Peds GI Flashcards
Pyloric Stenosis
general
Functional obstruction of the gastric outlet caused by hypertrophy and hyperplasia of the pyloric sphincter muscle
Epidemiology:
Most common cause ofintestinal obstructionin infants
Occurs in 1–3 of every 1,000 infants in the United States
Etiology:
Unknown
Genetic and environmental factors might play a role
Usually not present at birth
pyloric stenosis
RF
Sex
More common in boys — especially firstborn children — than in girls
Race
More common in whites of northern European ancestry
Premature birth (before 37 weeks)
More common in babies born prematurely than in full-term babies
Family history
History of pyloric stenosis in mother or father
Smoking during pregnancy
Nearly double the risk of pyloric stenosis
Exposure to macrolide antibiotics
Example: erythromycin to treat whooping cough
Mothers who took certain antibiotics in late pregnancy
pyloric stenosis
Sx
Symptoms
Initially,regurgitationafter feeding
Later, non-bilious, projectile vomiting immediately after feeding
Usually starts after 2-4 weeks of age
Poor weight gain
Infant shows signs of hunger (irritability, increasedsucking reflex)
pyloric stenosis
Signs
Signs
Firm, mobile, olive-shaped, 2-cmmass above and to the right of the umbilicus inepigastrium
Gastric peristaltic wave across the abdomen after feeding
Signs ofdehydration:
Sunkenfontanelles, delayed capillary refill, dry mucous membranes, and/or decreasedurineoutput may be present
NON bilious vomit
Vomiting might be mild at first and gradually become more severe as the pylorus opening narrows
pyloric stenosis
pyloric stenosis
patho
pyloric stenosis
labs
Laboratory studies
Hypochloremicmetabolic alkalosis
Hypokalemia
Dehydration leads to retention of sodium and elimination of potassium
Elevated bloodureanitrogen(BUN) and creatinine withsevere dehydration
pyloric stenosis
Imaging
US criteria
Ultrasound
Pyloric muscle thickness: > 4mm(the most discriminating and accurate criterion)
Pyloric muscle length: > 15mm
Pyloric diameter: > 15mm
Contrast studies
If diagnosis not confirmed by ultrasound, but still suspected
Target signordonut sign:classic cross-sectional appearance of thepylorusin the shape of a target or donut
pyloric stenosis
pyloric stenosis
Preoperative care
Fluid replacement + decompression
Correct electrolyte abnormalities
Restoration of acid-base balance
pyloric stenosis
Surgery and post op
Surgery
Ramstedt pyloromyotomy:
Short transverseskinincision plus longitudinal incision of pyloric muscle up to submucosa
Postoperative care
Oral feeding can be initiated within 12–24 hours
Persistent vomiting suggests incomplete pyloromyotomy or an alternative diagnosis
Hirschsprung Disease
general
Congenital anomaly of thecolon that is caused by the absence of ganglion cells at the Meissner’s plexus (submucosa) and Auerbach’s plexus (muscularis) of the terminal rectum that extends proximally
Associated with mutations in multiplegenes that are important for the growth and differentiation ofneural crest cells, most commonly in theRETgene
~1 in 5,000 live births in the US
Classification:
Sporadic:
Most common (70%)
Familial forms
As part of a genetic syndrome:
Down syndrome (DS)/trisomy 21: ~10% of individuals withHD have DS
“achalasia of the colon”
Hirschsprung Disease (HD)
patho
Caused by the failure of neural crest-derivedganglion cells to migrate into the distal colon → functional obstruction due to the arrest ofperistalsis
Aganglionic segment also have abnormal alterations in the expression ofreceptors,channels, cytoskeletalproteins, and neurotrophic factors
Auerbach’s plexus – causes smooth muscle relaxation
Meissner’s plexus – controls flow, epithelial cell absorption, and secretion
The rectum is always involved
Rectosigmoidcolon is most common (“short-segment disease”): 80%
Extension proximal to thesigmoid colon(“long-segment disease”): 15%–20%
Total colonic: 5% of cases
Muscularhypertrophy and dilatation of bowel proximal to obstruction, with possible progression tomegacolon and rupture (usually in thececum)
Total colonic aganglionosis including a short segment of the terminal ileum
HD
Triad
Classic triad of symptoms:
Delayed passage ofmeconium
> 48 hours in a term infant
Abdominal distension
Bilious vomiting
HD
Clin Man
Triad
Additional signs and symptoms in the neonatal period:
Explosive expulsion of gas and stool afterdigital rectal examination (temporary relief of obstruction)
Enterocolitis (more common if the diagnosis is delayed):
Sepsis withfever
Vomiting,diarrhea, and abdominal distension → toxic megacolon
Bowel perforation (cecal/appendiceal)
HD
Later presentations
Less severe functional obstruction (ultrashort-segment HD - < 4 cm from theinternal anal sphincter)
Symptoms and signs:
Chronic refractoryconstipation
Abdominal distension
Failure to thrive
HD
Dx from Hx
Suspected based on the clinical presentations in the neonatal or postnatal periods…No meconium in 24 hours start to worry about HD!
