SMLE Paediatrics 3

Question 1

A 10-month-old infant presents with fever, irritability, and a bulging anterior fontanelle. CSF analysis shows elevated WBCs with neutrophil predominance, low glucose, and elevated protein. What is the most likely causative organism?

Accepted Answer

Streptococcus pneumoniae

Answer

In infants aged 1-23 months, Streptococcus pneumoniae is the most common cause of bacterial meningitis, followed by Neisseria meningitidis and group B Streptococcus. The Hib vaccine has dramatically reduced H. influenzae meningitis.

Question 2

A child presents with a unilateral, painless abdominal mass that does not cross the midline. CT shows an intrarenal mass with areas of haemorrhage and necrosis. What is the most likely diagnosis?

Accepted Answer

Wilms tumour (nephroblastoma)

Answer

Wilms tumour is the most common renal malignancy in children, typically presenting between 3-5 years of age as a painless abdominal mass arising from the kidney. Unlike neuroblastoma, it does not cross the midline and is intrarenal in origin.

Question 3

A 6-year-old child presents with polydipsia, polyuria, weight loss, and a blood glucose of 22 mmol/L. Blood pH is 7.15 and ketones are strongly positive. What is the immediate priority in management?

Accepted Answer

IV fluid resuscitation with normal saline

Answer

In paediatric diabetic ketoacidosis, the immediate priority is IV fluid resuscitation with 0.9% normal saline to correct dehydration and restore circulation. IV insulin infusion (NOT bolus) is started after the first hour of fluid resuscitation to avoid cerebral oedema.

Question 4

A neonate presents with failure to pass meconium within 48 hours of birth, abdominal distension, and bilious vomiting. Barium enema shows a transition zone in the rectosigmoid. What is the diagnosis?

Accepted Answer

Hirschsprung disease

Answer

Hirschsprung disease (congenital aganglionic megacolon) presents with failure to pass meconium within 48 hours, abdominal distension, and bilious vomiting. Barium enema shows a transition zone between narrow aganglionic distal bowel and dilated proximal bowel.

Question 5

A 3-year-old child presents with abdominal mass, hypertension, and periorbital ecchymosis (raccoon eyes). Urine catecholamines (VMA and HVA) are elevated. What is the most likely diagnosis?

Accepted Answer

Neuroblastoma

Answer

Neuroblastoma arises from neural crest cells (sympathetic nervous system) and is the most common extracranial solid tumour in children. It characteristically produces catecholamines (elevated urinary VMA/HVA), can cross the midline, and causes periorbital metastases (raccoon eyes).

SMLE Practice Test

SMLE Practice Test

SMLE Paediatrics 3