A Rare Case of Life-Threatening Gangrenous Ileosigmoid Knotting: Successful Primary Anastomosis Without Stoma in a Carefully Selected Patient

Abstract

Ileosigmoid knotting (ISK) is a rare, rapidly progressive cause of intestinal obstruction that frequently results in bowel ischemia, gangrene, and high mortality if not treated promptly. In patients with gangrenous ISK, surgical management has traditionally favored bowel resection with stoma formation because of concerns regarding anastomotic failure. We report the case of a 60-year-old man who presented with acute intestinal obstruction and generalized peritonitis after six days of progressive symptoms. Following prompt resuscitation, emergency exploratory laparotomy revealed gangrenous ileosigmoid knotting involving approximately 60 cm of the distal ileum and the sigmoid colon. Resection of the nonviable bowel was performed, followed by primary ileo-ileal and colo-colic anastomoses without a diverting stoma because the bowel ends were well perfused, suitable for primary anastomosis, and there was no gross fecal contamination. The postoperative course was uneventful, with restoration of bowel function by postoperative day 2, and the patient was discharged on postoperative day 9 with satisfactory recovery. This case demonstrates that primary anastomosis without a diverting stoma may be a safe and feasible option in carefully selected patients with gangrenous ISK when favorable intraoperative conditions are present. It underscores the importance of early resuscitation, meticulous intraoperative assessment, and individualized surgical decision-making rather than a uniform approach to stoma formation.

Introduction

Ileosigmoid knotting (ISK), also known as compound volvulus, is a rare surgical emergency in which the ileum wraps around the sigmoid colon, or vice versa, creating a double closed-loop intestinal obstruction. This condition rapidly progresses to vascular compromise, bowel ischemia, and gangrene, making early diagnosis and prompt surgical intervention essential to reduce morbidity and mortality.¹

Although ileosigmoid knotting is uncommon worldwide, it occurs more frequently in regions where sigmoid volvulus is endemic, particularly in parts of Africa, Asia, and the Middle East. Globally, ISK accounts for approximately 1–2% of all cases of intestinal obstruction. However, in regions such as East Africa (Uganda, Ethiopia, and Kenya), Iran, and India, it represents 5–10% of intestinal obstructions reported in surgical series.^2–5

The condition predominantly affects males, with a reported male-to-female ratio of up to 4:1, and most commonly occurs in the third to fifth decades of life, although elderly patients may also be affected. Anatomical factors predisposing to ISK include a long and mobile small bowel mesentery, a narrow-based elongated sigmoid colon, and an empty small bowel, often following ingestion of a bulky meal.^1,2

Preoperative diagnosis of ileosigmoid knotting (ISK) remains challenging because of its nonspecific clinical presentation and radiological findings. Consequently, despite advances in cross-sectional imaging, most cases are diagnosed only during exploratory laparotomy. Reported preoperative diagnostic rates remain low, ranging from 0% to 28%.^1–3,6 Early recognition therefore requires a high index of clinical suspicion, particularly in patients presenting with features of acute intestinal obstruction accompanied by rapidly progressive abdominal pain, as timely diagnosis and prompt surgical intervention are critical for reducing bowel ischemia, gangrene, and mortality. When available, contrast-enhanced computed tomography (CT) may facilitate early diagnosis by demonstrating characteristic findings such as the whirl sign, twisted mesenteric vessels, and features of a double closed-loop obstruction, thereby enabling timely surgical intervention before irreversible bowel ischemia develops.^7,8

Delayed diagnosis frequently results in bowel strangulation, gangrene, sepsis, and shock, substantially increasing postoperative morbidity and mortality. Consequently, urgent resuscitation followed by early surgical intervention remains the cornerstone of successful management.⁹

In patients with gangrenous bowel, resection with stoma formation has traditionally been recommended because of concerns regarding anastomotic failure. However, stoma formation is associated with significant morbidity, psychological burden, and the need for subsequent reversal surgery. Emerging evidence suggests that primary anastomosis may be performed safely in carefully selected patients with favorable intraoperative conditions, including hemodynamic stability, well-perfused bowel ends, and the absence of gross fecal contamination.^1,2,9

This case report has been reported in accordance with the SCARE 2025 guidelines.¹⁰

The completed SCARE 2025 checklist is available as Supplementary File 1.

