Does a laparotomy provide the best outcome for preterm infants with a
median gestational age of <30 weeks with surgical necrotising enterocolitis?
James Hackett
Abstract
Aims: This literature review aims to analyse the safety and effectiveness of laparotomy surgery compared
with other interventions in the treatment of surgical necrotising enterocolitis in preterm infants with a
median gestational age of <30 weeks.
Methods: A literature search was carried out to find relevant academic papers researching the surgical
treatment of necrotising enterocolitis, specifically the outcomes of laparotomy surgery. The online
databases Scopus, PubMed and DISCOVER were used to undertake the literature search.
Results: Four papers were analysed, revealing that a substantial number of neonates suffering from
necrotising enterocolitis require a surgical intervention: the two leading procedures being peritoneal
drainage or laparotomy. Laparotomy was associated with lower mortality and better outcomes post operatively. Peritoneal drain is used on patients who are too unstable for surgery, possibly explaining why
it is associated with higher mortality.
Conclusion: Though medical management is favourable, surgery is often unavoidable due to the fast
progression of the disease with non-specific signs and symptoms. There is good evidence to show that
laparotomy provides the best surgical outcome compared with peritoneal drain, however the evidence is
not strong enough to suggest that PD should be made redundant in the treatment of NEC. Bell’s staging
can provide some guidance toward surgical decision making, but a clinically standardised practice
guideline would be beneficial.
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Introduction and Background
Overview of foetal gut development
The embryological development of the gut takes place between days 21-50 of gestation and begins when the yolk
sac is drawn into the embryo as endodermal germ layers fold laterally and cephalo caudally.1 This incorporates
the endodermal germ layer and lateral plate mesoderm into the embryo, forming the primitive gut tube. 2 The
primitive gut tube can be divided into three regions by its attachment to the yolk sac and blood supply. 1 The
foregut develops into the pharynx, oesophagus, stomach and first two sections of the duodenum and is supplied
by the coeliac artery, the midgut comprises the remainder of the duodenum, the small and large bowel, up to the
proximal two-thirds of the transverse colon and is supplied by the superior mesenteric artery and the hindgut
comprises the remainder of the large bowel and upper anal canal, and is supplied by the inferior mesenteric artery. 1
The lower foregut is attached to the abdominal wall anteriorly by the ventral mesogastrium and posteriorly by the
dorsal mesogastrium.1
Rapid growth of the midgut in week 6 causes some organs to herniate through th e umbilical cord, however due to
abdominal growth the midgut normally re-enters the abdomen in week 10, between weeks 10-13 most digestive
structures are fully formed and immaturely functioning. 1
What is necrotising enterocolitis?
Necrotising enterocolitis (NEC) is a condition affecting low birth weight, preterm neonates, typically between 7
and 14 days of life.3 It is characterised by coagulative necrosis of varying thickness in the immature gut wall
which is associated with intestinal ischaemia and bacterial colonisation. 4,5 The condition was first described in
1888 by Austrian pathologist Richard Paltauf, however the term NEC was first used to describe the condition in
1953 by Schmid and Quaiser.4 Since then there has been a steady increase in the incidence of NEC attributed to
the increasing number of premature babies successfully delivered by caesarean section, together with the
advancement of neonatal care, providing lifesaving interventions such as surfactant therapy, enabling preterm
infants to survive what were previously fatal conditions. 4 As susceptibility to NEC appears to be inversely related
to gestational age, surviving the premature birth makes the neonates highly susceptible to developing NEC. 3,4
Despite the condition being described more than a century ago, the aetiology of the condition is still uncertain, as
the cellular basis of the disease remains poorly understood, however key risk factors have been identified. 3,4,6 The
most important risk factor in the development of NEC appears to be prematurity, as the naïve physiology of
preterm neonates makes them more sensitive to changes in microbiota and gut vasculature, which can lead to
bacterial colonisation and ischaemia respectively. 7
Other primary risk factors include intrauterine growth restriction (resulting in low birth weight) and the
introduction of enteral feeding, however there seems to be no one individual factor precipitating NEC. 4,6
Diagnosing NEC
NEC can be difficult to diagnose clinically as it often presents with non-specific signs and symptoms such as
abdominal distension, feeding intolerance, bilious vomiting and haematochezia, with sudden progression to
perforation of the bowel and death in severe cases. 6 The main diagnostic feature of NEC is the radiological sign
known as pneumatosis intestinalis which shows air tracking in the bowel wall on abdominal X-ray and is thought
to indicate bacterial fermentation of intraluminal substrates. 3,6
Bell’s staging (table 1) provides a set of criteria to give a definite diagnos is of NEC and indicate the severity of
the condition which is useful in the decision making of whether or not the NEC needs to be managed surgically. 8
Treatment/Management of NEC
Not surprisingly, medical management of NEC has the best outcome for neonates and is the mainstay option;
treatment involves the administration of broad-spectrum antibiotics along with the cessation of enteral feeds.8
However when the complications of NEC fail to be managed medically, surgical intervention is inevitable. 8
According to a study by Srinivasjois et al the need for surgery in diagnosed NEC is extremely high in preterm
neonates with 88% of the study participants at Bell’s stage II requiring surgery.10 Although there is a high
incidence of preterm infants requiring surgery for NEC, the optimal initial surgical management is still not
definitively clear, as the need for any surgical intervention for NEC is associated with increased mortality. 11,12
One of the main ways to manage surgical NEC is with a laparotomy, a surgical incision to open the abdomen in
order to remove the necrotised bowel and preserve as much intestine as possible depending on the severity of
which results in anastomosis or stoma.8,12 Although medical treatment is the favourable option treating NEC,
surgical management, especially in preterm neonates, is unavoidable.8,10 Therefore, further research is needed to
establish the safest and most effective surgical management of NEC.
