Tuesday, October 23, 2012

Neonatal Intestinal Obstruction

A brief introduction to neonatal intestinal obstruction. A primer for medical students or residents of pediatric surgery on there first few day of training.

  • Atresia: Complete intrinsic occlusion of the intestinal lumen
  • Stenosis: Refers to localized narrowing of the bowel or a diaphragm with a small perforation,  causing incomplete obstruction.
Extrinsic: e.g., volvulus, peritoneal band, annular pancreas
Level of Obstruction:
e.g., pyloric atresia, duodenal atresia
e.g., ileal atresia or hisrschprungs disease

  • Neonatal sepsis
  • NEC
  • Hypothyroidism
  • Electrolyte imbalance
  • Birth trauma
  • Prematurity
  • Transplacental transfer of maternal medication
Clinical Presentation:
  • Bilious or non-bilious vomiting
  • Abdominal distention
  • No or delayed passage of meconium
Natural History:
  • Aspiration pneumonia
  • Sepsis
  • Biochemical and hematological derangements
Causes of death:
  • Congenital anomalies
  • Intercurrent infections
  • Prematurity
Prenatal Diagnosis:
  • Polyhydramnios
  • Detection of lower atresia by seeing multiple distended bowel loops
  • Perforation can be picked by
    • Ascites
    • Meconium pseudocyst formation,
    • Calcification
Preoperative Preparation:
  • Insert nasogastric tube
  • Pass intravenous line
  • Replace losses (10-20 ml/kg/H) until adequate urine output maintained
  • In case of pneumonia, peritonitis, sepsis start antibiotics
  • Send CBC, serum electrolyte and renal function tests blood grouping and cross match.
  • One stable perform imaging investigations
  • Double IV Fluid maintenance if gastrograffin is to be used
  • Echo to rule out associated cardiac anomalies
Postoperative Care:
  • Total Parenteral Nutrition till oral feeding
Specific Diseases:
Pyloric atresia-epidermolysis bullosa syndrome:
All reported cases have Died before 11 months with or without surgery

Pyloric web: 
Pylorus is obliterated by a diaphragm.

Pyloric stenosis: 
Diaphragm with a small central hole in it causing incomplete obstruction. Late prsenting patients will have metabolic alakalosis.

Duodenal Atresia:
Most common location for atresia
Embryology: Failure of duodenal recanalization after 3rd week of gestation
Associations: Down syndrome, Trisomy 21, Congenital Heart Disease, renal, central nervous system, or musculoskeletal system, extrahepatic pancreaticobiliary ductal system and pancreas.
Risk: Prematurity
Operative Treatment:
Type 1:
Duodenotomy, excision and duodenoplasty. (locate CBD  by gently pressing the GB)
Type 2 and 3:
Duodenoduodenostomy + LADDS if required

Duodenal stenosis: 
  • Diaphragm with a small central hole in it
  • Annular pancreas
  • Aberrant pancreatic tissue
  • Preduodenal portal vein
Differential Diagnosis: 
Malrotation. Confirm with upper GI contrast

Jejunal and Ileal Atresia:
Incidence: Distal Ileal and Proximal Jejunal atresia are most common
Embryology: Late intrauterine mesenteric vascular accidents such as volvulus, intussusception, internal hernias, bowel incarceration in an omphalocele or gastroschisis
Associations: Apple peal variety patients have  prematurity, malrotation, short gut syndrome, multiple atesia
  • Deficiency of coordinated peristalsis
  • Hyperplasia of ganglion cells in the dilated proximal segment
  • Absent acetylcholinesterase activity at the ends of proximal and distal atretic segments
Differential Diagnosis:
  • Meconium ileus
  • Hirschprungs Disease
Operative Treatment Principles
  • Preserve as much bowel as possible
  • Resect proximal dilated bowel
  • Tapering or Plication if short bowel syndrome is feared
  • Check for distal patency
  • End to End to End to Oblique Primary anastomosis is preferred
Malrotation occurs due to failure of gastrointestinal tract to complete its normal rotation and fixation as it return to abdominal cavity during 8th to 10th week of gestation
  • 50-75% present before one month
  • Upper GI contrast: extrinsic compression and torsion (corkscrew, coiled or bird’s beak sign)
  • Abdominal USG (Doppler USG) Relationship of Superior mesenteric artery and vein
  • Volvulus
Clinical Features:
  • Abdominal distention
  • Pain
  • Rectal bleeding
Natural history:
  • Hypotension
  • Respiratory failure
  • Systemic acidosis
  • Sepsis
  • Airless abdomen on x-ray. 
  • Can also be diagnosed by color doppler
  • It is a Surgical Emergency.
Operative Steps:
  • Evisceration of Bowel

  • Derotation in anticlockwise direction. 
  • Division of LADDS bands
  • Splaying of mesentery
  • Appendectomy
  • Small bowel is placed on left and cecum on right parallel to each other
Meconium Ileus:
Retention of think tenacious meconium in bowel causing obstruction
  • Giant meconium cyst
  • Meconium peritonitis,
  • calcification in the peritoneal cavity
Most common cause: 
Cystic Fibrosis. Rare in Asians
  • Present with adbdominal distention at birth.
  • In complicated meconium ileus the abdomen is erythrematous, oedematous, distened, with signs of peritonitis. When a mass is palpalble it indicated psudocsyt formation.
  • Soap bubble or Ground-glass appearanc
  • for complicated calcification, ascites, gas under diapgragm.
For Simple Meconium Ileus a Contrast enema is diagnostic and therapeutic. More than two is required. The success rate is around 60-70%.If not successful than laparotomy is needed.
Operative Principles:
  • Enterotomy in the dilated segment of bowel
  • Emulsify Meconium by gastrograffin or nacetylcysteine 1-4 %
  • Evacuate meconium
  • Preserve as much of bowel length as possible
  • With or without Stoma
For Complicated Meconium Ileus Operative resection with or without Stoma is required.
Postoperative Care:
  • Wash the distal loop with the indwelling catheter
  • Give oral n-acetylcystein
  • Start pancreatic enzymes
Hirschprungs Disease:
Caused by abnormal migration of neural crest cell. The early the failure the higher the aganglionic segement.Most commonly it is upto rectosigmoid junction
  • Per-Rectal Examination
  • Barium enema
  • Rectal biopsy
Rectal washouts to keep bowel clean
Surgical options:
  • Colostomy folowed by Duhamel
  • One stage endorectal pullthorugh open or laparoscopic using frozen section biopsy
Imperforate Anus:
Emergency Surgery:
  • Sigmoid lop colostomy
Definitive Management:
  • Investigate
  • Definitive Surgery
Meconium plug syndrome:
Inspissated and dehydrated meconium in the distal colon and rectum
  • Diabetic mothers
  • Hypothyroid babies
  • Premature infants
Differnetial Diagnosis:
  • Hirschprungs Disease: Rectal biopsy to rule out
  • Cystic Fibrosis: Sweat test after 6 weeks to rule out
  • Revealed and healed by contrast enema
Small left colon:
Diagnostic Pointer on xray is rectum is dilated but left colon not. Treatment is complex.

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