Case Presentation

A 60-year-old married male with primary-level education who worked as a subsistence farmer presented to the emergency department at Kampala International University Teaching Hospital with a 6-day history of progressively worsening generalized abdominal pain, abdominal distension, vomiting, and complete obstipation. The patient reported that his symptoms initially began with intermittent abdominal pain and progressive abdominal distension. He initially sought treatment at a nearby health facility, where he received symptomatic management without clinical improvement before being referred to our institution. The patient had no history of previous abdominal surgery, abdominal trauma, chronic constipation, gastrointestinal disorders, chronic comorbidities, or known drug allergies.

On examination, the patient was conscious but appeared dehydrated. His vital signs revealed hypotension with a blood pressure of 98/60 mmHg and tachycardia with a pulse rate of 102 beats per minute, while his temperature was within normal limits. The abdomen was markedly distended, with generalized tenderness, guarding, and rigidity. Bowel sounds were absent. Digital rectal examination revealed an empty rectum without fecal staining.

Laboratory investigations demonstrated a hemoglobin level of 16 g/dL, a white blood cell count of 14 × 10⁹/L, and a platelet count of 215 × 10⁹/L. Serum electrolytes showed mild hypernatremia (sodium 148 mmol/L), while potassium levels and renal function parameters were within normal limits.

A preoperative erect abdominal radiograph demonstrated markedly dilated small- and large-bowel loops with multiple air-fluid levels, consistent with acute intestinal obstruction, as shown in Figure 1.

Figure 1.

Preoperative erect abdominal X-ray showing dilated small and large bowel loops with multiple air–fluid levels, consistent with mechanical intestinal obstruction.

The patient was promptly resuscitated with intravenous crystalloids, nasogastric decompression, broad-spectrum antibiotics, analgesia, and urinary catheterization for urine output monitoring. Following adequate resuscitation, his hemodynamic status improved, with blood pressure increasing to 128/82 mmHg and pulse rate decreasing to 88 beats per minute.

An emergency exploratory laparotomy was performed. Intraoperative findings revealed a gangrenous sigmoid colon twisted 360° anticlockwise along its longitudinal axis. The distal ileum, approximately 60 cm proximal to the ileocecal junction, was tightly wrapped around the base of the sigmoid colon, forming an ileosigmoid knot, as shown in Figure 2. Both the involved ileal segment and sigmoid colon were gangrenous.

Figure 2.

Intraoperative view of ileosigmoid knotting. The black arrow indicates the knot, the green arrow shows the gangrenous sigmoid colon, and the blue arrow indicates the gangrenous ileum.

Following detorsion, the nonviable bowel segments, including approximately 60 cm of distal ileum and the affected sigmoid colon, were resected. The remaining bowel margins were carefully assessed and found to be well perfused and viable. Approximately 16 cm of distal ileum proximal to the ileocecal junction and a short segment of sigmoid colon proximal to the rectosigmoid junction were preserved. There was no evidence of bowel perforation or gross fecal contamination. The resected gangrenous bowel segments are shown in Figure 3.

Figure 3.

Resected gangrenous bowel segments.

Considering the patient’s hemodynamic stability after resuscitation, the absence of gross peritoneal contamination, and the presence of viable bowel margins, primary ileo-ileal and colo-colic anastomoses were performed without creation of a diverting stoma, as shown in Figure 4. Thorough peritoneal lavage was performed, and the abdomen was closed over a drain. The operation was performed by the lead senior general surgeon, who had more than five years of experience in emergency and gastrointestinal surgery.

Figure 4.

Bowel after resection and primary anastomosis. The black arrow indicates the colo-colic anastomosis.

The postoperative course was uneventful. The patient received intravenous fluids, antibiotics, analgesia, and gastric protection. Bowel function returned on postoperative day 2, allowing gradual reintroduction of oral feeding. He remained clinically stable throughout hospitalization and was discharged on postoperative day 9. At follow-up, he was asymptomatic with satisfactory bowel function. The postoperative course is summarized in Table 1.

Table 1.

