Treating sickle cell patients who present with acute abdominal pain can be difficult. These patients often experience painful vasoocclusive crises, which can include abdominal symptoms, making the timely diagnosis of surgical diseases challenging. Because sickle cell disease is not a common disorder, most surgeons have limited experience in managing surgical conditions in these patients. We present the cases of two patients with sickle cell disease who were found to have bowel ischemia and required surgery. We discuss the difficulties faced in managing these cases and review the available literature regarding these conditions.

Case reports
- Case 1—A 54-year-old African American woman with sickle cell disease presented to the emergency department reporting right hip and leg pain of 4 days duration. This presentation was typical of her painful vasoocclusive crises, which occurred once every several months. She had initially sought treatment and was hospitalized at another institution but asked to be discharged when her pain was not relieved by the narcotic medications that she was given.

On initial evaluation at our institution, the patient reported abdominal pain and constipation. She was afebrile but tachycardic to 115 beats per minute, and her oxygen saturation was 98%. Her laboratory tests were significant for a white blood cell (WBC) count of 31,700/mm³. A diagnosis of vasoocclusive sickle cell crisis was made, and she was admitted to the medical service for hydration and pain control.

The following morning, she developed right lower quadrant pain, tenderness to palpation, and a fever of 102°F, prompting empiric antibiotic therapy. Abdominal radiographs showed dilation of the cecum and transverse colon (Figure 1). On day 2 of hospitalization, her abdominal tenderness worsened and a surgical consultation was requested. Computed tomography (CT) scans of the abdomen revealed thickening of the right colon with pneumatosis (Figure 2). The patient underwent laparotomy that evening, which showed a markedly dilated right colon with significant thickening and no evidence of perforation. A right hemicolectomy was performed, and the pathology was consistent with ischemic colitis. The patient’s postoperative course was uneventful and she made a full recovery.

- Case 2—A 26-year-old African American man with relatively mild sickle cell disease presented to the emergency department reporting the sudden onset of diffuse abdominal pain, followed by several episodes of nonbilious, blood-tinged emesis. His symptoms included dizziness, but no fever, chills, or cough. These symptoms were preceded by diarrhea 1 day earlier, which included 15 watery, nonbloody stools. While his typical vasoocclusive crises included bilateral shoulder, chest, and abdominal pain several times a year, this presentation was marked exclusively by abdominal symptoms. He had not had any previous surgeries.

The patient was in significant discomfort at presentation but was hemodynamically stable. His abdomen was nondistended and did not manifest focal tenderness. A stool sample was negative for occult blood. He received intravenous fluids, morphine, and metoclopramide. Despite this therapy, his abdominal symptoms persisted and a surgical consultation was obtained. At that time, the patient exhibited tachycardia and hypotension, which rapidly improved after 2 L of intravenous fluids were administered. His abdominal examination revealed mild distension and minimal tenderness. Laboratory tests were significant for a WBC count of 13,400/mm³, hematocrit of 35%, and venous lactate of 6 mmol/L. An abdominal radiograph showed moderately dilated small bowel loops (Figure 3).

Surgical exploration was deferred because of improving hemodynamics and clinical parameters after aggressive fluid resuscitation. Lactate levels decreased to 4 mmol/L after administration of 5 L of crystalloids and supplemental oxygen.

Four hours later, the patient was again tachycardic but was also lethargic and had increased abdominal distension. An arterial blood gas evaluation found a pH of 7.25 (normal, 7.35–7.43), carbon dioxide of 38 mm Hg (normal, 35–45 mm Hg), oxygen of 129 mm Hg (normal, 80–105 mm Hg), and lactate of 6.7 mmol/L (normal, 0.5–2.2 mmol/L). He was immediately taken to the operating room for exploration. On arrival, he developed profuse emesis, requiring nasogastric tube decompression before rapid-sequence induction. Immediately after endotracheal intubation, he developed asystole followed by ventricular fibrillation. Despite full resuscitative measures, he died soon thereafter. An autopsy revealed strangulated loops of ileum encircled by a redundant sigmoid colon, a process known as ileosigmoid knotting (Figure 4).

