Necrotizing enterocolitis (NEC) is one of the most common reasons for a neonatal surgical emergency. The increased survival rate of premature babies due to advances made in neonatal intensive care has led to an increase in the incidence of NEC 1. However, despite the advancement in neonatal care, mortality due to NEC remains high 1,2. The following study describes our two and half years of experience in managing NEC at a tertiary care hospital in Oman. The aim of the study was to determine the incidence and mortality rate due to NEC at our centre and also to compare various parameters between medically and surgically managed patients.
Patients and methods
Between January 2010 and May 2012, 1139 neonates were admitted at our neonatal intensive care unit (NICU), out of whom 26 were diagnosed with NEC. The data of all these children were collected from the hospital information system and analysed. Parameters studied included sex difference, gestational age at birth, birth weight, maternal risk factors, patient risk factors, day of life when feeding was started, type of feed, day of life when signs of NEC appeared, any antecedent associations, clinical features, radiological features, blood investigations, requirement of surgery, surgical findings and outcome. A comparison of all these parameters between the patients managed nonsurgically and those managed surgically was also made. Statistical analysis was performed using statistical software SPSS V17 (IBM, Chicago, Illinois, USA). The study was approved by the hospital ethics committee.
A total of 1139 patients were admitted to the NICU during the study period, out of whom 514 (45.1%) weighed less than 2500 g at birth and 49 (4.3%) died during this study period. Twenty-six patients with NEC, including 14 male and 12 female neonates, were studied. Incidence of NEC during the study period was 2.28% of total admissions. Mean gestational age at birth was 29.8±3.7 weeks (range: 25–38 weeks). The mean birth weight was 1348.4±774.1 g (range: 610–3900 g). The distribution of NEC patients as per gestational age and birth weight is shown in Figs 1 and 2, respectively. The incidence of NEC in patients with birth weight less than 2500 g was 4.47%.
Maternal risk factors included pre-eclampsia in four mothers, threatened abortion in three, absent end diastolic blood flow on Doppler ultrasonography in three and premature rupture of membranes in one mother. Twenty (76.9%) neonates had respiratory distress syndrome because of prematurity; 19 (73.1%) were mechanically ventilated; a central venous catheter was inserted in 19 (73.1%) patients; 14 (53.8%) patients required inotrophic support; there was documented evidence of infection in 12 (46.1%) patients; 18 (69.2%) received blood transfusion (exchange transfusion in two); and 11 (42.3%) patients had patent ductus arteriosus as evident on echocardiography.
Enteral feeds were started from day 1 and continued up to day 7 of life. In 15 out of 26 (57.7%) patients, feeds were started on the second day of life. Seven (26.9%) babies were started on formula feed as breastmilk was not available for them. The average number of days of start of symptoms after admission was 17.5 days (range: 3–50 days). Feeds were changed in six babies, seven babies had features of sepsis and 10 received blood transfusion as preceding events before development of NEC.
Clinical features included abdominal distension, increased nasogastric tube aspirates, visible bowel loops and blood in stools. Abdominal radiographs showed distended small bowel loops in 10 patients, fixed loop on serial radiographs in four patients, pneumatosis intestinalis in six patients, pneumoperitoneum in five patients and ascitis in one patient.
The blood culture of two patients revealed the presence of coagulase-negative staphylococci (CONS); in two patients it showed Pseudomonas aeroginosa (with CONS in one), in one patient Escherichia coli and CONS and in another patient it showed Klebsiella pneumoniae; it was sterile in the rest of the patients. Occult blood in stools was positive for nine patients.
The mean duration for which patients were kept nil per oral was 9.5 days (range: 3–24 days). Antibiotics were given to all the patients for a mean duration of 11.2 days (range: 3–21 days). Total parental nutrition was given to 25 (96.1%) patients.
