1. Obstetrical Sonography II
Lecture 15
The Fetal Abdominal Wall and GI system
Harry H. Holdorf PhD, MPA, RDMS, RVT, LRT

2. Outline GASTROSCHISIS – Abdominal Wall OMPHALOCELE – Abdominal Wall
Bladder Extrophy – Abdominal Wall
Congenital Diaphragmatic Hernia – Abdominal Wall
Abdominal Ascites – Abdominal Wall
Persistent right umbilical vein – Abdominal Wall
Diaphragm – Abdominal wall
GASTROINTESTINAL ATRESIA
Esophageal atresia
Duodenal Atresia
Intestinal Atresia
Meconium Peritonitis
Teratomas
Meconium Ileus
Volvulus

3. The Gastro-Intestinal System

4. Esophagus
Difficult to image unless fetus is swallowing
Stomach
On transverse view, seen ovoid or round fluid collection in upper left abdomen
Muscular layer may be thickened in hypertrophic pyloric stenosis

5. Normal fetal esophagus

6. Color flow imaging of the esophagus aided by fetal swallowing

7. The fetal Stomach

8. GASTROSCHISIS
Protrusion of intestines into the amniotic cavity through an open defect in the anterior abdominal wall. Gastroschisis occurs adjacent to the cord insertion, usually on the right.
It is not covered by a membrane.
It results from a muscular defect, possibly related to vascular disruption.
Gastroschisis is not associated with an increased risk of chromosomal abnormalities.

9. Gastroschisis

10. Gastroschisis

11. Sonographic findings.
Loops of bowel seen extending into the amniotic cavity
Cord is seen adjacent to the defect
No membranous sac covers the hernia

12. OMPHALOCELE
Results from a failure of the intestines to return to the abdomen during the second stage of intestinal rotation.
They may contain a single loop of bowel, or most of the abdominal contents, depending on the severity. The defect is covered by a layer of amniotic epithelium, and is seen at the level of the umbilical cord insertion.

13. Rupture of the sac during vaginal delivery may cause sepsis.
There is a high association between omphalocele and other congenital anomalies (65-90% of fetuses seen have a cardiac defect or chromosomal abnormities, most commonly Trisomies 13 and 18), patients should receive genetic counseling.

14. Sonographic findings
Extra-abdominal mass, consisting of a combination of fluid-filled bowel loops, mesentery, omentum, liver, and sometimes pancreas and spleen
Mass contiguous with umbilical cord
Membranous sac covers the herniated organs

15. Omphalocele

16. Omphalocele

18. Bladder Exstrophy
This midline defect involves the lower abdominal wall as well as the anterior wall of the urinary bladder. Generally, bladder extrophy is an isolated defect, but can possibly be associated with genital anomalies such as cleft clitoris, epispadias, and the wide separation of pubic bones.

19. Midline defect involves the lower abdominal wall as well as the anterior wall of the urinary bladder.
Isolated defect
Protrusion of the urinary bladder
Possibly associated with genial anomalies – cleft clitoris, or wide separation of public bones
Bladder not ID over 30 minutes of scanning, but normal fluid
Possible soft tissue protrusion form lower abdominal wall
Separation of pubic bones

20. Bladder Exstrophy

21. EPISPADIAS:
Epispadias is a rare defect that is present at birth (congenital). It is located at the opening of the urethra. In this condition, the urethra does not develop into a full tube. The urine exits the body from the wrong place. Epispadias can occur with bladder exstrophy. In this rare birth defect, the bladder is inside out and sticks through the abdomen wall. Epispadias can also occur with other birth defects. Epispadias occurs in 1 out of every 117,000 newborn boys and 1 in 484,000 newborn girls. The condition is usually diagnosed at birth or soon afterward. Patients who have more than a mild case of epispadias will need surgery. Some people with this condition may continue to have urinary incontinence, even after surgery. Ureter and kidney damage and infertility may occur.

