J. Perinat. Med. Fetal anemia and heart rate patterns

Kariniemi: Anemia and heart rate 167

J. Perinat. Med.10 (1982)167

Fetal anemia and heart rate patterns

Veikko Kariniemi

Ist Department of Obstetrics and Gynecology,Helsinlci University Central Hospital, Helsinki, Finland

1 Introduction

Fetal heart rate (FHR) changes related to fetalanemia have not been investigated comprehen-sively. MODANLOU et al. [16] reported a case ofsevere fetal anemia due to a massive fetomaternaltransfusion of a fetus at 34 weeks of gestation.The newborn did well after cesarean section andneonatal intensive care. More recently, four othercase reports on severe fetal anemia have beenpublished [21, 8, 17,20]. A special morphologicalFHR pattern, the sinusoidal FHR curve, was ob-served in all five cases, although it was not recog-nised in one [21]. MANSEAU et al. [14] were thefirst to describe the sinusoidal FHR pattern, whichthey observed in nine Rh-immunized fetuses withpoor outcome. Later on, the association betweenthe sinusoidal heart rate pattern and Rh-immuniza-tion has been confirmed [18, 7, 22]. The sinus-oidal FHR pattern has also been attributed to amore diverse group of fetal distress [13, l, 3, 4, 5,15, 12, 23] and impending fetal death. Thesereports have in common that fetal hemoglobin(Hb) concentration was usually not determined.This report was prompted by observation of thesinusoidal FHR pattern in several cases of fetalanemia and by the diverse opinions regarding thepathophysiology of the pattern.

2 Material and methods

The anemic fetuses were searched from the recordsof those fetuses which received transfusions or ex-change transfusions in the years 1978 and 1979 at

Helsinki University Central Hospital. The cut-offlevel for Hb concentration in peripheral blood ofthe neonate was chosen 170 g/liter according to anormal material in the same hospital [9]. The cut-off level for umbilical Hb of the preterm babiesand for Hb of intrapartum capillary blood ofthe samples was chosen from the report of BUR-MAN and MORRIS [2].Two-hundred and thirty-five among 11976 infantsborn during this two-year period (2%) receivedtransfusions or exchange transfusions. Eighty-threeof them had thus defined anemia (0.7%). Thispopulation was divided into two groups: 13fetuses with Hb less than 80 g/liter (severe anemia)and 70 fetuses with Hb values between 80 and169 g/liter (moderate anemia). The antepartumdiagnoses, complications during labor and delivery,the mean durations of pregnancies, the meanweights of the newborn, the modes of delivery,and the fetal outcome s in these groups are shownin Tab. I. Hb values were estimated äs cyan-methemoglobin spectrophotometrically. Fetalanemia was detected in 19 fetuses by fetal bloodanalysis (FBA) performed according to SALING[19]. Neonatal anemia was detected from umbili-cal artery in 20 infants and from peripheral bloodduring the first day of life in 44 infants. All ofthese were presumed to have fetal anemia, since noneonatal bleeding was observed in them.All fetuses were electronically monitored ante- orintrapartum. All CTGs except two (case one withabdominal and case six with direct electro-cardio-graphy) were recorded by ultrasound. The cardio-

0300-5577/82/0010-0167$02.00© by Walter de Gruyter & Co. - Berlin · New York

168 Kariniemi: Anemia and heart rate

Tab. I. The gestational ages at birth, birthweights, modesof delivery, complications and clinical diagnoses in 13cases of severe and 70 cases of moderate fetal anemia.

Severeanemia

Moderateanemia

Hemoglobin concentrationg/liter (mean ± SD) 57 ± 16

(ränge) 30 - 77N 13Gestational age 35.4 ±4.2at birth weeks (mean ± SD)Birthweight g (mean ± SD) 2313 ± 685

(ränge) 1150-3150Cesarean sections 10Perinatal deaths 4APGAR score < 7 8

vt Causes of anemia- Rh-immunization 7- ABOimmunization -- KELL-immunization l- Fetomaternal 3

transfusions- Fetofetal transfusions -- Abruptio placentae 2- Unknown -

141 ± 19106-1697035.2 ± 4.1

2420 ± 968575-4250

327

27

353

25

24

3 Results

Thirty-eight of the anemic fetuses showed latedecelerations, 29 dient and nine sinusoidal FHRpatterns. No abnormal FHR patterns were seen inthe control material.The clinical data and FHR patterns related tosevere fetal anemia are shown in Tab. II and thoserelated to moderate fetal anemia and sinusoidalFHR pattern in Tab. III. Late decelerations andsinusoidal patterns were significantly more oftenassociated with severe than with moderate anemia(Tab. IV). Silent pattern of FHR was also moreoften associated with severe than with moderateanemia, but the difference was not significant inthis material.The fetal outcome after the sinusoidal FHRpattern was poorer than after FHR patterns with-out sinusoidal periods, but the differences werenot significant in this material (Tab. V).The nine sinusoidal FHR patterns found in thismaterial are reproduced in Fig. l a and Fig. 2. Inall but case one, the sinusoidal FHR pattern wasintermittent. Five other FHR patterns with sus-pected sinusoidal patterns were found in the groupof severe fetal anemia (Fig. Ib).

