Pyloric Stenosis — MCQs
Congenital pyloric stenosis causes: 1. Bilious vomiting 2. Non-bilious vomiting 3. Projectile vomiting 4. Non-projectile vomiting 5. Forceful vomiting
In a case of hypertrophic pyloric stenosis, which of the following metabolic disturbances are found?
A 24-day-old neonate presents with projectile vomiting and failure to gain weight. What is the most likely diagnosis?
Which electrolyte imbalance should be corrected before surgery in a patient with hypertrophic pyloric stenosis?
Which of the following metabolic derangements is associated with congenital pyloric stenosis?
A 6-week-old child with a history of vomiting undergoes an ultrasound, which shows an antral nipple sign or target sign, as shown in the image. What is the diagnosis?
All of the following are true about congenital hypertrophic pyloric stenosis except
A 1-week-old previously healthy infant presents to the emergency room with the acute onset of bilious vomiting. The abdominal plain film in the emergency department (A) and the barium enema done after admission (B) are shown. Which of the following is the most likely diagnosis for this patient?
The treatment of choice for congenital hypertrophic pyloric stenosis is :
Most common cause of acute intestinal obstruction in children is
Pyloric Stenosis Indian Medical PG Practice Questions and MCQs
Question 1: Congenital pyloric stenosis causes: 1. Bilious vomiting 2. Non-bilious vomiting 3. Projectile vomiting 4. Non-projectile vomiting 5. Forceful vomiting
- A. 2, 3, 4 & 5
- B. 1, 3 & 4
- C. All are seen
- D. 2, 3 & 5 (Correct Answer)
Explanation: ***2, 3 & 5*** - Congenital pyloric stenosis is characterized by **non-bilious vomiting** because the obstruction is proximal to the ampulla of Vater. - The vomiting is typically **projectile** and **forceful** due to the increased pressure in the stomach as it tries to overcome the narrowed pyloric channel. *2, 3, 4 & 5* - This option incorrectly includes **non-projectile vomiting (4)**; pyloric stenosis classically presents with projectile vomiting. - While non-bilious, projectile, and forceful vomiting are correct, the inclusion of non-projectile makes this option incorrect. *1, 3 & 4* - This option incorrectly includes **bilious vomiting (1)**; pyloric stenosis causes non-bilious vomiting as the obstruction is above the bile duct entry. - It also includes **non-projectile vomiting (4)** which is not typical for pyloric stenosis. *All are seen* - This is incorrect because **bilious vomiting** and **non-projectile vomiting** are not characteristic features of congenital pyloric stenosis. - The classic presentation is consistently non-bilious, forceful, and projectile.
Question 2: In a case of hypertrophic pyloric stenosis, which of the following metabolic disturbances are found?
- A. Metabolic acidosis
- B. Respiratory alkalosis
- C. Metabolic alkalosis with alkaline urine
- D. Metabolic alkalosis with paradoxical aciduria (Correct Answer)
Explanation: ***Metabolic alkalosis with paradoxical aciduria*** - Profound **vomiting** from pyloric stenosis leads to the loss of **gastric acid** (HCl), resulting in **metabolic alkalosis**. - The kidneys attempt to conserve sodium and water in response to ongoing fluid loss, leading to increased reabsorption of bicarbonate and excretion of hydrogen ions, resulting in a **paradoxical aciduria** despite systemic alkalosis. *Metabolic acidosis* - This condition is characterized by a **low pH** and **low bicarbonate** concentration in the blood. - It is typically caused by conditions like **diabetic ketoacidosis** or **lactic acidosis**, not the loss of stomach acid from vomiting. *Respiratory alkalosis* - This occurs due to **hyperventilation**, which causes an excessive elimination of **carbon dioxide** and a subsequent increase in blood pH. - It is not directly associated with the fluid and electrolyte imbalances seen in hypertrophic pyloric stenosis. *Metabolic alkalosis with alkaline urine* - While metabolic alkalosis is correct, **alkaline urine** would imply the kidneys are appropriately compensating by excreting excess bicarbonate. - In hypertrophic pyloric stenosis, the severe volume depletion triggers a compensatory mechanism in the kidneys causing hydrogen ion excretion leading to **acidic urine**, despite systemic alkalosis.
