Wilms tumor — MCQs

10 questions

A 63-year-old man presents with a 2-month history of increasing sensation of fullness involving his left flank. The patient reports recent episodes of constant pain. The patient is hypertensive (145/90 mm Hg) and is currently on medications including losartan and hydrochlorothiazide. His past medical history is otherwise unremarkable. He is a 30-pack-year smoker. His temperature is 37.7°C (99.9°F); pulse, 76/min; and respiratory rate, 14/min. Palpation of the left flank shows a 10 x 10-cm mass. The patient's laboratory parameters are as follows: Blood Hemoglobin 19.5 g/dL Leukocyte count 5,000/mm3 Platelet count 250,000/mm3 Urine Blood 2+ Protein negative RBC 45/hpf without dysmorphic features Abdominal CT scan confirms the presence of a large solid mass originating in the left kidney. These findings are most consistent with which of the following conditions?

A laboratory physician investigates the chromosomes of a fetus with a suspected chromosomal anomaly. She processes a cell culture obtained by amniocentesis. Prior to staining and microscopic examination of the fetal chromosomes, a drug that blocks cell division is added to the cell culture. In order to arrest chromosomes in metaphase, the physician most likely added a drug that is also used for the treatment of which of the following conditions?

A 3-year-old girl is brought to her pediatrician with 2 days of fever and abdominal pain. She has also been crying and complaining of pain while urinating. She was born at term without incident and was previously healthy at regular checkups. On presentation, her temperature is 102.2°F (39°C), blood pressure is 137/85 mmHg, pulse is 122/min, and respirations are 24/min. Physical exam reveals a palpable, painless, abdominal mass that does not cross the midline. Which of the following additional findings would be associated with this patient's disorder?

A 12-year-old boy comes to the physician for the evaluation of intermittent blood-tinged urine for several months. Four months ago, he had an episode of fever and sore throat that resolved without treatment after 5 days. During the past 2 years, he has also had recurrent episodes of swelling of his face and feet. 5 years ago, he was diagnosed with mild bilateral sensorineural hearing loss. His brother died of a progressive kidney disease at the age of 23. The patient appears pale. His temperature is 37°C (98.6°F), pulse is 70/min, and blood pressure is 145/85 mm Hg. Slit lamp examination shows a conical protrusion of both lenses. Laboratory studies show a hemoglobin concentration of 11 g/dL, urea nitrogen concentration of 40 mg/dL, and creatinine concentration of 2.4 mg/dL. Urinalysis shows: Blood 2+ Protein 1+ RBC 5–7/hpf RBC casts rare Which of the following is the most likely underlying cause of this patient's symptoms?

A 61-year-old man comes to the physician because of several episodes of dark urine over the past 2 weeks. He does not have dysuria or flank pain. He works in a factory that produces dyes. Since an accident at work 5 years ago, he has had moderate hearing loss bilaterally. He takes no medications. He has smoked a pack of cigarettes daily for 29 years and drinks one alcoholic beverage daily. Vital signs are within normal limits. Physical examination shows no abnormalities. His urine is pink; urinalysis shows 80 RBC/hpf but no WBCs. Cystoscopy shows a 3-cm mass in the bladder mucosa. The mass is resected. Pathologic examination shows an urothelial carcinoma with penetration into the muscular layer. An x-ray of the chest and a CT scan of the abdomen and pelvis with contrast show a normal upper urinary tract and normal lymph nodes. Which of the following is the most appropriate next step in management?

A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?

A 25-year-old man comes to the physician because of right-sided painless scrotal swelling that he noticed yesterday while taking a shower. He is currently sexually active with two female partners and uses condoms inconsistently. He immigrated to the US from Argentina 2 years ago. His immunization records are unavailable. He has smoked one pack of cigarettes daily for the last 5 years. He is 170 cm (5 ft 7 in) tall and weighs 70 kg (154 lb); BMI is 24.2 kg/m2. He appears healthy and well nourished. His temperature is 37°C (98.6°F), pulse is 72/min, and blood pressure is 125/75 mm Hg. The lungs are clear to auscultation. Cardiac examination shows no abnormalities. The abdomen is soft with dull lower abdominal discomfort. Testicular examination shows a solid mass in the right testis that is firm and nontender. A light held behind the scrotum does not shine through. The mass is not reduced when the patient is in a supine position. The remainder of the physical examination shows no abnormalities. Which of the following is the most likely diagnosis in this patient?

