Gastroschisis : Application of a preformed silo
The management options for gastroschisis involve either a primary operative closure under general anaesthetic or a staged closure with the aid of a custom or a preformed silo. The published results for each are similar and the initial management utilized, is often dependent on geographical location / center preference rather than interpretation of studies. This post explains the tips and tricks for application of the preformed Gastroschisis silo; ideal to know in general, but also a page of handy hints for 3am.
Where:
at the bedside and does not require a general anaesthetic.
Set up:
The patient should have iv access and be fully resuscitated. An NGT should be placed, on free drainage. Different units will have different guidelines on analgesia, sedation is not usually required, but some departments will give paracetamol pre-application.
Equipment:
preformed Gastroschisis silo, sterile gloves, plenty of gauze, warm saline. Preformed silos come in different sizes, for most term infants a size 4cm is the most appropriate. The size relates to the diameter at the base and silos are available in half cm sizes. Too small a silo and the ring can compress the bowel, too large a silo and the abdominal wall defect is stretched.
Technique:
Inspect the bowel – there is no need to separate the loops or treat any potential atresia, but it is important to ensure there is no bleeding, no band that needs treating and that the bowel is viable.
Clean the skin – use warm saline soaked gauze to clean the vernix off the skin. The silo dressing needs to stick well to allow suspension and subsequent reduction of contents.
Finger sweep the edge of the defect – place a finger into the defect and go around the whole circumference to ensure there are no attachments. You can start anywhere, but if you always start in the same place, for example the superior aspect, it helps to ensure you check the full circumference.
Gastroschisis silo set up – place a few mls of sterile saline or sterile water into the silo. This helps to lubricate the silo and makes it easier to advance the bowel.
Insert the bowel into the silo – hold the silo with the wings at 6 and 12 o’clock and DO NOT rotate the wings for the procedure. If you rotate the silo, you rotate the bowel and risk volvulus and ischaemia. Start with the apex of the bowel and slowly advance the bowel into the silo until it is all inside.
Insert the silo (and wing) into the abdomen – squeeze the circular base of the silo and insert one edge into the abdominal wall. Systematically insert the rest of the ring into the abdomen.
Stick the Gastroschisis silo down – dry the abdominal wall skin and stick down the dressing over the wings of the silo. Be careful not to touch the adhesive side of the dressing – it is very difficult to get off gloves. The dressing can be stuck in any orientation, but we would suggest you place the gap in the dressing under the umbilical cord.
Wrap the abdominal cord – keep the cord moist by wrapping in a non-adhesive dressing covered in cling film to prevent it drying out. The cord can be helpful in obtaining abdominal closure – which can be done sutured or sutureless. Some centres place the cord inside the abdominal cavity until closure.
Suspend the silo – place the cord through the top of the silo and attach to the top of the cot; depending on the type of cot, the cord can be tied over the cot or taped to it.
Staged Reduction of contents – again, different departments will have different protocols for reduction of contents, but effectively the silo is repeatedly squeezed over the next few days to reduce the bowel into the abdomen – we suggest the contents are reduced twice a day and ideally full reduction is obtained before 5 days. The silo is squeezed above the apex of the bowel and once the abdomen feels tight / no further reduction is possible at that point, a piece of cord tied above the apex of the bowel until the next reduction is due and the process repeated. Unit policy on analgesia should be followed.
Additional tips:
If when placing the silo it becomes twisted and it is difficult to know which flange should be at 6 and which at 12 o’clock, stop and start again. There is no problem with going back and restarting with the application of the silo, but you do not want to risk volvulus of the bowel.
If the defect is too small for the silo ring, the defect can be enlarged with an incision in the fascia – different people advocate midline or lateral. We go midline.
If the bowel looks discoloured in the silo: aspirate the NGT – if large aspirate, reassess after 15 minutes. If minimal aspirates or still concerned, reduce the pressure on the bowel by releasing the cord tie and reassess after a further 15 minutes. If neither of these help, remove the silo and upsize or make an incision in the fascia or progress to a different management option.
Double check that the NG is in the stomach and works to completely decompressed the stomach.