Idiopathic pneumoperitoneum diagnosed and treated differently in preterm infants: two case reports
Article information
Abstract
Pneumoperitoneum that develops in the absence of a perforated abdominal viscus and does not require laparotomy is considered to be idiopathic. Differentiating between idiopathic pneumoperitoneum and highly lethal perforation due to necrotizing enterocolitis in preterm infants is important. Herein, we report two cases of idiopathic pneumoperitoneum in preterm infants who underwent exploratory laparotomy and conservative treatment, respectively. The first patient was born at 32+5 weeks of gestation and developed pneumoperitoneum on day 7 of life. The patient underwent exploratory laparotomy and was diagnosed with idiopathic pneumoperitoneum after surgery. The second patient was born at 30 weeks of gestation. He developed pneumoperitoneum on the eighth day of life. Idiopathic pneumoperitoneum was suspected, and the patient was treated conservatively without laparotomy. Based on our awareness and experience of the first case of idiopathic pneumoperitoneum, we were able to treat the second patient conservatively. These cases will be helpful for diagnosing and treating pneumoperitoneum in preterm infants.
Introduction
Pneumoperitoneum is defined as the presence of free gas within the peritoneal cavity and is caused by perforation of the gastrointestinal tract in the majority of cases (>90%). However, approximately 10% of cases that result from a benign source and do not involve viscus perforation, do not require surgical intervention [1,2]. These cases of idiopathic pneumoperitoneum (IPP) develop in the absence of intestinal perforation and have been termed nonsurgical, spontaneous, asymptomatic, unexplained, or benign pneumoperitoneum in different reports [3,4]. IPP is a rare condition with only a few case reports [5,6]. The exact mechanism of air entry into the peritoneum remains unknown. However, the most likely mechanism is air tracking from the ruptured alveoli along the walls of the adjacent vessels into the mediastinum [4,7]. We present herein two cases of IPP in preterm infants who were successfully treated.
Case
Ethical statements: This report was approved by the Pusan National University School of Medicine Research Committee (IRB No. 2210-003-120). Written informed consent was obtained from the patients’ parents to publish this case report.
1. Case 1
A 2,310 g male baby was born at 32+5 weeks of gestation by vaginal delivery. His mother was a 27-year-old primigravida who was referred to our hospital at 28 weeks of gestation because of preterm labor. This patient was the first baby of a healthy Korean parent. The patient had no family history of congenital anomalies. The patient had Apgar scores of 6 and 8 at 1 and 5 minutes, respectively. On admission to neonatal intensive care unit, his vital signs showed a heart rate of 150 beats per minute and 95% of saturation of percutaneous oxygen (SpO2). However, the infant experienced respiratory difficulties. The patient was intubated and mechanically ventilated. Owing to deterioration of his respiratory symptoms, he underwent surfactant replacement therapy. The patient was placed on synchronized intermittent mandatory ventilation with a peak inspiratory pressure of 16 cm H2O, peak expiratory end pressure 5 cm H2O, respiratory rate of 30 breaths per minute, and 30% fraction of inspired oxygen (FiO2). Enteral feeding commenced on the first day of life and was gradually increased.
On day 7 of life, the abdominal distension worsened. Plain abdominal radiography revealed a pneumoperitoneum (Fig. 1). Chest radiography revealed no pneumothorax, pneumomediastinum, or interstitial emphysema. Vital signs including oxygen saturation and temperature were normal except for lower blood pressure than the previous days and the results of laboratory tests including white blood cell count and C-reactive protein (CRP) were normal. However, the patient often showed abdominal bowel loops and feeding intolerance. And the patient had umbilical catheters for the first 3 days of life. Therefore, necrotizing enterocolitis (NEC) could not be excluded. The patient underwent urgent bedside exploratory laparotomy to evaluate intestinal perforation due to NEC or spontaneous intestinal perforation. An exploratory laparotomy revealed no visceral perforation or meconium in the abdominal cavity. The patient was diagnosed with IPP. Two days after surgery, the patient was extubated and enteral feeding was recommended. On day 17, the enteral feeding was increased to 120 mL/kg/day. The remaining course of his hospital stay was uneventful, and he was discharged at 28 days of life (36+5 weeks of postmenstrual age).
Plain abdominal X-ray showing free peritoneal air occupying the entire abdomen in patient 1. (A) Supine view. (B) Lateral view.
2. Case 2
A 1,480 g male baby was born at 30 weeks of gestation by cesarean section. He was the 2nd of a set of twins born to a 35-year-old multigravida who was referred to our hospital at 28 weeks of gestation because of preterm labor. The patient had no family history of congenital anomalies. The patient had Apgar scores of 4 and 6 at 1 and 5 minutes, respectively. On admission to neonatal intensive care unit, his vital signs showed a heart rate of 120 beats per minute and 95% of SpO2. After birth, the infant experienced respiratory difficulties. Although the patient underwent surfactant therapy for respiratory distress syndrome, his respiratory symptoms deteriorated. Eventually, he required high-frequency ventilatory support and inhaled nitric oxide. The ventilator settings were: amplitude 30, frequency 12 Hz, mean airway pressure 17 mmHg, and FiO2 60%. Inhaled nitric oxide was administered at 20 ppm. On day 5 of life, inhaled nitric oxide was stopped, and the ventilator settings were gradually decreased. Subsequently, enteral feeding was commenced. One day later, the patient developed an abdominal distension. Plain abdominal radiography revealed ileus; therefore, enteral feeding was discontinued.