A 7-month-old boy presents to the emergency room with three episodes of vomiting and severe abdominal pain that comes and goes for the past two hours. The patient's most recent vomit in the hospital appears bilious, and the patient had one stool that appears bloody and full of mucous. The mother explains that one stool at home appears to be "jelly-like." On physical exam, a palpable mass is felt in the right lower quadrant of the abdomen. What is the next best diagnostic test for this patient?

A 4-week-old male presents with his parents to the pediatrician for a well-child visit. The patient’s mother reports that the patient was eating well until about one week ago, when he began vomiting after breastfeeding. His mother has tried increasing the frequency of feeds and decreasing the amount of each feed, but the vomiting seems to be getting worse. The patient now vomits after every feed. His mother states the vomitus looks like breastmilk. The patient’s mother is exclusively breastfeeding and would prefer not to switch to formula but worries that the patient is not getting the nutrition he needs. Two weeks ago, the patient was in the 75th percentile for weight and 70th for height. He is now in the 60th percentile for weight and 68th percentile for height. On physical exam, the patient has dry mucous membranes. His abdomen is soft and non-distended. Which of the following is the best next step in management?

Q10

Two hours after a 2280-g male newborn is born at 38 weeks' gestation to a 22-year-old primigravid woman, he has 2 episodes of vomiting and jitteriness. The mother has noticed that the baby is not feeding adequately. She received adequate prenatal care and admits to smoking one pack of cigarettes daily while pregnant. His temperature is 36.3°C (97.3°F), pulse is 171/min and respirations are 60/min. Pulse oximetry on room air shows an oxygen saturation of 92%. Examination shows pale extremities. There is facial plethora. Capillary refill time is 3 seconds. Laboratory studies show: Hematocrit 70% Leukocyte count 7800/mm3 Platelet count 220,000/mm3 Serum Glucose 38 mg/dL Calcium 8.3 mg/dL Which of the following is the most likely cause of these findings?

Wilms tumor US Medical PG Practice Questions and MCQs

Question 1: A 63-year-old man presents with a 2-month history of increasing sensation of fullness involving his left flank. The patient reports recent episodes of constant pain. The patient is hypertensive (145/90 mm Hg) and is currently on medications including losartan and hydrochlorothiazide. His past medical history is otherwise unremarkable. He is a 30-pack-year smoker. His temperature is 37.7°C (99.9°F); pulse, 76/min; and respiratory rate, 14/min. Palpation of the left flank shows a 10 x 10-cm mass. The patient's laboratory parameters are as follows: Blood Hemoglobin 19.5 g/dL Leukocyte count 5,000/mm3 Platelet count 250,000/mm3 Urine Blood 2+ Protein negative RBC 45/hpf without dysmorphic features Abdominal CT scan confirms the presence of a large solid mass originating in the left kidney. These findings are most consistent with which of the following conditions?