Question 3: A 24-day-old neonate presents with projectile vomiting and failure to gain weight. What is the most likely diagnosis?
- A. NEC
- B. Duodenal atresia
- C. Hirschsprung's disease
- D. Congenital Hypertrophic Pyloric Stenosis (Correct Answer)
Explanation: ***Congenital Hypertrophic Pyloric Stenosis*** - The classic presentation includes **projectile, non-bilious vomiting** in a neonate around 2-8 weeks old, leading to **failure to thrive**. - An **olive-shaped mass** (hypertrophied pylorus) may be palpable in the epigastrium. *NEC* - **Necrotizing enterocolitis (NEC)** is an inflammatory disease of the intestine, primarily affecting premature infants. - Symptoms typically include **abdominal distension**, bloody stools, and lethargy, rather than projectile vomiting. *Duodenal atresia* - Presents with **bilious vomiting** within the first 24-48 hours of life due to an obstruction below the ampulla of Vater. - An X-ray would show a **"double bubble" sign**, which is not implied by the provided symptoms. *Hirschsprung's disease* - Characterized by **failure to pass meconium** within the first 24-48 hours and chronic constipation. - Vomiting, if present, is usually **bilious** and associated with abdominal distension, not projectile in nature.
Question 4: Which electrolyte imbalance should be corrected before surgery in a patient with hypertrophic pyloric stenosis?
- A. Potassium
- B. Bicarbonate (HCO3)
- C. Chloride (Correct Answer)
- D. Sodium
Explanation: ***Chloride*** - Patients with **pyloric stenosis** lose gastric acid (HCl) due to repeated vomiting, leading to **hypochloremic metabolic alkalosis**. - Correcting **hypochloremia** is crucial for resolving the metabolic alkalosis and ensuring safe anesthesia and surgery. *Potassium* - While **hypokalemia** can occur secondary to the metabolic alkalosis and fluid shifts, it is not the primary electrolyte imbalance requiring immediate correction before surgery. - Correcting **chloride** levels often facilitates the renal reabsorption of potassium, helping to resolve hypokalemia indirectly. *Bicarbonate (HCO3)* - Elevated **bicarbonate** is a feature of the metabolic alkalosis in pyloric stenosis, but directly correcting it with bicarbonate administration is generally contraindicated. - The goal is to correct the underlying cause (**chloride deficit**), which will allow the kidneys to excrete excess bicarbonate. *Sodium* - **Hyponatremia** can occur in cases of severe dehydration or if excessive free water is administered, but it is not the primary or most critical electrolyte imbalance directly caused by pyloric stenosis itself. - The focus is often on fluid resuscitation and correcting the **chloride deficit** to stabilize the patient.
Question 5: Which of the following metabolic derangements is associated with congenital pyloric stenosis?
- A. Hypochloremic acidosis
- B. Hyperchloremic acidosis
- C. Hypochloremic alkalosis (Correct Answer)
- D. Hyperchloremic alkalosis
Explanation: ***Hypochloremic alkalosis*** - The forceful vomiting in **pyloric stenosis** leads to a significant loss of **gastric acid (HCl)**, resulting in **hypochloremia** and the metabolic picture of **alkalosis**. - The body attempts to compensate by retaining bicarbonate and excreting hydrogen ions, further contributing to the alkalosis. *Hypochloremic acidosis* - This condition is characterized by a low chloride level accompanied by **acidosis**, which contradicts the loss of acidic gastric contents seen in pyloric stenosis. - While chloride is lost, the predominant acid-base disturbance is alkalosis due to hydrogen ion loss. *Hyperchloremic acidosis* - This condition involves an elevated chloride level and acidosis, often seen in cases like **renal tubular acidosis** or severe diarrhea where bicarbonate is lost. - It is the opposite of the metabolic disturbance caused by the loss of gastric acid through vomiting. *Hyperchloremic alkalosis* - This imbalance would involve increased chloride and alkalosis, which does not align with the pathophysiology of pyloric stenosis where chloride is lost. - The body's compensatory mechanisms do not involve increasing chloride to an elevated level in this context.
