Impossibility of lowering the presenting part of the fetus
Last reviewed: 23.04.2024
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
Progressive advancement of the presenting part of the fetus in the cavity of the small pelvis (lowering) is an important sign of normal delivery. Lowering usually begins with the maximum opening of the cervix and is easily traced in the phase of deceleration and especially in the second stage of labor. In some parturient women, subsidence is completely absent.
Diagnostics. To make the diagnosis it is necessary to confirm the absence of the lowering of the presenting part of the fetus during the II period of labor. In most cases, the impossibility of lowering is associated with the presence of other abnormalities of labor activity - in 94.1% of women in labor a secondary stop of cervical dilatation was registered, in 78.4% - concomitant disorders caused by slowing of labor. Most often, the diagnosis is made on the basis of two vaginal examinations, which are performed at intervals of 1 hour in the II stage of labor.
Frequency. This anomaly complicates 3.6% of births.
Causes. In the overwhelming majority of parturient women with the impossibility of further lowering the presenting part of the fetus, there is a discrepancy between the size of the fetus and the pelvis of the mother.
Forecast. Since maternity wards who have obstructions to fetal passage through the birth canal, caesarean section is necessary, the prognosis should be given with caution.
Conducting births with the impossibility of lowering the presenting part of the fetus
Pregnant with the impossibility of further fetal movement through the birth canal requires an immediate cesarean section. In such cases, the discrepancy in size is too often an etiological factor, so it is better to erroneously perform a cesarean section in some women who might have vaginal births with their further development, rather than encounter the many complications observed in most parturient women with a mismatch between the fetus and the pelvis of the mother .
[