The Fetal Anterior Abdominal Wall

OB2

Two MOST COMMON abdominal wall defects

omphalocele

gastroschisis

When does fusion of the midline occur?

during the seventh week and is completed by the eighth week

When should the midgut herniation be completed?

by the end of the 12th week gestation

The midgut herniation is primordium of

small intestines

cecum

vermiform appendix

ascending colon

right half to two thirds of the transverse colon

Important to image to evaluate the following for presence of defects

cord insertion

fetal anterior abdominal wall

bladder and cloacal exstrophy

Omphalocele

when bowel loops fail to return to the abdomen from the midgut herniation

AFP slightly elevated

encased in a membrane consisting of peritoneum and amnion

2 types of omphaloceles

those that contain liver within the sac

those that contain a variable amount of bowerl but no liver

Omphaloceles that contain bowel only have a higher risk for

chromosomal abnormalities (35-65%)

other anomalies

Anomalies associated with omphaloceles

complex cardiac disease

gastrointestinal

neural tube

genitourinary tract anomalies

Limb-body wall complex

lethal disorder

acrania

encephalocele

facial clefts

extensive abdominal wall defect of the chest

abdomen and limb defects

Amniotic band syndrome

abnormal fusion of the amnion and chorion extends as a sheet from the cord and adheres to the fetus and the placenta

entangles or amputates fetal parts

Common findings with amniotic band syndrome

facial clefts

asymmetric encephaloceles

constriction or amputation defects of the extremities

clubfoot deformities

Bladder exstrophy

bladder outside of the pelvis

Anomalies associated with bladder exstrophy

anal atresia

spina bifida

lower limb defects

Pentalogy of Cantrell

large omphalocele

sternal cleft

anterior diaphragmatic hernia

ectopia cordis

defects of the diaphragmatic pericardium

Pentalogy of Cantrell may be associated with

cardiac defects

cleft lip/ palate

encephalocele

exencephaly

sirenomelia

trisomies 13, 18 and 45X

Beckwith-Wiedemann syndrome is suspected if these are found

organomegly

macroglossia

macrosomia

omphalocele

embryonic tumors

neonatal hypoglycemia

ear creases

Perinatal mortality approaches ____% when more than one fetal anomaly exists

80

Mortality rate of an omphalocele when it is isolated

10%

Gastroschisis

opening in the layers of the abdominal wall with evisceration of the bowel

A gastroschisis is almost ALWAYS to the _______ of the umbilical cord insertion

right

A gastroschisis is thought to be the consequence of:

atrophy of the right umbilical vein

disruption of the omphalomesenteric artery

Gastroschisis knows:

young mothers

males more than females

poor prognosis

higher AFP

only detected after 12 weeks

Gastroschisis sono findings

right paraumbilical defect of the abdominal wall

free-floating herniated small bowel

large bowel, stomach, gallbladder, urinary bladder, pelvic organs may be involved

bowel wall thickening

hydronephrosis

Common defects associated with amniotic band syndrome

limbs

cranium

face

thorax

abdominal wall

perineum

Bladder exstrophy

bladder becomes exposed on the lower abdominal wall

Cloacal exstrophy

results in exstrophy of the bladder which two hemi-bladders are separated by intestinal mucosa

Cloacal

becomes the rectum, urethra, and vagina

if misforms causes a split penis in boys

Ectopic cordis

exposed heart presents outside the chest wall through a cleft in the sternum

heart may present outside the thoracic cavity when a portion of all of the heart protrudes through a defect in the sternum

Ectopic cordis is associated with

omphalocele

cardiovascular malformations

craniofacial defects

Cleft sternum

may be either partial or absent without ectopia cordis and is typically a superior or total cleft

Associated with vascular malformations, including cavernous hemangiomas and omphaloceles

This side is MORE COMMON with a limb body wall complex

left side is 3x more common