Protracted labor is abnormally slow cervical dilation or fetal descent during active labor. Diagnosis is clinical. Treatment is with oxytocin, operative vaginal delivery, or cesarean delivery.
Active labor usually occurs after the cervix dilates to ≥ 4 cm. Normally, cervical dilation and descent of the head into the pelvis proceed at a rate of at least 1 cm/h and more quickly in multiparous women.
Protracted labor may result from fetopelvic disproportion (the fetus cannot fit through the maternal pelvis), which can occur because the maternal pelvis is abnormally small or because the fetus is abnormally large or abnormally positioned (fetal dystocia).
Another cause of protracted labor is uterine contractions that are too weak or infrequent (hypotonic uterine dysfunction) or, occasionally, too strong or close together (hypertonic uterine dysfunction).
Diagnosis of protracted labor is clinical.
The cause must be identified because it determines treatment.
Assessing fetal and pelvic dimensions and fetal position (see Physical Examination) can sometimes determine whether the cause is fetopelvic disproportion. For example, fetal weight> 5000 g (> 4500 g in diabetic women) suggests fetopelvic disproportion.
Uterine dysfunction is diagnosed by evaluating the strength and frequency of contractions via palpation of the uterus or use of an intrauterine pressure catheter.
Diagnosis is often based on response to treatment.
If the 1st or 2nd stage of labor proceeds too slowly and fetal weight is < 5000 g (< 4500 g in diabetic women), labor can be augmented with oxytocin, which is the treatment for hypotonic dysfunction. If normal progress is restored, labor can then proceed. If not, fetopelvic disproportion or intractable hypotonic dysfunction may be present, and cesarean delivery may be required.
In the 2nd stage of labor, forceps or vacuum extraction may be appropriate after evaluation of fetal size, presentation, and station (2 cm below the maternal ischial spines [+2] or lower) and evaluation of the maternal pelvis.
Hypertonic uterine dysfunction is difficult to treat, but repositioning, short-acting tocolytics (eg, terbutaline 0.25 mg IV once), discontinuation of oxytocin if it is being used, and analgesics may help.