Spontaneous decompression of sigmoid volvulus

Objectives: Spontaneous decompression is an uncommon outcome of sigmoid volvulus (SV). The aim of this study was to evaluate the clinical presentation, diagnosis, treatment, and follow-up of spontaneously decompressed SV. Methods: We utilized the data of our 1,063 SV patients, the most comprehensive monocenter SV series in the world. To obtain the worldwide data on the spontaneous decompression of SV, we researched the last 56-years’ literature in Web of Science and PubMed databases. Results: The incidence of the spontaneous decompression was 0.1% (1/1,063) in our SV series, whereas it was 1.5% (8/549) in the worldwide data (Fisher exact test, p = 0.001). By this way, cumulative spontaneous decompression rate was found as 0.6% (9/1,602). In the spontaneously decompressed cases, the main clinical features were abdominal pain/tenderness, distention, and obstipation, which were similar to management-required patients. However, the treatment and follow-up algorithm is still a relatively undefined subject. Conclusion: Spontaneous decompression of SV is a very rare clinical entity. The clinical presentation and diagnosis of the spontaneously decompressed SV look alike the management-required SV. However, as seen in most management-required patients, SV tends to recur in the spontaneously decompressed cases and a recurrence-reducing procedure is required in selected patients.


INTRODUCTION
Spontaneous decompression is an unusual outcome of sigmoid volvulus (SV), the rotation of the sigmoid colon around itself causing an obstruction in colonic passage. 1,2Although SV typically ranks among the literature knowledge related to intestinal system, its spontaneous decompression is a relatively unclarified subject due to its rarity. 3,4Ataturk University Faculty of Medicine is the biggest regional health organization in Eastern Anatolia, an endemic area for SV.This medical center has 1,063-patient experience with SV over 56.5year period from June 1966 to January 2023.This is the most comprehensive monocenter SV series over the world. 5,6For this reason, we wanted to share our opinion and clinical experience on the spontaneous decompression of SV.

METHODS
In our clinic, total 1,063 SV cases were treated during 56.5-year period from June 1966 to January 2023.Among them, the clinical data including treatment options of 612 patients (58.2%) were investigated retrospectively till June 1986, whereas 439 (41.8%) cases were evaluated prospectively thereafter.Following diagnosis and resuscitation, patients were treated with endoscopic decompression (those without bowel gangrene or peritoneal irritation) or emergency surgery (those with above-mentioned adverse situations or unsuccessful endoscopic decompression), while a case was spontaneously decompressed under medical observation in preoperational period.
To obtain the worldwide data on the spontaneous decompression, an investigation was performed in Web of Science 3 and PubMed 4 databases under the head of 'sigmoid volvulus' and related results were utilized together with our findings.To compare our results with worldwide data on the spontaneously decompressed SV, a statistical analysis was performed by using SPSS v22.0 system (IBM Corporation, Armonk, New York, United States).Categorical variables were compared by using Chi-Square or Fisher exact tests.Significance level was set up p<0.05.Ethical approval: Ethical approval was obtained from Ethical Committee of Ataturk University Faculty of Medicine (No: 88-2022).Written informed consent for scientific research was obtained from all participants.

RESULTS
In our 1,063-case series, spontaneous decompression was demonstrated in one patient (0.1%).As worldwide data on the spontaneous decompression of SV, among total 1,209 publications, 671 papers with undetailed data were excluded and the remained 538 articles were investigated.However, as demonstrated in Table-I, only four articles involving detailed data were found on this subject. 3,4Among them, in a relatively large series including 396 patients, Pattanaik 1 notified 0.5% of spontaneous decompression rate for SV, while this rate was reported as 3.0% (3/99) by Arnold and Nance, 7 4.0% (1/25) by String and DeCosse, 8 and 6.9% (2/29) by Lau et al. 9 Accordingly, the spontaneous decompression of SV was found to be statistically more common in worldwide data when compared with our results (1.5%, 8/549 vs. 0.1%, 1/1,063, respectively, Fisher exact test, p = 0.001).On the other hand, when our results were evaluated together with worldwide data, the spontaneous decompression rate was demonstrated as 0.6% (9/1,602).
In detailed evaluation, the main clinical features of the spontaneously decompressed cases were not different from that of the management-required patients, which mainly included abdominal pain/ tenderness, distention, and obstipation.Similarly, the main diagnostic procedures were plain abdominal X-ray radiograms in addition to computed tomography

DISCUSSION
In SV, the spontaneous decompression rate may rise up to 44.1% depending on the anamnesis of the patients. 10This relatively high rate, which doesn't reckon with diagnostic accuracy, may be explained by incomplete volvulus attacks arising from partial torsion of the sigmoid colon (≤180 o ) and such movements are accepted as physiological rotations, which generally resolve spontaneously. 11However, the actual rate of the spontaneous decompression following clinical diagnosis and under medical observation in a healthcare organization is quite low, which can be expected in about 2% of cases. 108][9] In our series, this rate was 0.1% (1 of 1,063 cases).As a result, when the diagnosis of SV in a health center is considered, total number of the reported patients with spontaneous decompression can be counted on the fingers of two hands.
8][9] As known, the most important anatomical prerequisite is dolichosigmoid (an elongated and dilated sigmoid colon with a long mesentery) in the development of both primary and recurrent SV. 12,13 In our opinion, repetitive SV attacks may cause mesenteric fibrosis, which forms a narrowbased mesentery resulting in both easy recurrence and the spontaneous decompression.Although there is no information about the pathophysiology of abovementioned cases reported in the literature, at least, this theory may apply to our patient.
Although literature findings have no detailed data on the ages and genders of the spontaneously decompressed cases, 1-4,7-9 all of the reported patients are adults.In our opinion, the presence of a relatively narrow abdominal cavity may make the spontaneous decompression difficult in children.Similarly, due to the similar reason, the spontaneous decompression may be difficult in pregnant women as well as in men, in the last which, a significant high incidence may cause an adverse outcome, as was seen in our case.
8][19] In clinical course, defecation including normal-appearing stool, degasification, and abdominal relaxation are the main features of the spontaneous decompression. 2 Although control CT may demonstrate the disappearance of the previous pathological abdominal findings, control x-ray radiography may also serve the same purpose (Fig. 1c).
..Limitations: Limited number of SV cases with spontaneous decompression in our series and worldwide data in addition to partial retrospective evaluation and long-term study period of our series are probable limitations of this study.However, to obtain sufficient material on SV in a prospective study is quite difficult due to relatively low SV incidence over the world, which obligates the retrospective evaluation of such long-term studies.

CONCLUSIONS
Spontaneous decompression is a very rare clinical entity, which is seen in about 0.1-6.9% of SV patients.In such cases, the clinical presentation and diagnosis look alike the management-required individuals.However, SV tends to recur in most spontaneously decompressed patients and the most suitable treatment option is to use a recurrence-reducing procedure in selected patients.

Table - I
: Spontaneous decompression of sigmoid volvulus in worldwide literature.