To the Editor: An 85-year-old woman with new-onset atrial fibrillation was started on warfarin and abdominal subcutaneous injection of enoxaparin 40 mg every 12 hours. On the third day, she complained of severe left lower quadrant abdominal pain that increased upon sitting up. Physical examination revealed a firm, tender left lower quadrant mass. Carnett's test was positive. Blood tests showed a drop in hemoglobin of 2 g/dL and mild leukocytosis. A computed tomography of the abdomen and pelvis showed a left rectus sheath hematoma (RSH) (Figure 1). Anticoagulation was held, and two units of fresh frozen plasma and two units of packed red blood cells were transfused. The hematoma stabilized, and hemoglobin rose to baseline levels. At 2-month follow-up, the patient was still doing fine. Computed tomography scan showing left rectus sheath hematoma (arrow). RSH is a rare cause of acute abdomen. It is due to a tear of the epigastric vessels (A. epigastrica superficialis) usually in the lower quadrant muscles.1 It has been associated with anticoagulation,2 abdominal trauma, pregnancy, subcutaneous abdominal injections of medications (low-molecular-weight heparin, insulin, and goserelin), severe bouts of coughing (causing sudden increase of intra-abdominal pressure), hemodialysis (anticoagulation with heparin during dialysis) or peritoneal dialysis (cannula insertion), laparoscopic procedures such as cholecystectomy, connective tissue diseases (such as Ehlers-Danlos), and hematological disorders.1 Spontaneous RSH is common in elderly people, especially those with cardiovascular disease.3 In two studies, elderly women were particularly at risk, with a female to male ratio of approximately 12:1.4,5 The majority of these patients were receiving subcutaneous injection of heparin, and many of them did not show excessive anticoagulation activity.5 RSH is reported even with the use of subcutaneous low-dose heparin, possibly due to accidental intramuscular abdominal injection and tearing of the epigastric vessels.6 Some elderly women might have a thin rectus abdominis, making them prone to accidental injury of the epigastric vessels during subcutaneous abdominal injections. On physical examination, the mass is tender, is on one side of the abdomen, and does not cross the midline. Carnett's test is usually positive.7 Carnett's test helps to differentiate pain originating from the abdominal wall from pain arising from intra-abdominal disorders.8 The site of maximal abdominal tenderness is palpated while the patient is lying supine. If the tenderness increases when the patient sits halfway up, then the test is said to be positive.8 In this case, the source of the abdominal pain is located in the abdominal wall muscles. If the tenderness is relieved, then the cause of pain is likely to be visceral, because the contracted rectus muscle protects the intra-abdominal viscera, and the test is said to be negative.8 In RSH, Carnett's test is positive, because the contraction of the rectus muscle compresses the hematoma and worsens the tenderness.7 On blood tests, there is always evidence of sudden onset anemia secondary to blood loss. The anemia can be severe, leading to hypovolemic shock.9 Other diagnostic modalities include ultrasound and computed tomography, the latter of which is preferred as a more-accurate imaging study than ultrasound.4 Treatment is variable depending on the speed and extent of the bleeding as well as the presence of comorbidities. It can be conservative, as in this case, in which bleeding stopped spontaneously after discontinuing anticoagulation treatment.4 Correction of the hypovolemia with intravenous fluids and blood transfusion is a priority. Fresh frozen plasma can be given if there is overanticoagulation. In some reports, bleeding was stopped through catheter coil embolization of the inferior epigastric artery.9 In other situations, surgical evacuation of the hematoma may be necessary. In high-risk patients such as elderly women and those with uremia, hemodyscrasia, or tendency to paroxysmal cough, a proper technique of injection in the subcutaneous abdomen should be sought. Alternatively, another site of subcutaneous injection of heparin such as the thigh may be preferable to abdominal subcutaneous injections.6 It might also be preferable not to use low-molecular-weight heparin in elderly patients because of their long bioavailability and the difficulty of rapidly reversing their action, as well as the difficulty of assessing the degree of anticoagulation, especially in the setting of renal dysfunction common in elderly populations. Financial Disclosures: The author, Dr. Fadi I. Jabr, has no financial disclosures to report in relation to this letter. Author Contributions: Dr. Fadi Jabr is the sole author of this letter. Sponsor's Role: No sponsor for this letter.
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Jan 1, 2024
Felix Spreter + 4
Open Access
