1. A 28-year-old nulligravid woman who has been unable to conceive for 2 years undergoes an endometrial biopsy. Her menses occur at regular 28-day intervals. Photomicrographs of the endometrial tissue are shown. This patient is at which of the following phases of her menstrual cycle?

A 23-year-old woman with type 1 diabetes mellitus is brought to the physician for a follow-up examination. She has a 2-year history of recurrent yeast infections. Genetic analysis shows a deficiency of myeloperoxidase. Which of the following is the most likely cause of the increased susceptibility to infections in this patient?

A 9-year-old girl is brought to the emergency department by her father because of severe pain in her right shoulder after a fall 1 hour ago. Physical examination shows pain on movement of the right shoulder and a tender right clavicle. An x-ray of the shoulder shows a nondisplaced fracture of the right clavicle. Which of the following structures of the clavicle will most likely assist in producing new bone to heal this fracture?

A screening program is instituted for detection of vaginal Chlamydia trachomatis infection among first-year women college students. At the initial screening, evidence of C. trachomatis infection is found in 500 of 2500 students. One year later, screening shows vaginal C. trachomatis infection in an additional 200 students. Which of the following is the annual incidence of C. trachomatis infection in this population of women students?

A 10-year-old boy is evaluated because of malaise and dark brown urine for the past 2 days. Laboratory studies show:

A peripheral blood smear is shown. Which of the following is the most likely diagnosis?

A 27-year-old woman has had severe lower left quadrant abdominal pain and vomiting for 3 hours. She is weak and hypovolemic, and frequent pelvic infections. Her last menstrual period began 9 weeks ago and lasted 4 days. Which of the following is the most likely site of the primary pathologic process?

A clinical trial is conducted to compare the efficacy of a surgical procedure versus medical management of gastroesophageal reflux disease. In the study, 800 patients are randomly assigned to either the surgical procedure group or the medical management group; each group consists of 400 patients. Of the patients assigned to the surgical procedure group, 75 do not undergo the operation during the study period. Of the patients assigned to the medical management group, 50 undergo the operation during the study period. In an intention-to-treat analysis, which of the following most accurately represents how many patients would be analyzed in the surgical procedure and medical management groups, respectively?

In an isolated population, a single mutation allele of the cystic fibrosis transmembrane regulator (CFTR) gene is present at a frequency of 0.1. The normal CFTR allele and the mutation allele are in Hardy-Weinberg equilibrium in this population. Which of the following is the approximate frequency of heterozygosity for the mutation in this population?

A 60-year-old man develops pain, erythema, and swelling of the right great toe. Serum uric acid concentration is three times normal. Which of the following findings is most common in patients with this condition?

A 26-year-old woman comes to the physician because of difficulty sleeping caused by intense itching of her arms and legs for 6 days. She has a 2-year history of gluten-sensitive enteropathy. Physical examination shows groups of tense blisters over the upper extremities, buttocks, and knees. Histopathologic examination identifies the lesions as subepidermal blisters. Direct immunofluorescence testing of the basement membrane zone within the blisters is done. The presence of which of the following patterns is most likely to confirm the diagnosis?

An 84-year-old woman is brought to the physician because of a 1-day history of confusion, severe fatigue, and constipation. Three days ago, she was discharged from the hospital after undergoing a total hip replacement. During the 5-day hospital stay, she received intravenous morphine therapy every 6 hours, resulting in pain relief. Her vital signs were within normal limits, and she was oriented to person, place, and time. On discharge, a morphine regimen of an oral-equivalent dose calculated using a standard intravenous-to-oral dose conversion table was prescribed. Today, her temperature is 36.1°C (97°F), pulse is 50/min, respirations are 10/min, and blood pressure is 104/64 mm Hg. Physical examination shows mildly constricted pupils that are poorly responsive to light. Which of the following age-related pharmacokinetic changes best explains this patient’s response to her current dose of oral morphine?

A 27-year-old man who works in a boiler room comes to the physician because he and his 32-year-old wife have been unable to conceive a child for the past 3 years. He had the mumps at the age of 12 years. He tells the physician that his wife was evaluated for infertility and test results were normal. He adds, “Could it be my work? I’ve heard that high temperatures cause infertility.” He is muscular and has a deep voice. Physical examination shows abundant facial and body hair and a normal penis. His testicles are 3 cm long. Semen analysis shows azoospermia. His serum follicle-stimulating hormone and luteinizing hormone concentrations are less than 1 mlU/mL. His serum testosterone concentration is 36 nmol/L (N=10-35). Which of the following is the most likely cause of the development of azoospermia in this patient?

