Surgical Ethics: Progress and Challenge

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Pediatric SurgeryA Power Review
Benedict C. Nwomeh, M.D. Assistant Professor of
Clinical Surgery Division of Pediatric Surgery
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2

• Which statement correctly characterizes changes
  in the cardiovascular system at birth?

• Pulmonary arterial resistance increases
• There is an increase in left atrial pressure
  relative to the right atrial pressure
• As the patent ductus arteriosus closes there is a
  decreased pulmonary blood flow
• The increased right atrial pressure contributes
  to the closure of the foramen secundum
• There is a decrease in systemic vascular
  resistance

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POSTNATAL CIRCULATION
Normal
PFC
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4

• Which of the following statements is true
  regarding abdominal wall defects?

• Gastroschisis results from a failure of the
  midgut to return to the abdominal cavity by the
  eleventh week
• Beckwith-Wiedemann Syndrome (omphalocele-macroglos
  sia-gigantism) has a high association with
  hyperglycemia and diabetic mothers
• The survival of infants with gastroschisis is
  nearly seventy percent
• The relatively high mortality of infants with
  omphalocele reflects the serious associated
  anomalies
• The liver and spleen are commonly herniated
  outside the abdominal cavity in infants with
  gastroschisis

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Abdominal Wall Defects

• Gastroschisis
• Defect adjacent to intact umbilical cord
• No peritoneal sac covers the viscera

• Omphalocele (Exomphalos)
• Located in the umbilical ring
• Sac present but may be ruptured
• Cord attached on to the sac

amnion
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PathogenesisGastroschisis

• Intrauterine rupture of umbilical cord
• Defect at site of involution of 2nd umbilical vein

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PathogenesisOmphalocele

• Failure of reduction of physiologic herniation of
  midgut at 6-10 weeks

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Omphalocele Vs Gastroschisis
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Associated AnomaliesGastroschisis

• Multiple anomalies rare (unlike omphalocele)
• Intestinal atresia 10-15

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Associated AnomaliesOmphalocele
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Prenatal Diagnosis

• High MSAFP and AChE
• Referral to high risk OB
• Preterm delivery doesnt protect bowel
• Spontaneous vaginal delivery
• Omphalocele C-section for large defects only

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Gastroschisis
Major problems

• Exposure of viscera
• Hypovolemia
• Hypoproteinemia
• Hypothermia
• Sepsis
• Adynamic ileus

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Omphalocele
Major problems

• Associated anomalies
• Respiratory insufficiency
• Loss of domain
• Risk of rupture

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Overall PrognosisGastroschisis
Survival() 10 35 75 85-95 91-96
Before 1960 1960-1970 1970-1980 1980-1990 1990-200
0
Based on 21 reported series
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Overall PrognosisOmphalocele

• Factors
• Associated anomalies
• Degree of prematurity
• Pentalogy of Cantrell - 75 mortality
• Overall survival 50-75

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5

• For each item below, choose
• (A) If the item is associated with Gastroschisis
  only
• (B) If the item is associated with Omphalocele
  only
• (C) If the item is associated with both
  Gastroschisis and Omphalocele
• (D) If the item is associated with neither
  Gastroschisis or Omphalocele

• Presence of a sac
• May contain small bowel, stomach, and colon
• Associated with malrotation
• Associated anomalies rare
• Intestine edematous and often matted at birth

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6

• Which statement is correct regarding small bowel
  atresia?

• Jejunal atresia results from a failure of the
  lumen to recanalize
• Nearly thirty percent of patients with
  jejunoileal atresia have Down's syndrome
• Atresias of the small intestine occur as the
  result of an intrauterine mesenteric occlusion
• The most common type of jejunoileal atresia is
  characterized by a septum or membrane
• Small bowel atresia is rarely associated with
  gastroschisis

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Duodenal AtresiaClassification
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Jejunoileal AtresiaClassification
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Gastrointestinal Atresias

• Incidence
• Duodenum 40
• Jejunoileal 45
• Colon 5
• Multiple 10.

