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TAS Gastroenterology > Abnormalities Arising From Abnormal Embryological Development ✅ > Flashcards

Abnormalities Arising From Abnormal Embryological Development ✅ Flashcards

1
Q

What abnormalities of the GI tract can result from abnormal embryological development?

A
  • Duodenal atresia or stenosis
  • Exomphalos
  • Gastroschisis
  • Meckel’s diverticulum
  • Midgut malrotation
  • Meconium ileus
  • Duplication cysts
  • Hirschsprung’s disease
  • Anorectal abnormalities
  • Intussusception
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2
Q

Where in the GI tract can atresia occur?

A

At any point

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3
Q

Are GI atresias single or multiple?

A

Can be either

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4
Q

Are atresias complete or incomplete?

A

Can be either

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5
Q

What is the most common site of GI atresia?

A

The duodenum

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6
Q

What is the incidence of duodenal atresia?

A

1 in 10,000-30,000 live births

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7
Q

Where do most duodenal atresias occur?

A

At the ampulla of Vater

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8
Q

What can cause a duodenal atresia?

A

Either a complete mucosal membrane or a blind-ending proximal loop, probably due to failure of canalisation of the duodenum after the 7th week

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9
Q

What causes failure of canalisation of the duodenum after the 7th week?

A

Ischaemia

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10
Q

What % of cases of duodenal atresia have associated abnormalities?

A

50%

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11
Q

Give 2 abnormalities that may be associated with duodenal atresia?

A
  • Down’s syndrome

- Prader-Willi syndrome

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12
Q

How might duodenal atresia present?

A
  • Antenatal presentation with polyhydraminos or ‘double bubble’ on ultrasound scan
  • Bilious vomiting, usually immediately after first feed
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13
Q

What is the incidence of exomphalos?

A

1 in 3000

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14
Q

What is exomphalos?

A

A midline defect of the anterior abdominal wall, where some of the organs line outside of the abdominal cavity

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15
Q

What are the organs encased in in exomphalos?

A

A membranous sac derived from the amniotic membrane

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16
Q

What organs are contained within the sac in exomphalos?

A

Vary, but can include stomach, intestine, liver, and spleen

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17
Q

What is the defect classified based on in exomphalos?

A

Size

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18
Q

What are the classifications of exomphalos?

A
  • Major (>4cm)

- Minor (<4cm)

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19
Q

What is exomphalos frequently associated with?

A
  • Other congenital abnormalities, such as trisomy 13, 18, and 21
  • Associated structural problems such as cardiac abnormalities
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20
Q

What % of cases of exomphalos are associated with other structural problems?

A

75%

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21
Q

When is exomphalos usually identified?

A

Antenatal scanning

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22
Q

What is the management of exomphalos?

A

Surgical correction

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23
Q

Do babies born with exomphalos need emergency surgery?

A

Generally not an emergency providing the intra-abdominal structures are well perfused (but depends on size of defect and if sac remains in tact)

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24
Q

What is the incidence of gastroschisis?

A

4 per 10,000

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25
Q

What are the risk factors for gastroschisis?

A
  • Low maternal age
  • Drug misuse
  • Low socioeconomic status
  • Smoking
  • Ethnic origin
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26
Q

What happens in gastroschisis?

A

The abdominal muscles are normal, but the stomach and intestines herniate through the anterior abdominal wall on the right-hand side of the umbilicus

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27
Q

What is often associated with gastroschisis?

A

Atresia

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28
Q

In what % of cases are there atresias associated with gastroschisis?

A

Up to 10%

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29
Q

What causes atresias in gastroschisis?

A

Ischaemia

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30
Q

Are other congenital anomalies usually present with gastroschisis?

A

No

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31
Q

What causes gastroschisis?

A

Spontaneous herniation of the intra-abdominal wall in utero, or from incomplete reduction of the abdominal contents during rotation during the first weeks of life

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32
Q

What is the site of herniation through intra-abdominal wall in gastroschisis?

A

Possibly at the site of the right omphalomesenteric artery

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33
Q

What is the difference between gastroschisis and exomphalos?

A

In gastroschisis, the abdominal contents are not exposed to amniotic fluid

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34
Q

What is the result of the organs not being exposed to amniotic fluid in gastroschisis?

A

Causes serositis with matting together of the intestines

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35
Q

What might be required if there is matting together of the intestines with gastroschisis?

A

May need resection after birth

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36
Q

What is the risk of intrauterine death with gastroschisis?

A

15%

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37
Q

Why is the risk of intrauterine death high in gastroschisis?

A

Due to ischaemia

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38
Q

What is the result of the high risk of intrauterine death in gastroschisis?

A

Serial antenatal ultrasound scans are recommended

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39
Q

How are babies with gastroschisis delivered?

A

Can be vaginal or operative, but should take place in a specialist paediatric surgical centre

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40
Q

What is done after birth in gastroschisis?