A. Wilms tumor
B. Transitional cell carcinoma
C. Adenoma
D. Renal cell carcinoma (Correct Answer)
E. Angiomyolipoma

Explanation: ***Renal cell carcinoma*** - The constellation of **flank pain**, a palpable **flank mass**, and **hematuria** is the classic triad of renal cell carcinoma. - Additional findings like **hypertension**, **polycythemia** (high hemoglobin of 19.5 g/dL due to erythropoietin production by the tumor), and **smoker status** further support this diagnosis. *Wilms tumor* - This is primarily a **childhood tumor**, typically presenting before the age of 5, which is inconsistent with this 63-year-old patient. - While it can present with a palpable mass and hematuria, the patient's age makes this diagnosis highly unlikely. *Transitional cell carcinoma* - This cancer usually arises in the **renal pelvis** or ureter and is strongly associated with smoking and painless gross hematuria. - However, a large solid parenchymal mass as described by the CT scan points away from transitional cell carcinoma, which generally involves the collecting system. *Adenoma* - Renal adenomas are typically **small, benign tumors** that are often found incidentally and rarely cause symptoms like palpable masses or flank pain. - They are not associated with paraneoplastic syndromes such as polycythemia or significant hypertension secondary to tumor activity. *Angiomyolipoma* - These are **benign tumors** composed of fat, smooth muscle, and blood vessels, often associated with **tuberous sclerosis**. - While they can cause flank pain or hemorrhage, they typically appear as **fat-containing lesions** on imaging, and this patient's presentation with polycythemia and significant hypertension points to a malignant process.

Question 2: A laboratory physician investigates the chromosomes of a fetus with a suspected chromosomal anomaly. She processes a cell culture obtained by amniocentesis. Prior to staining and microscopic examination of the fetal chromosomes, a drug that blocks cell division is added to the cell culture. In order to arrest chromosomes in metaphase, the physician most likely added a drug that is also used for the treatment of which of the following conditions?

A. Trichomonas vaginitis
B. Testicular cancer
C. Herpes zoster
D. Polycythemia vera
E. Acute gouty arthritis (Correct Answer)

Explanation: ***Acute gouty arthritis*** - The drug used to arrest chromosomes in metaphase is likely **colchicine**, which inhibits **microtubule polymerization** and spindle formation, thus arresting cells in metaphase. - **Colchicine** is a well-established treatment for **acute gouty arthritis** due to its anti-inflammatory properties, primarily through disrupting neutrophil functions. *Trichomonas vaginitis* - This condition is typically treated with **metronidazole** or **tinidazole**, which are antibiotics targeting protozoa and anaerobic bacteria. - These drugs do not inhibit microtubule assembly or arrest cells in metaphase. *Testicular cancer* - Testicular cancer is primarily treated with **BEP regimen** (bleomycin, etoposide, cisplatin), which does not include microtubule-inhibiting agents. - While vinca alkaloids (vincristine, vinblastine) do arrest cells in metaphase via microtubule inhibition similar to colchicine, they are not standard first-line agents for testicular cancer. - The question specifically asks about the primary clinical use of colchicine, which is gout, not cancer chemotherapy. *Herpes zoster* - Herpes zoster (shingles) is a viral infection treated with **antiviral medications** like acyclovir, valacyclovir, or famciclovir. - These antivirals work by interfering with viral DNA replication and do not target microtubule formation or cell division. *Polycythemia vera* - Polycythemia vera is a myeloproliferative neoplasm often managed with **phlebotomy**, **hydroxyurea**, or ruxolitinib. - These treatments aim to reduce blood cell counts or inhibit specific signaling pathways, none of which primarily involve arresting cells in metaphase by disrupting microtubules.

Question 3: A 3-year-old girl is brought to her pediatrician with 2 days of fever and abdominal pain. She has also been crying and complaining of pain while urinating. She was born at term without incident and was previously healthy at regular checkups. On presentation, her temperature is 102.2°F (39°C), blood pressure is 137/85 mmHg, pulse is 122/min, and respirations are 24/min. Physical exam reveals a palpable, painless, abdominal mass that does not cross the midline. Which of the following additional findings would be associated with this patient's disorder?

A. Ash leaf spots
B. Opsoclonus myoclonus
C. Epstein-Barr virus
D. 11;22 chromosome translocation
E. Aniridia (Correct Answer)