Question 6: A 6-week-old child with a history of vomiting undergoes an ultrasound, which shows an antral nipple sign or target sign, as shown in the image. What is the diagnosis?
- A. Congenital pyloric stenosis (Correct Answer)
- B. Umbilical hernia
- C. Small bowel obstruction
- D. Jejunal atresia
- E. Duodenal atresia
Explanation: ***Congenital pyloric stenosis*** - The ultrasound findings of an **antral nipple sign** and **target sign** are classic indicators of **hypertrophic pyloric stenosis**. - This condition presents with **projectile vomiting** in infants, typically between 3-6 weeks of age, due to hypertrophy of the pyloric muscle. *Umbilical hernia* - An **umbilical hernia** is a protrusion of abdominal contents through the umbilical ring. It is usually diagnosed clinically and presents as a bulge, not with vomiting. - Ultrasound for an umbilical hernia would show bowel loops or omentum protruding through the abdominal wall defect, not the specific pyloric signs described. *Small bowel obstruction* - While small bowel obstruction can cause vomiting, the ultrasound findings would typically show **dilated loops of bowel** and a **transition point**, not an antral nipple or target sign specifically at the pylorus. - Other clinical features, such as abdominal distention and absence of stool, would also be more prominent. *Jejunal atresia* - **Jejunal atresia** is a congenital anomaly where part of the jejunum is underdeveloped or absent, leading to a complete obstruction. - Ultrasound would reveal **dilated loops of small bowel**, typically without peristalsis past the obstruction, and polyhydramnios antenatally, but not the specific pyloric ultrasound signs. *Duodenal atresia* - **Duodenal atresia** is a congenital obstruction of the duodenum that typically presents with bilious vomiting soon after birth. - The characteristic ultrasound finding is the **"double bubble" sign**, representing a distended stomach and proximal duodenum, not the target or antral nipple sign seen at the pylorus.
Question 7: All of the following are true about congenital hypertrophic pyloric stenosis except
- A. Metabolic acidosis occurs (Correct Answer)
- B. More common in males
- C. RamStedt Pyloromyotomy is the treatment of choice
- D. Non Bilious vomiting is seen
Explanation: ***Metabolic acidosis occurs*** - Due to persistent **vomiting** from pyloric stenosis, there is a significant loss of **hydrochloric acid (HCl)** from the stomach. - This loss of gastric acid leads to **hypochloremic metabolic alkalosis** rather than acidosis. *More common in males* - **Pyloric stenosis** has a clear male predominance, with a male-to-female ratio of about 4:1. - This gender disparity is a well-established epidemiological feature of the condition. *RamStedt Pyloromyotomy is the treatment of choice* - The **Ramstedt pyloromyotomy** is the definitive surgical procedure for congenital hypertrophic pyloric stenosis. - This procedure involves incising the hypertrophied muscle of the pylorus while leaving the mucosa intact, thus relieving the obstruction. *Non Bilious vomiting is seen* - The vomiting in pyloric stenosis is typically **non-bilious** because the obstruction is proximal to the **ampulla of Vater**, where bile enters the duodenum. - Vomiting usually occurs forcefully (projectile) after feeding.
Question 8: A 1-week-old previously healthy infant presents to the emergency room with the acute onset of bilious vomiting. The abdominal plain film in the emergency department (A) and the barium enema done after admission (B) are shown. Which of the following is the most likely diagnosis for this patient?