A 43-year-old man with advanced chronic renal failure comes to the physician to discuss the possibility of undergoing kidney transplantation. He also has type 2 diabetes mellitus and hepatitis C. He has been receiving treatment with hemodialysis for 1 year. Before the physician has a chance to initiate the discussion on transplantation, the patient says that he is unsure about receiving a transplant. He adds that if he were to undergo the procedure, he would rather get a donor kidney from one of his relatives than from a cadaver. Which of the following is the most appropriate next statement by the physician?

A 25-year-old woman is brought to the emergency department 4 hours after she fell on an icy sidewalk and landed on her right arm. Examination of the right upper extremity shows decreased strength with elbow flexion. Sensation to pinprick is decreased over the lateral aspect of the forearm. A CT scan-style cross section of the right upper extremity is shown in the figure; the arrow indicates the injured nerve. This patient most likely sustained injury to a nerve supplied by which of the following nerve roots?

A 22-year-old woman comes to the physician 3 months after she noticed a painless, slowly enlarging mass on the left side of her neck. Physical examination shows a freely mobile, soft, cystic mass with a cutaneous surface opening. The physician explains that it is from incomplete fusion during embryonic development. Which of the following is the most likely location of the opening of the duct leading to the mass in this patient?

A 55-year-old man comes to the physician because of a 3-month history of intermittent pain in his right hip. He states that the pain is exacerbated by walking and resolves with rest. Examination of the right hip shows increased pain on abduction. Range of motion is limited by pain. An x-ray of the hip is shown. Which of the following types of collagen is most likely affected in this patient?

A 47-year-old man is admitted to the hospital because of acute pulmonary edema. Treatment is started with nesiritide, a drug that is structurally identical to endogenous human B-type natriuretic peptide. Which of the following is most likely to occur in this patient?

A 55-year-old man comes to the office for an initial visit at the insistence of his wife. He has not seen a physician for the past 15 years. He has a 1 -month history of mild shortness of breath when climbing stairs. He also has had a 23-kg (50-lb) weight gain during the past 15 years. He is 175 cm (5 ft 9 in) tall and now weighs 113 kg (250 lb); BMI is 37 kg/m2. His waist circumference is 107 cm (42 in). His pulse is 95/min, respirations are 20/min, and blood pressure is 160/90 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 97%. Physical examination shows no other abnormalities. Serum studies show:

The physician explains to the patient that he is at significant risk for atherosclerotic heart disease. The most appropriate therapy to decrease this patient’s risk for a myocardial infarction has which of the following effects?

A 16-year-old girl with bulimia nervosa is brought to the physician by her mother because of a 4-month history of nonbloody diarrhea. Her mother is concerned that she is abusing laxatives to maintain a low body weight. The patient is 165 cm (5 ft 5 in) tall and weighs 52 kg (115 lb); BMI is 19 kg/m2. Her temperature is 37.5°C (99.5°F), pulse is 120/min, respirations are 30/min, and blood pressure is 89/61 mm Hg. Which of the following sets of serum electrolyte concentrations is most likely in this patient?

A 25-year-old man sustains perforation of the large bowel in the area of the cecum during a motor vehicle collision. An exploratory operation is planned to resect the affected bowel. To prevent excessive intraoperative hemorrhage in this patient, it is most appropriate to ligate the terminal branch of which of the following arteries?

A slender 58-year-old woman with back pain has a vertebral compression fracture. Bone mineral density is 3.5 standard deviations below peak bone density of a reference group. Laboratory findings are:

Which of the following is the most likely diagnosis?

A 40-year-old woman comes to the physician for genetic counseling because of a family history of muscle weakness. She says that she has not I sought treatment because her symptoms are not severe, but her children have profound muscle weakness and fatigue. Sequence analysis of mitochondrial DNA shows a mutation in 50% of the mother’s mitochondrial DNA and in 100% of each of her children’s mitochondrial DNA. A | pedigree is shown. Which of the following genetic principles best explains the findings in this family?

A 2-month-old boy is brought to the physician because of decreased movement, weakness, and poor suck since birth. His sister died at the age of 2 years because of respiratory insufficiency. He is alert. Physical examination shows poor head control, absent deep tendon reflexes, and generalized hypotonia. Results of a mutation analysis show that he is homozygous for deletion of the survival motor neuron (SMN1) gene. Which of the following is the most likely mode of inheritance in this patient?

