Abdominal Wall Flashcards
What are the fetal anomalies associated with the Abdominal Wall?
5 Bladder Exstrophy Body Stalk Anomaly Cloacal Exstrophy Exomphalos Gastroschisis
Bladder Exstrophy
Prevalence: 1 in 30,000 births.
More common in males than in females: 2 to 1.
Ultrasound: Abdominal wall mass in the suprapubic region below a low insertion of the umbilical cord.
Non-visible bladder with normal volume of amniotic fluid.
Widely separated pubic bones, short and broad penis in males, hemiclitoris on either side of the bladder in females.
Assoc abnorm: The incidence of chromosomal abnormalities and genetic syndromes is not increased.
Follow up: Follow-up should be standard.
Prognosis: Survival rate is >95%. Surgery aims to achieve bladder closure and urinary continence, and epispadias repair.
Recurrence: No increased risk of recurrence.
Body Stalk Anomaly
Prevalence: 1 in 10,000 pregnancies.
More often in a younger age group and cocaine abuser.
Ultrasound: Presence of a major abdominal wall defect, severe kyphoscoliosis and short or absent umbilical cord. Typically, the liver is directly attached to the placenta without interposed umbilical cord and there is major distortion of the spine.
Assoc abnorm: The incidence of chromosomal abnormalities and genetic syndroms is not increased.
Exencephaly or encephalocoele, facial cleft, and limb amputations are common.
Follow up: If the pregnancy continues then follow-up should be standard.
Prognosis: Lethal condition either in utero or in early neonatal period.
Recurrence: No increased risk of recurrence.
Cloacal Exstrophy
Prevalence: 1 in 300,000 births.
Ultrasound: Low exomphalos, non-visible bladder and sacral spina bifida (in 50% of cases) with normal volume of the amniotic fluid.
The anatomy of cloacal exstrophy is complex but essentially there is a low exomphalos at the superior margin of the defect, small or large bowel protruding through the middle of two widely separated hemi-bladders, hypoplasia of the colon and anal atresia, splaying of the pubic bones, bifid penis in males, hemiclitoris on either side of the bladder in females, and spina bifida.
Assoc abnorm: The incidence of chromosomal abnormalities is not increased.
Other defects, mainly renal and vertebral, talipes, single umbilical artery, ambiguous genitalia (in males, the penis is divided and duplicated) are often found.
Follow up: Follow-up should be standard.
Prognosis: Survival: >90% after extensive reconstructive bladder, bowel and genital surgery.
Both males and females with this condition are capable of normal lifestyle and both sexes are fertile after surgery. Some form of urinary tract diversion is required for all.
Recurrence: No increased risk of recurrence.
Exomphalos
Prevalence: Only bowel in the sac: 1 in 100 at 11 weeks’ gestation, 1 in 800 at 12 weeks, 1 in 2,000 at 13 weeks.
Liver in the sac: 1 in 3,500 fetuses at 11 to 13 weeks.
Ultrasound: Midline sac containing bowel and / or liver with umbilical cord at the apex.
High exomphalos may contain the heart (pentalogy of Cantrell).
Low exomphalos may be associated with cloacal abnormality and spina bifida (OEIS complex).
Exomphalos containing bowel only at 11-13 weeks resolves by 20 weeks in 90% of cases.
Assoc abnorm: Chromosomal defects, mainly trisomies 18 or 13, are found in 30-50% of cases.
Genetic syndromes, mainly Beckwith-Wiedemann syndrome, are found in 10% of cases.
Defects in other systems, mainly cardiac, are found in 30-50% of cases.
Follow up: Ultrasound scans every 4 weeks to monitor fetal growth and amniotic fluid. It is best to monitor growth through estimation of fetal weight by the Sieme formula which uses biparietal diameter, occipitofrontal diameter and femur length, rather than formulas using abdominal circumference.
Prognosis: Isolated small / moderate exomphalos: survival >90%.
Isolated giant exomphalos: survival 80%.
Other defect: depends on defect, e.g. trisomy 18 is lethal.
Recurrence: Isolated: no increased risk.
Part of trisomies: 1%.
Part of Beckwith-Wiedemann syndrome: up to 50%.
Gastroschisis
Prevalence: 1 in 3,000 births.
Increased risk in young women and in those with cocaine abuse.
Ultrasound: Paraumbilical abdominal wall defect, usually to the right side, with associated evisceration of bowel, floating freely in the amniotic fluid with a normally inserted umbilical cord.
Assoc abnorm: The incidence of chromosomal abnormalities and genetic syndromes is not increased.
Assoc complications: Bowel atresias or obstruction secondary to volvulus and/or ischemia at the hernial orifice in about 10-30% of cases.
Fetal growth restriction in 30-60% of cases.
Spontaneous preterm birth in about 30% of cases.
Fetal death in 2-4% of cases.
Follow up: Ultrasound scans every 4 weeks to monitor growth, amniotic fluid, fetal oxygenation (UA-PI, MCA-PI and DV-PI) and intra-abdominal bowel dilatation.
In fetuses with abdominal wall defects it is best to monitor growth through estimation of fetal weight by the Sieme formula which uses biparietal diameter, occipitofrontal diameter and femur length, rather than formulas using abdominal circumference.
Prognosis: Survival: >90%
Main cause of death: short bowel syndrome.
Recurrence: 3%.