On day 8 of life, the abdominal distension worsened. Plain abdominal radiography revealed pneumoperitoneum (Fig. 2). Chest radiography revealed no features of air leak, except for right upper lobe atelectasis. However, his vital signs including oxygen saturation and blood pressure were normal and the results of laboratory tests including CRP were all normal. There was no any evidence of NEC including abdominal tenderness, gastrointestinal bleeding, and fever. We suspected him of IPP. Paracentesis was performed because of the severe abdominal distension. However, no liquid content suggestive of intestinal perforation was observed.
Plain abdominal X-ray showing free air in patient 2 (A, B: day of pneumoperitoneum onset). (C) Three days after onset, a lateral abdominal X-ray showed decreased pneumoperitoneum. (D) Four days after onset, pneumoperitoneum worsened after feeding. (E) Eight days after onset, the free air had nearly resolved.
The patient was diagnosed with IPP. On day 11 of life, enteral feeding was recommended because of improved pneumoperitoneum; however, the pneumoperitoneum worsened again after feeding. Therefore, paracentesis was performed again, which showed no evidence of bowel perforation. Subsequently, pneumoperitoneum resolved slowly and disappeared on day 15. Enteral feeding was also recommended on the same day. On day 18, the patient was extubated. After initiation of enteral feeding, the patient did not show the abdominal distension, visible bowel loop and inflammation or infection evidences on the results of his laboratory tests. Enteral feeding was proceeded successfully, and reached to 120 mL/kg/day on 24 days of life. He was transferred because of progressive intraventricular hemorrhage and post-hemorrhagic hydrocephalus at 1 month of age. After ventriculoperitoneal shunt at that hospital, he reached full enteral feeding uneventfully. He was discharged home on demand bottle feeding at 2 months of age.
Discussion
NEC, which requires surgical treatment, is a leading cause of pneumoperitoneum in preterm infants. By contrast, IPP requires conservative treatment and resolves within several days. Therefore, it is important to differentiate between IPP and highly lethal perforation caused by NEC in preterm infants [8]. Diagnosing IPP without exploratory laparotomy in preterm infants when a neonatologist encounters a case of pneumoperitoneum is difficult because of the high possibility of lethal perforation due to NEC. In fact, majority of reported Korean preterm cases of IPP involved exploratory laparotomies like our first case [9,10].
Our first patient showed ileus on X-ray, feeding intolerance and abdominal distension and had a history of umbilical catheterization. Therefore, we could not exclude NEC, although vital signs and laboratory tests were within normal range. Finally, he was diagnosed IPP after exploratory laparotomy. In our second case, we suspected IPP when the pneumoperitoneum appeared for the first time. Because there was no evidence of NEC and the patient showed stable vital signs including blood pressure. The patient had no history of umbilical catheterization contrary to our first case. Therefore, we decided to treat him conservatively.
However, conservative treatment is not easy because it is difficult to decide when enteral feeding should be commenced when the pneumoperitoneum persists for a long time. In our second patient, the pneumoperitoneum resolved within 8 days, which was the longest duration reported [3]. We attempted to feed the patient on day 3 of pneumoperitoneum but his condition worsened after feeding. Eventually, enteral feeding was recommended after resolution of pneumoperitoneum on day 8. Although enteral feeding was delayed, the second patient was successfully treated without general anesthesia or laparotomy.
Several reports have shown variations in the age of onset and duration of pneumoperitoneum among preterm infants treated conservatively [3,4]. Karaman et al. [4] reported a case of a preterm infant born at 30 weeks of gestation, in whom pneumoperitoneum developed on the third day of life and resolved within 2 days. Unfortunately, the patient died of sepsis at 33 days old. Duan et al. [3] reported six cases involving newborns, including one preterm infant, treated conservatively; they were aged between 4 and 25 days. The time to resolution of pneumoperitoneum was 3 to 8 days, which was longer than the 2 days reported by Karaman et al. More reports on feeding problems in cases of prolonged pneumoperitoneum are required for conservative treatment.
In the neonatal population, IPP occurs in 5.4% to 7.8% [11]. Although the cause of IPP remains unclear, the most likely cause of IPP is air tracking from the ruptured alveoli along the walls of the adjacent vessels into the mediastinum. However, there was no evidence of pneumothorax and pneumomediastinum in our two cases. Thus, mechanical ventilation and high intrathoracic pressure due to abdominal distension with concealed pulmonary interstitial emphysema were felt to be the cause. Majority of reported IPP cases were one of them, who was diagnosed after exploratory laparotomy or who had respiratory air leak syndrome [9,10]. Our second case is a rare case because the patient had no evidence of air leak syndrome and was very successfully treated conservatively. Based on our experience with the first case of IPP, we could treat the second patient conservatively.
In conclusion, we report two cases of IPP in preterm infants. One of them was misdiagnosed bowel perforation and performed exploratory laparotomy and the second one was successfully treated by conservative treatment. Our cases will help neonatologists diagnose and treat pneumoperitoneum in preterm infants. Neonatologists should be aware that IPP can occur in preterm infants on ventilator support. Furthermore, if a patient has mild clinical symptoms and stable vital signs and laboratory findings, IPP should be considered to avoid unnecessary surgery.
Notes
Conflicts of interest
No potential conflict of interest relevant to this article was reported.
Funding
This study was supported by a clinical research grant from the Pusan National University Hospital, 2023.
Author contributions
Conceptualization: KHP. Funding acquisition: KHP. Writing - original draft: SJP. Writing-review & editing: KHP. All authors read and approved the final manuscript.
Acknowledgements
We thank the parents of our patient for their cooperation and for providing their consent for publication.