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Duodenal Vs. Jejunoileal atresia
Duodenal Jejunoileal Incidence
15,000 11,000 to 110,000 to
15,000 Mechanism Failed recanalization Vascular
accident Multiple atresias Rare Common Associ
ated anomalies 50 Rare Polyhydramnios 50 24
Bilious emesis 85 82 Distension Rare U
sual
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Jejunoileal AtresiaDifferential Diagnosis

• Hirschsprungs Disease
• Meconium Ileus
• Meconium Plug
• Adynamic ileus secondary to medications or sepsis
• Malrotation with volvulus
• Intestinal duplication

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Atresias
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Atresias
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Jejunoileal Atresia Factoids

• Jejuno-ileal atresia occurs in 10 of cystic
  fibrosis infants (obtain genetic testing prior to
  discharge)
• 10-15 of patients will have more than one
  atresia
• Malrotation occurs in 10 of atresia patients
• Aganglianosis may coexist in addition to the
  atresia (especially colonic), so obtain suction
  rectal bx prior to ostomy takedown

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7

• A newborn girl who has not passed meconium during
  her first 24 hours has abdominal distension and
  bilious emesis. A plain X-ray is suggestive of
  jejunoileal atresia. Which of the following
  statements is true?

• A significant percentage of infants with this
  condition are premature
• These patients are at increased risk for cystic
  fibrosis
• A barium upper GI series should be done to define
  the abnormality more precisely
• The lesion is most likely located in the colon
• Congenital hypothyroidism is a common association

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8

• Which statement is correct regarding the
  diaphragm?

• the motor innervation of the lateral portion of
  the diaphragm is from ventral rami of L1, L2, and
  L3
• if the pleuroperitoneal membrane fails to develop
  by the eighth week, a posterolateral defect
  occurs
• nearly fifty percent of congenital diaphragmatic
  hernias occur on the left side
• a Morgagni hernia is located in the
  posterolateral area of the diaphragm, usually on
  the left side
• Morgagni hernias diagnosed in neonates are rarely
  symptomatic

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INCIDENCE

• Incidence is 14000 15000 live births
• Incidence is 12000 if stillbirths included

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EMBRYOLOGY

• Diaphragm forms between 4-8 weeks gestation
• Divides coelomic cavity into pleural and
  peritoneal cavities
• Central tendon derives from transverse septum
• Peripheral muscular portion arises from
  posterolateral pleuroperitoneal membranes which
  fuse with transverse septum
• Left side of diaphragm closes later than right
  side
• Therefore 80-90 of CDH occurs on the left

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ANATOMY
Parasternal hernia through foramen of Morgagni
Translocation of abdominal viscera through
posterolateral aperture in chest
Posterolateral hernia through foramen of Bochdalek
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PULMONARY HYPOPLASIA

• Survival related to degree of associated
  PULMONARY HYPOPLASIA and PULMONARY HYPERTENSION

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PULMONARY HYPOPLASIA

• Mediastinal shift contributes to hypoplasia of
  contralateral lung
• Pulmonary hypoplasia is bilateral but much worse
  on ipsilateral side
• Pulmonary hypoplasia causes inadequate gas
  exchange

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PULMONARY HYPERTENSION

• Pulmonary arterioles contain hypertrophied muscle
  making them highly reactive
• Arterioles sensitive to hypoxia, acidosis,
  hypercarbia, hypocarbia

• Pulmonary HTN contributes to persistent fetal
  circulation with shunting of blood from R ? L
  through PDA and PFO
• Hypoxemia causes a vicious cycle that perpetuates
  pulmonary HTN and hypoxemia

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Persistent Fetal Circulation
Normal
PFC
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PULMONARY HYPERTENSION

• Several vasodilators have been used to reduce
  pulmonary HTN but consistent beneficial effects
• Inhaled NO is a potent pulmonary vasodilator but
  still inconsistent beneficial effects
• Inotropes (dopamine/dobutamine) may help by
  increasing systemic BP minimizing R ? L shunting
• Avoidance of severe acidosis and hypercarbia
  important
• Permissive hypercapnia shows great promise (pH
  gt7.25 is OK)