-Ttocograms were evaluated visually. Late decelera-tions (LD) were recorded when two or more latedecelerations were observed. Silent pattern ofFHR (SP) was recorded when baseline FHR varia-bility was less than five beats per minute for fiveminutes or more. Sinusoidal FHR pattern wasdefined äs smoothed, rounded oscillation of FHRtwo to three cycles per minute with an amplitudeup to 40 beats per minute and lasting for at leastone minute.The control material consisted of 65 normal preg-nancies, of which more than 500 samples of FHRwere recorded by abdominal electrocardiography[11]. The incidence of abnormal FHR patterns insevere anemia was compared with that in moderateanemia to find out the possible' specific marker ofanemia. The statistical significance was calculatedby the 2 test with YATES' correction.

Fig. la. The sinusoidal periods of carcliograms found infetuses with severe anemia.

J. Perinat. Med. 10 (1982)

Kariniemi: Ancmia and hcart rate 169

Tab. II. The clinical data and fetal heart rate patterns associated

Clinical diagnosis

1. Rh-immunization2. Fetomaternal

transfusion3. Rh-immunization4. KELL-immunization5. Fetomaternal

transfusion6. Rh-immunization7. Rh-immunization8. Fetomaternal

transfusion9. Rh-immunization

10. Rh-immunization

11. Rh-immunization12. Hepatosplenomegalia

TORCH-syndrome?13. Rh-immunization

Hemoglobinconcentration

g/ltter age

3033

404355

566467

6970

7171

77

6'30'

0(UA)O(UA)58'

O(FBA)0(UA)O(UA)

10'O(FBA)

73'50'

O(FBA)

Week Modeofof deliverygesta-tion

2839

383438

383540

3037

2938

39

C/SC/S

C/SC/SC/S

C/SC/SC/S

C/Ssponta-neousC/Ssponta-neoussponta-neous

with severe fetal anemia.

Birth-weight

11501550

299019002420

315024802800

20703020

12802280

2990

APGAR Peri- Fetal heart rate patternsscore natal LD sp Re_ Per_

death cord- cent-175710' ing age

time sinus-(min) oidal

l/l/l + t- +1/3 + + +

1/6 + +2/4/6 + +4/6/8 +

8 + +8 + -4/7/9 +

1/8 + +9 +

2/3 + + +7 + - +

9 - -

80 99110 (68)?

030 (16)?15 73

160 70

20 (20)?

270 120

90 (6)?18 (11)?

0

(UA = umbilical artery, FBA = fetal blood analysis, C/S = caesarean section, LD = late decelerations, SP = silcntpattern Qess than five beats per minute) of fetal heart rate)

Tab. III. The clinical data and fetal heart rate patterns associated with moderate fetal anemia and sinusoidal fetal heartrate pattern.

Clinical diagnosis Hemoglobinconcentration

g/liter age

Week Modeofof deliverygesta-tion

Birth-weight

APGAR Peri- Fetal heart rate patternsscore natal LD sp Re_ per.

175710' ™d- <*nt-1/J/1" mg agetime sinus-(min) oidal

14. Rh-immunization15. Abruptio placentae

(Gemini, B)16. Hepatogestosis

17. Rh-immunization18. Rh-immunization

110113

137

155163

9'120'

120'*

O(UA)120'

3332

33

3527?

C/SC/S

sponta-neousC/Ssponta-neous

21801440

2040

15551590

5/83/8

7 +

99/1/5

+ + 30+ - 150

470

+ + 50+ 150

1611

2

183

(UA = umbilical artery, C/S = caesarean section, LD = late decelerations, SP = silent pattern (less than five beats perminute) of fetal heart rate)


170 Kaiiniemi: Anemia and heait rate

Fig. Ib. The suspected sinusoidal periods of cardiogramsfound in fetuses with severe anemia.

Tab. IV. Fetal heart rate patterns associated with severeand moderate fetal anemia.

