Laurens Schattenkerk

70 Chapter 3 Discussion This systematic review pooled the reported proportions on different types of ileus following abdominal surgery for birth defects in infants. These proportions can be seen as an approximation of the incidences of these complications. According to our reported approximation, these incidences were 7% for paralytic ileus, 6% for adhesive small bowel obstruction, 3% for anastomotic stenosis within one month after surgery and 4% after one month. Within the different birth defects there is a large variation in the occurrence and the spread of these forms of ileus. Although risk factor identification is beyond the scope of this review, the available literature gives some suggestions why these diseases seem to be more at risk. Out of all diseases paralytic ileus was most common in gastroschisis patients (14%). In these patients, a defect of the abdominal wall leads to extrusion of abdominal content antenatally. Postnatally, this content is reduced intra-abdominally either by primary closure or temporally use of silo and delayed closure. During both procedures the intestine is manipulated severely, which is known to increase the incidence and duration of paralytic ileus in adults [203]. Adhesions, which cause SBO, have long been accepted as a partly inevitable consequence of surgery. They occur as part of the natural healing process. It is hard to define the clinical significance of adhesions, since most are asymptomatic, but when they lead to small bowel obstruction, they can be fatal with mortality rates in children between 2-15% [278, 309, 310]. Recently duration of surgery and staged procedures have been identified as risk factors for SBO [222, 309, 311]. Our reported pooled incidence of 6% is comparable to most recent large (n≥100) individual cohort studies reporting on abdominal surgery in infants. These studies report an incidence of SBO between 6-10% [222, 312]. It is important to acknowledge that this review entails an aggregated incidence for birth defects only. Acquired diseases such as necrotizing enterocolitis, which seems to be at high risk with a reported incidence of SBO between 25-64%, are therefore not included [222, 309]. We found that patients with a malrotation, small intestinal atresia or gastroschisis were relatively most at risk of SBO. This is in concordance with previous studies [222, 278, 309-312]. We divided anastomotic stenosis into two groups based on reported occurrence within or after one month of surgery since early onset is suggested to be caused by technical error or tissue oedema, whereas a delayed onset and stricture formation is related to chronic inflammation in time leading to anastomotic scarring [18].

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