Most individualsare diagnosed in the 1st month of life
Less severe disease may not present with symptoms until 3 years of age (10% of cases)
HD
Dx testing
Contrast enema:
Pathognomonic sign of the “transition zone” (funnel-shaped segment between the aganglionicrectum and the proximal dilatedcolon)
Anorectal manometry:
Helpful inscreening individuals with ultrashort-segmentHD
Rectalbiopsy: necessary for confirmation of the diagnosis (absence ofganglion cells)
HD
Tx
Surgical resectionof the aganglionic segment of the bowel is the only definitive treatment
Ultrashort-segmentHD(aganglionosis < 4 cm from theinternal anal sphincter):
Medical management with diet, stool softeners,laxatives
Surgical management may be needed
HD
Meckels Diverticulum
Etiology
Omphalomesenteric duct:
Connects themidgutto theyolk sacin utero
Normally involutes between the 5th and 6th weeks of gestation
Omphalomesenteric duct that does not fully involute can give rise to:
AMeckel’s diverticulum(most common persistent remnant)
Omphalomesentericcysts
Omphalomesentericfistula(drain through umbilicus)
Fibrousbands (can causebowel obstruction)
Meckels diverticulum
Meckel’s scan:
Nuclear medicine scan utilizing radioactively labeled technetium that binds togastric mucosa
First-line test for hemodynamically stable patients and if suspicion is high
ts for GI bleeding
for stable pts
Intussusception
general
Condition in which part of the intestine (intussusceptum) telescopes into another part (intussuscipiens) of the intestine leading to obstruction; if untreated → progress tobowel ischemia
Ileocecal/ileocolic
Most common, accounts for 85%–90% of cases
Epidemiology:
Most common cause ofbowel obstructionin the 6–36-month age group
60% of cases within 1st year of life
Most prevalent around viral season (viral gastroenteritis)
intussusception
Peyer’s patches
“Tonsils of the intestines”
Collection of lymphoid follicles in the mucus membrane that lines the small intestine
Produce immunoglobulin A
Limits the epithelial adherence and penetration of bacteria (confines the bacteria to the mucosal surfaces)
Intussusception is consideredidiopathicif it does not involve a lead point
Lead point:
A lesion that gets trapped duringperistalsis and drags a segment of intestines into a distal part of the intestine
Tumor/polyp
Meckel’sdiverticulum
Duplication cyst
Vascular malformation
Hematoma
Telescoping of bowel into itself → obstruction and impaired lymphatic drainage
Increasing pressure in intussusceptum bowel wall → impairment of venous and lymphatic drainage → vascular compromise
Ischemia of intussusceptum mucosa → bowel mucosa infarcts and sloughs off → bloody stools
Transmuralnecrosisandperforationmay occur with prolonged ischemia
intussusception- Peds
Imaging:
Abdominal ultrasound:
Best initial test
Target sign:the invaginated portion of the bowel appears as aringon a target (outer bowel wall)
Pseudokidney sign:the appearance of the intussuscepted segment of bowel, which mimics a kidney
Abdominal CT:
Performed only if other modalities yield unclear diagnosis
Usually identifies an underlying pathology (lead point) if present
intussusception- peds
Contrast or pneumatic enema:
Confirmatory
Therapeutic as well as diagnosticfor ileocecal intussusception
Performed using ultrasound orfluoroscopy
Procedure:
Air/contrast is injected into the intestines to create pressure, which ejects the trapped part of the bowel out of the distal bowel
intussusception
Clinical Presentation – Older Children/Adults
intussusception- adult
PE findings
Physical exam:
Abdominal distention
Focal or diffuse tenderness
Peritonitisis a late presentation = ischemia/perforation
intussusception - adult
imaging
Imaging:
AbdominalX-ray:
Nonspecific
Can show obstructive pattern:
Dilatedsmall bowelloops
Pneumoperitoneum if perforation occurred
Abdominal CT scan:
Smallbowel obstruction:
Dilatedsmall bowelloops
Collapsed distalsmall bowelandcolon
Bowel wall thickening
Target sign
