Exomphalos

An exomphalos, also known as an omphalocele, results from herniation of abdominal organs through a central abdominal wall defect. 

This is different from gastroschisis, which occurs when bowel herniates through an abdominal wall defect lateral to a normal umbilicus. 

With exomphalos, a sac comprised of peritoneum, amnion and Wharton’s jelly covers the central herniation into the umbilical cord, whereas there is no sac protecting the exposed bowel in gastroschisis.1 

An exomphalos forms between the 6th – 10th week of gestation in about 1 in every5000 births.2 In Victoria, approximately 10 infants are born each year with this condition and, on average, three of them have the major form of the anomaly. Exomphalos is almost always diagnosed antenatally and when other major anomalies are identified, the pregnancy does not usually continue.3

There are two types: 

1. Exomphalos minor where the opening is less than 4 cm and only contains the intestine and omentum.
2. Exomphalos major (or Giant exomphalos) where the opening is greater than 4 cm and may contain the liver as well as the intestine.

Associations

• Associated anomalies are observed in up to 72% of infants4. 
• Of infants with normal karyotypes, nearly 80% have multiple other complications or anomalies.
• Multiple anomalies are more common with minor (< 4 cm) versus major exomphalos (55% vs 36%).

Antenatal

• Raised alphafetoprotein levels are detected in 90% of cases and combined with ultrasounds the diagnosis of abdominal wall defects is close to 100%.1
• Women should be referred to a Level 6 Maternity Service (Monash Medical Centre, Clayton, Mercy Hospital for Women (MHW), Royal Women’s Hospital (RWH)) multidisciplinary fetal diagnostic service as soon as possible if they are diagnosed externally so that detailed testing may be arranged to assess for the presence of the other known associations (as above) and options for ongoing care may be discussed.
• For pregnancies that are continuing, parents should receive antenatal multidisciplinary counselling from obstetricians, neonatologists, geneticists and paediatric surgeons in the maternal fetal medicine unit (MFM) or equivalent.
• Birth should be planned at a L6 Maternity Service or at a private hospital co-located with a L6 Maternity Service.
• Parents should be offered an orientation to the surgical NICU environment at MCH or RCH antenatally.
• The MFM teams should liaise with the MCH or RCH  neonatal teams via phone or email to handover relevant maternal and fetal information and an expected delivery date.
• On the day of anticipated birth (planned or spontaneous), the perinatal team should liaise with the hospital duty neonatologist or NICU ANUM who will in turn advise the paediatric surgeons about the impending birth.
• Where there is an obstetric imperative to deliver the baby, NICU access will not influence the timing of such births.

Postnatal 

Management of the infant is dictated by the size of the exomphalos, associated anomalies and whether the sac is intact after birth or not. 

The principles of management following birth and during the pre-transfer period includes addressing fluid resuscitation, gastric decompression, avoidance of hypothermia and care of the herniated abdominal contents. 

Preparation in the birth suite

• In exomphalos major, a caesarean section may reduce liver injury or sac rupture during vaginal delivery.
• Prepare for anticipated high-risk birth, as per unit protocol. Medical staff should attend the resuscitation. 
• Manage airway, breathing and cardiovascular status as per usual practice. These infants may have unsuspected pulmonary hypoplasia requiring early intubation and ventilation. In the compromised baby, to minimise gut over-distension, endotracheal intubation is favoured over providing prolonged mask ventilation or nasal CPAP.
• Congenital heart disease should be suspected if the infant is cyanosed/not responding to resuscitation.
• Newborns with abdominal wall defects require up to 2-3 times the amount of fluid of a normal term newborn and thus fluid resuscitation may be required early, especially if there is rupture of the covering sac.
• Once the cardiorespiratory status has been stabilised, inspect the sac and, if ruptured, manage as per the gastroschisis guideline. 
• If not ruptured, the exomphalos should be wrapped in cling wrap (transparent, latex free) as described below.
• Insert an 8Fr nasogastric tube (NGT) and aspirate the stomach. Leave on free drainage.
• Ensure adequate thermal control.
• Transfer the infant to the NICU/SCN for ongoing management within MCH or prepare for transfer to RCH NICU if the infant is born outside of MCH or its catchment area.

Positioning and wrapping of exomphalos 

• It is a clean procedure but does not need to be sterile.
• Construct a roll from a standard flannel nappy and cover the roll with cling wrap.
• Place the cling wrap covered roll as a 'doughnut' to support the exomphalos on the abdominal wall.
• Slide large piece of cling wrap under the infant’s buttocks and back and wrap it gently around the abdomen.
• Ensure the sac is not exposed to drying air.
• Avoid compressing the exomphalos and ensure the wrapped exomphalos is well supported using a second rolled towel or equivalent.
• Cotton wool covering or the use of moist packs is contraindicated

Exomphalos care immediately after birth (perinatal)