Summary of Postoperative Course and Follow-Up

Day	Vitals/RBS (mmol/L)	Therapy/Interventions	Urine Output	Bowel/Oral Intake	Abdominal Drainage	Key Events
1	Stable, RBS 8	IV fluid, antibiotic, and analgesic therapy	1200 mL	NGT in situ, no bowel sounds	50 mL sanguinous	–
2	Stable, RBS 7.8	Continuation of Day 1 therapy	1250 mL	Weak bowel sounds, passed flatus x2, NGT removed, oral sips started	50 mL sanguinous	Ambulation initiated
3	Stable, RBS 7.5	Continuation of IV therapies	1600 mL	Oral sips continued	20 mL serosanguinous	Catheter and drain removed; Control CBC and electrolytes normal
4–5	Stable, RBS 7.2	Continuation of IV therapies	1300 mL	Soft diet, passing stool	–	–
6	Stable, RBS 6.9	Switch to oral antibiotic and analgesic therapy	1500 mL	Normal diet, regular stools	–	–
7–9	Stable, RBS 7.0	Continuation of oral therapies	1400 mL	Normal diet, regular stools	–	Fully stable; discharged on Day 9
14	Stable, RBS 6.9	–	1500 mL	Normal bowel movements	–	CBC normal; stitches removed; wound healed; no complaints

Abbreviations: RBS, Random Blood Sugar; NGT, Nasogastric Tube; IV, Intravenous; CBC, Complete Blood Count.

Discussion

Overview and Pathophysiology

Ileosigmoid knotting (ISK), also known as compound volvulus, is a rare but life-threatening cause of intestinal obstruction characterized by torsion of the ileum around the base of the sigmoid colon or, less commonly, the sigmoid colon around the ileum, resulting in a double closed-loop obstruction.^1,2 This rapidly compromises the vascular supply to both bowel segments, leading to ischemia, gangrene, perforation, sepsis, and death if definitive surgical treatment is delayed. Owing to its rapid progression and high mortality, ISK remains one of the most challenging surgical emergencies requiring prompt recognition and intervention.^6,11 Although ISK accounts for only a small proportion of intestinal obstruction worldwide, it is encountered more frequently in regions where sigmoid volvulus is endemic, including East Africa, the Middle East, and parts of Asia. Several anatomical and physiological factors predispose individuals to this condition, including a long and mobile small-bowel mesentery, an elongated sigmoid colon with a narrow mesenteric attachment, and ingestion of a bulky meal following prolonged fasting, which increases small-bowel mobility and facilitates knot formation.^2–5

Clinical Presentation and Diagnosis

Patients with ISK typically present with sudden-onset abdominal pain, persistent vomiting, progressive abdominal distension, and absolute obstipation. Because the condition produces a double closed-loop obstruction with rapid vascular compromise, clinical deterioration is often swift, progressing to bowel ischemia, generalized peritonitis, septic shock, and multiorgan dysfunction if left untreated. Shock has been reported in up to 60% of patients and generally reflects advanced bowel ischemia and systemic sepsis. Early diagnosis remains challenging because the clinical presentation overlaps with that of other causes of acute intestinal obstruction. Nevertheless, clinicians should maintain a high index of suspicion in patients from regions where sigmoid volvulus is prevalent who present with severe abdominal pain disproportionate to the degree of abdominal distension, rapidly progressive symptoms, and radiographic evidence of simultaneous small- and large-bowel obstruction.^2,12 Early recognition, prompt resuscitation, and timely referral for emergency surgical intervention before the onset of bowel ischemia may prevent gangrene and allow bowel-preserving procedures, thereby avoiding bowel resection, primary anastomosis, or stoma formation.^5,13 In the present case, the patient presented six days after symptom onset, having initially sought care at a peripheral health facility where symptomatic treatment was instituted before referral to our center. This delay in presentation most likely contributed to the development of gangrene involving both the ileum and sigmoid colon as well as generalized peritonitis. Delayed presentation has consistently been associated with higher rates of bowel necrosis, septic complications, and mortality in previous studies. Nevertheless, following aggressive fluid resuscitation, the patient became hemodynamically stable and underwent timely definitive surgery, resulting in an uncomplicated postoperative recovery.¹³ Preoperative diagnosis of ISK remains difficult because plain abdominal radiographs usually demonstrate nonspecific features of intestinal obstruction without confirming the diagnosis.¹⁴ In contrast, contrast-enhanced computed tomography (CT) is regarded as the imaging modality of choice and may demonstrate characteristic findings such as the whirl sign produced by twisted bowel loops and mesenteric vessels, the beak sign at the points of obstruction, medial deviation of the descending colon, radially converging mesenteric vessels, and features of bowel ischemia including poor mural enhancement, bowel wall thickening, pneumatosis intestinalis, mesenteric edema, and free intraperitoneal fluid. However, CT should not delay operative intervention in patients with generalized peritonitis or hemodynamic instability. In our patient, the presence of generalized peritonitis following initial resuscitation warranted immediate exploratory laparotomy without additional imaging.^7,8,15 As reported in many previous series, the diagnosis was therefore established intraoperatively.¹²

