GastroschisisBMJ 2011; 343 doi: http://dx.doi.org/10.1136/bmj.d7124 (Published 15 November 2011) Cite this as: BMJ 2011;343:d7124
- Peter F Nichol, section chief of pediatric surgery
- 1Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA
Gastroschisis continues to be a challenging congenital anomaly. The defect results from a disruption at the junction of the right side of the umbilicus and abdominal wall, presumably during the late first trimester.1 The intestines herniate out of the abdominal cavity into the amniotic cavity. Animal models suggest that exposure to the amniotic environment substantially reduces intestinal length and delays the maturation of the enteric nervous system.2 3
Not surprisingly, the onset of normal intestinal function in neonates with gastroschisis can take weeks. Thereafter, these patients can have chronic problems with intestinal motility and absorption of nutrients.4 No doubt many surgeons and neonatologists have wondered how such a simple defect in the abdominal wall can cause so much trouble. In the linked cohort study (doi:10.1136/bmj.d6749), Bradnock and colleagues describe one year outcomes for a national cohort of infants with gastroschisis.5
The incidence of gastroschisis is increasing worldwide.6 7 The incidence varies for each country, but doing some simple calculations using an incidence of 1/2889,8 a world population of 7bn, and a crude birth rate of 20.3 per 1000 people, about 49 000 infants will be born with this defect in the next year. Given the variability of resources available in each country, not surprisingly outcomes in industrialised countries are better than those in the developing world.7 9 10
The silo closure technique was introduced in the 1960s. Performed in the operating theatre under sterile conditions, a teflon mesh was sewn to the ring of the gastroschisis defect and lined with plastic so the mesh did not adhere to the protruding intestine.11 The silo contents were serially tightened until completely reduced into the abdomen, at which point the fascia was closed. This technique was a major advance in the management of gastroschisis. It enabled barrier coverage of the exposed intestine, thereby preventing thermal and insensate fluid loss while reducing infectious risk in patients who could not be treated with primary closure. The preformed silo was introduced in 1995. It has a spring loaded ring that deploys under the defect within the abdomen.12 This enables the surgeon to cover the herniated intestine quickly without sewing the silo to the fascia. This is often done at the bedside in the neonatal intensive care unit instead of in the operating room. Owing to the ease of placement, this has become the preferred method of management for many surgeons. It is therefore likely that some patients who could successfully be closed primarily are managed with a preformed silo and delayed fascial closure.
Bradnock and colleagues examined the outcomes of patients with gastroschisis born over an 18 month period in 28 participating hospitals in the United Kingdom and Ireland. As expected, infants with complicated gastroschisis (intestinal pathology such as atresias or inflammatory peel) had worse outcomes than those with simple gastroschisis. Surprisingly, patients with simple gastroschisis managed with preformed silos fared worse than those managed with primary fascial closure; they had significantly higher mortality and took longer to reach full feeds. The results of this multi-institutional study of more than 300 patients are hard to ignore. The authors conclude that treatment options need to be compared in a randomised controlled trial. It is important, given all the potential variables, that such a study is comprehensive and longitudinal, as was the National Wilms Tumor Study in North America.
The study must answer several questions: what is done differently in primary closures that speeds the onset of intestinal function and achieves better outcomes? Infants with gastroschisis have tenacious meconium, similar to that of infants with cystic fibrosis. Does evacuating the intestine of this tenacious meconium, as is done in primary closure, hasten the onset of intestinal function? Should this technique be used in all patients regardless of closure technique?
It is not surprising that en masse reduction of dilated, meconium bloated intestine in a silo through a 3 cm defect in the abdomen can cause intestinal ischaemia. In Bradnock and colleagues’ study, intestinal ischaemia caused death in two patients with simple gastroschisis who were treated with a preformed silo. It is not known if the meconium was evacuated before placement of the silo. In addition, primary closures are performed in the operating theatre, whereas silos are typically placed in the neonatal intensive care unit, which is a less sterile environment. This could result in a higher rate of line infections and sepsis in patients receiving a silo. A higher rate of infections could delay the onset of intestinal function and have a deleterious effect on the neonatal liver, as was reported in patients treated with a preformed silo in Bradnock and colleagues’ study.
Future research should also investigate how the area around the silo should be dressed—how often and what type of dressing; what the bacterial counts are at the defect, whether they increase over time, and if the species change with antibiotic pressure; and whether the length of time the silo is in place correlates with the outcome.
Future research may show that management with a preformed silo carries certain immutable risks that are not associated with primary fascial closure. If that proves to be true, surgeons will need to ask themselves whether they have done everything possible to achieve primary closure before committing a patient to placement of a preformed silo.
Cite this as: BMJ 2011;343:d7124
Competing interests: The author has completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declares: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Provenance and peer review: Commissioned; not externally peer reviewed.