• The urgency of transfer to the Surgical NICU at MCH or RCH will depend on the size of the exomphalos and the presence of associated anomalies. 
• Unless the infant is born at Monash Medical Centre Clayton, PIPER (1300 137 650) must be notified as soon as possible after the baby is born. 
• Ensure the exomphalos remains wrapped and supported as described above.
• Establish vascular access. Arterial access is not required unless there is significant respiratory or circulatory compromise. Collect blood samples for baseline gas, electrolytes, glucose and culture when inserted.
• Check blood glucose immediately and monitor closely because of the association of Beckwith-Wiedemann syndrome with exomphalos minor.
• Give antibiotics: benzylpenicillin, gentamicin (preferably after blood culture).
• Ensure the baby is clinically assessed for other congenital anomalies.
• Nurse the infant in a temperature-controlled environment.
• Ensure appropriate cardiorespiratory and saturation monitoring is applied and monitor blood pressure.
• Commence maintenance fluid 10% Dextrose at 60 ml/kg/day to maintain blood glucose >2.6 mmol/L.
• Ensure NGT is aspirated hourly and remains on free drainage.
• Maintain an accurate fluid balance record for all infants, including gastric losses.
• Additional fluid boluses of 0.9% Sodium Chloride solution (i.e. Normal Saline) may be required.
• Review fluid balance and clinical status once a total of 40 ml/kg saline has been administered or as determined by the outcome of repeated assessment of capillary refill, heart rate, blood pressure and acid-base/lactate.
• At this point, ongoing fluid replacement needs to take account of possible clotting factor dilution and/or the need for colloid as opposed to further crystalloid.

Transfer to NICU with paediatric surgical services (MCH or RCH)

For infants not born at Monash Health Clayton, the retrieval team will:

• Treat the referral as urgent.
• Leave the exomphalos wrapped and undisturbed after ensuring it is well supported and the bowel has remained well perfused.
• Continue the fluid management regimen detailed above. 
• Monitor the infants temperature frequently. Patients with a ruptured exomphalos sac may have major problems with temperature control due to evaporative heat loss.

NICU care before, during and after surgery

• Inform the paediatric surgeons of the infant's arrival.
• Ensure continued support of the exomphalos.
• Unless there is an immediate need to act otherwise, for example concern about discoloration/vascular compromise of bowel, wait for the surgeon to arrive before disturbing the wrapped bowel.
• Discuss ongoing pre-operative fluid management with the duty neonatologist-default   is to commence/continue 10 ml/kg/hr of 0.9% NaCl + 20mmol KCl per 500ml bag of replacement fluid.
• Undertake usual NICU admission assessment and documentation.
• Collect blood for full blood examination, blood gas including lactate and glucose, electrolytes, coagulation profile and cross match (Neonatal extended expiry).
• Consider siting a urinary catheter to decompress the bladder.
• If nasogastric/orogastric losses are in excess of 20 mL/kg/day, manage according to MCH or RCH NICU protocol.
• Repeat biochemistry 8-12 hourly or as directed by clinical circumstances.
• Continue antibiotics (benzylpenicillin/gentamicin) and add Metronidazole if the sac and/or bowel is perforated or if the bowel appears significantly compromised by ischaemia.
• Insert a central venous access device (PICC) as soon as possible. 
• Order Total Parenteral Nutrition (TPN) as per MCH or RCH NICU guidelines and commence when available. 
• Counselling should be provided to parents when results of assessments for other anomalies are available and should take the infant’s current clinical condition into account.
  • Infants with life-threatening structural or chromosomal associations , such as severe pulmonary hypoplasia or critical congenital heart defects, have a poor prognosis and a frank discussion between the parents and the clinical teams should occur before aggressive management is undertaken. 

Nursing considerations

• On arrival, complete nursing admission assessment and documentation.
• Nurse infant in a temperature-controlled environment and use servo control for temperature balance and monitoring.
• Ensure appropriate cardiorespiratory and saturation monitoring is applied.
• Monitor exomphalos and report abnormalities to medical team.
• Ensure Nasogastric Tube (NGT) is placed on free drainage and aspirated hourly.
• Consider replacement of NGT losses as per NICU protocol.
• Document accurate fluid balance and undertake regular assessment of hydration status.
• Give fluids and medications as prescribed.
• Monitor intravenous cannula site(s) as per unit protocol.
• Ensure regular monitoring of electrolytes per medical orders.
• Undertake pain assessment as per hospital Neonatal Pain Assessment Tool.
• Show parents/family around the NICU.
• Provide ongoing explanation of continuing care to parents

Surgical management of exomphalos

• Surgery should be considered electively in all infants with an intact sac.5 
• The infant should have an urgent surgical referral if a rupture of the sac has occurred.5
• Treatment depends on the size of the defect, gestational age and presence of associated anomalies. 
• Small defects may be repaired with excision of the sac and primary closure of the fascia and skin.5
• In larger defects: 
  • Primary closure may be difficult due to excessively high intra-abdominal pressure.
  • In these cases, the sac is left intact and allowed to slowly granulate and eventually epithelialise over several months or even years.
  • Infants do not need to remain in hospital for the duration of the epithelialisation process and may be discharged home if they are not requiring respiratory support once they are able to consume sufficient calories to grow. 
  • Removal of the epithelialised sac, also known as the shell, and final closure of the fascia and skin will be undertaken by the surgical team when the sac contents have returned to the abdominal cavity.5

