From the Guidelines
Watershed areas of the colon, including the splenic flexure and the rectosigmoid junction, are particularly vulnerable to ischemic injury due to their limited blood supply and poor collateral circulation. These areas are common sites for ischemic colitis, which may present with abdominal pain, bloody diarrhea, or in severe cases, colonic necrosis 1. The splenic flexure represents the border between territories supplied by the superior and inferior mesenteric arteries, while the rectosigmoid junction marks the boundary between the inferior mesenteric and hypogastric arterial supplies.
Key Characteristics of Watershed Areas
- The splenic flexure (Griffiths' point) and the rectosigmoid junction (Sudeck's point) are the main watershed areas
- These areas have relatively poor collateral circulation, making them susceptible to hypoperfusion during episodes of low blood flow
- Ischemic colitis is a common condition affecting these areas, presenting with abdominal pain, bloody diarrhea, or colonic necrosis
- Understanding these watershed areas is crucial for diagnosing and managing colonic ischemia, particularly in elderly patients or those with cardiovascular risk factors, as noted in the management of lower gastrointestinal bleeding 1.
Clinical Implications
- Clinicians should be aware of the watershed areas of the colon when evaluating patients with symptoms of ischemic colitis
- Diagnostic colonoscopy is a valuable tool in identifying ischemic colitis and other conditions affecting the colon, with a diagnostic accuracy ranging from 72 to 86% in patients with lower gastrointestinal bleeding 1
- The use of colonoscopy can help identify the source of bleeding and guide management, including the potential use of therapeutic interventions to prevent further complications.
From the Research
Watershed Areas of the Colon
The colon has several weak points in its blood supply, known as watershed areas, which are more vulnerable to ischemic injury. These areas include:
- The splenic flexure, or Griffith's point
- Sudeck's point
- The ileocecal region
- The rectosigmoid region 2
Ischemic Colitis in Watershed Areas
Ischemic colitis can arise in these watershed areas, and the condition is characterized by a range of symptoms, including abdominal pain, bowel urgency, and passage of bloody diarrhea 3, 4. The presentation and severity of ischemic colitis can vary widely, and the disease can be associated with significant morbidity and mortality 5, 6.
Diagnosis and Management
Diagnosis of ischemic colitis is typically made clinically, with support from serologic, radiologic, and colonoscopic findings 3, 4. Colonoscopy is the most accurate diagnostic study, and it can help to identify the extent and severity of the disease 5, 6. Management of ischemic colitis is usually supportive, with bowel rest, fluid resuscitation, and antibiotics, although surgical intervention may be necessary in severe cases 5, 3, 4.
Importance of Early Recognition
Early recognition and prompt treatment of ischemic colitis are crucial for a favorable outcome, particularly in severe cases 5, 6. Delayed diagnosis and treatment can be associated with higher mortality rates, highlighting the importance of prompt recognition and management of this condition 6.