Table 1: Modified Bell’s S taging Criteria. Taken from Hall et al.9
S tage
Description
S ystemic
signs
I
IIA
IIB
IIIA
IIIB
S uspected NEC
Mild NEC
Moderate NEC
S evere NEC
S evere NEC
Temperature
instability, apnea,
bradycardia
Similar to stage I
M ild acidosis,
thrombocytopenia
Respiratory and
metabolic acidosis,
mechanical
ventilation,
Further
deterioration and
shock
hypotension, oliguria,
DIC
Intestinal
signs
Radiographic
signs
Increased gastric
residuals, mild
abdominal
distension, occult
blood in the stool
M arked abdominal
distension ±
Abdominal wall
edema and
tenderness ±
tenderness, absent
bowel sounds, grossly
bloody stools
palpable mass
Normal or mild
ileus
Ileus, dilated bowel
loops, focal
pneumatosis
Extensive
pneumatosis, early
ascites ± PVG
Worsening wall
edema with erythema
and induration
Evidence of
perforation
Prominent ascites,
fixed bowel loop, no
free air
Pneumoperitoneum
Objectives
This literature review aims to analyse the safety and effectiveness of laparotomy surgery compared with other
interventions in the treatment of surgical NEC in preterm infants with a median gestational age of <30 weeks.
Methodology
The literature search was carried out using the online databases Scopus, PubMed and DISCOVER using the
keywords ‘surgical necrotising enterocolitis’ with a further search field containing the word ‘laparotomy’.
Results
Four papers were selected for review (table 2).
Table 2: Papers selected for review.
Paper no.
Author
Title of paper
1
Rakshasbhuvankar et al.
Peritoneal drainage versus laparotomy for perforated necrotising enterocolitis or
spontaneous intestinal perforation: A retrospective cohort study. 11
2
Wright et al.
The outcome of critically ill neonates undergoing laparotomy for necrotising
enterocolitis in the neonatal intensive care unit: a 10-year review.8
3
Rees et al.
Peritoneal drainage or laparotomy for neonatal bowel perforation? A randomized
controlled trial.13
4
Hull et al.
M ortality and management of surgical necrotizing enterocolitis in very low birth weight
neonates: a prospective cohort study 12
Paper one: Rakshasbhuvankar et al’s retrospective cohort study (January 2004 to February 2010) aimed to
compare the outcomes of preterm neonates with a gestational age of <30 weeks undergoing peritoneal drainage
(PD) versus laparotomy. 39 infants were involved in the study, with 19 receiving PD and 20 re ceiving laparotomy.