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Prenatal Diagnosis
At level of 4-chamber heart view, stomach and
bowel are clearly visualized
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Prenatal Diagnosis
Obstruction of outlet of herniated stomach
produces gastric dilatation, lung compression and
polyhydramnios, linking severity of pulmonary
hypoplasia to the development of polyhydramnios
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Prenatal Diagnosis
Fetal MRI shows polyhydramnios, and bowel in the
left chest
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Prenatal Diagnosis
Fetal MRI shows heart pushed to the right, and
bowel in the left chest
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Radiologic Diagnosis
(L) CDH
(R) CDH
(L) CDH

• Loops of intestine in thoracic cavity
• Absence of intestine in abdominal cavity
• NG tube in chest
• Shift of mediastinum to contralateral side

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Radiologic Diagnosis

• Loops of bowel in left chest
• Shift of mediastinum to right
• Compression of right lung

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Treatment

• Intensive preoperative management crucial in
  determining ultimate postoperative result
• Orogastric decompression of stomach/intestine
• Mechanical ventilation to reduce hypoxemia and
  acidosis
• Vasodilators to improve pulmonary artery HTN
• Spontaneous respiration and permissive
  hypercapnia to minimize barotrauma until
  pulmonary HTN resolved
• In severe cases ECMO may be useful

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9

• A newborn develops tachypnea, cyanosis, and
  grunting with respirations. The chest X-ray shown
  is obtained. Initial therapy should consist of

• Insertion of a left chest tube
• Nasotracheal suction, antibiotics, and postural
  drainage
• Mask ventilation with 100 oxygen
• Paralysis followed by endotracheal intubation
• Immediate extracorporeal membrane oxygenation
  (ECMO)

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10

• Increased mortality in neonates with CDH is
  associated with

• Insufflation of nitric oxide
• In utero diagnosis
• Delay in surgical repair gt24 hours
• Hyperventilation
• Persistent arterial pH lt7.35

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12

• Which statement is correct regarding the
  development of the midgut?

• the midgut extends from the ligament of Treitz to
  the cecum
• the midgut normally undergoes a 270 degree
  clockwise rotation
• longitudinal intestinal growth is nearly complete
  by 40 weeks gestation
• a midgut volvulus occurs when the midgut twists
  in a clockwise direction about the superior
  mesenteric artery and vein
• Ladd's bands extend from the cecum across the
  first portion of jejunum and results in a
  proximal jejunal obstruction

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What is Malrotation?

• Failure of rotation and fixation of the midgut by
  the 12th week of gestation

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Embryology
A 6 wks non-rotation B 8 wks C 9 wks
incomplete D 11 wks E 12 wks complete
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Normal Fixation

• Broad based mesentery
• Duodenum, ascending descending colon fixed in
  the retroperitoneum

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Malrotation and Midgut Volvulus

• Ladds Bands

• Narrow mesentery predisposes to volvulus

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Imaging StudiesUGI

• Malrotation may be an asymptomatic, incidental
  finding

• This patient has malrotation, but no evidence of
  volvulus or bowel obstruction

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Midgut Volvulus
Corkscrew sign
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Midgut VolvulusA Surgical Emergency
Untwist the Volvulus Counterclockwise
.. turn back the clock
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Ladds Procedure

• Untwist the volvulus
• Divide Ladds bands
• Appendectomy
• Broaden the mesentery by placing the small bowel
  to right and colon to the left

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Too Late...

• Pan-necrosis

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Tragic...

• Dead gut leads to
• Dead child
• Short bowel syndrome

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Midgut VolvulusPrognosis

• Full recovery if the bowel is viable
• 5 risk of late adhesive SBO
• Virtually 100 fatal if there is infarction of
  the entire midgut
• Short Bowel Syndrome
• Prolonged TPN
• Line sepsis
• Cholestasis
• Small bowel liver transplantation

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• Which of the following about pancreatic divisum
  is correct?

