Open myelomeningocele (MMC) in neonates constitutes a neurosurgical emergency requiring early closure of the defect to prevent the sequelae of ascending infection, namely meningitis and further damage to the exposed neural tissue (Attenello et al, 2016; Beier et al, 2019; Mazzola et al, 2019). Children with a history of bacterial meningitis are at greater risk of reduced intellectual and cognitive function later in life (Grimwood et al, 2000). Following MMC repair and other lower spinal surgeries, neonates/infants require meticulous postoperative wound care to prevent wound dehiscence and infection, which requires prolonged hospital stay and further treatment including surgery.
Although wound dressings have been used since antiquity, there continues to be uncertainty about their efficacy in preventing surgical site infection in wounds healing by primary intention (Broughton et al, 2006; Dumville et al, 2016; Jones et al, 2017). In contemporary practice, surgical wound care can be divided broadly into exposed wound and application of contact dressings. The main dressing material types include foam, absorbent, film, silver-containing, hydrocolloid and antimicrobial dressings. Previous studies have been limited by the small sample size and risk of bias in terms of allocation concealment and outcome assessment, and have focused on wounds of clean surgery and potentially contaminated surgery (Dumville et al, 2016). Therefore, there is ongoing debate regarding which particular dressing material is more effective (Dumville et al, 2016).
There have been no studies reporting on wound management in open MMC or other lower spinal surgeries during infancy, and most clinical practice is currently non-evidence based. At the authors' institute, before the described technique was introduced, the main dressing type was dry gauze secured with an overlying adhesive dressing. Antimicrobial dressings were not routinely used because the authors considered that prevention of wound contamination in the first place was the most significant modifiable post-operative factor.
Among the many essential properties, one function of a dressing is to provide a physical barrier to contamination (Baranoski and Ayello, 2012). However, application of a waterproof occlusive dressing for lumbosacral wounds is challenging due to:
Despite best efforts, a single adhesive dressing does not reliably obliterate the space in the natal cleft (Figure 2). There is often a gap between the skin and the adhesive dressing along the cleft, which has an inverted ‘delta’-shaped cross-section (Δ). This creates a tunnel for loose stool to track rostrally towards the wound, increasing the risk of wound contamination. It also necessitates frequent dressing changes that further expose the wound to infective and physical insult.
This article describes the ‘transverse guard’ technique routinely used in the authors' unit which:
The authors also outline the comparative wound infection rates between newborns undergoing open MMC repair in whom the transverse guard dressing was used with newborns in whom the guard was not used.
Methods
Dressing technique
Following surgery, the dressing is applied using the technique outlined below:
This means that, if loose faecal material tracks rostrally into the natal cleft towards the ‘guard’, it is absorbed; it stains the rolled-up gauze, which serves as a colour indicator, in addition to its function a physical barrier to the contaminant (Figure 4c). It also directs the contaminant over the surface of the main dressing.
The transverse guard can be changed, as required, leaving the main dressing undisturbed.
The baby is nursed prone or lateral initially, as per standard practice.
Findings
The transverse guard was introduced in November 2017, so a retrospective review of all neonates who had undergone open MMC repair between March 2016 and May 2020 was performed. Operations beyond 3 days of life were excluded to allow uniform population comparison. The protocol of the authors' institute is to perform early open MMC repair within 72 hours of life, preferably within 48 hours, provided the neonates are stable for transfer from the maternity units and for general anaesthesia.
The following parameters were collected:
Rates of infection were compared between the two groups: that in whom conventional dressings were used with that in whom the technique described above was used.
Over the 42 months of the retrospective review, 31 neonates had undergone open MMC repair within 3 days of birth. The transverse guard dressing technique was used in 14 of these, and not used in the other 17. The number of babies undergoing further surgery for wound revision was 7% (1/14) in the transverse guard dressing group and 12% (2/17) in the non-transverse guard group. All of them had clinical signs and/or microbiological confirmation of infection.
There were no significant differences between the groups for age and predisposing factors (Table 1).
| Transverse-guard dressing group | Non-transverse guard dressing group | |
|---|---|---|
| Number of patients | 14 | 17 |
| Male-to-female ratio | 1:0.75 | 1:1.4 |
| Mean age at myelomeningocele repair | 1.3 days | 1.2 days |
| Microorganism | Candida albicans | Escherichia coli (extended spectrum beta lactamase), Staphylococcus aureus |
| Wound complications requiring revision surgery | 1 (7%) | 2 (12%) |
Discussion
Wound care following repair of open MMC and other lower spinal surgery in infants presents a unique challenge. The infection rate following MMC repair is estimated to be between 7% and 12% (Beier et al, 2019). Although there is lack of robust evidence in the setting of spinal surgery during infancy, it is commonly accepted that lumbosacral wounds in close proximity to the perianal region are at high risk of infection from faecal contamination (Agag et al, 2008). This notion is supported by the reduced soft tissue infection in patients with better bowel management (Echols et al, 2007). Recent molecular-based studies have shown that multiple bacterial species are present in faeces as early as birth (Milani et al, 2017; de Muinck and Trosvik, 2018).
The transverse guard forms an additional physical barrier between the perianal area and the main wound. Even if loose faecal material tracks up the natal cleft, it is absorbed by the guard before it can reach the main wound dressing. The advantage of this dressing is that the faecal material does not actually reach the wound due to the overlapping film dressing arrangement shown in Figure 3. At most, it reaches the outside of the main wound dressing. Figure 4c demonstrates the effectiveness of this function. In such situations, only the guard, rather than the entire main dressing, requires changing. Thus, the transverse guard is effective at addressing the two main challenges of lower spinal wound care in infants; namely, it reduces:
The added advantages of this technique are its simplicity and its ease of application.
The authors' experience suggests that the use of the transverse guard results in a reduced rate of wound complication/infection that would require further surgery compared with the non-transverse guard group. However, the number of cases is too small to allow for a definitive conclusion on the rate of infection in the two groups and is not sufficient to demonstrate a significant difference. In biological terms, even if the transverse guard does not reduce the wound infection rate, it should not increase it. Regardless of efficacy, at the very least, the use of the guard reduces the frequency of dressing changes.
Limitations
Although the transverse guard, which acts as a physical barrier, reduces contamination of the main wound and helps reduce the frequency of dressing changes, larger studies are needed to ascertain whether the ensuing reduced contamination is associated with a reduction in the rate of wound infections.
Conclusion
Wound care following lumbosacral spinal surgery in infants, especially the repair of open MMC in the newborn, is challenging. The transverse guard technique described in this article is a simple, cheap and effective method of minimising spinal wound contamination, which has the additional benefit of reducing the frequency of main wound dressing changes.