Classification Systems and Relevance to the Case

Classification systems are valuable in understanding the mechanism, severity, and prognostic implications of ileosigmoid knotting (ISK), while also guiding operative decision-making. The classical classification categorizes ISK according to the bowel segment initiating the twist and the direction of rotation (Table 2).⁵

Table 2.

Classical Classification of Ileosigmoid Knotting

S/N	Type of ISK	Percentage (%)	Active Component	Passive Component	Direction of Rotation
1.	Type 1A	53.9–57.5	Ileum	Sigmoid colon	Clockwise
	Type 1B		Ileum	Sigmoid colon	Anticlockwise
2.	Type 2A	18.9–20.65	Sigmoid colon	Ileum	Clockwise
	Type 2B		Sigmoid colon	Ileum	Anticlockwise
3.	Type 3	1.5	Ileocecal segment	Sigmoid colon	Not specified
4.	Type 4	Not defined	Undetermined	Undetermined	Not specified

Abbreviation: ISK, Ileosigmoid Knotting.

Type I, the most common variant, occurs when the ileum actively wraps around the base of the sigmoid colon; Type II occurs when the sigmoid colon actively rotates around the ileum, whereas Types III and IV represent less common and indeterminate forms, respectively. In the present case, the intraoperative finding of the distal ileum tightly encircling the sigmoid colon was consistent with Type I ileosigmoid knotting (ISK), the most common subtype, accounting for 53.9–57.5% of reported cases, followed by Type II (18.9–20.6%), Type III (1.5%), and unclassified forms, with the direction of torsion being clockwise in approximately 60.9–63.2% of cases.^3,16 Although the classical classification describes the anatomical mechanism of knot formation, it provides limited prognostic value and offers little guidance for operative decision-making. To overcome these limitations, Atamanalp proposed a prognostic classification that incorporates patient age, American Society of Anesthesiologists (ASA) physical status, bowel viability, and intraoperative bowel condition, thereby providing a more practical framework for predicting outcomes and guiding surgical management (Table 3).⁹

Table 3.

Atamanalp Classification for Ileosigmoid Knotting (2021)

Group	Definition	Recommended Surgical Treatment	Mortality (%)	Morbidity (%)
IA	G0, A0, ASA I–III	Decompression alone or decompression with sigmoid colopexy/mesopexy/mesoplasty or sigmoid resection and primary anastomosis	1–10	5–25
IB	G0, A1 or ASA IV–V	Decompression	10–30	20–40
IIA	G1, A0, ASA I–III, B0	Ileal or sigmoid resection with primary anastomosis	5–20	10–30
IIB	G1, A1 or ASA IV–V or B1	Ileal or sigmoid resection with stoma	20–50	30–60
IIIA	G2, A0, ASA I–III, B0	Ileal and sigmoid resection with primary anastomosis	10–30	20–40
IIIB	G2, A1 or ASA IV–V or B1	Ileal and sigmoid resection with one primary anastomosis and one stoma	30–60	40–80

Abbreviations: A0, Age below regional life expectancy; A1, Age equal to or above regional life expectancy; ASA I–III, No to severe systemic disease without immediate life threat; ASA IV–V, Life-threatening systemic disease or moribund patient; B0, Normal bowel ends suitable for primary anastomosis; B1, Increased anastomotic risk (perforated bowel, borderline ischemia, marked edema, or marked diameter discrepancy after resection); G0, Viable bowel; G1, Gangrene involving either the ileum or the sigmoid colon; G2, Gangrene involving both the ileum and sigmoid colon.