A

A protective membrane is placed over the eviscerated abdominal contents to prevent them from drying out, and urgent surgery is usually required to close the defect

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41
Q

Is primary or secondary closure used in gastroschisis?

A

Can be either

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42
Q

When will secondary closure of gastroschisis be done?

A

If the defect is too large to replace all the contents in one stage without causing respiratory compromise from splinting of the diaphragm

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43
Q

What may be used to preserve the intestinal contents when complete closure of gastroschisis is awaited?

A

A silo

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44
Q

Why does it often take time for feeding to be established in gastroschisis?

A

Due to poor intestinal mobility

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45
Q

What may be required due to difficulties in establishing feeding in gastroschisis?

A

A prolonged course of parenteral nutrition

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46
Q

What is the overall survival of gastroschisis?

A

90%

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47
Q

How common is Meckel’s diverticulum?

A

2-4% of newborn infants

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48
Q

What causes Meckel’s diverticulum?

A

The remnant of the omphalomesenteric duct does not fully regress and remains attached to the ileal mucosa

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49
Q

What kind of mucosa is present in a Meckel’s diverticulum?

A

Gastric

50
Q

What is the result of a Meckel’s diverticulum containing gastric mucosa?

A

It produces acid

51
Q

How can Meckel’s diverticulum be detected?

A

Using a technetium-99m scan

52
Q

What is the sensitivity of a technetium-99m scan at detecting Meckel’s diverticulum?

A

85%

53
Q

What is the specificity of a technetium-99m scan at detecting Meckel’s diverticulum?

A

95%

54
Q

How can Meckel’s diverticulum present?

A
  • Lower GI bleeding
  • Intussusception
  • Small bowel volvulus
55
Q

Is Meckel’s diverticulum always symptomatic?

A

No, it may never cause problems, depending on the size of the sac

56
Q

How is symptomatic Meckel’s diverticulum managed?

A

Surgical resection

57
Q

What can failure of the omphalomesenteric duct to regress rarely result in?

A

An intestinal fistula

58
Q

How might an intestinal fistula present?

A

Umbilical discharge

59
Q

What does an intestinal fistula appear similar to?

A

An umbilical granuloma

60
Q

How can an intestinal fistula be differentiated from an umbilical granuloma?

A

In an intestinal fistula, it is possible for a catheter to be inserted

61
Q

How is an intestinal fistula managed?

A

Surgical resection

62
Q

What is midgut malrotation?

A

When the intestine lies in an abnormal position within the peritoneal cavity

63
Q

What is the risk with midgut malrotation?

A

There is a risk of torsion (volvulus) around the superior mesenteric artery axis

64
Q

What causes malrotation?

A

Incomplete rotation of the gut contents during the first 11 weeks of embryogenesis

65
Q

What is the most common defect in midgut malrotation?

A

The duodenum lies to the right of the vertebral column instead of the left, with the caecum lying in the upper abdomen to the left of the duodenum.

66
Q

What forms in the most common defect in midgut malrotation?

A

Bands of peritoneum (Ladd’s bands)

67
Q

Where do Ladd’s bands form?

A

They pass from the caecum, across the duodenum, to the posterior abdominal wall

68
Q

What might Ladd’s bands cause?

A

Extrinsic obstruction of the duodenum

69
Q

What can obstruction of the duodenum caused by Ladd’s bands in midgut malrotation cause?

A

Bilious vomiting, usually in infancy

70
Q

What complication might arise in midgut malrotation?

A

Midgut volvulus and ischaemia

71
Q

Why is there an increased risk of midgut volvulus and ischaemia in midgut malrotation?

A

As a result of the malrotation, the midgut has a short attachment to the base of the superior mesenteric artery, and so may twist clockwise around this pedicel, resulting in ischaemia

72
Q

When should midgut volvulus be suspected?

A

In any child with bilious vomiting

73
Q

Why is it important to consider midgut volvulus in any child with bilious vomiting?

A

As the ischaemia could potentially be reversed if the Ladd’s bands are divided and the pressure from the arterial supply to the midgut is relieved

74
Q

How might children with midgut malrotation present?

A

Subacute symptoms of intermittent abdominal pain and vomiting

75
Q

What is the investigation of choice in midgut malrotation?

A

Barium meal

76
Q

Why is a barium meal the investigation of choice in midgut malrotation?

A

As it can show the position of the duodenal-jejunal flexible

77
Q

Why is the true incidence of midgut malrotation unknown?

A

Because there are probably individuals with undiagnosed malrotation who have never had any problems

78
Q

When will children with midgut malrotation not have any problems?

A

If the pedicle is long enough

79
Q

What causes meconium ileus?

A

Pancreatic insufficiency

80
Q

How does pancreatic insufficiency cause meconium ileus?