Explanation: ***Aniridia*** - The clinical presentation of a **palpable, painless abdominal mass** that does not cross the midline, along with **hypertension** and symptoms suggesting a urinary tract infection (fever, dysuria, abdominal pain) in a 3-year-old girl, is highly indicative of **Wilms tumor (nephroblastoma)**. - **Aniridia** (absence of the iris) is a congenital anomaly strongly associated with **Wilms tumor**, particularly as part of the **WAGR syndrome** (Wilms tumor, Aniridia, Genitourinary anomalies, and intellectual disability), caused by a deletion on chromosome 11 that includes the *WT1* gene. *Ash leaf spots* - **Ash leaf spots** are hypopigmented macules characteristic of **tuberous sclerosis complex**, a genetic disorder associated with hamartomas in various organs, including the brain, kidney, heart, and skin. - While tuberous sclerosis can be associated with kidney lesions (e.g., angiomyolipomas), it does not typically present with a solitary renal mass like a Wilms tumor, nor are ash leaf spots directly linked to nephroblastoma. *Opsoclonus myoclonus* - **Opsoclonus-myoclonus syndrome (OMS)**, also known as **dancing eyes-dancing feet syndrome**, is a rare neurological disorder characterized by rapid, chaotic eye movements (opsoclonus) and involuntary muscle jerks (myoclonus). - In children, OMS is most commonly a **paraneoplastic syndrome associated with neuroblastoma**, a tumor of the sympathetic nervous system, which typically presents with an abdominal mass that **often crosses the midline** and can present with systemic symptoms like pallor and periorbital ecchymoses, rather than the specific renal origin suggested by the lack of midline crossing. *Epstein-Barr virus* - The **Epstein-Barr virus (EBV)** is the causative agent of **infectious mononucleosis** and is implicated in various lymphoproliferative disorders and certain cancers, such as **Burkitt lymphoma** and nasopharyngeal carcinoma. - While Burkitt lymphoma can present as an abdominal mass, EBV is not directly associated with Wilms tumor. *11;22 chromosome translocation* - The **t(11;22)(q24;q12) translocation** is the characteristic cytogenetic abnormality found in **Ewing sarcoma**, a highly aggressive malignant tumor of bone and soft tissue. - Ewing sarcoma can present as a soft tissue mass, but it is not a renal tumor and does not typically present with the specific clinical features of Wilms tumor such as severe hypertension or aniridia.

Question 4: A 12-year-old boy comes to the physician for the evaluation of intermittent blood-tinged urine for several months. Four months ago, he had an episode of fever and sore throat that resolved without treatment after 5 days. During the past 2 years, he has also had recurrent episodes of swelling of his face and feet. 5 years ago, he was diagnosed with mild bilateral sensorineural hearing loss. His brother died of a progressive kidney disease at the age of 23. The patient appears pale. His temperature is 37°C (98.6°F), pulse is 70/min, and blood pressure is 145/85 mm Hg. Slit lamp examination shows a conical protrusion of both lenses. Laboratory studies show a hemoglobin concentration of 11 g/dL, urea nitrogen concentration of 40 mg/dL, and creatinine concentration of 2.4 mg/dL. Urinalysis shows: Blood 2+ Protein 1+ RBC 5–7/hpf RBC casts rare Which of the following is the most likely underlying cause of this patient's symptoms?

A. IgA deposits
B. WT1 gene mutation
C. Defective type IV collagen (Correct Answer)
D. Autosomal-recessive kidney disease
E. Type II hypersensitivity reaction