Surgical complications 

• Short-term complications depend on the size of the lesion, type of surgery, gestational age and associated anomalies.6 These include: 
  • Abdominal compartment syndrome (more common with primary closure of larger defects). 
  • A tear of Glissen’s capsule of the liver may occur when removing the sac covering the liver. 
  • Inadvertent damage of the bladder may occur if it is within the exomphalos. 
  • Infection risk in infants with a patch or mesh. 
  • Bowel adhesions may develop post-operatively.
  • Volvulus of a malrotated bowel.

Managing an exomphalos after surgery 

• Routine post-operative medical care, such as weaning of ventilatory support and analgesia, intravenous fluid and nutrition orders, etc., will be managed by the NICU clinical teams.
• Feeds will start when the surgical and neonatal teams agree the infant is systemically well and gastrointestinal function is normalising, as evidenced by passage of flatus and/or stool and reduced fluid losses via the oro/nasogastric tube.
• Time to reach full enteral feeds varies and may take several months for infants with exomphalos major.
• Many infants with exomphalos will require oro/nasogastric tube feeds, either due to their associated anomalies or persistent tachypnoea and fatigue.
• Infants may require additional calories for growth provided by fortification of feeds, or in some cases prolonged TPN, and referral to a Dietitian is recommended if weight gain is below average.
• Infants with exomphalos major who are discharged home without undergoing surgical repair may need home nasogastric feeds and oxygen support.
• Careful discharge planning is required to ensure that regular review for growth assessments and dressing changes are arranged. These will be required 1 – 2 weekly initially.
   

• Gastro-oesophageal reflux (GOR) is common.
• 60% of infants with exomphalos will have feeding problems and need a tube, or fortified feeds, or both.2
• Volvulus may occur, as all infants with exomphalos have non-rotation of their intestine
• Ventral and inguinal herniae.
   

• The 1-year survival rate of liveborn infants in a UK study was 92% for isolated exomphalos, 81% in cases with multiple anomalies, and 27% in cases with severe chromosomal abnormalities.7
• Most infants without associated anomalies survive with good long-term growth and neurodevelopment.
   

1. Drewett M, Michailidis GD, Burge D. The perinatal management of gastroschisis. Early human development. 2006 May 1;82(5):305-12. DOI:10.1016/j.earlhumdev.2006.02.003 
2. Christison-Lagay ER, Kelleher CM, Langer JC. Neonatal abdominal wall defects. In Seminars in Fetal and Neonatal Medicine 2011 Jun 1 (Vol. 16, No. 3, pp. 164-172). WB Saunders. DOI:10.1016/j.siny.2011.02.003
3. Consultative Council on Obstetric and Paediatric Mortality and Morbidity (CCOPMM). Congenital anomalies in Victoria 2015–2016. Melbourne: Victorian Congenital Anomalies Register; 2018. 47 p.
4. Poddar R, Hartley L. Exomphalos and gastroschisis. Continuing Education in Anaesthesia, Critical Care & Pain. 2009 Mar 4;9(2):48-51. DOI:10.1093/bjaceaccp/mkp001
5. Hutson JM, O'Brien M, Beasley SW, Teague WJ, King S, editors. Jones' clinical paediatric surgery. John Wiley & Sons Incorporated; 2015.
6. Bruch S, Langer J. Omphalocoele and Gastroschoisis. In Purri P, editor. Newborn Surgery. 3rd edition. London: Hodder and Stoughton Ltd; 2011. p. 605-611.
7. Springett A, Draper ES, Rankin J, Rounding C, Tucker D, Stoianova S, Wellesley D, Morris JK. Birth prevalence and survival of exomphalos in England and Wales: 2005 to 2011. Birth Defects Research Part A: Clinical and Molecular Teratology. 2014 Sep;100(9):721-5. DOI:10.1002/bdra.23301

Bibliography

Great Ormond Street Hospital for Children NHS Foundation Trust. Exomphalos: Information for Families [Internet]. London: Great Ormond Street Hospital for Children NHS Foundation Trust. 2016 [updated August 2016; cited August 2019]. 

Starship Child Health-Newborn services clinical practice committee. Surgery-management of abdominal wall defects in the neonate [Internet].  Auckland: Starship Child Health; 2005 [updated April 2005; cited August 2019]. Available from: https://www.starship.org.nz/guidelines/surgery-management-of-abdominal-wall-defects-in-the-neonate

Sakonidou S, Ali K, Farmer I, Hickey A, Greenough A. Mortality and short‐term morbidity in infants with exomphalos. Pediatrics International. 2018 May;60(5):438-41.
DOI:10.1111/ped.13537