The Exomphalos

 The exomphalos is a hernia of the abdominal viscera in which the umbilical wall is transformed into a thin and fragile membrane whose rupture constitutes a neonatal event of extreme gravity. The outcome for this congenital anomaly is further complicated by other factors such as prematurity, associated malformations, the means for care and their availability, and finally the risks incurred from the effects of an abdominal hypertension following a hasty and forced reduction of the herniated viscera. The progress in the field of neonatology and the development of a original method of reduction have dramatically improved the vital outcome, but at the price of an important morbidity and a prolonged hospitalization...

        1. During the anatomical dissection one records:

• the avascular structure of the peritoneo-amniotic membrane whose edge is the seat of an intense cellular activity from wich the epidermization process will develop and spread to all of the membrane in a few weeks.
• the polar implantation of the umbilical cord,
• the integrity of the abdominal wall musculature,
• the massive adhesion of the ileo-coecal junction to the membrane and the high incidence of the disrotation of the intestine.

2. The volume of herniated liver determines the dimension of the parietal defect and the size of the exomphalos; three anatomical types are described :

The small exomphalos ( type I ), the parietal defect measures less than 5 cm in diameter, and is easily corrected through a one-time procedure. The ‘’intracordonal exomphalos’’, in which the umbilical cord is correctly implanted is a particular aspect of this type.
The large exomphalos ( type II ) in which the parietal defect measures more than  5 cm can contain all the movable viscera ( intestine, stomach, spleen, ovaries... )
The giant exomphalos ( type III ), the hépato - intestinal content fills so much of  the available abdominal space that the reduction of all the herniated viscera can become a laborious task and almost impossible to close. The liver hernia can create a cardiogenic shock resulting from the folding of the inferior veina cava.

 

3. The Inspection of the sac and its content allow to distinguish :

• the clear exomphalos with a transparent and intact membrane with identifiable content
  ( stage A ),
• the infected exomphalos with its opaque and thickened or necrosed sac ( stage B ),
• the eviscerated intestine ( stage C ). The antenatal rupture exposes the viscera to the amniotic fluid whose irritative effects are more serious than those of the postnatal contamination. The bowel eviscerated before birth are dilated with thickened and rigid walls and surrounded by the gelatinous substance. The evisceration which occurred during the delivery or later is at first glance impressive, since it concerns most of the contents of the abdominal cavity, but without noticeable damage to the intestine and its mesentery.

4. The anatomical (types I, II ,III) and evolutive criteria (stages A,B,C), can be intricated with the following morbid conditions  :

    * the delay of the meconium evacuation evokes a possible intestinal atresia.
    * the immaturity of the thermo - regulation and defense mecanisms, physical distress, chromosomic aberrations,
    * The "gorgeous looking child" with a birth weight more than 4kg should develop a hypoglycemia -a component of the Beckwith-Wiedmann syndrome – which can have a negative long-term effect on brain development if it goes unrecognized .
    * Finally, septicemia is the most misleading condition occuring in the newborn. It will be evoked in the lethargic, hypothermic or subicteric newborn; petechiales eruptions are often the lone symptom of a latent sepsis, while the bloody bronchial secretions or the development of a sclerema announce a fatal outcome.

5. The goal of the radical cure is to introduce the viscera into an abdominal cavity they have never occupied before and maintain them there without creating intrabdominal hypertension.
A radical intervention is possible in the case of the type I treated earlier, with the transluscent membrane and without associated anomalies.
But in fact, the one-stage procedure is counterindicated when the child is hospitalized beyond 48 hours, or when the vital prognosis worsens. Similarly it is not recommended when the exomphalos exceeds the abdominal cavity. The forced integration of the viscera in a tiny space hobbles the diaphragm’s movements and the irrigation of the viscera, it induces a state of acute distress ( dyspnea, ileus, oliguria, oedema of the distal extremities, metabolic acidosis ...) which rapidly becomes irreversible. Under such conditions, the therapeutic program has to have a sole preoccupation: to prevent the risks of evisceration and infection; the reduction and the parietal repair can be undertaken at a later time once the vital prognosis permit it.

6. The omphalic sac can long remain intact and is liable to be epidermized from the cutaneous edges, provided it is maintained free from the desiccation and infection. When t is inadequately or badly isolated, the membrane dries up and scales under the action of bacterial colonies, this is the starting point - even in the absence of spliting - of the peritoneal infection. Moreover, the evisceration worsens this state by creating metabolic complications (dehydration and hypoprotidemia) .