Severe Moderate panemia anemia

LatedecelerationsSilent pattern

Sinusoidal

yesnoyesnoyesno

1128549

27432149

565

<0.01

NS

<0.05

Tab. V. The sinusoidal fetal heart rate pattern äs an indi-cator of fetal outcome.

Sinusoidalfetal heart rate

APGAR score < 7

Perinatal death

yesnoyesno

Yes

6327

No

2945

965

P

NS

NS

A negative, but not significant linear correlation(r = - 0.68) was found befween fetal Hb concen-tration and the percentage of the sinusoidal pat-tern.

:̂ 4 Discussion

This study Supports the earlier reports which indi-cate that sinusoidal FHR pattern is suggestive offetal anemia. In this inaterial late decelerationswere even more often associated with anemia thansinusoidal pattern, but they are known to be lessspecific markers of anemia. Most often they areobserved in association with uteroplacental in-sufficiency. Late decelerations probably indicateimpairment of the oxygen transport during con-tractions, due to reduced volume of hemoglobin.According to the present study, the cause of fetalanemia and sinusoidal FHR pattern may be blood

f l L...4 l

Fig. 2. The sinusoidal cardiograms recorded from fetuseswith moderate anemia.

J. Periüat, Med. 10 (1982)


group incompatibility with subsequent hemolyticdisease of the fetus or fetal haemorrhage in feto-maternal or fetofetal transfusion and abruptioplacentae. Thus this material does not supportsome previous suggestions that sinusoidal FHRpattern would be peculiar to Rh-immunization[14, 18, 7, 22] except in the sense that Rh-diseasecauses more difflcult hemolysis than other im-munizations.The sinusoidal FHR patterns described in thisreport were found by surveying the records ofanemic neonates. Thus it does not give any answerto the question whether or not the other suggestedcauses of sinusoidal pattern, such äs placental in-sufficiency [13] or postmaturity [4] äs such, exist.Recently we have found one sinusoidal FHR pat-tern in a postmature fetus, but a coexisting anemiawas also detected. Our recent material of FHRvariability with more than 500 samples of FHRrecorded by abdominal fetal electrocardiographyduring 65 normal pregnancies does not containa single sinusoidal period, nor does the group ofsuspected intrauterine growth retardation contain

It has been suggested that a sinusoidal FHR pat-tern is a sign of impending fetal death [16, 7, 10].In this material the fetal outcome after the sinus-oidal FHR pattern was poorer than without thispattern, but the difference was not significant.This study Supports the previous investigations[16, 7] showing that in some cases even a severelyanemic fetus with a sinusoidal FHR pattern (cases3 and 4) can be saved with cesarean section, if thepattern is recognised.A previous study suggested that a fetal bloodanalysis for determination of blood pH should beperformed when a sinusoidal FHR pattern is ob-served during labor [20]. We agree with anotherreport [1] that a more comprehensive FBA withdetermination of Hb concentration and bloodgroup should be performed. It should also be con-sidered during the antepartum period, if amnioticfluid is found to be mature. A KLEINHAUER-BETKE test on maternal blood for fetal Hb mightbe helpful in diagnosing the fetomaternal trans-fusion. In this material, the test was found to bepositive in one case (case 8) and negative in two(cases 2 and 5).

The sinusoidal FHR pattern was intermittent inthis material in all but one case (case 1), in whichHb concentration was lowest. Thus this study givessome support to a previous Suggestion [22] that acontinuous sinusoidal pattern has an ominous andpossibly agonal significance. It is, however, pos-sible to save even these fetuses with cesarean sec-tion [16] or intrauterine transfusion and cesareansection [7]. It should also be noted that even witha fairly low fetal Hb (cases 2 and 4) the sinusoidalpattern is only intermittently observable. Thechanging amplitude of the sinusoidal pattern (äs inFig. 2) even to a silent patterns (äs in case 8)makes the pattern intermittent and difficult torecognize [14]. The low amplitude of the sinus-oidal pattern (äs in cases 2,4 and 11) makes themeven more difficult to recognize, especially if thebeat-to-beat recording has failed.The intermittent nature of the sinusoidal FHRpattern also gives a possible explanation for thefact that it has been observed in some cases onlybefore [7] or only after [17] the intrauterinetransfusion. The intrauterine transfusion wasperformed on six fetuses in this series. In one case(case 17) the sinusoidal pattern was observed onlyafter two transfusions. It was seen before and afterthe transfusion in two cases (cases 4 and 9) and itwas not seen at all in association with three trans-fusions. The transfusion procedure itself couldhardly be the cause of the sinusoidal FHR pattern.