A 53-year-old woman is brought to the emergency department because of a 1 -week history of severe chest pain and cough productive of moderate amounts of thick yellow sputum. She currently takes no medications. She is not in acute respiratory distress. Her temperature is 37.6°C (99.6°F), pulse is 95/min, respirations are 32/min, and blood pressure is 120/80 mm Hg. A chest x-ray shows consolidation of the right lower lobe of the lung. Culture of sputum grows Streptococcus pneumoniae. Treatment with antibiotics is started. This patient is most likely to sustain injury to normal pulmonary tissue by inflammatory cells releasing which of the following mediators?

A 56-year-old man comes to the physician because of a 4-day history of fatigue and malaise. He has hypertension treated with a diuretic and an ACE inhibitor and osteoarthritis and gout treated with nonsteroidal anti-inflammatory drugs. Two weeks ago, allopurinol was added to his medication regimen. His temperature is 38.1°C (100.6°F). Physical examination shows an erythematous rash over the anterior trunk. Laboratory studies show:

A renal biopsy specimen shows normal glomeruli and a prominent lymphocytic/histiocytic infiltrate in the periglomerular and peritubular tissues. An occasional eosinophil and rare segmented neutrophils are also present. There is no necrosis. Which of the following is the most likely pathogenesis of the disease process in this patient?

A 12-year-old boy is brought to the physician by his mother because of swelling, itching, and redness of his back that began 10 minutes after he was lying in the grass shirtless. Physical examination shows linear edematous eruptions on the back. A secondary mediator of this patient’s hypersensitivity reaction is produced by mast cells de novo in response to the allergen. After release of histamine, mast cells will begin de novo synthesis of which of the following substances?

An 83-year-old man from Puerto Rico is admitted to the hospital because of abdominal pain and blood in his stool for 1 month. He has had an 11-kg (25-lb) weight loss during this period. The patient speaks little English and is accompanied by his children and extended family. The physician wishes to evaluate the patient for possible colon cancer, including ordering a colonoscopy. The patient’s family requests that he not be told any bad news and that they be allowed to make the decisions about his treatment. Which of the following is the most appropriate next step by the physician?

A 1000-g (2-lb 3-oz) male newborn is delivered at 28 weeks’ gestation to a 25-year-old primigravid woman. Apgar scores are 6 and 8 at 1 and 5 minutes, respectively. Three days after oral feeding is started, he has abdominal distention, and he passes soft, bloody stools. Which of the following is the most likely cause of the bloody stools in this patient?

A 45-year-old woman with chronic liver disease secondary to hepatitis C comes to the physician for a follow-up examination. Abdominal examination shows ascites and hepatosplenomegaly. Serum studies show decreased concentrations of total thyroxine (T4); serum concentrations of thyroid-stimulating hormone (TSH) and free thyroxine (FT4) are within the reference ranges. Which of the following best explains these laboratory results?

A 4-year-old boy is brought to the physician by his parents because of developmental delays and speech difficulty. He has two maternal uncles with intellectual disability. His height and weight are at the 30th percentile. Physical examination shows a large, long head with a prominent jaw, wide forehead, and large ears. There is a high arched palate, and hyperextensible fingers and joints. His speech is difficult to understand, he has a 15-word vocabulary, and he uses single words only. Which of the following is the most likely diagnosis?

A 71-year-old man comes to the physician because of a 6-month history of calf pain and discomfort when he walks more than two blocks; he is unable to walk farther than three blocks. The pain quickly subsides with rest. He also has hypertension and type 2 diabetes mellitus. Physical examination shows weak dorsalis pedis pulses bilaterally and an ankle brachial index of 0.67. The physician knows of a drug that would improve this patient’s symptoms and walking distance by altering platelet function and providing direct arterial vasodilation. This drug is most likely which of the following?

A 24-year-old woman is brought to the emergency department 30 minutes after sustaining abdominal trauma in a motor vehicle collision. She is hypotensive. Rupture of the spleen is suspected. Several attempts to insert a catheter in the left subclavian vein for a blood transfusion are unsuccessful, and she develops worsening dyspnea. Breath sounds are decreased in the left lung. A chest x-ray is shown. Which of the following structures is most likely indicated by the arrows?

A 65-year-old man develops his third episode of pneumonia during the past 8 months. The pneumonias have been localized to the right middle lobe of the lungs. Which of the following studies is most likely to establish the cause of these recurrent pneumonias?