The study showed that the outcome of mortality before discharge was significantly worse in the PD group, as was
the likelihood of a hospital stay >3 months (p=0.038).11
Paper two: Wright et al’s study aimed to retrospectively evaluate the outcomes of neonates who underwent a
laparotomy between 2001 and 2011. Of patients who had laparotomies performed on the NICU, 67% died within
6.5 hours after surgery and a further 13% died after months in hospital. They note that laparotomies have a h igher
mortality rate when performed on the NICU arguing this may be because these patients are already too unstable
to be transferred to theatre therefore one would expect more complications .8
Paper three: Rees et al’s randomised control trial (RCT) aimed to investigate whether PD, compared with
laparotomy, improved the survival outcome of extremely low birth weight neonates with NEC and bowel
perforation. An international multicentre RCT was carried out between 2002 and 2006 in which 69 patients were
randomised (35 PD, 34 laparotomy); consent of one patient was later withdrawn. The survival rate was 18/35
(51.4%) for drain and 21/33 (63.6%) with laparotomy, in the PD group a delayed laparotomy was performed on
26/35 (74%) of the patients after a median of 2.5 days.13
Paper four: Hull et al’s paper prospectively evaluated 655 centres in the US to establish mortality benchmarks
in the treatment of surgical NEC with laparotomy vs. PD. There were 17,159 patients who were diagnosed with
NEC and of those patients 8,935 were operated on (mortality 35%), 6,131 (69%) received laparotomy only
(mortality 31%), 1,283 were given PD and a laparotomy (mortality 34%) and 1,521 had PD only (mortalit y
50%).12
Discussion
The optimal surgical management of NEC is still a controversial issue.14 This stems from the fact that two main
modalities are used to surgically manage NEC (PD and laparotomy), with various studies showing them to have
similar mortality outcomes.11 With no definitive research demonstrating which is best, surgeons and academics
continue to argue in favour of one or the other. 7,15
There are pros and cons to each of these surgical methods . For example, PD allows the removal of toxic effluents
from the peritoneal cavity under local anaesthetic, allowing the abdomen to decompress and hopefully facilitating
spontaneous healing of the intestine.11 PD also prevents the premature infant from being put under general
anaesthetic and then undergoing the physiological stress from the induced t rauma of laparotomy.7 However
drainage treatment does not remove the necrotic tissue and it is plain to see the complications involved with this,
such as chronic infection and sepsis, but also potential lifelong morbidity e.g. due to toxic cytokine action on the
CNS.11
In contrast laparotomy provides a hastier and more permanent intervention, with the objective of removing
gangrenous/perforated tissue whilst keeping intact as much viable intestine as possible. 7,11 Laparotomy is a high
risk procedure as it involves general anaesthetic and open surgery, and also carries a number of post-operative
risks such as parenteral nutrition and high stoma output resulting in fluid and electrolyte imbalance, stoma
retraction or prolapsed. Infants also encounter complications due to increased resting energy expenditure as a
result of the wound healing process.7
Rakshasbhuvankar et al’s data showed that PD had decidedly worse outcomes than those receiving laparotomy,
yet despite this PD was being performed on a regular basis due to clinician choice without being based on any
formal criteria.11 This highlights how clinicians may carry out the procedure they feel most comfortable
performing, rather than the procedure that is in the patients best interests. 13 This supports Wright et al’s suggestion
that more research is needed to distinguish the patients at highest risk of mortality and to create a prediction model
aiding surgical decision-making through the use of criteria to indicate what procedure would be in patients’ best
interests, rather than a ‘one size fits all’ surgical procedure. 8
Rees et al found that PD is ineffective both as a stabilising measure and as definitive treatment, however they
found that 95% of paediatric surgeons in the UK use PD as an option for surgical NEC. 13 A possible reason for
the popularity of PD, despite evidence showing its poor outco mes, is that it can be done at the patient’s bedside
and is not as technically demanding as laparotomy, nor is it as physiologically demanding on the patient. 13
Hull et al showed similar results: that PD was associated with a much higher mortality rate compared with
laparotomy with a number patient’s needing a laparotomy after undergoing PD anyway. 12 A point raised by
several papers is that PD is often used in the most premature and critically ill patients who are too unstable to be
moved to theatre,7 therefore it stands to reason that these patients would be associated with the highest rates of
mortality, meaning whether or not a laparotomy is used is of little consequence. This was shown by Wright et al
where laparotomy was performed on the NICU for patients who were too unstable to be moved to theatre, showing
that these patients had greater mortality rates despite the use of laparotomy.8
The data from the papers reviewed shows that laparotomy often provides the best outcome for surgical NEC;
however the data and results are not conclusive enough to prove this significantly, as there are many confounding
factors making it impossible to have one gold standard, definitive treatment for this condition.
Conclusion
Despite some evidence to show that laparotomy provides the best surgical outcome compared with PD, it is not
strong enough to suggest that PD should be made redundant in the treatment of NEC. Bell’s staging can provide
some guidance toward surgical decision making but the method and treatme nt ultimately remains at the treating
clinician’s discretion.
The literature suggests that the real problem stems from differing opinions on when and how to treat NEC
surgically: more research is needed to establish a prediction model to identify high risk patients and provide the
procedure that is in their best interests. From the literature reviewed it seems that laparotomy is a more definitive
surgical intervention compared with PD, as in various studies many patients undergoing PD required laparotomy
as well. Despite what a lot of the data proposes, more RCT evidence is needed to show definitively that laparotomy
provides the best outcome for preterm neonates with surgical NEC.
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