23. Sonographic findings
Bladder not identified over 30 minutes of scanning but normal AFV
Possible soft tissue protrusion from lower abdominal wall
Separation of pubic bones (diastasis)
Micorphallus in male fetus

24. Bladder Extrophy-The cord insertion is visualized above the protruding mass that contains bladder and bowel loops.

25. Congenital Diaphragmatic Hernia
CDH is the most common developmental abnormality of the diaphragm. The small bowel, stomach, spleen, colon and liver may herniated into the chest.
Hernias usually occur on the left side 80% of the time and are associated with pulmonary hypoplasia if large.
Cardiomedastinal shift is the most recognizable sonographic feature. The Sonographer should be aware of CDH associations with other anomalies, frequently cardiac and brain.

26. CDH is common
Small bowl, stomach, spleen colon and liver may herniate into the chest.
Usually occur on the left side (80%) and associated with pulmonary hypoplasia if large
Cardio-mediastinal shift can occur
Associated with other anomalies
ID of fluid-filled bowel and stomach within the thoracic cavity at level of 4 chamber view of heart
Heart displaced from the left chest toward the right
Associated Polyhydramnios

27. Sonographic findings
ID of fluid-filled bowel and especially stomach within the thoracic cavity at the level of the four chamber view of the heart
Heart displaced from the left chest toward the right
Associated Polyhydramnios

28. CDH (Congenital Diaphragmatic Hernia)

29. CDH

30. Abdominal Ascites
Ascites in the fetal abdomen is most commonly associated with a condition called Hydrops Fetalis.

31. Abdominal Ascites

32. Fetal ascites with skin edema

33. Persistent right umbilical vein
When the umbilical vein courses toward the left side of the fetal abdomen, this is called persistent right umbilical vein.
The umbilical vein is actually entering the right portal vein of the liver rather than the left portal vein.
This variation itself is not pathogenic, but can be seen with some anomalous conditions, and therefore warrants a detailed investigation for other fetal anomalies.

34. PRUV

35. PRUV-Transverse color Doppler scan of the abdomen demonstrating the right umbilical vein (pointing towards the stomach).

36. Rule of thumb: If the umbilical Vein is seen coursing towards the fetal stomach (which is located on the left side of the fetal abdomen, this is called persistent right umbilical vein.

38. Diaphragm
Appears as a hypoechoic curved line separating the more echogenic fetal lungs from the liver and the stomach

39. Diaphragm

40. GASTROINTESTINAL ATRESIA
Esophageal atresia
This is the discontinuation of the esophagus. 90% are accompanied by a distal trachoesophageal fistula.
There is a 30-70% association with other congenital malformations, including cardiovascular, gastrointestinal, genitourinary, and musculoskeletal anomalies.

41. Discontinuation of the esophagus.
70% have other malformations
Small or absent fluid-filled stomach
Failure to demonstrate the stomach on serial sonograms
Polyhydramnios

42. Esophogeal Atresia Sonographic Findings
Small to absent fluid-filled stomach
Failure to demonstrate stomach on serial sonograms
Associated Polyhydramnios
Not always detectable with ultrasound

43. Esophageal atresia is a congenital medical condition which affects the alimentary tract. It causes the esophagus to end in a blind-ended pouch rather than connecting normally to the stomach. It occurs in approximately 1 in 4425 live births.
Congenital esophageal atresia (EA) represents a failure of the esophagus to develop as a continuous passage. Instead, it ends as a blind pouch. Tracheoesophageal fistula (TEF) represents an abnormal opening between the trachea and esophagus. EA and TEF can occur separately or together. EA and TEF are diagnosed in the ICU at birth and treated immediately.
This condition takes several different forms, often involving one or more fistulas connecting the trachea to the esophagus (tracheoesophageal fistula).
This birth defect arises in the fourth fetal week, when the trachea and esophagus should begin to separate from each other.