• results in two anatomically separated pancreatic
  bodies
• is the result of extrauterine vascular compromise
• is never associated with pancreatitis
• represents a failure of anastomosis between the
  two pancreatic ducts
• none of the above

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Pancreas Embryology

• Pancreas develops from two primordia
• Islet cells differentiate from duodenal wall
• Dorsal pancreatic bud
• Ventral pancreatic bud
• Gland fusion at 7 weeks
• Acini develop at 12 weeks
• Ductal fusion delayed until perinatal period

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Errors of Pancreatic Development

• Aplasia and hypoplasia
• Hyperplasia and hypertrophy
• Dysplasia
• Ductal anomalies
• Rotational anomalies
• Annular pancreas
• Heterotopic pancreas
• Pancreas divisum
• Cysts
• Vascular and lymphatic anomalies
• Neoplasm
• Cystic fibrosis

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Primitive Foregut
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Annular Pancreas Embryology

• Pancreas develops from two primordia
• Dorsal pancreatic bud
• Ventral pancreatic bud

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Annular Pancreas Embryology

• Pancreas develops from two primordia
• Dorsal pancreatic bud
• Ventral pancreatic bud

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Annular Pancreas Embryology
Santorini

• Pancreas develops from two primordia
• Dorsal pancreatic bud
• Ventral pancreatic bud

Wirsung
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Annular Pancreas Embryology

• Lecco Fixation of the tip of the ventral
  pancreatic bud to the duodenal wall, preventing
  normal rotation of ventral pancreas
• Baldwin The ventral pancreas consists of paired
  primordia, one migrates anteriorly and the other
  posteriorly around the duodenum

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Annular Pancreas Pathology

• Most common form of extrinsic compression of the
  duodenum
• Gross Findings
• Thin, flat segments of pancreatic tissue
  partially or completely surround 2nd portion of
  duodenum
• May cause complete or partial obstruction
• Found in 20 of duodenal stenosis or atresia
• 70 of patients have duodenal stenosis or atresia

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Annular Pancreas Pathology

• Most common form of extrinsic compression of the
  duodenum
• Gross Findings
• Thin, flat segments of pancreatic tissue
  partially or completely surround 2nd portion of
  duodenum
• May cause complete or partial obstruction
• Found in 20 of duodenal stenosis or atresia
• 70 of patients have duodenal stenosis or atresia

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DuodenoduodenostomySide-to-side
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Pancreas Divisum

• Prevalence 10
• Failure of fusion of primordial ducts
• Duct of Santorini drains body, tail, and uncinate
  process via minor papilla
• Risk of pancreatitis greater with stenosis of
  minor papilla
• Incidence 25 in unexplained recurrent
  pancreatitis

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Pancreas Divisum

• Diagnosis by ERCP or MRCP
• Sphincteroplasty of minor papilla, if symptomatic
• Pancreatico-jejunostomy if chronic pancreatitis
  with dilated duct

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14

• Which of the following about annular pancreas is
  correct?

• is treated by division of the pancreatic ring to
  relieve duodenal obstruction
• is often totally asymptomatic
• results from failure of migration of the superior
  and inferior medial and lateral halves of the
  pancreas
• presents with hyperglycemia in the newborn period
• is associated with nesidioblastosis

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15

• Which of the following statements about
  Hirschsprungs disease is TRUE?

• It is a congenital aganglionosis of the myenteric
  plexuses
• Meconium passage is typical of the disease
• It produces lack of relaxation of the
  noninnervated bowel
• The last 10cm of bowel proximal to the dentate
  line normally lacks plexuses
• Ultrashort disease is usually detected at birth

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Embryology

• Defect in the development of the enteric nervous
  system
• Neural crest derivatives
• Migration occurs in a cranial to caudal fashion
• Migration begins during the fifth week of
  gestation and should be completed by the twelfth
  week

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Incidence

• 14000 live births
• MF ratio 41 (except in long segment disease
  where it is closer to 11)
• Familial cases 6 of total

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Anatomy and Pathology

• Gross
• Dilated, thickened proximal, ganglionic bowel
• Transition zone
• Distal (aganglionic) bowel appears normal

