in intensity and is characterized as sharp. The pain is also colicky and radiates to the left groin. The patient has no nausea or vomiting. He is in moderate distress and has trouble lying still during the examination. Urinalysis shows hematuria. A day later, the patient passes a urinary stone. Abdominal imaging reveals several additional kidney stones. Which of the following is the most likely underlying cause of this patient's kidney stones?

↓ intestinal Ca-oxalate formation Crohn disease is associated with oxalate kidney stones. Impaired bile acid absorption in the terminal ileum leads to loss of bile acids in feces with subsequent fat malabsorption. Intestinal lipids then bind calcium ions, and the resulting soap complex is excreted. Free oxalate (normally bound by calcium to form an unabsorbable complex) is absorbed and forms urinary calculi (enteric oxaluria).