Splenic-flexure syndrome

Ischemic colitis is usually encountered in elderly persons and often occurs without a clear precipitating cause. The severity may range from mild, with reversible mucosal changes (transient nongangrenous colitis), to severe, with transmural infarction and gangrene.[1,2] While colonic ischemia is not as common in adults under age 60, it is being recognized more frequently in this population.[2] Some younger patients affected with this condition have underlying vascular disorders or a hypercoagulable state, such as a deficiency of protein C, protein S or antithrombin III. However, many others are relatively healthy. In this younger population, nongangrenous ischemic colitis can be transient and benign. It is likely that primary care physicians will encounter ischemic colitis in their practices. The following three cases from our practice are illustrative.

Illustrative Cases

CASE 1

A previously healthy 36-year-old man presented to the emergency department with a one-day history of crampy lower abdominal pain, tenesmus and bloody diarrhea without associated fever or vomiting. He had no previous history of bowel problems or recent exposures. The family history was negative. The only medication. that the patient was taking was tramadol for a shoulder injury. He did not smoke, but he did chew tobacco.

Physical examination revealed significant left lower quadrant tenderness without peritoneal signs. The patient's white blood cell count was 18,000 per [mm.sup.3] (18.0 x [10.sup.9] per L). Other laboratory results were unremarkable. The patient was admitted to the hospital and given intravenous fluids. Colonoscopy demonstrated severe ischemic colitis involving the left portion of the colon. The patient improved quickly and was discharged within 48 hours.

CASE 2

A 48-year-old woman presented with a four-day history of nausea, vomiting and diffuse abdominal cramping followed by bloody diarrhea. The patient was afebrile and had no recent exposures, travel, antibiotic use or previous history of bowel problems. The patient was taking timolol drops for glaucoma, skeletal muscle relaxants (Some Compound) and fluoxetine. She had undergone a hysterectomy without an oophorectomy, and she had never received estrogen therapy. She had a family history of colon cancer. She smoked one pack of cigarettes per day.

Physical examination revealed diffuse mild abdominal tenderness without peritoneal signs. Rectal examination demonstrated dark red guaiac-positive stool. The patient's white blood cell count was 14,900 per [mm.sup.3] (14.9 x [10.sup.9] per L). Colonoscopy was performed the following day and revealed a 20-cm segment at the splenic flexure consistent with ischemic colitis. The patient recovered without further intervention.

CASE 3

A previously healthy 42-year-old woman presented with a one-day history of low-grade temperature, nausea, vomiting, lower abdominal cramping, and watery, then bloody diarrhea. She had no recent exposures, travel or antibiotic usage. She had a history of irritable bowel syndrome and a family history of colon cancer. She was a nonsmoker and had been taking conjugated estrogen (Premarin) since her hysterectomy for fibroid tumors several years previously.

Physical examination revealed left lower quadrant tenderness without peritoneal signs. The patient's white blood cell count was 16,800 per [mm.sup.3] (16.8 x [10.sup.9] per L). Results of other laboratory tests, including a hematocrit, were unremarkable. She was admitted for intravenous hydration. Colonoscopy revealed patchy regions of inflammation in the transverse to left portion of the colon. Pathologic changes noted on biopsy were consistent with ischemic colitis. Estrogen therapy was discontinued. The patient recovered over a four-day period and was doing well at one month follow-up.

Background and Terminology

Until the 1950s, the only recognized manifestation of colonic ischemia was catastrophic bowel injury and gangrene. In 1963, the first cases of noncatastrophic, reversible colonic injury due to transient ischemia were described.[3] In 1966, the term "ischemic colitis" was introduced to include a spectrum of injury patterns seen with colonic ischemia, ranging from transient mucosal changes to ischemic stricture formation to transmural infarction and gangrene.[1] Currently, the term ischemic colitis is used to refer to any disorder involving colonic ischemia. In its severe form, ischemic colitis is a serious, life-threatening condition; when associated with shock, it is generally fatal.

In contrast, the term "transient ischemic colitis" is used to refer to a small subset of patients with colonic ischemia who typically have a benign, transient course. At the outset, it is not possible to predict which patients have transient ischemic colitis and which have a more severe form. Thus, transient ischemic colitis is a diagnosis made in retrospect, only after following the evaluation and clinical course of a patient over time. Estimates are that up to one half of cases of ischemic colitis are transient in nature.[4] At this time, the incidence of ischemic colitis is unknown mainly because patients with milder disease may not seek care, symptoms may resolve before studies are performed, or the condition may be misdiagnosed.[4]

Etiology

Colonic ischemia results from a sudden, usually temporary, reduction in splanchnic blood flow. The extent of damage to the colon is related to a number of factors, including the duration of the decrease in blood flow, the amount of vasculature involved, the presence of adequate collateral circulation and the presence of an underlying condition.[5,6] Occasionally, a clear precipitating cause of reduced blood flow may be present, such as surgery involving the aorta,[7] or hypovolemic shock[5,8] (Table 1). Long-distance running, in which blood flow is preferentially diverted away from the colon,[9] and especially cocaine use, with its intense vasoconstrictive properties,[10] have also been associated with colonic ischemia. Many cases;however, occur spontaneously in the absence of an obvious precipitating event.

[Figure 1 ILLUSTRATION OMITTED]

Differential Diagnosis

In younger adults with symptoms consistent with ischemic colitis, the most common alternative diagnoses are acute infectious enteritis, pseudomembranous colitis and inflammatory bowel disease. Other less likely possibilities include diverticulitis or bleeding diverticulosis, colon cancer, bowel strangulation and arteriovascular malformations (Table 2). Acute mesenteric ischemia should also be considered, especially in seriously ill or toxic-appearing patients. This condition represents ongoing mesenteric insufficiency that can lead to irreversible ischemic damage.[4]

COPYRIGHT 1997 American Academy of Family Physicians
COPYRIGHT 2004 Gale Group