PCI is a rare condition characterized by multilocular gas-filled cysts localized in the submucosa and subserosa of the gastrointestinal tract[
5,13-17]. The term “pneumatosis intestinalis” was first used by Duo Vernoi during postmortem observations. A PCI diagnosis in surviving patients was first established by Hahn in 1899. A PCI diagnosis
via preoperative radiological findings was first described by Baumann-Schender in 1939. The condition originally described by Duo Vernoi is what we now consider primary PCI. The term “secondary PCI” was coined by Koss in 1952, who analyzed 213 pathological specimens and attributed 85% of the cases to a secondary disease[
1-3].
Several hypotheses have been proposed regarding the development of PCI, although its pathogenesis is still controversial. Two main hypotheses regarding the fundamental pathogenesis of PCI are mechanical and bacterial[
17]. The mechanical hypothesis postulates that PCI develops when defects in the mucosa, in combination with increased intraluminal pressure, allow gas to infiltrate the gastrointestinal (GI) tract wall. A subgroup of patients with severe pulmonary conditions may present with PCI arising from pulmonary causes, such as cough and rapid changes in intra-abdominal pressure. The bacterial hypothesis proposes that PCI develops when gas-producing bacteria gain entry into the GI tract wall and produce gas pockets. Much of the supporting evidence for these two hypotheses is derived from observational studies, and mechanical and bacterial mechanisms may occur simultaneously[
4,6,7].
Although PCI may occur anywhere in the gastrointestinal tract, from the esophagus to the rectum, it is usually seen in the intestine. A previous study reported that 20%-51.6% of all PCI cases involve the small intestine, 36%-78% involve the colon, and 2%-22% include both the small intestine and colon. The small intestine was involved in 57.1% of the cases we presented here and 42.9% involved the small intestine and the colon[
1,2,6,8].
PCI is not a disease but a clinical entity. The etiology can be classified by considering factors thought to play a role in its development. Based on this notion, PCI can be divided into primary and idiopathic (15%) or secondary (85%) type[
9]. No identifiable underlying or predisposing factor is present in the primary or idiopathic type. However, numerous gastrointestinal diseases, including appendicitis, necrotizing enterocolitis, Crohn’s disease, pyloric stenosis, ulcerative colitis, diverticular disease, necrotizing enterocolitis, gastroduodenal ulcer, and sigmoid volvulus, may accompany PCI as a secondary cause. PCI has also been reported as accompanying some non-gastrointestinal diseases, such as chronic obstructive pulmonary disease, collagen tissue diseases, acquired immune deficiency syndrome, and glucocorticoid use. PCI cases secondary to surgical or endoscopic trauma have also been reported[
10,11].
Lesions are usually localized to the left hemicolon or its mesentery or to the submucosal layer and are frequently characterized by segmentary involvement in the primary form of the disease. However, involvement is usually subserosal in the secondary form, and occurs in the stomach, small intestine, and right colon, usually in a generalized or segmented pattern[
7].
The incidence of PCI is unknown, because it is usually asymptomatic. Symptoms, if any, are usually secondary to an underlying disease. Together with non-specific symptoms, such as abdominal discomfort, diarrhea, constipation, rectal bleeding, tenesmus, or loss of weight, severe complications, including volvulus, intestinal obstruction, tension pneumoperitoneum, bleeding, intussusception, and intestinal perforation may be seen in 3% of patients[
18-23].
Radiological tools are important for diagnosing PCI. These include plain radiographs, USG, barium series, CT, CT-colonoscopy, magnetic resonance imaging and MRI-colonography, endoscopy, and colonoscopy[
19,20]. X-ray is of great importance, because it is readily available in every emergency room. Cysts usually appear as radiolucent shadows, similar to a bunch of grapes, close to the intestinal lumen on radiographs. Free air underneath the diaphragm may be seen if these cysts perforate. An appearance of bulging into the lumen as a filling defect is seen on barium-colon radiographs[
15,23]. Linear or spot-like hyperechoic images may be seen in the intestinal wall on USG. CT is the most useful method for diagnosing PCI and is important because it provides data on other abdominal pathologies. However, CT may not provide data on intestinal ischemia and necrosis[
1,4,7,12]. The colonoscopic findings may be similar to multiple polyposis or collections of submucosal tumors, but subserous pneumatosis may go undetected[
20]. A laparoscopic exploration is quite useful to confirm a PCI diagnosis, if the physical examination findings are suspicious, and particularly in cases that are not preoperatively diagnosed clearly using the above-mentioned radiological methods. Diagnostic laparoscopy provides the convenience of converting to open surgery as well as confirming the diagnosis.
When presence of such an entity is confirmed radiologically, gastroenterologic surgeons begin to feel annoyance. The answer to the question, “What should we do to these patients?” is correlated with the experience of each surgeon on that entity. The approach to a patient with PCI should be determined by evaluating the underlying causes and exam findings together. A specific treatment is not recommended in asymptomatic patients who are detected as having PCI radiologically and whose examination findings are negative. Conservative approaches, including nasogastric decompression, intestinal rest, antibiotic therapy and oxygen, are recommended for patients with positive examination findings and normal biochemical parameters who are confirmed radiologically to have no intestinal ischemia or perforation[
24]. Applying 250 mmHg PO
2 pressure or 70% oxygen inhalation for 5 d or 2.5 atmospheres of hyperbaric oxygen pressure for 150 min/d for 3 consecutive days can lead to resolution of gas collection within a cyst[
10,13,24,25]. An urgent laparotomy is necessary in cases of intestinal ischemia, obstruction, intestinal bleeding, or peritonitis[
14,16]. Definitive surgery should be performed during a laparotomy if necrosis, perforation, or marked ischemia is observed in the intestine. Furthermore, no additional surgical procedures should be conducted unless other pathology is detected in addition to serosal or subserosal air cysts.
Consequently, clinical suspicion, physician experience, radiological tools, and team spirit are important in terms of the approach to PCI. When and how to treat these patients is the main issue to lower mortality and morbidity.
