Prospective Studies in Progress Drainage of Abdominal Abscesses With or Without Instillation of Fibrinolytic Agents

This is a single institution, prospective, randomized clinical trial involving patients who present to Children's Mercy Hospitals and Clinics with perforated appendicitis with an abscess or are diagnosed with an abscess following appendectomy and have a drain inserted as part of their postoperative abscess care.

Drains will not be placed for research purposes only. This will be a definitive study. The primary outcome variable is length of hospitalization after drainage.

A power calculation was based on the mean and standard deviation from our previous prospective trial on the treatment of patients presenting with an appendiceal abscess who were managed with a drain (Journal of Pediatric Surgery 45:236-240, 2010). In our previous prospective trial on abscess drainage, the mean time in the hospital after drainage was 3.6 days. We believe the new protocol could ideally reduce this need for hospitalization to 2.5 days after drainage. With a generous estimated standard deviation of two days using a power of 0.8 and significance established at α = 0.05, analysis yielded a need of 31 patients in each arm.

After drain placement, one group is managed per current institutional protocol which consists of flushing the drain with 13 mL of normal saline twice a day. Previously, 10 mL was used but in preparation for this study, a drain was filled with fluid to determine the volume in the drain and saline ran out of the holes in the end of the tube when three mL was injected. Since this three mL remains in the drain, by using 13 mL, we are assured that 10 mL of solution will reach the abscess.

The other group undergoes the same drain placement, but the drain will be flushed with a solution containing tissue plasminogen activator (tPA). The tPA solution consists of 1.3 mg of tPA in 13 mL of normal saline. The drain is flushed with the solution at the time of placement, then twice a day while the drain is in place. If the abscess will not accept 13 ml, then the amount that can be instilled with gentle manual syringe pressure is used.

In both groups, the drain will be managed by both the interventional radiologists and the surgeons and discontinued when the drainage has decreased to under or near 20 cc/day. Drains are discontinued on agreement between the radiologist and involved surgeon. The radiologist determines the need for repeat imaging for patient management.

Daily management is typically performed by the surgery service with radiology input depending on the day and time of day.

Both groups will have the same antibiotic regimen on the basis of our previous prospective trials and as required/tolerated by the patient.

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