Discussion
Sickle cell disease is characterized by abnormal hemoglobin molecules that change the red blood cells from round to an elongated shape. Specifically, an amino acid substitution in the beta chain of hemoglobin is the defective mechanism responsible for hemoglobin S (HbS) found in patients with this disease.¹ Deoxygenation leads to polymerization of HbS, decreased solubility, and the sickle conformation of red blood cells.¹ Sickled cells are poorly deformable and have increased adherence properties. This causes microvascular occlusion of multiple organs, which has been termed “vasoocclusive crisis.” Inheritance patterns involve both the sickle cell gene B⁵ and the sickle-thalassemia gene B⁰ and can range from homozygosity to heterozygosity. Heterozygotes of the B⁵ gene are termed “sickle-trait” carriers and are typically asymptomatic.¹

Abdominal pain is a frequent symptom in patients with sickle cell disease. While 50% of vasoocclusive crises include abdominal pain, they are usually associated with pain in the chest, back, and joints. When abdominal pain is the only symptom, and especially when it is accompanied by fever, leukocytosis, and localized abdominal tenderness, other abdominal conditions must be considered in the differential diagnosis.² Obtaining a detailed patient history is useful in determining whether the nature of the abdominal pain is typical of the patient’s usual symptoms during a vasoocclusive crisis. Unusual abdominal pains should prompt a workup for other possible diagnoses.

Chronic hemolysis in patients with sickle cell disease almost always leads to the formation of pigment gallstones by adolescence, which can be complicated by acute cholecystitis. The clinical diagnosis of acute cholecystitis is relatively straightforward, and a number of radiological studies can be used to verify clinical suspicion. In contrast, appendicitis is frequently missed in patients with sickle cell disease because there is considerable overlap between its symptoms and those of a vasoocclusive crisis involving the abdomen. Acute splenic sequestration is seen only in very young patients with sickle cell disease and is easily diagnosed by its fulminant presentation with massive splenomegaly and hypovolemic shock.

Mesenteric ischemia affecting the small bowel or colon is an exceedingly rare but potentially life-threatening condition that must be considered in sickle cell patients who present with acute abdominal pain. Unlike thromboembolic mesenteric occlusive disease, which usually affects the proximal superior mesenteric vessels, sickle cell patients typically develop occlusion of small vessels at the level of postcapillary venules.³ While uncommon, this can progress to significant bowel ischemia. Three cases of ischemic colitis have been reported in the literature.^4-6 Small bowel ischemia is also rare, with five reported cases in sickle cell patients.^7-11

Although small bowel obstruction can occur in sickle cell patients, especially in those who had previous abdominal surgery, primary obstruction is rare. Ileosigmoid knotting is an unusual form of volvulus seen in developing countries with high-fiber diets and carries an extremely high mortality rate.¹² A constrictive knot is formed by a redundant sigmoid colon and an elongated ileum. One acts as the active portion and the other as the passive portion of an ileosigmoid knot. Constriction of the sigmoid colon by an elongated ileum occurs more commonly than an ileal knot by the sigmoid colon, which was seen in one of the patients discussed in this report. To our knowlege, there have been no previous reports of ileosigmoid knotting in a patient with sickle cell disease.

Conclusion
Our report describes two patients with sickle cell disease who had acute abdominal pathology that required surgical intervention. One had ischemic colitis, underwent a segmental colectomy, and had an uneventful recovery. The other had a rapidly deteriorating course due to an extremely rare cause of primary small bowel obstruction and died before surgery could be undertaken. Both patients were initially thought to be experiencing painful vasoocclusive crises, which can be difficult to distinguish from other diseases involving the abdomen. Performing early CT scans should be strongly considered for patients with sickle cell disease and unusual abdominal pain. Although laparoscopy was not used for either of our patients, it may be a useful modality as well, especially when one is faced with diagnostic uncertainty.

Acknowledgments
We would like to thank Drs. Michael Harris and Sharon Zisman for their clinical expertise.

References
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