Abdominocentesis

Chapter 155 Abdominocentesis



Karl Jandrey, DVM, DACVECC



KEY POINTS



• Cytology of peritoneal fluid obtained by abdominocentesis may yield a diagnosis and lead to further directed therapy or emergency surgery.

• The focused assessment with sonography for trauma, or FAST, protocol is a rapid and simple technique to detect free abdominal fluid. A needle paracentesis may be successful if directed toward the identified areas.

• A blind-needle paracentesis may yield peritoneal fluid when 5.2 to 6.6 ml/kg of abdominal fluid is present.

• A peritoneal dialysis catheter used for abdominocentesis may detect the presence of 1 to 4.4 ml/kg of abdominal fluid.

• Complications of abdominocentesis include the introduction or spread of infection, laceration of a viscus, and hemorrhage from a punctured vessel or organ.


INTRODUCTION


Frequent physical examinations are the most informative portion of the diagnostic evaluation of an emergency or intensive care patient with abdominal disease. Assessment of the abdomen should be as complete as time and the patient’s condition permit. Increasing abdominal size and progressive pain can be important clues for intraabdominal injury. Consequently, measurements of the abdominal girth at the umbilical level should be made soon after admission. This baseline measurement can be used to assess subsequent significant changes. Abdominal rigidity and tenderness are important clinical signs of peritoneal irritation by blood or intestinal contents. Although physical examination findings can help in the discovery of abdominal disease, they do not further a diagnosis. Samples of peritoneal fluid obtained by abdominocentesis, however, may yield the diagnosis of an abdominal disease process and lead to directed and specific therapy.



INDICATIONS


Indications for abdominocentesis are (1) radiographic loss of serosal detail, (2) abdominal injury without obvious peritoneal entry wounds, (3) shock, multiple injuries, or signs of abdominal injury after blunt trauma, (4) head or spinal injury precluding reliable abdominal examination, (5) persistent abdominal pain or fluid distention of unknown cause, and (6) postoperative complications possibly caused by leakage from an enterotomy or anastomotic site.1 Periumbilical ecchymosis (Cullen sign) may indicate hemorrhage in the peritoneum or retroperitoneum. Contraindications to abdominocentesis include coagulopathy, organomegaly, or distention of an abdominal viscus. Intestinal or uterine penetration is rare unless the viscus is dilated and adherent to the abdominal wall.2 Complications include the introduction or spread of infection, laceration of a viscus, and hemorrhage from a punctured vessel. Following the techniques described below will reduce the risk of complications.



TECHNIQUE


Abdominocentesis is completed using a single paracentesis or four-quadrant approach. Single paracenteses are done with an open-needle or a closed-needle technique. Ultrasonographic guidance can highlight a smaller accumulation offluid and allow for a more directed approach for abdominocentesis.



Focused Assessment With Sonography for Trauma


The focused assessment with sonography for trauma, or FAST, protocol was studied in dogs to prove that it is a rapid and simple technique to detect free abdominal fluid in the emergency room by veterinary clinicians with minimal previous ultrasonography experience.3 This technique scanned four regions in longitudinal and transverse planes of the abdomen with dogs in lateral recumbency. These regions are areas where fluid accumulation commonly occurs: caudal to the xiphoid process, midline over the urinary bladder, and each flank. Of 100 dogs studied within 24 hours of a motor vehicle accident, 45 had free abdominal fluid. A diagnosis was made in all 40 of the dogs that received an abdominocentesis (29 with ultrasonographic guidance); 38 had hemoabdomen, 2 had uroabdomen. Diagnostic peritoneal lavage was not performed on any of the dogs.



Patient Preparation


Patient positioning in left lateral recumbency may be most effective to avoid puncture of the spleen. Restraint may be completed manually or with sedatives and analgesics. Before the abdomen is penetrated, a wide surgical clip and preparation of the site using aseptic technique must be completed along the ventral midline centered at the umbilicus (Color Plate 155-1). If abdominal ultrasonography has revealed a focal area of peritoneal fluid accumulation, a standard aseptic clip and preparation of that location is prudent.



Closed-Needle Abdominocentesis


A closed-needle diagnostic abdominocentesis can be completed using a 20- or 22-gauge needle placed on an extension set that is attached to a 6- or 12-cc syringe. Local anesthetic infusion of 2% lidocaine may be used at the abdominocentesis site. Penetration of the abdominal cavity can be completed in the right cranial quadrant caudal to the edges of the liver, because peritoneal fluid is gravity dependent and the falciform fat may extend along midline to the umbilicus. Gently insert the needle completely at this site and avoid further movement of the needle tip to prevent laceration of internal structures. Withdraw the peritoneal fluid and observe for clots if the fluid is hemorrhagic. Fluid within the abdominal cavity should not clot; hemorrhagic fluid obtained from puncture of the spleen, liver, or any vessel will clot readily. If the abdominal fluid clots, remove the needle and attempt abdominocentesis in another location. Cytologic and biochemical analysis and culture of the abdominal fluid should be completed immediately after removal.


A closed-needle abdominocentesis may also be used for therapeutic removal of peritoneal fluid. Therapeutic removal of large volumes of fluid may be indicated if the abdominal distention impairs diaphragmatic motion, increases abdominal pressure impeding blood flow to the visceral organs, or causes pain. To maintain a closed system, a three-way stopcock can be placed between the syringe and extension set. Another extension set placed on the stopcock can be directed into a bowl or graduated cylinder. Free gas should not be evident on radiographs after a closed-needle abdominocentesis.

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Sep 10, 2016 | Posted by in SMALL ANIMAL | Comments Off on Abdominocentesis

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