1. CLINICAL CORRELATES OF THE
MIDGUT DEVELOPMENT
BY DR ADUGNA DAGNE (YEAR 1 RADIOLOGY RESIDENT)
ST.PAUL HOSPITAL MELLINIUM MEDICAL COLLEGE
DECEMBER -2017

2. Accepted model of midgut maturation involves 4 distinct stages:
• (1) herniation
• (2) rotation
• (3) retraction
• (4) fixation
Developmental anomaly of midgut and its clinical correlates

3. 1. Errors/defect of herniations;
•1.1 Omphalocele
•1.2 Gastroschisis
Umblical hernia

4. 1.1 Omphalocele/exomphalos
• Greek words "omphalos“ = naval, and "cele“= pouch.
• Median abdominal wall defect into which abdominal contents herniate
• Persistent of abdominal contents in to proximal(base) part of umblical
cord
• No abdominal muscles, fascia and skin near the umblicus
• Covering of hernial sac is peritoneum and amnion

5. Cont…
Incidence
• 1/5,000 births only bowel , 1/10,000 births with liver
Etiology
Liver containing omphalocele
• – Primary failure of body wall closure (5-8 weeks)
Bowel only omphalocele
• – Failed return of physiologic gut herniation (6-10 weeks)

6. Cont…
Genetics;
• Chromosomal abnormalities (30-40%) in utero, less common at birth
(IUFD or termination)
― Trisomy 18 (most common), 13,21, Triploidy
• Syndromes include: Beckwith Wiedemann syndrome, pentalogy of
Cantrell, cloacal exstrophy….
Associated structural abnormalities;
• 25-30% of cases
– CVS: 50% of associated anomalies
– GIT: 40% ; Malrotation always present
; bowel atresias
– Others: MSK, CNS,GUS

7. Diagnosis of omphalocele
1. Antenatal ultrasound;
2. MRI;
Findings;
• T1WI ; Best for showing if colon is involved
– Meconium has high signal
• T2WI
― Liver dark
―Fluid-filled bowel is bright
; Helpful to evaluate suspected additional anomalies

8. Ultrasonographic findings;
• Best diagnostic clue;
• Smooth midline protruding abdominal wall mass covered by
membrane
• Color Doppler shows cord inserts on mass
• Smaller AC
Check ?
1. Size ; varies depending on content of omphalocele
– Large if liver involved (> 8 cm called giant)
– Small if liver not involved (bowel only)

9. U/s cont…
2. Contents ; well seen with ultrasound;
• Liver + SI is most common
• Larger defects with spleen, bladder, stomach
Bowel-only omphalocele
• Multiple bowel loops , usually seen as echogenic (non-fluid filled bowel)
• look for peristalsis
3. Umbilical cord inserts onto membrane(Color Doppler)
– Usually centrally but can be eccentric

10. U/s cont…
4. Omphalocele membrane
―Peritoneum on inside and amnion on outside with sandwiched Wharton jelly
―Mostly thin but can also be multicystic (from cystic degeneration of WJ)
5.Ascites is common
– Almost always present by 3rd trimester
6. Polyhydramnios is common
7. fetal anatomic scan
Always look for features of syndromes and chromosomal abnormalities
when an omphalocele is seen

11. DDX
Physiological gut herniation ;
• Presents as a mass at umbilical cord insertion
• Consider only < 11.4 weeks / CRL < 55 mm
• Should not exceed 7 mm in diameter and never contain the liver
Gastroschisis;
• Bowel wall thickened and dilate , look UCI
Bowel floating in ascites ; mimic floating bowel in amniotic fluid
• seen with gastroschisis
Umbilical Cord Cyst
• Often coexist
• Cysts near abdominal wall insertion site can mimic bowel herniation
• 1st-trimester cysts tend to resolve

12. Prognosis;
• Depend on size and associated anomaly
• Survival is 80-90% if normal chromosomes and no syndromes/ other
significant anomalies
• Giant omphalocele with mortality of 25%
• Stillbirth and neonatal death rates correlate with associated anomalies
Treatment;
• Delivery at tertiary care
• Benefits of cesarean section controversial
(May be recommended in cases of very large omphaloceles)
• Surgical treatment based on size
○ Primary closure if small
○ Delayed surgical closure if large

13. Omphalocele containing liver.
A: Sagittal image of fetus demonstrating large omphalocele (arrow) containing a region of
homogeneous tissue representing liver (L).
B: Color Doppler image of large omphalocele (arrow) showing vessels in the herniated portion of
the liver (L). Umbilical vessels (arrowhead) are seen inserting into the omphalocele sac.

