Is pneumoperitoneum an absolute indication

for surgery in necrotizing enterocolitis?

Vijai D. Upadhyaya, A. N. Gangopadhyay, Anand Pandey, Ashish Upadhyaya,

T. Vittal Mohan, S. C. Gopal, D. K. Gupta

Varanasi, India

Author Affiliations: Department of Pediatric Surgery, IMS, BHU, Varanasi, India (Upadhyaya VD, Gangopadhyay AN, Pandey A, Upadhyaya A, Moahan TV, Gopal SC, Gupta DK)

Corresponding Author: Vijai D. Upadhyaya, Department of Pediatric Surgery, IMS, BHU, Varanasi, 221005, India (Tel: +91-0542-2309275; Email: upadhyayavj@rediffmail.com)

Background: Necrotizing enterocolitis (NEC) is the most common gastrointestinal medical/surgical emergency in neonates. Non-operative support is needed in 70% of NEC cases, and surgical intervention in the rest 30%. Historically, pneumoperitoneum has been considered as an absolute indication for laparotomy. In the present study we emphasize that pneumoperitoneum is not an absolute indication for exploratory laparotomy in NEC cases. 

Methods: We prospectively studied 58 patients with severe NEC having pneumoperitoneum on abdominal X-ray in the last 5 years. At the time of admission, the patients were given intravenous fluid, total parental nutrition, blood transfusion and broad spectrum antibiotics followed by abdominal tapping (paracentesis). All the patients with pneumoperitoneum were closely monitored for 48 hours if abdominal tapping was repeated. When the disease seemed to worsen clinically, radiologically and laboratorially, the patient was subjected to exploratory laparotomy.

Results: Of the 58 patients, 40 were treated conservatively whereas 18 underwent surgical intervention. The overall mortality in the present study was 12.1%, including 5% of the patients managed conservatively and 27% of the patients undergoing surgery.

Conclusions: Pneumoperitoneum is not an absolute indication for surgery in cases of neonatal NEC. Most of the patients can be treated conservatively.

Key words: necrotizing enterocolitis; neonates; pneumoperitoneum; surgery

                   World J Pediatr 2008;4(1):41-44

Introduction

Necrotizing enterocolitis (NEC) is an inflammatory gastrointestinal disease of unknown etiology that primarily affects the preterm neonates or sick newborns.^[1] It is characterized by intestinal necrosis with an incidence of 0.3-2.4 per 1000 live births and is the most common gastrointestinal emergency in neonates.^[2] NEC is present in 6% of very low birth weight (<1500 g) and 8% of extremely low birth weight (ELBW; <1000 g) infants.^[3] The exact cause of NEC is unclear but it is believed that an ischemic insult damages the bowel lining so that mucus is not produced, leaving the bowel susceptible to bacterial invasion. Infants may present with ileus manifested by abdominal distention, bilious gastric residuals (after feedings) that may progress to bile emesis and gross or microscopic blood in the stools. Sepsis may be manifested by lethargy, temperature instability, increased apneic spells, and metabolic acidosis. Certain newborns are at a particular risk like premature infants, those with amnionitis caused by prolonged rupture of membranes, with asphyxia at birth, fed with hyperosmolar formula, and those requiring exchange transfusion.^[4] Commonly patients with NEC have involvement of the terminal ileum followed by colon and proximal bowel.^[4,5] Most of these patients respond to conservative treatment and only one-third patients require surgical intervention. It is important to differentiate NEC from isolated intestinal perforation (IP),^[6-8] which is less common and affects about 2% of ELBW infants. NEC carries a high mortality rate^[9-11] and is responsible for 50% of the mortality^[12] in ELBW babies who are treated surgically. This study was conducted to show whether pneumoperitoneum in NEC cases is an absolute indication for surgical treatment.

Methods

This prospective study was undertaken in the Department of Pediatric Surgery, University Hospital, Institute of Medical Sciences, Banaras Hindu University, Varanasi India from January 2000 to December 2005. A total of 58 consecutive clinically suspected neonates with severe NEC associated with pneumoperitoneum (evident on plain X-ray either erect or lateral decubitus positions) were studied. The suspected cases of NEC without pneumoperitoneum were excluded. The study was approved by the Ethical Committee of the University and informed consent was obtained from the parents. Seventy-two percent of the patients were referred from medical neonatal intensive care unit (NICU) and the rest 28% were directly admitted to the neonatal surgical ICU. On admission, intravenous fluid and broad spectrum antibiotics were prescribed (ceftazidime, metrogyl and amikacin). All the patients were subjected to abdominal X-ray at erect and lateral decubitus positions, routine blood investigation, complete blood test, analysis of serum electrolytes, arterial blood gas, blood culture and renal function tests. Abdominal girth, erythema of anterior abdominal wall, along with other clinical parameters such as respiratory rate, heart rate, temperature, capillary filling time, SaO2 and blood pressure were monitored. All these patients with pneumoperitoneum were subjected to abdominal tapping (paracentesis) using a No. 20 French cannula and the aspirate was sent for culture and sensitivity test. All patients were assessed clinically by improvement of vital parameters, abdominal girth and erythema of the anterior abdominal wall, biochemical or hematological parameters, and serial abdominal X-rays (decrease in diameter of bowel and/or number of air fluid level, and whether pneumoperitoneum was resolved or not). If pneumoperitoneum was evident after 24 hours of the 1st tapping, repeated abdominal tapping was done. When pneumoperitoneum was even evident after the 2nd abdominal tapping or if there was any deterioration in clinical or investigation parameters, the patients were subjected to surgical intervention, usually 24 hours after the 2nd tapping. The patients were followed up at an interval of 4 months for 1 year and then an interval of 6 months for 3 years.

