Neonatal Surgery Flashcards
What forms the primitive gut embryologically
Embryonic disc folds in the cephalocaudal direction and transversely to form the endoderm-lined cavity of the primitive gut
What are the divisions of the primitive gut
- Pharyngeal gut
- Foregut
- Midgut
- Hindgut
From where are the muscular contributions of the gut derived
Mesoderm
What does the foregut give rise to
- Trachea
- Oesophagus
- Stomach
- Duodenum
- Liver
- Pancreas
- Spleen
What results from abnormal closure of the oesophagotracheal septum
Tracheo-oesophageal fistula
From where is the liver derived
Hepatic diverticulum - endodermal outgrowth from the distal end of the foregut
From where is the uncinate process of the pancreas derived
Ventral pancreatic bud
When is the connection formed between the rectum and the outside and how does this occur
- Week 9
- Rupture of the anal membrane underlying the anal pit
Describe Gastroschisis
- Defect in the abdominal wall to the right of the umbilicus
- Bowel is eviscerated, thickened and matted
- No sac
What is Gastroschisis associated with
Intestinal atresias (10%)
How is Gastroschisis treated
Preformed spring-loaded silos allows the bowel to reduce into the abdomen by gravity. The defect can then be closed.
Describe exomphalos (omphalocele)
Hernia inclusive of bowel into the base of the umbilical cord, i.e. covered by a sac
How is exomphalos (omphalocele) categorised
- Major = defect >5cm
- Minor = defect <5cm
What is exomphalos (omphalocele) associated with
- Trisomies
- Cardiac defects
How is exomphalos (omphalocele) treated
Closure of the defect in one or more stages (if the abdomen is not large enough to accept the bowel then it can be left to epithelialise and the contents be gradually reduced before 1 year)
List the VACTERL conditions
- Vertebral anomalies
- Anorectal anomalies
- Cardiac
- Tracheo-Esophageal
- Renal
- Limb
What maternal feature is associated with oesphageal atresia
Maternal polyhydramnios
How does oesophageal atresia present
Present at birth with a ‘mucousy’ baby, choking or turning blue on feed
What is oesophageal atresia
A section of the oesophagus is missing resulting in it ending in a blind-ended pouch
What percentage of babies with oesophageal atresia will have a tracheo- oesophageal fistula
75%
How is oesophageal atresia diagnosed
Confirmed by trying to pass and NG tube and taking a CXR. There are tube coils in the upper thorax. Gas in the stomach indicates a fistula between the trachea and distal oesophagus.
How is oesophageal atresia treated
Disconnection of the tracheo-oesophageal fistula and anastomosis of the upper and lower oesophagus through a right thoracotomy
What are the complications associated with oesophageal atresia surgery
- Anastomotic leak
- Anastomotic stricture
- GORD
- Recurrent fistula
What chromosomal abnormality is associated with duodenal atresia
Downs Syndrome
What is duodenal atresia
Congenital absence of complete closure of a portion of the lumen of the duodenum
How does duodenal atresia present
At birth with bile-stained vomiting
How is the diagnosis of duodenal atresia confirmed
AXR - ‘double bubble sign’ of gas in the stomach and proximal duodenum
How is duodenal atresia treated
Side-to-side duodenoduodenostomy
Describe low and intermediate anorectal anomalies in boys
- Rectum present and passes through a normal sphincter complex
- Fistulous track to the surface of the perineum, usually anteriorly onto the scrotum
How are low and intermediate anorectal anomalies treated in boys
If meconium is visible a local ‘cut-back’ procedure can be performed to open the fistula back to the rectum in anticipation of normal continence
In high anorectal anomalies, where does the fistulous track develop
Rectum to urethra
How is faeces diverted in imperforate anus
High sigmoid colostomy
Describe the pathophysiology of midgut malrotation
- As the physiological midgut hernia reduces, the mesentery usually rotates to bring the caecum to the RIF and the DJ flexure to left of the midline
- Failure of this rotation leaves the caecum high in the RUQ and the DJ flexure mobile in the midline
How is midgut malrotation diagnosed
Upper GI contrast study and USS
How is midgut malrotation managed
Urgent laparotomy to untwist the bowel (Ladd procedure if volvulus is present)
How does Meconium ileus present
Delayed passage of meconium and abdominal distension
How is Meconium ileus treated non surgically
- Gastrograffin enema
- NG N-acetyl cysteine
What is the surgical management of Meconium ileus
- Surgical removal of the plugs
- Temporary ileostomies
What chromosomal disorder is associated with Hirschsprung’s disease
Down’s Syndrome
What causes Hirschsprung’s disease
- Failure of ganglion cells (neural crest origin) to migrate down the hindgut
- Causes a functional obstruction at the junction between normal and aganglionic bowel
Describe the distribution of bowel affected by Hirschsprung’s disease
- 80% rectum/sigmoid
- 20% involves entire colon
How does Hirschsprung’s disease present
Presents in the first few days of life with:
- Low intestinal obstruction
- Failure to pass meconium
- Abdominal distension
- Bile-stained vomiting
How is the diagnosis of Hirschsprung’s disease confirmed
Rectal biopsy - no ganglion cells in the submucosa (suction biopsy for neonates; strip biopsy if older)
How is Hirschsprung’s disease treated
Three-stage surgical procedure:
- Defunctioning colostomy with multiple biopsies
- Pull-through procedure to bring down ganglionic bowel
- Closure of the colostomy
What is the main complication of Hirschsprung’s disease
Enterocolitis associated with C.diff toxin
Describe Necrotising Enterocolitis
Acute inflammatory condition of the neonatal bowel that may be associated with areas of bowel necrosis and a systemic inflammatory response syndrome
What is the primary risk factor for necrotising enterocolitis
Prematurity
List the signs and symptoms of necrotising enterocolitis
- Feed intolerance
- Delayed gastric emptying
- Abdominal distension, tenderness and ileus
- Blood PR
- Peritonitis if perforation occurs
How is necrotising enterocolitis managed
- Supportive
- NBM with parenteral nutrition
- Surgical resection of necrotic bowel
What is the key determinant of survival in necrotising enterocolitis
Birthweight
How are congenital diaphragmatic hernias categorised
- Posterolateral (Bochdalek)
- Anterior (Morgagni)
What is the most common type of congenital diaphragmatic hernia
Posterolateral (Bochdalek) - 90% left sided
How is congenital diaphragmatic hernia managed
Repair of the diaphragmatic defect after a few days with either suture or prosthetic gore-tex patch
When do the facial primordia appear during development
4th week
List the 5 facial primordia
- Frontonasal prominence
- Maxillary prominences (paired)
- Mandibular prominences (paired)
When does the palate develop
Between weeks 5 and 12
What are the two major groups of cleft lip and palate
- Clefts involving the upper lip and anterior part of the maxilla, with or without palate involvement
- Clefts involving hard and soft regions of the palate
What deficiency in pregnancy may be implicated in the development of cleft lip/palate
Vitamin B complex
What is the risk of having a second affected child with cleft lip compared to the general population
4% Vs. 0.1%
What causes cleft lip
Failure of merging the medial nasal prominence and maxillary prominence
What conditions are associated with neonatal intestinal malrotation
- Exomphalos
- Diaphragmatic hernia
What condition is associated with a scaphoid abdomen
Bochdalek hernia (herniation of the abdominal contents into the chest)
What causes unilateral cleft lip
Failure of nasolabial muscle ring fusion
What structures may a Bochdalek hernia contain
Stomach
What structures may a Morgagni hernia contain
Transverse colon