14. Picture after birth;
Both pictures are taken from internet

15. 1.2. Gastroschisis
• Greek gastro (stomach) plus schisis (split), misnomer
• Herniation of the intraabdominal contents through a full thickness
paramedian abdominal wall defect,
• Usually measures 2-4 cm
• Not involve the umblical cord
• Usually on the right side, lateral to umbilicus (rare left-sided)
• More common in male,
• No membrane and floats freely in the amniotic fluid

16. Incidence; 1/2,000 births, usually SI
Genetics
• Most are sporadic
• Chromosomal syndromes 1.2% and nonchromosomal syndromes (0.7%).
Associated abnormalities
• GI abnormalities (80-90%)
• Malrotated or nonrotated bowel in all cases

17. Etiology; unknown
Proposed;
Failed closure of ventral body wall at 5-7 weeks
• Deficient mesoderm may be etiology of abnormal body wall folding
• Ischemic injury to anterior abdominal wall (MC)
• Weakness of the wall by abnormal involution of right umblical vein

18. Diagnosis;
Prenatal ultrasound;
MRI
T2WI ; High signal in exteriorized bowel loops
• Helpful when visualization compromised
( Maternal obesity, oligohydramnios…)
• Helpful to evaluate suspected additional anomalies

19. Ultrasonographic findings;
Best diagnostic clue;
 irregular protruding anterior abdominal wall mass with normal
umbilical cord insertion (UCI)
 No covering membrane
 Smaller AC for GA

20. u/s cont…
1. Contents ;
– Large amount of bowel "out" is typical
□ Small bowel always involved
□ Large bowel often involved
– Stomach and bladder may externalize
– Rarely liver
Types;
• Simple gastroschisis (80-90%)
No additional anomalies, no significant bowel dilation
• Complex gastroschisis ; dilated bowel, extruded liver, other anomalies
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21. u/s cont…
2. Bowel dilation (> 7 mm considered dilated)
– Extracorporeal bowel dilation is common (88%)
• Not predictive of bowel atresia
• Progressive as pregnancy advances
– Intraabdominal bowel dilation (IABD) more predictive of bowel
pathology
• > 14 mm associated with ↑ rates of atresia (29%)
• IABD < 14 mm with 91% negative predictive value for atresia
3. Bowel wall appearance
– Thickened, echogenic, matted, nodular
• 2° chemical peritonitis from amniotic fluid exposure
• Fibrinous, serosal deposit "peel"
– Associated with atresia, other bowel pathology

22. u/s cont…
4. Stomach often malpositioned
– Stomach "pulled" toward UCI
5. Oligohydramnios more common than polyhydraminos
– Poly. suggests atresia /obstruction
6. Fetal growth restriction (25%)
7. Pulsed Doppler
○ Abnormal umbilical artery flow associated with FGR, bowel obstruction,
fetal demise
8. Color Doppler to locate the cord in relation to the herniation.

23. Gastroschisis with progressive bowel dilatation
A: Transverse color Doppler image of abdomen in 18-week fetus nondilated loops of free flowing
bowel (arrow) herniated through gastroschisis defect. The umbilical cord insertion (arrowhead),
with flow visible in the umbilical vessels with color, is intact.
B: Image of abdomen in same fetus at 32 weeks demonstrating dilatation of the herniated bowel
(arrows) in the gastroschisis
32 weeks
18weeks

24. Picture of gastroschisis after birth;
Both picture taken from internet

25. Natural History & Prognosis
• Condition of the bowel at birth is the single most important prognostic
• Greater dilation of the bowel loops suggests poorer prognosis, especially
if over 20 mm
Survival for;
• simple gastroschisis approaches 100%
• Complex; mortality rates 28-50%
- Most consider lethal if liver involved
• Intra-uterine mortality rate of 10-15%.

