Abdominal wall defects

Question 1

Anomalies associated with Pentalogy of Cantrell

Answer 1

Not every case will have all 5 abnl, and some cases may have assoc anomalies, usually midline defects such as cleft lip/palate, sirenomelia, exencephaly

Question 2

Heart position in Pentalogy of Cantrell vs ectopia cordis

Answer 2

Heart in PoC is normally positioned within the chest, but with a subtle shift in axis.

Question 3

Most common heart abnormality in Pentalogy of Cantrell, others?

Answer 3

Most common = VSD
Others = ASD, pulmonic stenosis, ToF, LV diverticulum

Question 4

Other anomalies associated with Pentalogy of Cantrell

Answer 4

Vertebral and digital anomalies, including kyphoscoliosis and clinodactyly
Craniofacial - encephalocele, cleft lip, microphthalmia, low set ears
2VC
Absent left lung
Cloacal exstrophy
Fetal ascites

Question 5

Ddx of Pentalogy of Cantrell

Answer 5

Ectopia cordis
Body-stalk anomaly
Simple omphalocele
Amniotic band syndrome

Question 6

Management of pregnancy w/ Pentalogy of Cantrell

Answer 6

Estimate size and contents of omphalocele
Careful sono exam for other abnl
Karyotype
Surveillance for IUGR, PTL, rupture of omphalocele membrane
Reserve cesarean for obstetric indications, or if giant omphalocele

Question 7

Genetics of Pentalogy of Cantrell

Answer 7

Primarily thought to be sporadic
Chrom abnl not usual, but abnl in 13 & 18 reported
Possible X-linked

Question 8

What is an omphalocele?

Answer 8

Defect in ventral abdominal wall characterized by absence of abdominal muscles, fascia, skin. Defect is covered by a membrane that consists of peritoneum and amnion.

Question 9

Where does the umbilical cord insert in omphalocele?

Answer 9

Insets into the membrane at a location distant from the abdominal wall.

Question 10

Why and when does omphalocele occur?

Answer 10

Abnormality during process of body infolding at 3-4 weeks gestation.

Question 11

Incidence of omphalocele

Answer 11

1/4000-7000 livebirths, 1/300-400 combined livebirths & stillbirths

Question 12

Epidemiology of omphalocele

Answer 12

Associated with AMA

Question 13

Ruptured omphalocele vs gastroschisis

Answer 13

Defects are usually larger with ruptured omphalocele and have at least exposed, if not extracorporeal, liver

Question 14

What is Beckwith-Wiedemann syndrome?

Answer 14

Aka exomphalos-macroglossia-gigantism syndrome. Consists of omphalocele, visceromegaly, macroglossia, and severe neonatal hypoglycemia.
Cardiac abnl frequent.
Malignant tumors in 10% - Wilm’s tumor, hepatoblastoma, adrenal tumors
Macroglossia & visceral enlargement rarely seen prior to 3rd trimester.

Question 15

Frequency of visceral malformations with omphalocele

Answer 15

50-70% of cases

Question 16

Frequency of chromosomal abnl w/ omphalocele

Answer 16

30-60%

Question 17

The absence of liver in the omphalocele increases or decreases the likelihood of chromosomal abnl & perinatal mortality?

Answer 17

Interestingly, it increases the likelihood. (In other words, small defects are associated with an increased risk of chromosomal abnl).

Question 18

Predominant chromosomal abnl w/ omphalocele

Answer 18

T18 (17 of 19 cases w/ chrom abnl in one series)

Question 19

Risk of chromosomal abnl in central vs epigastric omphalocele

Answer 19

Central - 70%
Epigastric - 12%

Question 20

Risk of associated anomalies in omphalocele

Answer 20

65% of 349 cases detected antenatally

Question 21

Risk of associated anomalies in omphalocele w/ a nl karyotype

Answer 21

56.00%

Question 22

Incidence of associated congenital heart disease w/ omphalocele

Answer 22

25.00%

Question 23

Does MSAFP have a higher sensitivity for omphalocele or gastroschisis?

Answer 23

Much higher for gastroschisis (for cutoff of >2.5 MoM and >3.0 MoM, detection rates were 98% and 96% for gastroschisis, and 71% and 65% for omphalocele).

Question 24

Management of pregnancy w/ omphalocele

Answer 24

Estimate size and contents of omphalocele, location of cord insertion relative to herniation, presence of amnioperitoneal membrane
Careful sono exam for other abnl, including fetal echo
Chromosomal analysis
Consultation with pedi surgery, genetics, neonatology, pedi cards
Surveillance for IUGR (6-35%) & PTL (25-65%), and for omphalocele rupture

Question 25

Risk of significant pulmonary hypoplasia and pulmonary hypertension w/ omphalocele

Answer 25

Up to 50%. Fetology recommends MRI for lung volume assessment at 32-34w.

Question 26

Mode of delivery w/ omphalocele

Answer 26

Controversial. If small, Fetology recommends vaginal delivery. If giant (>5 cm) or extracorporeal liver, then CD may be necessary to avoid dystocia.

Question 27

Recurrence risk of omphalocele

Answer 27

Depends on cause:
If T18, then 1% or age-related maternal risk, whichever is higher
IF Beckwith-Wiedemann - may be as high as 50%
If isolated - generally considered sporadic, but at least 17 cases of familial omphalocele have been described (?AD)

Question 28

What is gastroschisis?

Answer 28

An isolated abdominal wall defect to the right of normally inserted umbilical cord, usually 2-3 cm in diameter

Question 29

Why and when does gastroschisis occur?

Answer 29

Occurs secondary to incomplete closure of the lateral folds during the 6th week of gestation

Question 30

How does the eviscerated bowel from gastroschisis look at birth? Why?

Answer 30

Has a thick, edematous appearance described as a “peel”. The peel involves the serosa and is composed of fibrinand collagen. Thought to be caused by an inflammatory rxn due to amniotic fluid exposure, combined with constriction at the abdominal wall defect.

Question 31

Epidemiology of gastroschisis

Answer 31

Young maternal age - fourfold increased risk
Cigarette use - 2.1-fold greater risk
?Seasonal variation - deliveries in 1st quarter of the year
Methamphetamine & cocaine use

Question 32

Normal events of bowel migration

Answer 32

The midgut that will normally form the small bowel, cecum, ascending and proximal transverse colon is connected to the yolk sac
This connection is reduced to a narrow yolk stalk as the amniotic cavity expands and yolk sac is pulled away from embryo
The mesentery suspending the midgut rapidly elongates, and a U-shaped loop of midgut herniates into umb cord
The loop then rotates 90 degrees counterclockwise about the SMA
By 11w, the loops return to the abd cavity by rotating counterclockwise another 180 degrees

Question 33

By what GA should the bowel be completely intra-abdominal?

Answer 33

12 weeks. Earliest diagnosis of gastroschisis was 12w 3d.