Z Geburtshilfe Neonatol 2021; 225(S 01): e49
DOI: 10.1055/s-0041-1739815
Abstracts | DGPM

M-sign in middle cerebral Doppler waveforms and umbilical artery Doppler before, during and after fetal myelomeningocele repair

L Vonzun
1   Universitätsspital Zürich, Klinik für Geburtshilfe, Zürich, Schweiz
,
M Gonser
2   Helios-Kliniken Wiesbaden, Klinik für Geburtshilfe, Wiesbanden, Deutschland
,
U Moehrlen
3   Kinderspital Universität Zürich, Departement für Kinderchirurgie, Zürich, Schweiz
,
L Mazzone
3   Kinderspital Universität Zürich, Departement für Kinderchirurgie, Zürich, Schweiz
,
M Meuli
3   Kinderspital Universität Zürich, Departement für Kinderchirurgie, Zürich, Schweiz
,
F Krähenmann
1   Universitätsspital Zürich, Klinik für Geburtshilfe, Zürich, Schweiz
,
R Zimmermann
1   Universitätsspital Zürich, Klinik für Geburtshilfe, Zürich, Schweiz
,
N Ochsenbein-Kölble
1   Universitätsspital Zürich, Klinik für Geburtshilfe, Zürich, Schweiz
› Author Affiliations
 

Background Increased pulse wave reflection in the fetal arterial system, illustrated by a second systolic flow acceleration in middle cerebral artery (MCA) resulting in an M-signed Doppler waveform, allows interpretation of fetal systemic vasoconstriction. Accordingly, an M-sign indicates significantly increased vasoconstriction. In adults, blood pressure is controlled by systemic vasoconstriction and rises with increasing intracranial pressure in order to maintain cerebral perfusion. Hence, a possible analogy could be expected in fetuses with spina bifida. However, up to now, little is known about vascular regulation of these fetuses before during and after fetal MMC (fMMC) repair. Therefore, the aim of this study was to systematically analyze MCA and uterine artery (UA) Doppler waveform changes before, during, and after fMMC repair.

Patients and Methods Nineteen pregnant women who underwent fMMC repair were included. Fetal MCA-Doppler waveforms were prospectively analyzed before, during and after fMMC repair, and categorized as follows: normal systolic downslope, systolic shoulder, second systolic peak (M-sign), and concave systolic downslope. These MCA waveforms were related to maternal and fetal characteristics, to anesthetic medication and to UA waveforms.

Results Before fMMC repair, all fetuses repeatedly presented M-signs. After initiation of desflurane for general anesthesia, systolic shoulder and M-sign vanished in 15/19 (79%) fetuses (binomial test, p<0.02) and 12/19 (63%) showed transient UA-ARED flow. A significant association between these two Doppler findings were found (p=0,009). For MCA waveform changes progressive evolution was observed throughout the operation. UA-ARED flow occurred with a timely delay of 97±30 min from the beginning of surgery. After fMMC repair, signs of increased pulse wave reflection reappeared but resolved over time (27±20 days) in all fetuses.

Conclusion Both fMMC with concomitant increased intracranial pressure as well as the intrauterine repair influence fetal vascular regulation. This phenomenon can be illustrated by MCA-Doppler waveforms. On one side, anesthetic agents transiently eliminated the possibly, MMC induced, fetal vasoconstriction and, thus, the M-sign, and on the other side they led to a transient loss of UA-ED flow, by specific drug induced increaed the pulsatility index of the umbilical artery UA-PI. Both changes might be interpreted as a result of the potent vasodilatative effect of the deflurane on the fetal arterial system. Finally, fMMC repair led to normalization of MCA-Doppler waveforms indicating return to normal fetal vascular regulation.

Zoom Image
Fig. 1 MCA Doppler showing a second systolic peak resulting in M-signed waveform before fMMC repair.


Publication History

Article published online:
26 November 2021

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