26. Treatment;
No consensus on time of delivery and time of surgical treatment
 Wide variability in institutional practice patterns
 Recent study shows prevalence of IUFD does not ↑ at > 35 weeks
 Primary closure versus delayed closure
Most infants are treated surgically on the first day of life.
Delivery at tertiary care center
○ Careful control of body fluids and heat loss
○ Increased risk of bowel injury due to improper handling during transport

27. Complications of gastroschisis;
• In utero bowel obstruction and perforation
• Peritonitis; meconium peritonitis
• Necrotizing enterocolitis
• Short gut syndrome
• Fistula formation

28. Umblical hernia
• When the intestine returns to the abdominal cavity during the 10weeks
and then later herniate again through an imperfectly closed
umbilicus,(umblical ring)
• The umblical scar fails to form or weak
• Common type(10%) of newborns and common in prematures
• Usually the greater omentum and part of SI, is covered by subcutaneous
tissue and skin,
• Usually ranges in diameter from 1 - 5 cm and the defect is via the linea
alba

29. • Usually the hernia doesn’t reach its maximum size until end of 28 days
• It protrude during crying, straining or coughing
• Surgery is usually not indicted unless the hernia persists to the age of 3
to 5 yrs

30. types Physiologic hernia omphalocele gastroschisis Umblical hernia
Stages of anomaly 6- 12weeks 3-5weeks 5-6weeks After birth
Genetics Sporadic familiar Sporadic sporadic
Organ herniation
and location
Small intestine Small intestine,
liver
SI Usually greater
omentum, smt SI
Cord insertion and
covering of hernia
Normal insertion,
skin intact
On apex of
herniated sac, skin
defect, membrane
covering
Normal,
to left of
evisceration, skin
defect, no
membrane on
defect
Normal CI,
SC tissue and skin
Other anomaly Rare Common Less common Less common
Abnormal
karyotype
Not reported 30-40% rare rare
Table comparing different types of anterior abdominal wall defects

31. 2. Errors of rotations;
2.1 Non-rotation of the midgut loop
2.2 Reversed rotation of the midgut loop
2.3 Mixed rotation of the midgut loop

32. 2.1 Non-rotation of the midgut loop
• Also called left sided colon
• Normal first 90 degree anticlockwise rotation
• Fails to undergo the next 180-degree counterclockwise rotation
• As a result, the SI lies on the right side of the abdomen, and the entire LI
is on the left side.
• The cecum and appendix lie just inferior to the pylorus of the stomach
• Usually asymptomatic

33. Pictures of nonrotation;
The SI lies on the right side of the abdomen, and the entire LI is on the left side.
LtRt

34. 2.2 Reversed rotation
• Normal initial 90-degree counterclockwise rotation
• but the second 180-degree rotation occurs clockwise , so the net
rotation of the midgut is 90 degrees clockwise.
Effects ;
• Duodenum lies anterior to SMA and transverse colon is posterior to SMA
Transverse colon may be ;
 Obstructed by pressure from SMA
 Become retroperitoneal

35. Picture of reversed rotation
Rt Lt

36. 2.3 Mixed rotations / Malrotations
• Failure of the midgut loop to complete the final 90 degrees of rotation
Effects;
• Improperly positioned and incompletely fixed intestine are prone to
midgut volvulus
Example
• The cecum is fixed to the posterolateral abdominal wall by peritoneal
bands that pass over the duodenum.(DO)

37. • When midgut volvulus occurs, the SMA may be obstructed, resulting in
infarction and gangrene of the intestine.
Final Effects;
• In utero = atresias of SI
• Infants are prone to midgut volvulus and present s/s of IO

38. Diagnosis of malrotation
• Asymptomatic or S/S of IO
• Hemodynamic stable confirm dx
Usually
• Ultrasound
• Barium study

39. Malrotation
u/s ; normal doesn’t exclude
Clues;
1. 3rd part of the duodenum is not in the normal retromesentric
position
2. Dilated duodenum caused by obstruction by ladds bands
3. Abnormal position of SMV either anterior or to the left
4. Whirlpool sign of volvulus
• caused by a bowel wrap around SMA, creating a pattern like
whirlpool

40. Whirlpool sign on color doppler ultrasound; taken from internet

41. Barium study
Corkscrew sign
• describes the spiral appearance of the distal duodenum and proximal
jejunum in the setting of midgut volvulus
AP film;
• DJ flexure to the right of midline, inferiorly
• proximal dilatation of the duodenum
Lateral view;
• DJ flexure doesn’t cross the spine
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42. 6/25/2018 42
AP and Lateral barium study, shows DJF to the right of midline and
inferiorly and anteriorly
Rt
AP lateral

