Omphalocele

Omphalocele Definition

Omphalocele also referred to as exomphalos is a birth defect that involves the abdominal wall, wherein the baby’s intestines, liver and other organs are found outside of abdominal area due to impairment in the development of abdominal wall muscles.

The intestines are noted to be covered and protected by a thin layer of tissue and can be readily seen for assessment and evaluation. The herniated organs in omphalocele are being covered by the Wharton’s jelly and the amnion as the pregnant woman reaches the 10 weeks age of gestation.

Omphalocele is a problem in the abdominal wall which has some similarity with gastrochisis, wherein there is no complete closure of the anterior abdominal wall, resulting to the protrusion of the intestines outside of the fetal body. The difference it has from gastrochisis is that, the protruding organs are being wrapped by a thin membranous sac, and it is not found floating in the amniotic fluid just like a case of gastrochisis.

The incidence of omphalocele is approximately 1 case for every 4000 births. It is being associated with some severe malformations, like cases of heart anomalies and defects of the neural tube. Based on some studies, about 15% of babies born with omphalocele are also having chromosomal problems.

Symptoms

An existing omphalocele of a baby can be easily noted by any member of the health team who will perform the assessment and evaluation in relation to the problem, although some babies may not present any symptom of the problem.

Clinical manifestations include:

Presence of a bump on the outside portion of the abdominal wall
Sticking out of abdominal contents outside of the abdominal wall
Small omphaloceles involves only the intestines to remain outside the baby’s body
Large omphaloces involves other organs protruding outside the body aside from the intestines
Breathing difficulty for those with problems of the lungs

Other birth problems of babies who have omphalocele:

Heart problems
Spine problems
Digestive tract problems
Lung problems
Urinary tract problems

Causes

The exact cause of omphalocele is not yet known. An omphalocele can be caused by impairment in the rotation of the bowel contents as it tries to return back into the abdomen during the period of development.

There are some studies that propose various theories which might end up with omphalocele formation and these are:

Failure of the bowel to normally return back into the abdomen between the 10-12 weeks age of gestation
Persistence of the body stalk that goes beyond 12 weeks age of gestation
Failure of the lateral mesodermal body folds to have central migration

Predisposing factors that might lead to the formation of an omphalocele:

Consumption of alcohol and tobacco during the pregnancy
Certain medications taken like the selective serotonin-reuptake inhibitors during pregnancy
Obesity among women prior to the pregnancy

Other birth disorders that are linked with omphalocele are the following:

Chromosomal abnormalities
Cardiac defects
Congenital diaphragmatic hernia
Edward’s syndrome
Patau syndrome
Beckwith-Wiedemann syndrome

Diagnosis

Omphaloceles can be detected through the following:

Routine ultrasonographic surveillance/ultrasonography is the best modality used for fetal assessment to check for an existing anomaly and to specify the anatomical location of the affected site

Image 3 – Color Doppler ultrasound scan showing omphalocele

Investigation of uterine size disparity from period of conception
Evaluation on increased level of maternal alpha-fetoprotein
Diagnostic amniocentesis when the omphalocele is being suspected from prenatal sonography for some anomaly in the chromosomal structure
Prenatal magnetic resonance imaging can be helpful in the analysis of any anomaly present and it can be utilized as an adjunct test together with ultrasonography
Fetal echocardiogram to assess the presence of any heart problem by the fetus

Ultrasonographic results of omphalocele may reveal the following:

Presence of fetal anterior abdominal mass
Wharton’s jelly can be detectable
Attachment of the umbilical cord with the apex of the herniated mass
Fetal ascites can be observed within the herniated sac
Polyhydramnios and oligohydramnios might be present

Treatment

Surgical correction is the main management to be done to correct herniated intestines or organs.

Treatment approaches depends on the following factors to consider from newborn patients:

Specific size of the omphalocele, either small or large
Gestational age of the baby
Presence of other chromosomal abnormalities or birth defects

Primary surgery for small size of omphalocele

Staged repair using multiple surgeries for large-sized omphaloceles are done at the time when the baby grows
Topical application made up of painless drying agents are applied on the membrane of large omphaloceles
Cesarean birth in a special facility might be recommended for large and giant omphaloceles
Special material called “silo” is used to cover the exposed organ until all the affected organs are moved back inside the abdomen

Image 4 – Repair of omphalocele

Repair schedule according to severity of defect with affected babies:

Small omphaloceles can be easily repaired by surgeons with a simple operative procedure and requires shorter stay in the nursery department
Large ompaholoceles may need some staged repair and with several weeks to stay in the nursery department
Giant omphaloceles need some complex type of reconstruction that can take several weeks, several months or several years to fix the problem

Potential complications after surgical management are:

Feeding difficulty
Reflux
Growth delay
Bowel obstruction
Breathing problems which can be long term

Survival rate

Babies diagnosed with omphalocele disorder usually do well in terms of their recovery. The rate of survival is greater than 90% if the main problem is only related with omphalocele. For those babies who have omphalocele and the presence of other serious problems, the rate of survival is only about 70% of the cases.

Pictures

Image 5 – Omphalocele pictures in neonates

Image Source

References:

https://www.nlm.nih.gov/medlineplus/ency/article/000994.htm
http://emedicine.medscape.com/article/404182-overview
What is the outcome for a fetus with omphalocele?, Repair of large omphaloceles and ICN care at https://fetus.ucsfmedicalcenter.org/omphalocele
Chung DH. Pediatric surgery. In: Townsend CM Jr, Beauchamp RD, Evers BM, Mattox KL, eds (2012). Sabiston Textbook of Surgery. 19th ed. Philadelphia, PA: Saunders Elsevier; chap 67.
Danzer E, Victoria T, Bebbington MW, Siegle J, Rintoul NE, Johnson MP, et al (2012). Fetal MRI-calculated total lung volumes in the prediction of short-term outcome in giant omphalocele: preliminary findings. Fetal Diagn Ther. 31(4):248-53.
Schnur J, Dolgin S, Vohra N, Soffer S, Glick R (2008). Pitfalls in prenatal diagnosis of unusual congenital abdominal wall defects. J Matern Fetal Neonatal Med. 21(2):135-139.