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.

Antenatal Counselling

Antenatal counselling for paediatric surgeons is principally to provide the parents-to-be with evidence-based information on the surgical management of the presumed diagnosis, to answer their questions and to help support them make informed decisions. We are not obstetricians or neonatologists and it is not appropriate for us to try and answer their specialized questions on anything other than the paediatric surgical management of the condition; albeit some of the more general questions we can cover and we may have a preference on the need, or not, for caesarean section. Ideally, therefore, antenatal counselling should be carried out in a multidisciplinary clinic alongside specialized feto-maternal obstetricians and neonatologists. When this is not possible, patients should be provided with the opportunity to meet the other disciplines separately.

Everyone will have their own approach to the consultation and this post is not claiming to be the only technique but aims to provide a reproducible structure which you can adapt as you see fit; in my view, it’s a pretty good start. As per any patient interaction start by checking what they already know. The antenatal counselling should then cover the following 5 questions; four ‘what’s’ and one ‘where’:

What is the anomaly?

Basic description of the abnormality and how it is different compared to normal anatomy. This is also the chance to explain what we have seen on imaging that raises the suspicion of the specific diagnosis, any potential differential diagnoses and any common associations. For example, polyhydramnios and an absent stomach bubble being suggestive of oesophageal atresia, but that there are some rarer things it may be any we will, therefore, confirm the diagnosis after birth. If the child has got oesophageal atresia there are also some other associations we would also look for and the baby would, therefore, have a renal and heart scan etc after birth. You have to gage each consultation to work out the right level of detail for that parent/parents.

What is going to happen in the rest of the pregnancy?

Most of this should be left to the obstetrician to answer, but if counselling on your own, a general description of follow up scans and what is being looked for / what we might be worried about – e.g. hydrops in lung lesions or intra-abdominal bowel dilatation in gastroschisis.

What will happen after delivery?

Brief description of what they should expect, for example, that a congenital diaphragmatic hernia will be electively intubated or a congenital lung lesion will be observed

Are there other investigations that need to occur, for example, is there a potential for an associated cardiac anomaly that may not have been antenatally detected.

What are the likely long term implications?

Is there associated mortality or potential long term issues such as continence with myelomeningocele?The details vary depending on the anomaly but we have a duty to be honest and clear. Parents will also vary and different people will want different levels of information. Offering a chance for a second antenatal counselling session may help reduce anxiety, and providing written information allows parents to relook at the information in their own time frame.

Where will they deliver?

Do they need to deliver at your centre or can they deliver nearer to home? This will vary based on the likely diagnosis and geography. In the UK, with a child unlikely to need intervention, delivering nearer to home may be the most appropriate. In Australia where there’s the potential, the child may need transfer and the paediatric surgery centre is thousands of miles/kilometres away then delivering in the paediatric surgery centre to prevent mum and baby being separated postnatally may be more sensible. Also worth reassuring them that if there’s an emergency, they go to the nearest centre and they will be appropriately managed which may include transfer, but allows them and the foetus to be checked.

Additional tips to consider:

Ask if they know the sex – it makes the consultation more personable and allows you to avoid the awkward ‘it’ reference. Some carers may even use a name.

One of my colleagues always starts by stating it is NOT the fault of the parents – he backs this up with an explanation of why; I think this is really good for the parents to hear, but be careful with gastroschisis in recreational drug abusers for example (Risks of gastroschisis ).

Be as positive as possible but don’t give false hope – neither they nor you can change the diagnosis and pregnancy is stressful enough without making the next few weeks harder. They need to know that they are safe, we will deal with whatever we face as it happens and that they and their child will get excellent care. BUT, do not give false hope. Unfortunately, not all congenital diaphragmatic hernias will have a good outcome. Be realistic, be fair.

Do not get bogged down in minutiae – tell them the most likely outcome, not every little detail; most babies with gastroschisis are discharged fully fed at 6 weeks. Some babies take a bit longer, some get home earlier. There are some babies with gastroschisis that also have an associated blockage in the bowel (atresia) which needs further surgery, but we will deal with that if it occurs. They do not need to know at this stage about the rare risks of NEC, or late adhesional obstruction, or distress with the umbilical appearance in gastroschisis.

Finally, termination of pregnancy – it is not our role to advocate for or against termination of pregnancy. The structure outlined above allows us to provide parents with the information available, an idea of how confident we are in the diagnosis and the overall likely long term implications. With clear and honest information provided to them the parents can then decide how they wish to progress with the pregnancy.

References:

Antenatal diagnosis of surgically correctable anomalies: effects of repeated consultations on parental anxiety. Aite L, Trucchi A, Nahom A, Zaccara A, La Sala E, Bagolan P. J Perinatol. 2003 Dec;23(8):652-4. doi: 10.1038/sj.jp.7210992.