43. Additional effect of malrotations;
Includes
• Atresia
• Duplication of intestinal loops and cyst

44. 3. Errors of retraction
• It is considered a remnant of the omphalomesenteric-vitelline duct,
which connects the yolk sac to the midgut through the umbilical cord.
• This duct is typically obliterated by the 5-8th week of gestation.
Failure of closure results in:
• diverticulum (~90% of cases)
• omphalomesenteric fistula
• enterocyst
• fibrous band

45. Picture showing different fate of omphaloenteric duct

46. 3.1 Ileal Diverticulum (Meckel’s Diverticulum)
• It is named after Johann Friedrich Meckel, who described its anatomy
and embryology in 1809
• A remnant of the proximal part of the yolk stalk that fails to degenerate
results in a fingerlike blind pouch that projects from the ileum.
• Occurs in about 1/50 people

47. Conti…
• most common structural congenital anomaly of GIT
• Is a true diverticulum
• Arises from the antimesenteric border of the SI
• it is usually asymptomic and only occasionally leads to abdominal pain
and/or rectal bleeding

48. Conti…
Histology
• lined with heterotopic mucosa in up to 60% of cases:
• gastric mucosa ~62%
• pancreatic ~6%
• gastric and pancreatic ~5%
• jejunal ~2%
• Brunner glands ~2%
• gastric and duodenal ~2%

49. Rule of TWO

50. Complications;
• gastrointestinal haemorrhage :
• most common complication (30%).
• Large mostly self-limiting bright red rectal bleed.
• small-bowel obstruction:
• adhesion
• luminal obstruction from diverticulitis or foreign body impacted or
enterolith formation
• volvulus
• intussusception: particularly if the diverticulum inverts
• Littre hernia: inclusion of the diverticulum into a hernia
• inflammation: Meckel diverticulitis
• perforation

51. Radiographic features
• Detected incidentally or after complication.
Ultrasound
• limited value in the diagnosis of an uncomplicated Meckel d.
• show a blind-ending peristaltic loop connected to the small bowel.
CT
• limited value in uncomplicated cases, seems normal bowel loop.
• Show a fluid- or air-filled blind-ending pouch that arises from the
antimesenteric side of the distal ileum.
• diverticulum may invert and appear as an intraluminal polypoid
lesion .

52. Angiography or CT angiography
• If bleeding
Barium study
• barium filling a blind-ending tube arise from the ileum.
Scintigraphy
• Scintigraphy with 99mTc-Na-pertechnetate has a limited sensitivity
(~60%). It, however, aids in the diagnosis of diverticula with ectopic
gastric mucosa.
• Pertechnetate is taken up by mucin-secreting cells of the gastric mucosa
and ectopic gastric tissue. Higher sensitivity in children (~85-90%).

53. 6/25/2018 53
This small bowel follow-through image shows barium filling a blind-ending
tubular structure (arrow) that is arising from the ileum.

54. Stenosis and Atresia of the SI
• Partial occlusion(stenosis) and complete occlusion (atresia) ;
• 1/3rd cases of IO
• Most often in the duodenum (25%) and ileum (50%).

55. Etiology
Vascular injury most accepted theory of development; multiple possible
mechanisms
– Kinking of mesenteric artery during malrotation/ malfixation
– Fetal hypotension(distress)
Associated abnormalities;
○ Frequently associated with other GI anomalies
– Gastroschisis
– Malrotation

56. Surgical classification system of jejunoileal atresia:
Type I: Membranous atresia
○ Web or diaphragm occluding bowel segment
○ No mesenteric defect
○ Normal bowel length
• Type II: Blind ends separated by fibrous cord
○ No mesenteric defect
○ Normal bowel length
• Type IIIa: Blind ends with complete separation
○ V-shaped mesenteric defect
○ Short bowel
• Type IIIb: Affects long contiguous segment of jejunum and ileum (rare
familial form)
○ Remaining segments have spiraled apple-peel appearance
○ Large mesenteric defect
• Type IV: Multiple small bowel atresias

