Atlas of Procedures in Neonatology, 4th Edition

Miscellaneous Sampling


Subdural Tap

  1. Lee Woods
  2. Indications (1,2,3 4)
  3. To diagnose acute subdural collection over the cerebral convexities (hemorrhage, effusion, empyema) (5,6,7,8 and 9)

Computed tomography (CT), now generally available, is a safer method for detecting subdural fluid. Subdural tap should be reserved as a diagnostic tool for the infant who is too unstable to be transported for CT scanning.

  1. To sample convexity subdural collection for hematologic, microbiologic, and biochemical studies
  2. To drain convexity subdural collection to reduce increased intracranial pressure or to prevent the development of craniocerebral disproportion

Repeated therapeutic subdural taps should not be performed unless the infant is symptomatic or the head size is growing rapidly. Surgical intervention is indicated if subdural taps are not effective in controlling these symptoms (3).

  1. Contraindications
  2. Clinical instability when risk exceeds potential benefit
  3. Uncorrected thrombocytopenia or bleeding diathesis
  4. Infection in the skin or underlying tissue at or near the puncture site
  5. Equipment

All equipment must be sterile, except safety razor and facemask.

  1. Gloves and facemask
  2. Cup with iodophor antiseptic solution
  3. Gauze swabs
  4. Drapes or surgical towels
  5. Two short bevel needles, 19 to 22 gauge x 1 in, with stylets
  6. Specimen tubes with caps
  7. Adhesive bandage
  8. Safety razor
  9. Precautions
  10. Use strict aseptic technique as for a major procedure (see Chapter 4).
  11. Insert the needle as far laterally as possible at the border of the anterior fontanelle or along the coronal suture, at least 1 to 2 cm from the midline, to avoid puncturing the sagittal sinus. Do not direct the needle medially during insertion.
  12. Remove the needle if there is not a definite change in resistance on penetrating the dura after insertion to approximately 0.5 to 1 cm.
  13. Hold the needle securely at all times to avoid inadvertent movement of the needle tip. Grasp the needle firmly or apply a hemostat at approximately 1 cm from the beveled end of the needle to prevent inadvertent advancement of the needle into the cerebral cortex.
  14. Allow fluid to drain spontaneously. Do not aspirate with a syringe.
  15. Limit fluid collected to 15 to 20 mL from each side. Removal of larger volumes can lead to bleeding into the subdural space.
  16. If frequent taps are required, vary the puncture site slightly to prevent fistula formation.
  17. Following the procedure, apply pressure to the scalp for 2 to 3 minutes to prevent fluid leak from the puncture site or subgaleal fluid collection.
  18. Technique (1,10,11)
  19. Place the infant supine, with the crown of the head at the table edge. Monitor cardiorespiratory status.
  20. Have the assistant restrain the infant and steady the infant's head (Fig. 17.1).
  21. Shave the head over a wide area surrounding the anterior fontanelle (Fig. 17.1).
  22. Locate the junctions of the coronal sutures and anterior fontanelle.
  23. Put on mask. Wash hands thoroughly and put on sterile gloves.



FIG. 17.1. Position and restraint for subdural tap. Stippling demonstrates area to be prepared for procedure. An arrow indicates site for needle puncture.

  1. Clean the fontanelle and surrounding area three times with antiseptic solution. (See Chapter 4 for aseptic preparation for major procedure.)
  2. Begin at the fontanelle and wash in enlarging circles.
  3. Allow antiseptic to dry. Blot excess with sterile gauze.
  4. Cover infant's head with sterile drapes, leaving the anterior fontanelle and the infant's nose and mouth exposed.
  5. 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 sites (1,12,13,14 and 15).

  1. Insert the needle slowly through the coronal suture, just lateral to its junction with the anterior fontanelle (see Fig. 17.1).
  2. Hold the needle perpendicular to the skin surface.
  3. 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. 17.2).
  4. 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.
  5. Advance until a “pop” is felt upon penetrating the dura. Remove the stylet (Fig. 17.2).
  6. Allow fluid to drain spontaneously into the sterile tubes until flow ceases or a maximum volume of 15 to


20 mL is reached. Fluid is sent for protein content, cell count, and culture.

