30. Paracentesis: Abdominal

Learning outcomes

By the end of this section, you should know how to:

▪ prepare the patient for this procedure

▪ collect and prepare the equipment

▪ assist the medical practitioner with abdominal paracentesis as required.

Background knowledge required

Revision of the anatomy and physiology of the abdominal organs, with special reference to the peritoneum

Revision of ‘Aseptic technique’ (seep. 381)

Revision of ‘Infection prevention and control’ (seep. 151).

Indications and rationale for abdominal paracentesis

Abdominal paracentesis is the removal of fluid from the peritoneal cavity through a sterile cannula or needle (Campbell 2001). Medication is sometimes introduced into the peritoneal cavity by the same route. The procedure may be performed for the following reasons:

▪ to obtain a specimen of abdominal fluid for diagnostic purposes

▪ to relieve intra-abdominal pressure caused by increased fluid within the abdominal cavity. This is called ascites and may occur in association with several conditions:

— congestive cardiac failure involving dysfunction of the right side of the heart

— chronic hepatic disease

— malignant disease with metastases in the liver

▪ to introduce medication into the peritoneal cavity, e.g. cytotoxic therapy for malignant disease.

Outline of the procedure

Abdominal paracentesis is carried out by a medical practitioner using an aseptic technique. A mask and sterile gown, as well as sterile gloves, should be worn.

The site of insertion is midway between the umbilicus and the symphysis pubis along the midline. The skin is cleansed with antiseptic lotion and a local anaesthetic is administered, the area round the site being covered with sterile towels. A small skin incision is made with a sterile blade, and a trocar and cannula or a catheter and introducer are inserted into the peritoneal cavity. The trocar/introducer is removed, allowing fluid to flow through the cannula. The specimens of abdominal fluid required for investigation are collected at this stage by holding the appropriately labelled sterile containers under the flow of fluid, maintaining asepsis. The cannula may be removed and a sterile dressing applied, or it may be stitched in position and attached to sterile tubing and a closed drainage bag if drainage is to be maintained. A suitable sterile dressing should be applied around the cannula.

The flow of drainage fluid is regulated with a gate clamp or roller clamp to prevent too rapid a reduction of intra-abdominal pressure. Initially, only 1L of fluid should be allowed to drain, before regulating the flow to 100 ml per hour or as prescribed by the medical practitioner. This should prevent the patient developing symptoms of shock because of the sudden lessening of pressure in the abdominal cavity.

In palliative care settings having a drainage catheter in situ may be considered, to reduce the discomfort associated with ascites (McNamara 2000). Some patients may be managed at home (Moorsom 2001).