110 Section IV ■ Miscellaneous Sampling

6. Clean the fontanelle and surrounding area three times

with antiseptic solution. (See Chapter 5 for aseptic

preparation for major procedure.)

a. Begin at the fontanelle and wash in enlarging circles.

b. Allow antiseptic to dry. Blot excess with sterile gauze.

7. Cover infant’s head with sterile drapes, leaving the

anterior fontanelle and the infant’s nose and mouth

exposed.

8. Locate the coronal suture by palpation at the lateral

corner of the anterior fontanelle.

 Generally, anesthesia is not required, but local injection of lidocaine at this time or application of topical

anesthetic cream prior to cleaning the area can be used

for local anesthesia at the puncture site (1,10–13).

9. Insert the needle slowly through the coronal suture,

just lateral to its junction with the anterior fontanelle

(see Fig. 18.1).

a. Hold the needle perpendicular to the skin surface.

b. Grasp the needle shaft with thumb and index finger, bracing the hand against the infant’s head to

maintain control of the needle during insertion

(Fig. 18.2).

c. As the needle advances through the skin, pull the

scalp slightly to create a Z-like track through the

underlying tissue. This will help prevent fluid leakage from the puncture site or into the subgaleal

space after removal of the needle.

10. Advance until a “pop” is felt upon penetrating the dura.

Remove the stylet (Fig. 18.2).

11. Allow fluid to drain spontaneously into the sterile tubes

until flow ceases or a maximum volume of 15 to 20 mL

is reached. Send fluid for protein content, cell count,

and culture.

12. If no fluid appears, replace the stylet and remove the

needle slowly. Do not reattempt procedure on the same

side.

13. Repeat the procedure on the opposite side with a new,

sterile needle.

14. After removing the needle, apply firm pressure to the

puncture site with sterile gauze for 2 to 3 minutes.

15. Dress the puncture site with a small adhesive bandage.

Fig. 18.1. Position and restraint for subdural tap. Stippling

demonstrates area to be prepared for procedure. An arrow indicates site for needle puncture.

Fig. 18.2. Coronal section of anatomic drawing showing subdural needle penetrating the dura in a patient with

bilateral convexity subdural fluid collections. Operator’s

fingers are placed for maximal stabilization of the needle.