Explanation: ***Defective type IV collagen*** - This patient presents with a classic triad of symptoms: **progressive kidney disease** (elevated creatinine, blood-tinged urine, family history), **sensorineural hearing loss**, and **ocular abnormalities** (lenticonus on slit lamp exam). These findings are highly suggestive of **Alport syndrome**, which is caused by a defect in **type IV collagen**. - The family history of a brother dying of progressive kidney disease at a young age further supports a genetic cause, and the intermittent blood-tinged urine after an upper respiratory infection can be a feature of Alport syndrome, often misinterpreted as IgA nephropathy early in its course. *IgA deposits* - **IgA nephropathy** can present with recurrent episodes of gross hematuria, often following an upper respiratory infection, similar to the initial presentation of this patient's blood-tinged urine. - However, IgA nephropathy typically does not involve **sensorineural hearing loss** or **ocular abnormalities** like lenticonus. *WT1 gene mutation* - A **WT1 gene mutation** is associated with **Denys-Drash syndrome** and **Frasier syndrome**, which involve nephropathy and, in some cases, gonadal abnormalities or ambiguous genitalia. - While these can cause kidney disease, they do not typically present with the characteristic ocular findings (lenticonus) or sensorineural hearing loss seen in this patient. *Autosomal-recessive kidney disease* - While Alport syndrome can have autosomal recessive inheritance (10-15% of cases), this option is too broad and does not specify the underlying **molecular defect** (type IV collagen). - The family history pattern here (affected brother, male proband) is more consistent with **X-linked Alport syndrome** (85% of cases), and this non-specific option does not pinpoint the actual pathogenic mechanism that links all the patient's symptoms. *Type II hypersensitivity reaction* - A **type II hypersensitivity reaction** involves antibody-mediated cellular destruction or dysfunction, such as in Goodpasture syndrome, where antibodies attack the glomerular basement membrane. - This mechanism does not explain the long-standing, progressive nature of kidney disease combined with sensorineural hearing loss and ocular defects. Instead, these are characteristic of an underlying structural protein defect.

Question 5: A 61-year-old man comes to the physician because of several episodes of dark urine over the past 2 weeks. He does not have dysuria or flank pain. He works in a factory that produces dyes. Since an accident at work 5 years ago, he has had moderate hearing loss bilaterally. He takes no medications. He has smoked a pack of cigarettes daily for 29 years and drinks one alcoholic beverage daily. Vital signs are within normal limits. Physical examination shows no abnormalities. His urine is pink; urinalysis shows 80 RBC/hpf but no WBCs. Cystoscopy shows a 3-cm mass in the bladder mucosa. The mass is resected. Pathologic examination shows an urothelial carcinoma with penetration into the muscular layer. An x-ray of the chest and a CT scan of the abdomen and pelvis with contrast show a normal upper urinary tract and normal lymph nodes. Which of the following is the most appropriate next step in management?

A. Palliative polychemotherapy
B. Transurethral resection of tumor with intravesical BCG instillation
C. Radical cystectomy (Correct Answer)
D. Transurethral resection of tumor with intravesical chemotherapy
E. Radiation therapy

Explanation: ***Radical cystectomy*** - The patient has an **urothelial carcinoma** that has **penetrated the muscular layer**. This indicates an **invasive bladder cancer (T2 or greater)**, for which radical cystectomy is the standard of care to achieve cure. - While imaging showed no distant metastasis, the deep invasion into the muscle requires aggressive surgical removal of the bladder, prostate (in men), and seminal vesicles, along with pelvic lymph node dissection. *Palliative polychemotherapy* - This option is typically reserved for patients with widespread **metastatic disease** or those who are not surgical candidates, which is not the case here. - The patient's initial workup shows no evidence of distant metastasis, making a curative approach like surgery more appropriate. *Transurethral resection of tumor with intravesical BCG instillation* - This approach, often used for **high-grade non-muscle invasive bladder cancer**, is insufficient for muscle-invasive disease. - **BCG instillation** aims to prevent recurrence and progression in superficial disease but cannot eradicate cancer that has invaded the muscularis propria. *Transurethral resection of tumor with intravesical chemotherapy* - Similar to BCG, **intravesical chemotherapy** is primarily effective for **non-muscle invasive bladder cancer** to prevent recurrence or treat carcinoma in situ. - It does not provide adequate treatment for cancer that has invaded the detrusor muscle, as systemic or deeper treatments are required. *Radiation therapy* - While radiation therapy can be considered for bladder cancer, it is typically used in specific situations, such as for patients who are **not surgical candidates** or as part of a **bladder-sparing trimodality therapy** (TURBT, chemotherapy, and radiation) for highly selected patients. - For muscle-invasive disease without clear contraindications for surgery, **radical cystectomy** offers better long-term survival rates.

Question 6: A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?