A 3-year-old girl is brought to the physician because of intermittent abdominal pain, constipation, and irritability for 1 month. She lives with her family in a 50-year-old house that is currently being renovated. Physical examination shows pallor. Laboratory studies show a normocytic, hypochromic anemia and an increased plasma concentration of 5-aminolevulinic acid (5-ALA). Her blood lead concentration is 50 pg/dL (N<10). A decreased activity of which of the following enzymes is most likely in this patient?

A 34-year-old man with AIDS comes to the physician because of muscle aches and reddish brown urine for 12 hours. He began treatment with trimethoprim-sulfamethoxazole 1 day ago as prophylaxis against Pneumocystis jirovecii (formerly P. carinii) infection. A sample of blood after centrifugation shows red serum. Which of the following is the most likely explanation for these changes?

A 20-year-old man comes to the physician because of a 2-month history of recurrent headaches. Funduscopic examination shows papilledema and a small retinal lesion consistent with a retinal hemangioblastoma. An MRI of the brain shows a lesion in the cerebellar midline. A CT scan of the abdomen shows cystic lesions in the pancreas. Which of the following is the most likely diagnosis?

The neoplasm indicated by X in the MRI of the head is most likely to first cause which of the following symptoms?

Clomiphene enhances female fertility because of which of the following characteristics?

A 66-year-old woman comes to the physician 1 day after the sudden onset of weakness of her right arm and leg. She has a 6-year history of breast cancer. On physical examination, the tongue deviates to the left when protruded. Neurologic examination shows a right pronator drift and right-sided hemiparesis of the upper and lower extremities. Sensation is intact. Injury to which of the following labeled structures in the photograph of the brain best explains this patient’s hemiparesis?

Development of the metanephros begins with initial specification of the metanephric blastema and sprouting of the ureteric bud and culminates with nephron differentiation and formation of the glomerulus. This cascade required for development of the collecting system and the nephron is best described as a sequence of which of the following interactions?

To assess antigen-presenting cell function in a clinical study, skin explants are cultured from a volunteer and analyzed for Langerhans cell maturation and differentiation. Increased expression of which of the following surface markers is most indicative of Langerhans cell activation in this subject?

The photomicrograph is of a stained stool smear. Chronic infection with this organism is most likely to cause which of the following?

A 70-year-old man has angiodysplasia of the ascending colon. Which of the following is the most likely complication?

A 37-year-old man with HIV infection comes to the physician for a routine examination. He began treatment with zidovudine (AZT), lamivudine (3TC), and efavirenz 8 months ago. Physical examination today shows no abnormalities. Laboratory findings from 6 months ago and today are shown in the table.

The drug resistance in this patient is most likely due to which of the following steps of HIV viral replication?

A 35-year-old woman undergoes flexible nasopharyngoscopy because of chronic episodes of bacterial sinusitis. Purulent discharge from the right sphenoethmoidal recess is noted during the procedure. Which of the following best describes the location of this structure?

An 86-year-old man is brought to the physician because of a 3-week Physical examination shows several ecchymoses and numerous red history of several minor wounds that are healing slowly. He lives alone, and his diet consists of toast and tea. and purple macules around hair follicles. Which of the following best explains these findings?

A female newborn delivered at term is found to have a cleft palate with cleft lip bilaterally. Physical examination shows no other abnormalities. Cranial ultrasonography shows no abnormalities. Failure of fusion at which of the following sites is the primary cause of this patient’s cleft lip?

A 48-year-old man is brought to the emergency department because of a 2-day history of shortness of breath, fatigue, decreased appetite, and cough productive of blood- tinged sputum. He has a 2-month history of hypertension that is currently untreated. His temperature is 37.1°C (98.8°F), pulse is 88/min, respirations are 18/min, and blood pressure is 150/85 mm Hg. Physical examination shows no rash. A few scattered, coarse crackles are heard on auscultation. Laboratory studies show:

Which of the following is the most likely diagnosis?

A previously healthy 54-year-old man comes to the clinic because of light-headedness for 6 hours. His symptom began after skiing at a resort at an altitude of 2743 m (9000 ft). He has been taking a carbonic anhydrase inhibitor since 2 days before arrival at the resort. His blood pressure is 110/60 mm Hg while sitting and 95/50 mm Hg while standing. Physical examination shows no other abnormalities. Which of the following is the most likely cause of his orthostatic hypotension?