7. The primary care is conducted in the operating theater by the surgeon as befits a major intervention . The excess amount of cord is ligated and excised, the abdominal wall is then washed with the warm physiologic solution, brushed with the soap and disinfected. The membrane is then cleared from all deposit, and covered with an occlusive and loosely fitted sterile bandage.
During this primary stage, one needs to attend to a possible hypoglycemia often associated with hypocalcemia, and add to the daily fluid therapy vitamin intake (hydrosoluble and vitamin K), proteins (plasma or albumin) , gammaglobulin in case of evisceration and a large specter antibiotherapy. It is advisable to decompress the intestinal content by suction using a naso-gastric tube thrust beyond the pylore and by physiologic serum enema. Finally, the child is placed in the incubator, and his position changed from side to side every thirty minutes.

8. the modalities of the surgical cure are determined by the physical state and the volume of the herniated viscera.
From a tactical point of view, one disposes of several means:
        * the one-time closure, or
        * the transformation of the exomphalos in eventration through the epidermization of the omphalic sack ( Grob procedure),
          or by cutaneous cover (Gross procedure),  or
        * the progressive reduction (Schuster procedure)

The conservative method relies on the epidermization of the membrane from the cutaneous edges. The sac is maintained in isolation and desinfected through daily brushing with an antiseptic solution such as Betadine which is preferable to mercurochrome. A few days later one observes the appearance of small epidermal islands which confluence gradually and turn the sac into a skiny membrane within a matter of weeks.

The covering of the viscera by the adjacent skin mobilized to the median line. The membrane is maintained intact ( Gross procedure), or is excised after checking the content of the abdominal cavity (Soper method). The viscera thus reduced occupy an interstitial space between the cutaneous and the musculo–fascial parietal layers. The exomphalos is therefore transformed into a ventral hernia which can be attended to later.

     The parietal repair stage involves :

* the excision of the membrane to the exception of the area of adhesion to the coecal   junction so as to prevent a stercoral fistula from occuring, * the meticulous exploration of the gut in search of any associated anomaly   malrotation , atresia, stenosis, diaphragmatic defect..., * the integration of the protruding viscera, * the reconstitution of the abdominal wall in layers.
This parietal repair stage is guided by the degree of abdominal tension as measured by intravesical pressure which is to be constantly maintained under 25 cm of water. The physiologic comfort of the patient is checked by observation of the extremities coloration , the respiratory rythm and if need be by gazometry. In case of abdominal hypertension, the use of artificial ventilation remains the most reliable way providing that the servitudes this method imposes are closely observed.

    
The progressive reduction method consists of substituting a synthetic pouch to the omphalic membrane. It needs to be resistant enough to withstand external manipulations.The purpose is to push the viscera into the abdominal cavity without disturbing the abdominal hydrodynamics.

Schuster was the pioneer in this field, his procedure dramatically transformed the prognosis for the exomphalos. The first material used was a membrane made of siliconed dacron (Silon), other less rigid materials have since been developed such as Teflon or Op-Silon; the latter is produced in translucent sheets which are very supple, porous,  permeable to gases and perhaps bactericide.

The high cost of these synthetic membranes limits their utilization in our contry. We were  inspired by Ugbam who uses a simple bag of physiologic solution whose undeniable advantages are : easy availability of the material, sterility, malleability, transparency and impermeability to bacteria. After excision of the membrane, the synthetic pouch is transformed into a cone whose base is sutured to the facia’s edges ( Schuster’s procedure) or preferably to the cutaneous periphery ( Cordero’s procedure). The volume of the cone is gradually reduced by a strangling action until the total integration the vicsera.
However the use of this material presents some disadvantages. Because of its inert texture and its constant exposure to the air, it constitutes a prime environment for bacterial colonization and mainly for the candidas that swarm rapidly to the abdominal cavity through the anchor points of the membrane, the appearance of a muguet is its telltale sign that this problem has developped. Brushing Nystatine on and its oral administration does not have to wait for a biological confirmation.

    Attending to the eventration is a laborious undertaking. Indeed, it concerns an atypical ventral hernia because of the massive adhesions that have developed between the viscera (liver, intestine) and superficial parietal plans. On the other hand, it has no favorable effect on the capacity of the abdominal cavity which remains cramped. Two artifices are used to create the space necessary for the definitive integration of the viscera.
        *The insufflation through the left flank of monoxide nitrogen under sono and cardiographic controls allows to correct the eventration without much discomfort within two weeks.
        *The other means consists of the use of a silastic sheet to fill the parietal defect.

9. Therapeutic indications
The multiplicity of anatomical and clinical aspects creates several situations that we can summarize as follows:

In actual fact, the situations are  more complex than those summarized in this table because other factors should intervene: associated digestive anomaly, prematurity, dysmetabolism, cardiopathy...

                                         Nevertheless, several imperatives have to be underlined: