Fetal heart rate pattern during decompression of a hydrocephalic head.. Case report

British Journal of Obstetrics and Gynaecology August 1986, Vol. 93, pp. 881-882

Fetal heart rate pattern during decompression of a hydrocephalic head. Case report MIRIAM KATZ, ISRAEL MEIZNER, ARNON WIZNITZER, ZION J . HAGAY

Case report A 23-year-old primigravida, at approximately 40

weeks gestation, was admitted to the Soroka Medical Centre delivery room in active labour. Her past medical and family history were unremarkable and according to her, the present pregnancy had been uneventful. She had not attended for antenatal care and was seen for the first time by an obstetrician in the delivery room. On admission, her blood pressure was 110/ 70mmHg with a regular pulse rate of 80/min. General physical examination revealed no abnormalities. The uterine height was 43 cm, she had a singleton fetus in vertex presentation, with the head high above the pubic brim. An ultrasound scan demonstrated a hydrocephalic fetal head with a biparietal diameter of 11.4cm and brain cortex thickness of 0.6 cm. The cervix was fully effaced and 8 cm dilated. External monitoring recorded regular uterine contractions and an internal scalp electrode registered baseline bradycardia with normal baseline variability (Fig. 1A). TO enable vaginal delivery, transabdominal puncture of the hydrocephalic head was performed and under ultra-

Department of Obstetrics and Gynaecology, Soroka University Hospital and Faculty of Health Sciences, Ben-Gurion University of the Negev, P.O. Box 151, Beer-Sheva 84101, Israel MIRIAM KATZ Senior Lecturer ISRAEL MEIZNER Lecturer ARNON WIZNTTZER Resident ZION J . HAGAY Resident Correspondence: Miriam Katz

sonic guidance, 400 ml of cerebrospinal fluid was drained. During the decompression, the fetal heart rate was monitored continuously and Fig. 1B shows the fetal heart rate pattern after drainage of cerebrospinal fluid. Baseline heart rate changed from severe to moderate bradycardia. Shortly thereafter the patient was delivered spontaneously of a stillborn 3.8 kg male infant. The post mortem diagnosis was severe hydrocephalus with no other concomitant malformation.

Comment The normal fetal heart rate pattern is the result of interaction between the sympathetic and parasympathetic components of the autonomic nervous system (Renou et al. 1969). Elevated intracranial pressure (head compression) has been found to cause persistent baseline bradycardia (Mocsary et al. 1970; Young & Weinstein 1976). It is therefore consistent that elevated intracranial pressure caused severe baseline bradycardia in the present case. The drainage of cerebrospinal fluid caused a dramatic shift from overtly abnormal to normal fetal heart rate pattern. This provides convincing evidence that intracranial pressure plays a critical role in the pathophysiology of fetal heart rate patterns.

References Mocsary, P., Gaal, J. D . , Komaromy, B., Mihaly, G. Y., Pohanka, D. & Suranyi. S. (1970)Relationship between fetal intracranial pressure and fetal heart

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Fig. 1. Cardiotocograph showing (A) bradycardia with normal variability before puncture and (B) rise of basal heart rate with normal variability after drainage of 400 ml of cerebrospinal fluid. rate during labour. Am J Obstet Gynecol106,407411. Renou, P., Newman, W. & Wood, C. (1969) Automatic control of fetal heart rate. Am J Obstet Gynecol 105, 949-953. Young, B. K. & Weinstein, H. M . (1976) Moderate

fetal bradycardia. Am J Obstet Gynecol 126, 271274.

Received 5 December 1985 Accepted 30 Junuury 2986