44. Associations
Other birth defects may co-exist, particularly in the heart, but sometimes also in the anus, spinal column, or kidneys. This is known as VACTERL syndrome because of the involvement of Vertebral column, Anorectal, Cardiac, Tracheal, Esophageal, Renal, and Limbs. It is associated with polyhydramnios in the third trimester.
Diagnosis
This condition is visible, after about 26 weeks or it may be detected soon after birth as the affected infant will be unable to swallow its own saliva. Also, the newborn can present with gastric distention, cough, apnea, and cyanosis
Any attempt at feeding could cause aspiration pneumonia as the milk collects in the blind pouch and overflows into the trachea and lungs. Furthermore, a fistula between the lower esophagus and trachea may allow stomach acid to flow into the lungs and cause damage. Because of these dangers, the condition must be treated as soon as possible after birth.

45. Esophageal Atresia

47. Duodenal Atresia
This is the most common perinatal intestinal obstruction. Causes include failure of normal embryonic development, choledochal cysts, superior mesenteric artery defect, and extrinsic pressure.
65% of fetuses with duodenal atresia have a karyotype abnormality or an associated malformation at birth, most commonly cardiac and vertebral anomalies. 30% of infants with DA have Down syndrome.

48. Duodenal atresia is the congenital absence or complete closure of a portion of the lumen of the duodenum.
Approximately 20-40% of all infants with duodenal atresia have Down syndrome Approximately 8% all infants with Down syndrome have duodenal atresia.
It is also associated with polyhydramnios.
The diagnosis of duodenal atresia is usually be ultrasound of the abdomen, which shows two large air filled spaces, the so-called "double bubble" sign The air is trapped in the stomach and duodenum. Since the closure of the duodenum is complete in duodenal atresia, no air is seen distal to the duodenum.

49. Duodenal Atresia
Most common perinatal intestinal obstruction
30% have Down’s syndrome
Double bubble sign- distention of the stomach and first portion of the duodenum
Polyhydramnios

50. Sonographic Findings
“Double bubble sign” due to simultaneous distention of stomach and first portion of the duodenum
Polyhydramnios

51. Duodenal Atresia

52. Duodenal Atresia

53. Intestines
Normally mixed echogenicity to cystic in appearance. Peristalsis should be seen by late second trimester. Meconium – a mixture of bile and swallowed vernix, epithelium, and fetal hair, becomes packed in the large bowel and may appear as highly echogenic areas within the bowel.

54. Intestinal Atresia
Obstruction of the intestine, with subsequent distention of bowel loops, may occur anywhere along the intestinal tract or at the level of the anus. The precise site is frequently indeterminate.

55. Intestinal Atresia
Obstruction of the intestine
Distention of bowel loops
Multiple fluid-filled bowel loops
Increased bowel peristalsis
Possible perforation – indicated by abdominal calcifications and ascites
Polyhydramnios

56. Intestinal atresia is a malformation where there is a narrowing or absence of a portion of the intestine. This defect can either occur in the small or large intestine.
The different types of intestinal atresia are named after their location:
Duodenal atresia - malformation of the duodenum, part of the intestine that empties from the stomach
Jejunal atresia - malformation of the jejunum, the second part of the intestine extending from the duodenum to the ileum
Ileal atresia - malformation of the ileum, the lower part of the small intestine
Colon atresia - malformation of the colon

57. Intestinal atresias are often discovered before birth: either by ultrasounds show a dilated intestinal segment due to the blockage, or by the development of polyhydramnios These abnormalities are indications that the fetus may have a bowel obstruction
Some fetuses with bowel obstruction have abnormal chromosomes. An amniocentesis is recommended because it can determine not only the sex of the baby, but whether or not there is a problem with the chromosomes.
Fetal and neonatal intestinal atresia treated with using laparotomy after birth. If the area affected is small, the surgeon may be able to remove the damaged portion and join the intestine back together. In instances where the narrowing is longer, or the area is damaged and cannot be used for period of time, a temporary stoma may be placed.

58. Sonographic findings
Multiple fluid-filled bowel loops
Small bowel internal diameter >7mm
Increased bowel peristalsis
Possible perforation, indicated by abdominal calcifications and ascites
Polyhydramnios
Often difficult to determine exact site of obstruction

59. Intestinal Atresia

60. Intestinal Atresia

61. Meconium Peritonitis
Peritoneal inflammatory reaction occurs following an intrauterine bowel perforation.
Perforation may occur after the fetal bowel obstruction caused by intestinal atresia, volvulus, or Meconium ileus. Cystic fibrosis is considered to be the etiology in 30-40% of all patients because of thick, sticky Meconium.

