Labor dystocia, also known as difficult or obstructed labor, refers to a wide range of conditions, from abnormally delayed cervix dilation or fetal descent during active labor to trapping of the fetal shoulders following head delivery (called as shoulder dystocia).
The majority of women who have never given birth before experience this issue during labor. Labor or giving birth is staged by doctors and professionals, namely stages 1, 2, 3, and 4. Of all primary cesarean deliveries, up to 15% to 30% and 10% to 25%, may result from first and second-stage labor arrest, respectively.
The causes of dystocia are classified into the three P’s, namely passage, passenger, and power. Power refers to uncoordinated uterine activity or short, infrequent contractions that prolong labor. This is common in first-time mothers who are at risk. Passage refers to instances where the fetus is in a transverse or breech position, or have macrosomia (birth weight >=4.5 kg), or instances when the fetal shoulder arrests labor. Finally, passage pertains to the pelvis of the mother. A round pelvis is ideal for labor; however, some women may be born with an oval pelvis. If a first-time mother's fetus's head has not engaged into her pelvis by 37 weeks, she may have a tiny pelvic brim resulting in difficulty in labor.
Dystocia has no signs or symptoms, and there is no definitive way to predict if it will happen. Your doctor may not notice the problem until after the baby's head is born. It becomes clear when the baby's head comes out and then pulls back against the area between the vagina and rectum (perineum). This is referred to as the "turtle sign."
Doctors use labor curves (aka partogram), which show how quickly a woman's cervix should change when she is in labor. Deviations from these curves, especially rates of cervical change slower than expected from the partogram, are called protracted or arrest disorders and represent labor dystocia.
Indication of labor arrest is described in terms of labor duration and widening of the cervix. If there is more than 20 hours of labor for first-time mothers or more than 14 hours of labor for multiple-time mothers then it is a sign of labor arrest. If the cervix widens at a rate of less than 1.2 cm per hour for first-time mothers and less than 1.5 cm per hour for multiple-time mothers.
The best way to treat dystocia depends on the condition of the mother and the health of the baby. Oxytocin is used when dystocia is caused by weak uterine contractions. For a fetal head that is stuck in a transverse position, a forceps delivery can be done. Doctors can also use a vacuum extraction to deliver the baby in dystocia.
There are a number of ways to help diagnose labor earlier, either directly or indirectly (for example, the way pain is treated), prevent labor dystocia, or speed up labor after a dystocia diagnosis.
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Fuchs F. (2015). Prévention des facteurs de risque de la dystocie des épaules avant l'accouchement [Prevention of shoulder dystocia risk factors before delivery]. Journal de gynecologie, obstetrique et biologie de la reproduction, 44(10), 1248–1260. https://doi.org/10.1016/j.jgyn.2015.09.050
Shields, S. G., Ratcliffe, S. D., Fontaine, P., & Leeman, L. (2007). Dystocia in nulliparous women. American family physician, 75(11), 1671–1678.
Cleveland Clinic (2022). Shoulder Dystocia. Retrieved November 6, 2022, from https://my.clevelandclinic.org/health/diseases/22311-shoulder-dystocia
CGMH.org (2022). Dystocia. Retrieved November 6, 2022, from https://www1.cgmh.org.tw/intr/intr5/c6700/OBGYN/f/web/Dystocia/index.htm