Sinusoidal fetal heart rate pattern in severe fetal anemia from feto-maternal transfusion

Massive Feto-Maternal Hemorrhage: Diagnosis by Cardiotocography, Doppler Ultrasonography and ST Waveform Analysis of Fetal Electrocardiography

A 34-year-old healthy gravida 2 para 1 presented after an uncomplicated pregnancy at term with a 2-day history of diminished fetal movements. Fetal anemia was suspected by fetal heart rate monitoring and Doppler estimation of the fetal peak blood flow velocity of the middle cerebral artery. We were also fortunate to register pathological ST waveform changes of the fetal ECG indicating fetal hypoxia. The diagnosis of a massive feto-maternal hemorrhage was confirmed by an extremely high fraction of erythrocytes containing fetal hemoglobin in maternal blood and, after delivery, by placental histology.

Sinusoidal heart rate pattern: Reappraisal of its definition and clinical significance

OBJECTIVES

To address the clinical significance of sinusoidal heart rate (SHR) pattern and review its occurrence, define its characteristics, and explain its physiopathology.

BACKGROUND

In 1972, Manseau et al. and Kubli et al. described an undulating wave form alternating with a flat or smooth baseline fetal heart rate (FHR) in severely affected, Rh-sensitized and dying fetuses. This FHR pattern was called 'sinusoidal' because of its sine waveform. Subsequently, Modanlou et al. described SHR pattern associated with fetal to maternal hemorrhage causing severe fetal anemia and hydrops fetalis. Both Manseau et al. and Kubli et al. stated that this particular FHR pattern, whatever its pathogenesis, was an extremely significant finding that implied severe fetal jeopardy and impending fetal death. UNDULATING FHR PATTERN: Undulating FHR pattern may be due to the following: (1) true SHR pattern; (2) drugs; (3) pre-mortem FHR pattern; (4) pseudo-SHR pattern; and (5) equivocal FHR patterns. FETAL CONDITIONS ASSOCIATED WITH SHR PATTERN: SHR pattern has been reported with the following fetal conditions: (1) severe fetal anemia of several etiologies; (2) effects of drugs, particularly narcotics; (3) fetal asphyxia/hypoxia; (4) fetal infection; (5) fetal cardiac anomalies; (6) fetal sleep cycles; and (7) sucking and rhythmic movements of fetal mouth. DEFINITION OF TRUE SHR PATTERN: Modanlou and Freeman proposed the following definition for the interpretation of true SHR pattern: (a) stable baseline FHR of 120-160 bpm; (b) amplitude of 5-15 bpm, rarely greater; (c) frequency of 2-5 cycles per minute; (d) fixed or flat short-term variability; (e) oscillation of the sinusoidal wave from above and below a baseline; and (f) no areas of normal FHR variability or reactivity.

PHYSIOPATHOLOGY

Since its early recognition, the physiopathology of SHR became a matter of debate. Murata et al. noted a rise of arginine vasopressin levels in the blood of posthemorrhagic/anemic fetal lamb. Further works by the same authors revealed that with chemical or surgical vagotomy, arginine vasopressin infusion produced SHR pattern, thus providing the role of autonomic nervous system dysfunction combined with the increase in arginine vasopressin as the etiology.

CONCLUSION

SHR is a rare occurrence. A true SHR is an ominous sign of fetal jeopardy needing immediate intervention. The correct diagnosis of true SHR pattern should also include fetal biophysical profile and the absence of drugs such as narcotics.

Severe fetomaternal hemorrhage: a review

The etiology, clinical presentation, obstetrical antecedents, and outcome of pregnancies complicated by large fetomaternal hemorrhage (FMH) were reviewed by doing a MEDLINE search from 1966 to the present and manual search before 1966. One hundred thirty-four infants with FMH > 50 dl were reported in the literature. The primary variables: birth weight, gestational age, presence of sinusoidal fetal heart rate pattern, decrease or absent fetal body movements (FBM) estimated the amount of fetomaternal bleeding and the pretransfusion hemoglobin. Other variables included the condition of the infants at birth, erythroblasts, and reticulocyte blood counts at birth, as well as the year of publication. Thirty-five of the 134 cases were preterm. Twenty infants born to mothers reporting decreased or absent FBM survived. FBM was absent in 17 cases for a period ranging between 24 hours and 7 days. In this group, six infants survived, five were stillborn, and five died in the neonatal period. A sinusoidal heart rate (SHR) pattern was reported in 21 cases. A SHR pattern was associated with decreased FBM in 13 cases (39.3 percent). Fifteen cases with sinusoidal fetal heart rate pattern survived (71.4 percent). Both decreased or absent FBM and SHR patterns were reported more often in 1990 or later than before 1990 (P < .0017 and P < .008, respectively). The cause of FMH was not known in 82 percent of the cases. The most common presenting symptoms of FMH were anemia at birth (35.2 percent), decreased or absent FBM (26.8 percent), and unexpected stillbirths (12.5 percent). Seventeen intrauterine transfusions were performed in nine cases (eight survived). A negative correlation was found between pretransfusion hemoglobin and FMH (r = -0.35; P = .0019). No significant difference was found between the cases with FMH of > 200 ml or < 200 ml. Thus, decreased or absent FBM, SHR pattern, or hydrops fetalis are late signs of FMH. Other means of early detection are needed. The role of intrauterine transfusion (IUT) needs to be better defined. The inadequate outcome data indicate the need to follow infants born with large FMH into childhood to document the effect on the central nervous system.

Sinusoidal fetal heart rate pattern due to massive feto-maternal transfusion

A 30-year-old woman presented with mild abdominal discomfort and decreased fetal movements in the 34th week of her third pregnancy. Fetal monitoring revealed a sinusoidal heart rate pattern, and abdominal delivery was promptly performed, with the newborn having a hematocrit of 7% due to massive fetomaternal transfusion. Fetal resuscitation was followed by a favorable outcome. The sinusoidal heart rate is discussed, with emphasis on the need for proper and prompt recognition of its significance.

Continuous twenty-four hour recording of the fetal cardiac rhythm during normal pregnancies

Recording the fetal cardiac rhythm (FCR) is currently the technique most widely used to assess the well being of the fetus. In view of the importance of the decisions taken on the modifications of the FCR, the authors have recorded and analysed over 24 consecutive hours 10 resting women manifesting a strictly normal pregnancy. They observed no modification in the basal cardiac frequency, very few declarations and above all, never any signs of a flat or sinusoidal rhythm. Flattening of the FCR is invariably pathological. It must not be interpreted as "fetal sleep" period, but it should intensify the surveillance.

Acute feto-maternal transfusion--diagnostic considerations

A sinusoidal fetal heart rate pattern followed by severe deceleration was encountered in a fetus at 39 weeks' gestation during antepartum fetal nonstress testing. The only indication for fetal monitoring was a maternal complaint of cessation of fetal movements. The abdominally-delivered newborn was found to be severely anaemic and the cord was tightly wrapped round its body. A pathophysiological mechanism for massive feto-maternal transfusion is suggested. Various laboratory tests were utilized to identify the condition, quantitate the amount of transfusion, and estimate the time of its occurrence. Globin synthesis studies in maternal blood indicated that a significant fetal blood loss had occurred within 24 hours of delivery. The significance of these findings as applied to the clinician is discussed.