A. "Does the diarrhea typically precede the constipation, or vice-versa?"
B. "Is the diarrhea foul-smelling?"
C. "Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"
D. "Are the symptoms worse in the morning or at night?"
E. "Can you tell me more about the symptoms you have been experiencing?" (Correct Answer)

Explanation: ***Can you tell me more about the symptoms you have been experiencing?*** - This **open-ended question** encourages the patient to provide a **comprehensive narrative** of their symptoms, including details about onset, frequency, duration, alleviating/aggravating factors, and associated symptoms, which is crucial for diagnosis. - In a patient presenting with vague, intermittent symptoms like alternating constipation and diarrhea, allowing them to elaborate freely can reveal important clues that might not be captured by more targeted questions. *Does the diarrhea typically precede the constipation, or vice-versa?* - While knowing the sequence of symptoms can be helpful in understanding the **pattern of bowel dysfunction**, it is a very specific question that might overlook other important aspects of the patient's experience. - It prematurely narrows the focus without first obtaining a broad understanding of the patient's overall symptomatic picture. *Is the diarrhea foul-smelling?* - Foul-smelling diarrhea can indicate **malabsorption** or **bacterial overgrowth**, which are important to consider in some gastrointestinal conditions. - However, this is a **specific symptom inquiry** that should follow a more general exploration of the patient's symptoms, as it may not be relevant if other crucial details are missed. *Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life* - Quantifying pain intensity is useful for assessing the **severity of discomfort** and monitoring changes over time. - However, for a patient with intermittent rather than acute, severe pain, understanding the **character, location, and triggers** of the pain is often more diagnostically valuable than just a numerical rating initially. *Are the symptoms worse in the morning or at night?* - Diurnal variation can be relevant in certain conditions, such as inflammatory bowel diseases where nocturnal symptoms might be more concerning, or functional disorders whose symptoms might be stress-related. - This is another **specific question** that should come after gathering a more complete initial picture of the patient's symptoms to ensure no key information is overlooked.

Question 7: A 25-year-old man comes to the physician because of right-sided painless scrotal swelling that he noticed yesterday while taking a shower. He is currently sexually active with two female partners and uses condoms inconsistently. He immigrated to the US from Argentina 2 years ago. His immunization records are unavailable. He has smoked one pack of cigarettes daily for the last 5 years. He is 170 cm (5 ft 7 in) tall and weighs 70 kg (154 lb); BMI is 24.2 kg/m2. He appears healthy and well nourished. His temperature is 37°C (98.6°F), pulse is 72/min, and blood pressure is 125/75 mm Hg. The lungs are clear to auscultation. Cardiac examination shows no abnormalities. The abdomen is soft with dull lower abdominal discomfort. Testicular examination shows a solid mass in the right testis that is firm and nontender. A light held behind the scrotum does not shine through. The mass is not reduced when the patient is in a supine position. The remainder of the physical examination shows no abnormalities. Which of the following is the most likely diagnosis in this patient?

A. Testicular tumor (Correct Answer)
B. Testicular torsion
C. Scrotal hernia
D. Hydrocele testis
E. Orchitis

Explanation: ***Testicular tumor*** - A **painless, firm, and nontender solid mass** in the testis that does not transilluminate and is not reducible is highly suspicious for a testicular tumor. - The patient's age (25 years old) is within the typical demographic for **testicular cancer**, and the recent discovery further supports this diagnosis. *Testicular torsion* - Characterized by **sudden onset of severe pain**, scrotal swelling, and tenderness, often associated with nausea and vomiting. - The patient in this case presents with a **painless** mass, which makes testicular torsion unlikely. *Scrotal hernia* - A hernia typically presents as a **reducible mass** that may increase in size with maneuvers like coughing, and it often transilluminates. - The mass described here is **not reducible** and does not transilluminate, ruling out a simple scrotal hernia. *Hydrocele testis* - A hydrocele is a collection of fluid in the tunica vaginalis, which typically presents as a **painless, soft, and transilluminating** scrotal swelling. - The mass in this patient is described as **solid** and does not transilluminate, making hydrocele unlikely. *Orchitis* - Orchitis is an **inflammation of the testis**, which usually presents with pain, tenderness, swelling, and sometimes fever. - The patient's mass is explicitly described as **painless** and nontender, which is inconsistent with orchitis.