62. Meconium Peritonitis
Peritoneal inflammatory reaction following an intrauterine bowel perforation.
Cystic fibrosis is a likely etiology because of thick, sticky Meconium.
Brightly echogenic, intra-abdominal foci

63. Meconium peritonitis refers to rupture of the bowel prior to birth, resulting in fetal stool (meconium) escaping into the surrounding space (peritoneum) leading to inflammation (peritonitis). Despite the bowel rupture, many infants born after meconium peritonitis in utero have normal bowels and have no further issues. Twenty percent of infants born with meconium peritonitis will have vomiting and dilated bowels on x-rays which necessitates surgery. Meconium peritonitis is often diagnosed on prenatal ultrasound where it appears as calcifications within the peritoneum. Infants with cystic fibrosis are at increased risk for meconium peritonitis.

64. Sonographic findings
Brightly echogenic, intra-abdominal foci which cast an acoustic shadow
Fetal ascites and Polyhydramnios

65. Meconium Peritonitis

66. Meconium Peritonitis-Calcifications are seen throughout the abdomen in this 17 week fetus with meconium peritonitis

67. Teratomas
Usually arises from the sacral area. Three pathologic types exist: Mature, immature and malignant.
They frequently are hypervascular and consists of solid and calcified components
They are described by the site of origin:
Pre-sacral
Sacrococcygeal

68. Teratomas
Germ cell tumors usually arising from the sacral area
Complex, large mass seen in the fetal pelvis or arising from the fetal rump.
May contain cystic, solid, and calcified components

69. Sonographic findings
A complex, large mass seen in the fetal pelvis of arising from the fetal rump
May contain cystic, solid, and calcific components
Possible differential diagnosis includes Myelomeningocele

70. Teratomas

71. Teratomas

72. Meconium ileus
Sometimes the meconium becomes thickened and congested in the ileum, a condition known as meconium ileus. Meconium ileus is often the first symptom of cystic fibrosis. In cystic fibrosis, the meconium can form a black- green mechanical obstruction in a segment of the ileum. Beyond this there may be a few separate grey-white globular pellets. Below this level, the bowel is a narrow and empty micro-colon. Above the level of the obstruction, there are several loops of hypertrophied bowel distended with fluid. No meconium is passed, and abdominal distension and vomiting appear soon after birth.
About 20% of cases of cystic fibrosis present with meconium ileus, while approximately 20% of one series of cases of meconium ileus did not have cystic fibrosis. The presence of meconium ileus is not related to the severity of the cystic fibrosis. The obstruction can be relieved.

73. Meconium ileus

74. volvulus
A volvulus is a loop of the bowel whose nose has twisted on itself. The American Heritage Stedman's Medical Dictionary defines volvulus slightly differently as "abnormal twisting of the intestine causing obstruction," which adds obstruction in the definition, and would be the more clinically significant term.
Midgut volvulus occurs in patients (usually in infants) that are predisposed because of congenital intestinal malrotation Segmental volvulus occurs in patients of any age, usually with a predisposition because of abnormal intestinal contents (e.g. meconium ileus) or adhesions. Volvulus of the cecum, transverse colon, or sigmoid colon occurs, usually in adults, with only minor predisposing factors such as redundant (excess, inadequately supported) intestinal tissue and constipation.
Regardless of cause, volvulus causes symptoms by two mechanisms. One is bowel obstruction, manifested as abdominal distension and vomiting. The other is ischemia (loss of blood flow) to the affected portion of intestine. This causes severe pain and progressive injury to the intestinal wall, with accumulation of gas and fluid in the portion of the bowel obstructed. Ultimately, this can result in necrosis of the affected intestinal wall, acidosis, and death. Acute volvulus therefore requires immediate surgical intervention to untwist the affected segment of bowel and possibly resect any unsalvageable portion.