According to the updated 2021 Atamanalp classification, our patient was categorized as Class IIIA because he was younger than the regional male life expectancy in Uganda (62.9 years; A0), had gangrene involving both the ileum and sigmoid colon (G2), had no major comorbidities (ASA I–III), and the bowel ends were suitable for primary anastomosis (B0). This classification recommends resection of both gangrenous bowel segments followed by primary ileo-ileal and colo-colic anastomoses in carefully selected patients with favorable intraoperative findings, without the routine use of a diverting stoma. The surgical approach adopted in our patient was therefore consistent with these recommendations and was supported by his uneventful postoperative recovery and favorable clinical outcome.

The present case highlights the clinical utility of contemporary classification systems beyond simply describing disease morphology. Incorporating validated prognostic factors into surgical decision-making allows treatment to be individualized according to the patient’s physiological status and intraoperative findings rather than relying solely on the presence of bowel gangrene. This approach may reduce unnecessary stoma formation while maintaining patient safety in appropriately selected cases.⁹

Surgical Management and Decision-Making

Emergency laparotomy remains the cornerstone of treatment for ileosigmoid knotting because of the high risk of rapid progression to bowel ischemia, gangrene, perforation, and sepsis. The choice of surgical procedure depends primarily on intraoperative findings, including bowel viability, the extent of gangrene, the degree of peritoneal contamination, and the patient’s physiological status following resuscitation. In patients with viable bowel, detorsion with or without sigmoid fixation or elective sigmoid resection may be appropriate to prevent recurrence. However, when bowel gangrene is present, resection of all nonviable bowel is mandatory.^1,5,17 Traditionally, resection followed by stoma formation has been recommended for patients with gangrenous ISK because of concerns regarding anastomotic leakage in the setting of bowel edema, sepsis, hemodynamic instability, or gross fecal contamination. Although this approach reduces the risk of catastrophic anastomotic failure in high-risk patients, it is associated with considerable morbidity, including stoma-related complications, psychological distress, reduced quality of life, prolonged hospitalization, and the need for a second operation for stoma reversal. Consequently, stoma formation should not be considered mandatory in every patient with gangrenous ISK but rather reserved for those with unfavorable intraoperative or physiological conditions.^2,17

Recent evidence supports primary resection and anastomosis in carefully selected patients who have adequate physiological reserve, achieve hemodynamic stability following resuscitation, demonstrate well-perfused bowel ends after resection, and have no gross fecal contamination or overwhelming sepsis.^18,19 The updated 2021 Atamanalp classification similarly recommends primary anastomosis without routine diversion in appropriately selected patients with gangrene involving both bowel segments, provided that favorable intraoperative conditions are present. Several recent case reports and institutional series have demonstrated favorable outcomes using this selective approach, with acceptable morbidity and low rates of anastomotic complications.⁹

In the present case, although the patient presented six days after symptom onset with gangrene involving both the ileum and sigmoid colon, aggressive preoperative resuscitation restored hemodynamic stability. At laparotomy, all gangrenous bowel was completely resected, the remaining bowel ends were well vascularized, and there was no bowel perforation or gross fecal contamination. These findings favored primary ileo-ileal and colo-colic anastomoses without a diverting stoma. The patient’s uneventful postoperative recovery and satisfactory functional outcome support the appropriateness of this individualized surgical strategy. Nevertheless, this approach should be reserved for experienced surgeons and carefully selected patients after meticulous intraoperative assessment. In unstable patients or where bowel viability is uncertain, creation of a diverting stoma remains the safer option.^2,20

Implications from the Present Case

The present case demonstrates that successful management of gangrenous ileosigmoid knotting does not invariably require diverting stoma formation. Despite delayed presentation with gangrene involving both the ileum and sigmoid colon, the patient achieved an excellent postoperative outcome following primary ileo-ileal and colo-colic anastomoses. This favorable result was likely attributable to prompt preoperative resuscitation, meticulous intraoperative assessment, complete resection of all nonviable bowel, preservation of well-perfused bowel ends, and the absence of gross fecal contamination. These factors collectively supported the safety of primary anastomosis in this carefully selected patient.