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Location of Disease
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Associated conditions

• Most often an isolated disorder
• Downs syndrome (trisomy 21) in 5-16 of patients
• Other rare associated conditions
• Trisomy 18
• Ondines curse (central hypoventilation syndrome)
• Waardenburg Syndrome (total colonic
  aganglionosis)
• Smith-Lemli-Opitz Syndrome
• MEN Type 2A

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Diagnosis

• Up to 90 of children now diagnosed in the
  neonatal period
• Failure to pass meconium within 48 hrs after
  birth
• Enterocolitis
• Symptoms (neonatal)
• abdominal distention
• poor feeding
• bilious emesis
• Symptoms (older patients)
• chronic constipation
• abdominal distention
• poor weight gain

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Differential diagnosisFailure to pass meconium

• Mechanical Obstruction
• Meconium Ileus
• Meconium Plug
• Hirschsprungs Disease
• Intestinal Atresia
• Imperforate Anus

• Functional Obstruction
• Prematurity
• Maternal Magnesium
• Small left colon syndrome
• Sepsis
• Hypothyroidism
• Intestinal Neuronal Dysplasia

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Diagnostic Work-Up

• Radiographic studies
• Rectal biopsy
• Anorectal manometry (rare)

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Plain abdominal Xray
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Barium enema

• Unprepped bowel
• Allows for the determination of colon caliber
• Microcolon
• suggests an unused colon
• seen in meconium ileus, small bowel atresias
• Findings in Hirschsprungs
• distended proximal colon
• transition zone
• rectum smaller in caliber than sigmoid

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Rectal biopsy

• Provides diagnostic information
• Suction biopsy performed at bedside in neonates
• Submucosa required
• Full thickness biopsies more often performed in
  older patients under anesthesia

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Light Microscopy

• Absence of submucosal (Meissners) and
  intermuscular (Auerbachs) ganglia
• Increase in Ach nerve fibers (parasympathetic)
  in submucosa
• No skip lesions
• Transition zone may show hypoganglionosis or IND

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Ganglion cells
Normal
Hirschsprungs
Courtesy, R. Jaffe, CHP, Pathology
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Acetylcholinesterase staining
Hirschsprungs
Normal
Courtesy, R. Jaffe, CHP Pathology
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Anorectal Manometry

• Usually reserved for older patients with history
  of chronic constipation
• Absence of relaxation reflex diagnostic of
  Hirschsprungs
• Less useful in children

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Treatment

• Initial stabilization
• fluid resuscitation
• NG decompression
• culture and start antibiotics
• rectal tube and irrigations
• Surgery

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ANATOMIC THERAPY OF A PHYSIOLOGIC DISEASE
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Classic Surgical Approach

• Leveling colostomy at time of diagnosis
• Define extent of aganglionosis
• Pull-through procedure
• Swenson
• Duhamel
• Soave

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Leveling procedure

• Identifies the level of ganglion cells
• Seromuscular biopsy
• Frozen section
• Colostomy to relieve obstruction

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Leveling procedure
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One stage Trans-anal Endorectal (Soave)
Pull-through
Submucosal dissection from just above dentate line
Dissection up to level of peritoneal reflection
Mucosal tube everted through the anus with rectum
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One stage Trans-anal Endorectal (Soave)
Pull-through
Rectal muscle cuffsplit
Rectum divided in ganglionated level (above
biopsy site)
Coloanal anastomosis
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Surgical procedures
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Swenson
Duhamel
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New Surgical Techniques
1964 Boley Surgery 56 1015-1017 New
modifiction of the surgical treatment of
Hirschsprungs disease
1980 So, HB. et al JPS 15
470-471 Endorectal pull-through without
preliminary colostomy in neonates with
Hirschspungs disease
1995 Georgeson, KE JPS 30 1017-1022 A new
surgical technique for the treatment of
Hirschsprungs disease
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New surgical techniques

• Laparoscopically assisted pull-through
• Single stage procedure
• Biopsies and colonic mobilization performed
  laparoscopically
• Endorectal dissection performed transanally

Georgeson, Ann Surg, 1999
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• The most effective treatment for Hirschsprungs
  disease is

• Prokinetic drugs
• Excision of the dilated colon and ileocolostomy
• Resection of the distal rectum with a rectorectal
  pull-through
• Resection of the colon with an ileoanal
  anastomosis using a J-pouch
• Myotomy of the distal rectum

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17

• An infant in the NICU with progressive abdominal
  distension has the x-ray shown. Which of the
  following statements about this condition is NOT
  true?