Laparotomy was performed in 11 (42.3%) patients. Five patients had pneumoperitoneum. Surgical findings and outcomes are shown in Table 1. The comparison of various study parameters in patients managed conservatively and by laparotomy is shown in Table 2. It can be seen that, except for raised C-reactive protein (CRP) and thrombocytopaenia, all other parameters were similar in both the groups. The mean platelet count in patients managed surgically was significantly lower than that in patients managed medically (106.5 vs. 218.1 cells/µl of blood; P=0.0204). Similarly the mean CRP level was also higher in patients managed surgically than in those managed medically (104 vs. 54 mg%; P=0.0414).
Five (19.2%) patients died during the course of their treatment and 10.2% of the total deaths in the NICU during the study period were due to NEC.
The reported incidence of NEC in premature and preterm neonates is 3–7% 3,4. Mortality rates from NEC are high, ranging from 15 to 30% 3–5. Cases of NEC are usually sporadic, although there have been reports of outbreaks. These outbreaks occur more commonly in crowded nurseries. The incidence and mortality rates (2.28 and 10.2%, respectively) of NECs at our centre are consistent with those reported worldwide.
Prematurity and low birth weight are the two most consistent features associated with the development of NEC 6. Twenty-four patients (92.3%) in the present study were premature, and 23 (88.5%) weighed less than 2500 g at birth. Another important association with NEC is the starting of enteral feeds 7. Increased incidence of NEC in the babies given formula feeds has also been well documented in the literature 8. In the present study 26.9% of babies received formula feeds before the onset of signs of NEC.
Many cases of NEC are managed medically, but roughly 20–40% of patients require surgical intervention 9. Some of these cases are due to progression of disease during medical treatment, but many infants present acutely with severe disease requiring immediate operation.
A previous study from Oman performed by Samuel and Sajwany 10 reported 31 children aged between 48 days and 24 months who were initially treated for gastroenteritis, which later developed complications of NEC. The main initial complaints in these patients were diarrhoea and vomiting. Almost 88% of their patients had severe sepsis complicated by hypovolaemic shock and hypotension. All of their patients had bleeding in their rectum, abdominal distension and pneumatosis intestinalis 10. Twelve patients (38.7%) in their study were managed surgically. Only two of their surgically managed patients survived, whereas only seven survived in the medically managed group. Thus, the total mortality in their series was 70.9%, which is very high compared with the 19.2% described in the present study.
Nair et al.11 reported four neonates (birth weight: 810–1030 g) who developed NEC following an eye examination after topical instillation of mydriatics. However, they could not establish any casual relationship between the use of eye drops and the development of NEC. They suggested toxic effects of the eye drops either by atropine-like activity of cyclopentolate on the gut or by the sympathomimetic action of phenylephrine causing splanchnic vasoconstriction. In the present study, 22 (84.6%) patients underwent an eye examination to rule out retinopathy of prematurity.
In our study thrombocytopaenia and high CRP (at the time of appearance of the first clinical sign) were found to be the two factors positively associated in patients who required surgical management. There was no significant difference between gestational age, birth weight, presence of sepsis, presence of a central venous line, respiratory distress syndrome, need for mechanical ventilation, blood transfusion, inotrophic support, leucocyte count and positive blood culture in patients managed conservatively and surgically. A low platelet count was a positive finding in patients who required surgical management (P<0.05). Kenton et al.12 had reported that a low platelet count is an important marker for gangrene of the bowel and it can be used as a direct indicator of the requirement for surgical intervention. Although our study showed the same, we were not able to ascertain the cutoff value of platelets indicating the need for surgery because of the small sample size.
Elevated CRP level was another important marker predicting the need for surgical management in the present study. Pourcyrous et al.13 suggested that elevated CRP level can be used to differentiate paralytic ileus from NEC. Although CRP is a nonspecific marker of acute inflammatory states its elevated value can be used to identify patients with NEC who may require surgery.
The important limitation of our study is the small sample size, as the study was conducted in a recently established neonatal surgical centre in Oman.
We finally conclude that the incidence and mortality rates of NEC in Oman are similar to those reported in the literature. A low platelet count and high CRP levels at the time of onset of clinical features are the two important factors that can be used to predict the need for urgent surgical management in otherwise conservatively managed patients.
Conflicts of interest
There are no conflicts of interest.
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