  1. If no fluid appears, replace the stylet and remove the needle slowly. Do not reinsert on the same side.
  2. Repeat the procedure on the opposite side with a new, sterile needle.
  3. After removing the needle, apply firm pressure to the puncture site with sterile gauze for 2 to 3 minutes.
  4. Dress the puncture site with a small adhesive bandage.

FIG. 17.2. 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.

  1. Complications (10,11)
  2. Subdural bleeding from laceration of the superior sagittal sinus or smaller vessels or from removal of excessive fluid with shift of intracranial contents and rebleeding
  3. Development of chronic subdural fluid collection (16,17)

This complication may develop more frequently in infants treated with subdural tap. In one series of cases, 41.6% of patients treated with subdural tap developed chronic subdural collections, compared with 13% of those treated with craniotomy (17).

  1. Subgaleal fluid or blood accumulation
  2. Failure of the procedure to remove clotted subdural blood
  3. Infection

In one small series of cases, 1 of 12 infants (8%) treated with subdural tap developed subdural empyema after multiple taps (17).

  1. Trauma to the underlying cortex caused by inserting the needle too far
  2. Fistula formation after repeated taps


  1. Haslam RHA.Neurologic evaluation. In: Behrman RE, Kliegman RM, Jenson HB, eds. Nelson Textbook of Pediatrics. 17th ed. Philadelphia: Saunders; 2004:1973.
  2. Brett EM, Harding BN.Intracranial and spinal cord tumours. In: Brett EM, ed. Paediatric Neurology. 3rd ed. New York: Churchill Livingstone; 1997:537.
  3. Volpe JJ.Intracranial hemorrhage: subdural, primary subarachnoid, intracerebellar, intraventricular (term infant), and miscellaneous. In: Neurology of the Newborn. 3rd ed. Philadelphia: Saunders; 1995:373.
  4. Curless RG.Subdural empyema in infant meningitis: diagnosis, therapy, and prognosis. Childs Nerv Syst. 1985;1:211.
  5. Hobbs C, Childs A-M, Wynne J, et al. Subdural hematoma and effusion in infancy: an epidemiological study. Arch Dis Child.2005;90:952.
  6. Ney JP, Joseph KR, Mitchell MH.Late subdural hygromas from birth trauma. Neurology. 2005;65:517.
  7. Whitby EH, Griffiths PD, Rutter S, et al. Frequency and natural history of subdural haemorrhages in babies and relation to obstetric factors. Lancet.2004;363:846.
  8. Young S, MacMahon P, Kovar IZ.Subdural intravenous fat collection: an unusual complication of central intravenous feeding in the neonate. J Parenter Enteral Nutr. 1989;13:661.
  9. Stine MJ, Harris H.Subdural collection of intravenous fat emulsion in a neonate. Complication of central venous catheterization for total parenteral nutrition. Clin Pediatr. 1985;24:40.
  10. Barone MA.Pediatric procedures. In: McMillan JA, Feigin RD, DeAngelis CD, et al., eds. Oski's Pediatrics: Principles and Practice. 4th ed. Philadelphia: Lippincott Williams & Wilkins; 2006:2671.
  11. Ferriero D, Buescher ES.Central nervous system. In: Taeusch HW, Christiansen RO, Buescher ES, eds. Pediatric and Neonatal Tests and Procedures. Philadelphia: Saunders; 1996:409.
  12. Anand KJ, Johnston CC, Oberlander TF, et al. Analgesia and local anesthesia during invasive procedures in the neonate. Clin Ther.2005;27:844.
  13. O'Brien L, Taddio A, Lyszkiewicz DA, et al. A critical review of the topical local anesthetic amethocaine (Ametop) for pediatric pain. Paediatr Drugs.2005;7:41.
  14. Kaur G, Gupta P, Kumar A.A randomized trial of eutectic mixture of local anesthetics during lumbar puncture in newborns. Arch Pediatr Adolesc Med. 2003;157:1065.
  15. Taddio A, Ohlsson A, Einarson TR, et al. A systematic review of lidocaine–prilocaine (EMLA) in the treatment of acute pain in neonates. Pediatrics.1998;101:e1.
  16. Katona F, Balazsm, Berenyi M, et al. Subdural effusion in the first six months of life. Acta Paediatr Acad Sci Hung.1982;23:219.
  17. Gutierrez FA, Raimondi AJ.Acute subdural hematoma in infancy and childhood. Childs Brain. 1975;1:269.