Results

In the present study, 49 patients were premature and 9 were full-term neonates (Table 1). Their mean weight was 1674 g (range 950-3000 g). All of them suffered from severe NEC with radiological evidence of pneumoperitoneum with or without pneumatosis intestinalis and fixed loop. The complaints and clinical manifestations of the patients are summarized in Table 2. In 87.9% (51/58) of the patients, blood biochemistry was abnormal but later was corrected by intravenous fluid. In 21 patients with positive peritoneal fluid culture results, 17 (80.9%) were reported to have Gram-negative bacterial growth. Of the 58 patients in whom abdominal tapping was done as an initial treatment, 21 improved clinically and required no further surgical intervention, in the rest 37 patients with repeated abdominal tapping 19 patients responded well and 18 patients required surgical intervention because they did not improve clinically and/or radiologically after two trails of abdominal tapping or the clinical deterioration was suspected. All these patients on exploration had massive NEC, which required bowel resection combined with colostomy or ileostomy. Of the 18 patients undergoing surgical intervention, 16 were premature and 2 were full-term. The mean hospital stay of the patients treated conservatively was 16 days, whereas that of the the patients who required surgical treatment was 31 days. The overall mortality was 12.1% in the total 58 patients, including 2 of the 40 patients (5%) managed conservatively and 5 of the 18 patients (27%) requiring surgery (Table 3). Of the 7 deaths, 5 occurred in the patients requiring surgical intervention. During follow up, 5 patients managed conservatively developed intestinal stricture, none of the patients treated surgically developed intestinal stricture.

Discussion

NEC, one of the lethal diseases, accounts for 15% of deaths in premature infants weighing less than 1500 g. Two-thirds of patients with NEC respond well to conservative treatment, whereas one-third of patients required surgical treatment. Medical treatment of NEC is dependent on orogastric decompression, parenteral antibiotics, and fluid electrolyte acid base normalization with or without parenteral nutrition. Options for surgical treatment include (a) peritoneal drainage^[13] when the patient is very sick or (b) laparotomy with definitive surgery when the condition of the patient is stable. Few studies recommend peritoneal drainage as an initial treatment (termed as primary peritoneal drainage, PPD) followed by surgery when the condition of the patient is stable,^[13] whereas others suggest that PPD may serve as a definitive therapy.^[14,15] Most studies on the outcome of PPD and laparotomy showed similar survival rates.^[16] Moss et al^[17] stated that the type of operations for perforated NEC does not influence the survival rate in preterm infants.

The absolute indication for surgery in NEC is bowel perforation, characterized by either pneumoperitoneum^[4,9,18] or positive  paracentesis^[2,19-21] because occult perforation can be found in up to 50% of patients.^[15] Other indications for surgery are signs of peritonitis, absent bowel sounds with diffuse guarding and tenderness, erythema and edema of the abdominal wall,^[22] clinical deterioration,^[20] persistent abdominal tenderness,^[22] persistently dilated loop^[23] and gasless abdomen with ascites on abdominal radiograph.^[21,22] The present study was conducted to investigate whether pneumoperitoneum is an absolute indication for surgery in cases of NEC.

Spontaneous intestinal perforation (SIP),^[24-26] which mimics NEC, can be distinguished from NEC by lack of systemic involvement, absence of other clinical signs common to bowel perforation, lack of pneumatosis intestinalis, its earlier onset in infants of smaller birth weight, and extreme prematurity. Focal intestinal perforation^[27] seen in a few premature infants of low birth weight is similar to SIP in appearance. In the present series, all patients had two or more signs of severe NEC according to Bell's classification.^[28]

About 65.5% of the patients recovered after abdominal tapping and supportive treatment, whereas 31.0% required exploratory laparotomy. A mortality of 5% was observed in the patients who responded to conservative treatment but the rate was 27% in patients who underwent surgical intervention. The difference was of no statistical significance. Goyal et al^[29] and Sharma et al^[30] reported the similar results.

In conclusion, pneumoperitoneum seems not to be an absolute indication for surgical intervention in cases of NEC. Initial abdominal tapping (paracentesis) may be effective and safe in patients with NEC with clinical and radiological evidence of pneumoperitoneum.

Funding: None.

Ethical approval: The study was approved by the Ethical Board of Banaras Hindu University and valid written informed consent was obtained from the parents.

Competing interest: None.

Contributors: Upadhyaya VD, Pandey A and Moahan TV contributed to the manuscript construction. Gangopadhyay AN, Gopal SC and Gupta DK helped in manuscript design and discussion, and Upadhyaya A helped in statistical analysis.

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Received June 27, 2007 Accepted after revision November 25, 2007