- A. Hypertrophic pyloric stenosis
- B. Acute appendicitis
- C. Jejunal atresia
- D. Malrotation with volvulus (Correct Answer)
Explanation: ***Malrotation with volvulus*** - The acute onset of **bilious vomiting** in a 1-week-old infant is a **surgical emergency** and highly suggestive of intestinal obstruction, with malrotation with volvulus being a critical consideration. - The barium enema image (B) shows the **ligament of Treitz** located to the right of the midline, indicating **intestinal malrotation** and a **corkscrew pattern** of the duodenum, which is pathognomonic for **midgut volvulus**. *Hypertrophic pyloric stenosis* - Typically presents with **non-bilious projectile vomiting** and palpable **pyloric olive mass**, usually appearing between 3 to 6 weeks of age, not at 1 week with bilious vomiting. - Imaging would reveal an **elongated, narrowed pyloric channel** (string sign) and thickened pyloric muscle, not the findings seen in the barium study. *Acute appendicitis* - This is an **extremely rare diagnosis** in a 1-week-old infant and typically presents with localized pain, fever, and leukocytosis, which are not the primary symptoms described. - Acute appendicitis would not explain the **bilious vomiting** or the specific findings on the barium study related to intestinal rotation. *Jejunal atresia* - Presents with bilious vomiting and abdominal distension, often diagnosed prenatally or shortly after birth due to proximal dilation and distal collapse of the bowel. - While it causes obstruction, the barium study in jejunal atresia would show a **blind-ending jejunum** and not the distinct malrotation and volvulus features (e.g., corkscrew sign, abnormal Treitz location).
Question 9: The treatment of choice for congenital hypertrophic pyloric stenosis is :
- A. Duodenojejunostomy
- B. Heller's operation
- C. Ramstedt's operation (Correct Answer)
- D. Gastrojejunostomy
Explanation: ***Ramsted's operation*** - **Ramstedt pyloromyotomy** is the definitive surgical treatment for **congenital hypertrophic pyloric stenosis**. - This procedure involves a longitudinal incision through the serosa and muscular layers of the hypertrophied pylorus, stopping short of the mucosa, to relieve the obstruction. *Duodenojejunostomy* - This procedure involves connecting the **duodenum to the jejunum**, typically performed to bypass an obstruction or resection in the distal duodenum or pancreas. - It is not indicated for **pyloric stenosis**, which is an obstruction at the gastric outlet. *Heller's operation* - Also known as **Heller myotomy**, this procedure is used to treat **achalasia**, a disorder affecting the esophagus. - It involves cutting the muscle fibers of the lower esophageal sphincter to facilitate food passage into the stomach, which is unrelated to **pyloric hypertrophy**. *Gastrojejunostomy* - This surgical procedure creates a connection between the **stomach and the jejunum**, bypassing the duodenum. - It is typically performed for conditions like **duodenal obstruction** or distal gastric tumors, not for primary pyloric muscle hypertrophy.
Question 10: Most common cause of acute intestinal obstruction in children is
- A. Inguinal hernia
- B. Intussusception (Correct Answer)
- C. Volvulus
- D. None of the options
Explanation: ***Intussusception*** - **Intussusception** is the most common cause of **acute intestinal obstruction** in children, particularly between 3 months and 3 years of age. - It occurs when a segment of the intestine telescopes into an adjacent segment, leading to obstruction and potentially **ischemia**. *Inguinal hernia* - While an **incarcerated inguinal hernia** can cause intestinal obstruction, it is less common than intussusception as the primary cause of acute obstruction in children generally. - It is more frequent in **neonates and infants** but overall incidence of obstruction is lower than intussusception. *Volvulus* - **Volvulus** refers to a twisting of the intestine on its mesentery, often associated with **malrotation**, leading to obstruction and vascular compromise. - While a serious cause of obstruction, especially in neonates, it is less common overall than intussusception in the pediatric population. *None of the options* - This option is incorrect because **intussusception** is a recognized and frequent cause of acute intestinal obstruction in children.
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