57. Diagnosis ;
Prenatal ultrasound
MR Findings
• May better delineate site of obstruction
• Obstructed fluid-filled loops
○ Low-signal T1WI, high-signal T2WI
○ May allow diagnosis of multiple atresia
○ Look for high-signal meconium in normal colon on T1W

58. Ultrasound;
• Sensitivity reported as high as 100% for jejunal and 75% for ileal atresia
• Bowel diameter > 17 mm with polyhydramnios increase specificity of
diagnosis

59. Ultrasound for atresia;
○ Echogenic bowel in 2nd trimester may be 1st sign
○ Triple bubble for proximal jejunal atresia
○ Sausage-shaped and dilated, fluid-filled bowel loops
○ Hyperperistalsis of obstructed segments often seen in real time

60. Jejunal vs. ileal atresia
Jejunal
– shows a short segment of dilated bowel
– Greater bowel dilatation
―More likely to have enlarged stomach
– Less likely to perforate
– Higher association with FGR and polyhydraminos
Ileal
– multiple loops of dilated bowel
– Less distensible, with earlier perforation
– Usually not associated with polyhydramnios

61. DDx
Anal atresia;
Absent anal target sign(Hyperechoic mucosa with hypoechoic ring)
Normal Colon
• Can appear prominent in 3rd trimester, normal caliber 18 mm
Duodenal Atresia
• Double bubble and no bowel dilatation beyond duodenum
Volvulus
○ Dilated bowel segment shows no peristalsis
○ Heterogeneous lumen contents from hemorrhage/necrosis
• May be indistinguishable early

62. Jejunal atresia.
A: Transverse view through the fetal abdomen reveals a dilated segment of bowel
(arrows).
B: There is moderate-to-severe polyhydramnios

63. Ileal atresia,
transverse view through the fetal abdomen reveals multiple,dilated,fluid filled
loops of bowel. The amniotic fluid pool is normal

64. In this fetus with polyhydramnios at 31 weeks, dilated bowel can be traced from the
stomach to the duodenum, terminating in a blind-ending loop of proximal jejunum
(Right)
Postnatal radiograph after air injection into the NG tube shows the proximal jejunal
blind-ending loop, with a gasless distal abdomen.
Proximal jejunal atresia was confirmed surgically
Proximal jejunal atresia

65. 4. Errors of fixation
Abnormalities of the mesenteries;
• At first all parts of the SI and LI have a mesentery and suspended from
the posterior abdominal wall.
• After the completion of rotation of the gut, some fixed others not
The original mesentery persists as;
• The mesentery of small intestine,
• The transverse mesocolon,
• The pelvic mesocolon.

66. Examples of errors of fixations;
• 4.1 Volvulus; where parts of intestine, that are normally retroperitoneal,
may have mesentery.
• 4.2 Adhesion; where parts of intestine, which normally, have a
mesentery, may be fixed by abnormal peritoneal attachment.
• 4.3 Sub-hepatic cecum
• 4.4 Mobile cecum

67. Subhepatic cecum and appendix
Due to failure of the cecum to elongate and descend into the RLAQ or
If the cecum adheres to the inferior surface of the liver when it returns to
the abdomen
it will be drawn superiorly as the liver diminishes in size
As a result, they remain in their fetal positions.
More common in males and occur in 6% of fetuses.
it may create a problem in the diagnosis of appendicitis and during
appendectomy.

68. Pictures of subhepatic cecum and high-riding
appendix

69. Mobile cecum;
• Results from incomplete fixation of the ascending colon.
• In 10% of people, the cecum has an abnormal amount of freedom.
• In very unusual cases, it may herniate into the right inguinal canal.
• Clinically significant because of the possible variations in the position of
the appendix and because risk of cecal volvulus

70. Take off message;
• When gastroschisis or omphalocele is detected in the first trimester, the
next step is ruling out additional anomalies.
• Follow up scan is very important
• Save life through safe abdominal scan

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72. THANK YOU!!
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73. References
• Langman medical embryology 12th edition
• The Developing Human Clinically Oriented Embryology 8th Edition
• Before We Are Born Essential Of Embryology And Birth Defect 9th Edition
• Larsen’s Human Embryology 5th Edition
• Atlas of ultrasound in obstetric and gynecology 2nd edition
• Callen’s ultrasonography in obstetrics and gynecology 6th edition
• Internet source
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