• Radiographic signs can precede most of the
  clinical findings
• More than 90 of patients will require abdominal
  exploration within 24 hours
• The condition is associated with prematurity
• The terminal ileum and right colon are most
  commonly affected
• Intestinal ischemia is the cause

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An infant in the NICU with progressive abdominal
distension has the x-ray shown. Which of the
following statements about this condition is NOT
true?
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Necrotizing Enterocolitis

• Commonest, most lethal GI condition of LBW
  infants
• lt 1500g, incidence is 6, 15 of deaths after 1
  week
• NEC is a disease of survivors

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Risk factors for NEC

• Prematurity
• Enteral alimentation
• GI microbial flora
• Respiratory insufficiency
• Congenital heart disease
• Medications (Indomethacin, Vit E)
• Maternal cocaine use

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Clinical Presentation

• Abdominal distention in a stressed, preterm baby,
  with feeding intolerance and bloody stools
• Palpable bowel loops
• Erythema of abdominal wall
• Bilious emesis

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Abdominal Wall Erythema
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Radiographic Findings

• Bowel distention
• Pneumatosis intestinalis
• Portal veinous gas
• Pneumoperitoneum
• Ascites

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Pneumatosis Intestinalis
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Portal Venous Gas
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Pneumoperitoneum
120
Pathology

• Most frequent site is terminal ileum, then colon
• Pan-necrosis 10-20 of patients
• Marked distention of bowel, subserosal gas
  collections, skip areas, fibrinous exudate
• Microscopic lesion coagulation necrosis of
  superficial, mucosa, edema, hemorrhage, mucosal
  ulceration

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Pneumatosis
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Pan-necrosis
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Histology
Hemorrhagic Necrosis
Pneumatosis
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Pathogenesis of NEC
Perinatal stress (birth asphyxia)
Reduced intestinal blood flow
Gut barrier failure - migration/repair
Bacterial translocation
Inflammatory response (local and systemic)
Necrosis and peritonitis
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Treatment of NEC

• NG tube
• Correct hypovolemia and electrolytes
• TPN
• Antibiotics
• Enterbacteriacie, Pseudomonas, Salmonella,
• Staphylococci
• Anaerobes
• 30 incidence coag-neg staph

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NEC Indications for Operation

• Pneumoperitoneum
• Positive Paracentesis
• Fixed Loop of Bowel
• Abdominal Wall Erythema
• Abdominal Mass
• Portal Venous Gas

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NEC Operative Management

• Segmental Necrosis
• Resection Stoma
• Resection Primary Anastomosis
• Pan-Necrosis
• Proximal intestinal diversion with or without
  limited segmental resection
• Peritoneal drainage alone
• Peritoneal drainage delayed laparotomy

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18

• Factors that suggest postoperative chemotherapy
  or radiation therapy would be necessary for a
  patient with Wilms tumor include all of the
  following except

• Age of the patient
• Stage of the tumor
• Undifferentiated sarcomatous changes
• Anaplastic changes
• Bilateral disease

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19

• Local recurrence of Wilms tumor is strongly
  associated with all of the following EXCEPT

• Diffuse anaplasia
• Capsular penetration
• Intraoperative tumor spillage
• Omission of regional lymph node sampling
• Local invasion into liver or spleen

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20

• Pediatric Wilms tumor

• Is synchronously bilateral in more than 25 of
  cases
• Usually presents as painless hematuria
• Develops from nephrogenic rests
• Is the most common childhood cancer
• Requires postoperative radiotherapy to prevent
  recurrence

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Questions
?