Fig. 3. The sinusoidal-simulating pattern of fetal heartrate recorded one hour after intramuscular pethidine wasgiven to the mother. The sinusoidal patterns associatedwith fetal anemia have more rounded and smoothcd pat-tern and a lower frequency.


172 Kariniemi: Anemia and heart rate

A recent report suggested that alphaprodine (anarcotic analgesic) administered to the mothercould be the cause of a sinusoidal FHR pattern[6]. We observed a similar change of FHR afteradministration of intramuscular pethidine to themother (Fig. 3). This pattern, however, lacks thesmoothing and rounding which is so peculiar to

the sinusoidal pattern due to fetal anemia. It alsohas a higher frequency thanf the sinusoidal pattern.In conclusion, typical FHR patterns for fetalanemia are late decelerations observed withperiods of intermittent sinusoidal pattem, whichprobably becomes continuous with worseninganemia.

Summary

A retrospective survey was performed of the clinicalrecords and cardiotocograms (CTG) of fetuses born in1978 and 1979 at Helsinki University Central Hospitalwith hemoglobin concentration iess than 170 g/liter inperipheral blood or umbilical artery. Eighty-three fetuses(0.7%) had thus defined anemia. Thirty-eight of themhad late decelerations, 29 silent and nine sinusoidal fetalheart rate (FHR) patterns. Late decelerations and sinus-

' Keywords: Anemia, fetus, heart rate.

oidal patterns wäre significantly more often associatedwith severe (hemoglobin concentration Iess than 80 g/liter) than with moderate anemia. The fetal outcome interms of perinatal death and low APGAR scores aftersinusoidal pattern was poorer than without this pattern,but the difference was not statistically significant. It isconcluded that intermittent sinusoidal FHR pattern withlate decelerations is suggestive of fetal anemia.

Zusammenfassung

Fetale Anämie und HerzfrequenzmusterVon den zwischen 1978 und 1979 im „Helsinki Uni-versity Central Hospital" geborenen Kindern mit einemHämoglobinwert von < 170 g/l im peripheren Blut oderin der Nabelarterie, wurde eine retrospektive Studie derKrankengeschichte und der Kardiotokogramme (CTG)durchgeführt. 83 der Kinder (0,7%) hatten eine solcheAnämie.38 von ihnen hatten späte Dezelerationen, 29 einestumme und 9 eine sinusähnliche fetale Herzfrequenz

Schlüsselwörter: Anämie, Herzfrequenz, Neugeborenes.

(FHF). Späte Dezelerationen und sinusähnliche Mustergingen signifikant häufiger mit einer schweren Anämie(Hämoglobinwert 80 g/l) einher, denn mit einer müdenAnämie. Zwar waren die Folgen für die Neugeborenen(perinatale Sterblichkeit und APGAR scores) mit sinus-ähnlichen Mustern schlechter als ohne diese Muster, dochwar der Unterschied statistisch nicht signifikant. Zusam-menfassend kann gesagt werden, daß ein intermittentessinusähnliches FHF Muster mit späten Dezelerationeneine fetale Anämie vermuten läßt.

Resume

Anemie fetale et traces de frequences cardiaques.On a fait une etude retrospective des histoires cliniques etcardiogrammes (CTG) d'enfants nes en 1978 et 1979, a„Helsinki University Central Hospital", avec un tauxdliemoglobine inferieur a 170 g/l dans le sang peripher-ique ou dans Tariere ombilicale: 83 enfants (0,7%)avaient cette anemie precitee. 38 de ceux-d avaient unedeceteration retardee, 29 un trace de frequence cardiaquefetale (FCF) süencieux et 9 un trace de FCF sinusoidale.

Mots-cles: Anemie, fetus, frequence cardiaque.

Les decelerations retardees et les traces sinusoiclauxetaient plus frequemment associes a une anemie severe(concentration dTiemoglobine < 80 g/l) qu'a une anemiemoderee. L'etat fetal exprime en termes de mort perina-tal et de bas scores APGAR apres le trace sinusoMal etaitplus mauvais que sans ce trace, mais cette differencen'etait pas statistiquement significative.En conclusion, on peut dire que le trace de la FCF sinus-oi'dal intermittent avec decelerations retardees, suggereune anemie fetale.

Acknowledgement: This work was supported by YRJÖ JAHNSSON Foundation.

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Received December 10, 1981. Accepted February l,1982.

Veikko Kariniemi, M. D.Ist Department of Obstetrics and Gynecology,Helsinki University Central HospitalHaartmanink. 2SF-00290 Helsinki 29Finland


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J. Perinat. Med. Fetal anemia and heart rate patterns