Acquired cause of gastric outlet obstruction in infants leading to nonbilious projectile vomiting characterized by hypertrophy and hyperplasia of the pylorus muscles
- M/C cause of gastric outlet obstruction (GOO) in infants
- Surgical emergency
Salient features:
PERISTALSIS: By IkaN (Nakeya Dewaswala, M.D.)
- P – Peristalsis (Visible peristalsis in abdomen)
- Y – Yuck! Vomiting (non-bile stained projectile vomiting)
- L – Lump in abdomen which is on the Left side
- O – Olive mass, Doughnut sign on USG
- R – Ramstedt’s pyloromyotomy, mass moves on respiration
- I – Imbalance of electrolytes
- C – Circular muscle hypertrophy
History:
Historically, it was first described as a disease entity in 1888 by Harald Hirschsprung.
Etiology
Risk factors:
- Birth rank (firstborns)
- Maternal age
- Sex (males, 4-5x risk)
- Family history
- Monozygosity in twins
- Drug intake: Erythromycin (in early infancy)
Pathophysiology
Pyloric hypertrophy and hyperplasia:
Hallmark of pyloric stenosis is marked hypertrophy and hyperplasia of both the circular and longitudinal muscular layers of the pylorus. This thickening leads to the narrowing of the lumen of the gastric antrum. The pyloric canal becomes lengthened. The muscles of the pylorus become thickened. The mucosa becomes edematous and thickened. When severe, the stomach becomes dilated secondary to gastric outlet obstruction. This obstruction induces immediately postprandial, nonbilious, projectile emesis.
Metabolic derangements:
Severity and duration of symptoms enhance loss of fluid, electrolytes and cause severe acid–base imbalance.
- Severe, prolonged vominting leads to dehydration with oliguria and anuria, hypokalaemia, hypochloraemia, severely metabolic alkalosis with compensatory respiratory acidosis
Presentation
Clinical triad:
- Non-bilious projectile vomiting (100%): Gradually increases (progressive) in frequency and severity to become projectile in nature
- Visible gastric peristalsis (47.6%)
- Palpable epigastric olive mass (33.3%)
Physical examination
After feeds
- Vigorous peristaltic wave (left hypochondrium → umbilicus)
- Olive shaped firm, nontender, hard pylorus (1-2 cm) in right upper quadrant (RUQ) (75-80% infants)
- Reverse peristaltic waves
- Signs of dehydration: Depressed fontanelles, dry mucous membranes, decreased tearing, poor skin turgor, and lethargy
Diagnosis
Laboratory workup:
- Hypochloremic, hypokalemic metabolic alkalosis: Classic electrolyte imbalance 2° to vomiting of gastric acid and subsequent volume contraction
- Paradoxical aciduria
USG
- Longitudinal view: Thickened and lengthened pylorus
- Muscle thickness of > 4 mm
- Pylorus length of > 16 mm
- Specific signs:
- Target sign: Transverse section of duodenum appears as a target crosshair
- Anterior-nipple sign: Double layered pylorus protruding into the gastric antrum
- Cervix sign: Uterine cervix-like appearance due to hypertrophic pyloric mucosa
Barium-sontrast study:
If ultrasound inconclusive
- String sign: String-like appearance of a narrowed lumen
- Double track sign: Duplicated appearance of pylorus due to puckering of mucosa
- Caterpillar sign: Giant hyperperistaltic waves
- Shoulder sign: Indentation of pylorus into fluid-filled antrum
- Mushroom sign: Indentattion of pylorus into base of duodenum
Differential diagnosis:
- Midgut volvulus: Twisting of malrotated bowel which can present in the first month of life with bilious vomiting
- Other differentials: Gastroenteritis, acute renal failure, sepsis, hernia, colic, constipation, necrotizing enterocolitis, trauma, toxic megacolon, Hirschsprung disease, testicular torsion, appendicitis, and urinary tract infection
Management
Correct dehydration & electrolyte imbalance
Immediate management
- 0.45% NS + dextrose + KCl
Ramstedt’s pyloromyotomy
Surgical (definitive) management which relieves obstruction by longitudinal splitting of the pylorus muscle