This case adds to the growing body of evidence suggesting that routine stoma formation may not be necessary in every patient with gangrenous ISK. Instead, the decision should be individualized according to the patient’s physiological status, bowel viability, degree of peritoneal contamination, and the operating surgeon’s experience. The updated Atamanalp classification provides a useful framework for identifying patients who may safely undergo primary anastomosis without diversion. Nevertheless, because the available evidence is derived primarily from case reports and small case series, larger multicenter studies are required before broader recommendations can be made.⁹

Although our patient experienced an uneventful recovery, this favorable outcome should not be interpreted as evidence that primary anastomosis is universally superior to stoma formation. Rather, the present case illustrates that, in carefully selected patients managed by experienced surgeons, primary anastomosis represents a feasible and safe alternative to routine diversion. In patients with persistent hemodynamic instability, questionable bowel perfusion, severe sepsis, or gross fecal contamination, creation of a diverting stoma remains the more appropriate and safer surgical option.¹⁷

Strengths and Limitations

Strengths

This case provides detailed clinical, radiological, intraoperative, and postoperative documentation of a rare gangrenous ileosigmoid knotting successfully managed with primary ileo-ileal and colo-colic anastomoses without stoma. It also discusses management in the context of the updated Atamanalp classification and current evidence.

Limitations

As a single case report, the findings cannot be generalized to all patients with gangrenous ileosigmoid knotting. The favorable outcome reflects careful patient selection, adequate resuscitation, favorable intraoperative findings, and experienced surgical management. Longer follow-up and larger studies are needed to establish the safety and broader applicability of primary anastomosis without diversion.

Conclusion

In patients with gangrenous ileosigmoid knotting, surgical management should be individualized based on the patient’s physiological status, intraoperative findings, bowel viability, and the operating surgeon’s expertise. While diverting stoma remains an appropriate and often safer option for patients with hemodynamic instability, gross fecal contamination, questionable bowel perfusion, or severe sepsis, primary resection with ileo-ileal and colo-colic anastomoses may be considered in carefully selected patients who have well-perfused bowel ends, achieve hemodynamic stability following adequate resuscitation, and have no evidence of gross contamination. The present case supports the selective use of primary anastomosis without diversion in such patients, although larger studies are required to further define patient selection criteria and long-term outcomes.

Funding Statement

The authors received no specific funding for this work from any funding agency in the public, commercial, or not-for-profit sectors.

Highlights

• Gangrenous ileosigmoid knotting is a rare surgical emergency requiring urgent diagnosis and definitive surgical management.

• Successful primary ileo-ileal and colo-colic anastomoses were performed without a diverting stoma following complete resection of gangrenous bowel.

• Careful patient selection, effective resuscitation, viable bowel margins, and the absence of gross fecal contamination supported safe primary anastomosis.

• This case illustrates that primary anastomosis without diversion may be feasible in carefully selected patients managed by experienced surgeons.

• The updated Atamanalp classification may help guide individualized surgical decision-making in gangrenous ileosigmoid knotting.

Ethical Approval and Consent

Ethical approval was not required for this case report in accordance with the institutional policies of Kampala International University Teaching Hospital because no experimental intervention was performed. Written informed consent was obtained from the patient for publication of this case report and the accompanying clinical images. A copy of the written consent is available for review by the Editor-in-Chief upon reasonable request.

Author Contributions

Frank Joshua Ruhazwe (FJR), Demoz Abraha Weldemichael (DAW), Mugenyi Michael (MM), Abdikani Ali Hassan (AAH), Bienfait Mumbere Vahwere (BMV), Mugarura Anwar (MA), Maslah Osman Ali (MOA), Mohamed Abukar Nor (MAN), Mohamed Seleban Jama (MSJ), and Abdullahi Ahmed Ali (AAA) all made a significant contribution to the work reported. DAW served as the lead surgeon and performed the surgical procedure with the assistance of FJR, AAH, MSJ, and AAA. FJR, MSJ, and AAA prepared the initial manuscript draft.

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors declare that they have no competing interests or conflicts of interest related to this work.