Question 8: A 7-month-old boy presents to the emergency room with three episodes of vomiting and severe abdominal pain that comes and goes for the past two hours. The patient's most recent vomit in the hospital appears bilious, and the patient had one stool that appears bloody and full of mucous. The mother explains that one stool at home appears to be "jelly-like." On physical exam, a palpable mass is felt in the right lower quadrant of the abdomen. What is the next best diagnostic test for this patient?

A. Peripheral blood culture
B. Exploratory laparotomy
C. Kidney, ureter, bladder radiograph
D. Complete blood count with differential
E. Abdominal ultrasound (Correct Answer)

Explanation: ***Abdominal ultrasound*** - An abdominal ultrasound is the **next best diagnostic test** for this patient, as the clinical presentation (sudden onset of severe, intermittent abdominal pain, bilious vomiting, **currant jelly stool**, and a palpable **sausage-shaped mass in the right lower quadrant**) is highly suggestive of **intussusception**. - Ultrasound is **non-invasive**, provides real-time imaging, and can confirm the diagnosis by visualizing the characteristic **"target sign" or "donut sign"**, indicating one segment of the bowel telescoping into another. *Peripheral blood culture* - A peripheral blood culture would be considered if there were strong signs of **sepsis or bacteremia**, such as fever, lethargy, or other systemic inflammatory responses, which are not the primary concern here. - While infection could cause abdominal pain, the classic signs of intussusception (currant jelly stool, palpable mass) point away from an initial bacterial infection requiring blood cultures. *Exploratory laparotomy* - Exploratory laparotomy is a surgical procedure and would be considered an **intervention or treatment**, not the initial diagnostic test, especially when less invasive options are available. - It is typically reserved for cases where non-invasive diagnostics are inconclusive or when there are signs of **perforation or peritonitis** requiring immediate surgical intervention. *Kidney, ureter, bladder radiograph* - A KUB radiograph might show signs of obstruction like dilated bowel loops or absence of gas in the colon, but it is **not definitive for intussusception** and has low sensitivity for diagnosing it. - It would not provide the detailed soft tissue visualization necessary to confirm the telescoping of the bowel that an ultrasound would. *Complete blood count with differential* - A CBC with differential would provide information about the patient's **hemoglobin, white blood cell count**, and platelet count, which can indicate infection or anemia. - While it may show elevated white blood cells in response to inflammation or ischemia, it is a **non-specific test** and would not definitively diagnose intussusception.

Question 9: A 4-week-old male presents with his parents to the pediatrician for a well-child visit. The patient’s mother reports that the patient was eating well until about one week ago, when he began vomiting after breastfeeding. His mother has tried increasing the frequency of feeds and decreasing the amount of each feed, but the vomiting seems to be getting worse. The patient now vomits after every feed. His mother states the vomitus looks like breastmilk. The patient’s mother is exclusively breastfeeding and would prefer not to switch to formula but worries that the patient is not getting the nutrition he needs. Two weeks ago, the patient was in the 75th percentile for weight and 70th for height. He is now in the 60th percentile for weight and 68th percentile for height. On physical exam, the patient has dry mucous membranes. His abdomen is soft and non-distended. Which of the following is the best next step in management?

A. Abdominal radiograph
B. Trial of empiric proton pump inhibitor
C. Supplement breastfeeding with formula
D. Abdominal ultrasound (Correct Answer)
E. Trial of cow's milk-free diet