A

It causes the distal ileum to become impacted with thick, viscous meconium

81
Q

What is meconium ileus associated with in most cases?

A

Cystic fibrosis

82
Q

What % of newly diagnosed children with CF develop meconium ileus?

A

20%

83
Q

What are duplication cysts?

A

Congenital cysts attached to the gastrointestinal tract

84
Q

Where do gastrointestinal cysts occur?

A

Can occur anywhere in the GI tract between mouth and anus, but are most commonly found in ileocaecal region

85
Q

What is the histological nature of a duplication cyst related to?

A

The adjoining structure

86
Q

How might duplication cysts present?

A

As abdominal mass or obstruction

87
Q

How are duplication cysts managed?

A

When problems occur, surgical excision is required

88
Q

What is the problem in Hirschsprung’s disease?

A

There is an absence of ganglion cells in a variable segment of the bowel (aganglionosis)

89
Q

What is the incidence of Hirschsprung’s disease?

A

1 in 5000 live births

90
Q

What gender is Hirschsprung’s disease more common in?

A

Boys

91
Q

What site is affected in Hirschsprung’s disease?

A

The sigmoid and rectum are the most commonly affected sites, although the whole colon and, very rarely, the entire large and small bowel can be affected

92
Q

What does the lack of ganglion cells cause in Hirschsprung’s disease?

A

Inability of the bowel to relax, resulting in functional bowel obstruction

93
Q

When should Hirschsprung’s disease be suspected?

A

In infants who have not passed meconium in the first 48 hours of life, or in infants who present with bowel obstruction

94
Q

What examination feature is suspicious of Hirschsprung’s disease?

A

Dramatic decompression on DRE (‘explosive diarrhoea’)

95
Q

What measures should be taken in DRE in infants?

A

Should be performed by a senior doctor, and limited to only one examination when possible

96
Q

How is a diagnosis of Hirschsprung disease confirmed?

A

Rectal biopsy to confirm absence of ganglion cells

97
Q

What kind of biopsy is used to confirm Hirschsprung disease in younger children?

A

Suction rectal biopsy

98
Q

What kind of biopsy is used to confirm Hirschsprung’s disease in older children?

A

Strip rectal biopsy

99
Q

How is Hirschsprung’s disease managed?

A

Surgery to remove aganglionic section of bowel

100
Q

What is one of the major complications of Hirschsprung’s disease surgery?

A

Enterocolitis

101
Q

How does enterocolitis following Hirschsprung’s disease surgery present?

A
  • Malaise
  • Fever
  • Diarrhoea
  • Generalised sepsis
102
Q

What causes enterocolitis after Hirschsprung’s disease surgery?

A

The pathophysiology is incompletely understood, but thought to be due to gastrointestinal stasis, altered gut flora, and impaired mucosal immunity

103
Q

What is the incidence of anorectal anomalies?

A

1 in 2500 births

104
Q

What is the pathophysiological of anorectal anomalies?

A

Poorly understood, but thought to be due to failure of the breakdown of tissue at the caudal end of the GI tract in week 3 of gestation

105
Q

When are anorectal anomalies most commonly identified?

A

On routine postnatal check

106
Q

What % of infants with anorectal anomalies have other congenital abnormalities of the GI or GU tract?

A

60%

107
Q

What congenital abnormalities might accompany anorectal anomalies in boys?

A

Fistula to urethra

108
Q

What congenital abnormality may accompany anorectal anomalies in girls?

A

Vestibule adjacent to vagina

109
Q

What should be considered in infants presenting with anorectal anomalies?

A

Other anomalies, such as VACTERL

110
Q

Is Intussusception considered an embryological abnormality?

A

Not classically

111
Q

Can intussusception occur in the presence of a structurally normal gut?

A

Yes

112
Q

Why is intussusception associated with congenital abnormalities of the GI tract?

A

Even minor gut abnormalities, such as a polyp or Meckel’s diverticulum, may predispose a child to this condition

113
Q

What is intussusception?

A

When one section of the intestine invaginate into another section

114
Q

What complication can intussusception result in?

A

Obstruction

115
Q

Where in the bowel does intussusception occur?

A

Most common site is ileo-caecal junction, but can occur at other sites if there is a lead point (e.g. polyp or Meckel’s diverticulum)

116
Q

How do patients with intussusception usually present?

A
  • Acute onset abdominal pain
  • Drawing up of legs
  • Pallor
  • Redcurrant jelly stool
117
Q

What is the limitation of redcurrant jelly stool as a sign of intussusception?

A

It is a late sign

118
Q

How is intussusception diagnosed?

A

Ultrasound

119
Q

What is found on US in intussusception?

A

Target-shaped mass

120
Q

How is intussusception managed?

A

Aim to reduce with air enema, but surgical reduction may be required

TAS Gastroenterology (17 decks)

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