75. volvulus

76. Homework Part 1
List all abnormalities and conditions with which Oligohydramnios is associated.
Polyhydramnios is associated with many conditions. List as many as you can.
Define premature rupture of membranes (PROM)
What are the sonographic fetal findings in a patient with PROM?

77. What are three distinctive features of gastroschisis?
What are three distinctive features of omphalocele?
What is bladder Exstrophy?
What sonographic findings might suggest bladder Exstrophy?

78. What is the most recognizable sonographic feature of a congenital diaphragmatic hernia (CDH)?
List other sonographic findings of CDH, as well as possible associated anomalies.
True or false: Esophageal atresia is very commonly accompanied by a distal trachoesophageal (T-E) atresia.
List the sonographic findings of esophageal atresia.

79. Describe how duodenal atresia may appear sonographically.
What other anomalies are associated with duodenal atresia?
Intestinal atresia may occur anywhere along the intestinal tract, and often the site of obstruction is indeterminate. What are the sonographic findings of an intestinal atresia (other than duodenal atresia??
What is Meconium peritonitis?
What findings might raise suspicion for Meconium peritonitis in a fetus?

80. Homework Part 2
1. What are the consequences of the failure to visualize the fetal stomach?
2. What are the consequences of an Esophageal Atresia?
3. Why would you, as a sonographer, be concerned that your fetal exam patient demonstrated echogenic small bowel?
4. What sign would be expected in a fetus with duodenal atresia? Explain your answer- what do the findings represent?

81. 5. Define and give the ramifications of Meconium peritonitis.
What are the causes?
What is the prognosis of the fetus diagnosed with this?
What is the US finding?
6. Explain the anomaly of Persistent Right Umbilical Vein.
7. Define Umbilical Vein Varix
8. List the causes of fetal splenomegaly
9. Is the differential diagnosis for cystic abdominal mass different between the male and female fetus? Explain

82. 10. Explain the embryonic development of the fetal gastrointestinal tract (the fetal gut).
11. Define Cloacal Exstrophy
12. Define Limb-Body Complex
13. Explain the importance of the relationship of the cord insertion to an abdominal wall defect.
14. Define Uterine Synechia

83. Homework
List all abnormalities and conditions with which Oligohydramnios is associated.
Polyhydramnios is associated with many conditions. List as many as you can.
Define premature rupture of membranes (PROM)
What are the sonographic fetal findings in a patient with PROM?

84. Take home test  
1. In the late gestation, the hypoechoic contents of the fetal colon typically represent
Normal muscle of the bowel
Meconium
A distal obstruction, such as anal atresia
An inflammatory reaction to bowel perforation

85. 2. With endovaginal scanning, a small soft tissue mass is seen anterior to the abdominal wall of an 11 week embryo, at the location of the umbilical cord insertion. What is the probable explanation for this finding?
Early diagnosis of an omphalocele
Early diagnosis of a gastroschisis
Normal herniated bowel in the umbilical cord
Amniotic band syndrome causing evisceration

86. 3. The fetal urinary bladder is not observed at the beginning of the obstetrical sonogram. The Sonographer should
Consider a diagnosis of bilateral renal agenesis
Search carefully for associated cardiac anomalies
Continue with the rest of the exam, and re-check for bladder filling after minutes
Try a higher frequency transducer for better image resolution.

87. 4. Which of the following statements regarding diaphragmatic hernias is not true?
Most diaphragmatic hernias occur on the right side
A differential diagnosis for a fluid-filled mass on the lung is CCAM type I
Severe diaphragmatic hernias include bowel and even liver
There is associated Polyhydramnios with a diaphragmatic hernia

88. 5. An omphalocele defect, in addition to ectopic cordis, is associated with
Meckel-Gruber syndrome
Pentalogy of Cantrell
Fetal alcohol syndrome
Edward’s syndrome

89. 6. Duodenal atresia is characterized by which of the following sonographic findings?
Oligohydramnios
Multiple fluid-filled structures in the fetal abdomen
Failure to demonstrate the stomach on two consecutive exams
Polyhydramnios

90. FIN