Explanation: ***Abdominal ultrasound*** - The history of **progressive non-bilious vomiting** after every feed, worsening over time, and **weight percentile drop** in a 4-week-old infant strongly suggests **pyloric stenosis**. The best next step for diagnosis is an abdominal ultrasound which can visualize the thickened pylorus (>3-4 mm muscle thickness, >14-16 mm channel length). - The physical exam finding of **dry mucous membranes** indicates dehydration, a common complication of recurrent vomiting. *Abdominal radiograph* - An abdominal radiograph is generally not the initial imaging of choice for diagnosing pyloric stenosis, as it is less sensitive and specific than ultrasound for visualizing soft tissue structures like the pylorus. - While it may show a **dilated stomach** or **absent gas in the distal bowel**, these findings are not diagnostic of pyloric stenosis and do not pinpoint the obstruction. *Trial of empiric proton pump inhibitor* - A proton pump inhibitor would be considered for **gastroesophageal reflux disease (GERD)**, but the **worsening pattern of vomiting after every feed** and **rapid weight loss** are atypical for simple GERD and point to a more serious mechanical obstruction. - Treating with a PPI would delay the proper diagnosis and treatment of pyloric stenosis, which requires surgical intervention (pyloromyotomy). *Supplement breastfeeding with formula* - While ensuring adequate nutrition is important, simply supplementing with formula will not resolve the underlying issue of **pyloric obstruction**, and the infant will likely continue to vomit and experience dehydration. - This approach would delay definitive diagnosis and treatment, potentially leading to further compromise of the infant's health. *Trial of cow's milk-free diet* - A cow's milk-free diet is indicated for suspected **cow's milk protein allergy (CMPA)**, which can present with vomiting, but typically also includes symptoms like **bloody stools**, **eczema**, or **colic**, which are not reported here. - The **progressive non-bilious vomiting after every feed** and rapid weight loss are more characteristic of a mechanical obstruction like pyloric stenosis than a dietary allergy.

Question 10: Two hours after a 2280-g male newborn is born at 38 weeks' gestation to a 22-year-old primigravid woman, he has 2 episodes of vomiting and jitteriness. The mother has noticed that the baby is not feeding adequately. She received adequate prenatal care and admits to smoking one pack of cigarettes daily while pregnant. His temperature is 36.3°C (97.3°F), pulse is 171/min and respirations are 60/min. Pulse oximetry on room air shows an oxygen saturation of 92%. Examination shows pale extremities. There is facial plethora. Capillary refill time is 3 seconds. Laboratory studies show: Hematocrit 70% Leukocyte count 7800/mm3 Platelet count 220,000/mm3 Serum Glucose 38 mg/dL Calcium 8.3 mg/dL Which of the following is the most likely cause of these findings?

A. Intrauterine hypoxia (Correct Answer)
B. Transient tachypnea of the newborn
C. Hyperinsulinism
D. Congenital heart disease
E. Intraventricular hemorrhage

Explanation: ***Intrauterine hypoxia*** - **Chronic intrauterine hypoxia** stimulates erythropoietin production, leading to **polycythemia** (Hct 70%) and **hyperviscosity**, which can cause poor feeding, vomiting, jitteriness, and circulatory disturbances like prolonged capillary refill and facial plethora. - The mother's history of **smoking** during pregnancy is a significant risk factor for intrauterine hypoxia and **intrauterine growth restriction (IUGR)**, contributing to the newborn's small size for gestational age (2280g at 38 weeks). *Transient tachypnea of the newborn* - Characterized by **respiratory distress** due to delayed clearance of fetal lung fluid, presenting with tachypnea, grunting, and retractions. - While this newborn has tachypnea (respirations 60/min), the primary symptoms point towards **hyperviscosity syndrome** and hypoglycemia, not primarily respiratory issues. *Hyperinsulinism* - This condition primarily causes **hypoglycemia** (glucose 38 mg/dL) due to excessive insulin production. - However, it does not explain the presence of **polycythemia**, facial plethora, prolonged capillary refill, or the mother's smoking history. *Congenital heart disease* - Can cause symptoms like **cyanosis**, poor feeding, and tachypnea, and some forms could contribute to hypoxia. - It does not directly explain the **polycythemia** or the mother's smoking history as a causal factor for all presenting signs. *Intraventricular hemorrhage* - Typically seen in **premature infants** and can cause neurological symptoms like lethargy, hypotonia, and seizures. - While jitteriness can be a symptom, it does not account for the **polycythemia**, facial plethora, or improved feeding with interventions for hyperviscosity.

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