We report two cases in which face presentation occurred with posterior and anterior chin position, respectively. In both cases clinical findings were confirmed by the use of suprapubic three-dimensional (3D) ultrasound.
In the first case, a 36-year-old woman, gravida 2 para 1, was admitted to our labor ward at 39 weeks' gestation because of onset of active labor. Two hours later, at vaginal examination, the cervix was dilated (5 cm) and typical facial features were clearly recognizable at palpation. The fetal chin could be detected in a posterior position. Another 2 hours later, cervical dilatation had progressed to 9 cm, and face presentation with posterior chin was clinically confirmed. An ultrasound volume was acquired suprapubically and a hyperextended fetal head approaching the fetal back was visually demonstrated during offline analysis (Figure 1). Cesarean delivery of a healthy male weighing 3200 g was subsequently performed. The deflexed face presentation with occiput anterior position was confirmed intraoperatively.
In the second case, a 34-year-old woman, gravida 1, was admitted to our labor ward at 38 weeks' gestation. Labor progressed until cervical dilatation reached 8 cm within 5 hours of admission. At digital examination the fetal nose was recognizable below the left pubic ramus, raising the suspicion of a deflexed fetal head with anterior chin. At suprapubic ultrasound the fetal spine was in a posterior position. An ultrasound volume was then acquired and offline analysis showed a deflexed cephalic presentation with the fetal occiput approaching the fetal back and a hyperextended fetal neck directly below the ultrasound probe (Figure 2). When labor did not progress, Cesarean delivery of a healthy female weighing 3060 g was subsequently performed. The deflexed face presentation with anterior chin position was confirmed intraoperatively.
Three varieties of deflexed cephalic presentations are traditionally acknowledged according to the degree of head extension, i.e. bregma, brow and face1. In face presentation the head presents with the submentobregmatic diameter, which at around 9.5 cm is as large as that in vertex presentation. In these cases vaginal delivery is sometimes possible, but this ultimately depends on the fetal mentum position2. If the mentum is anterior, the chin can use the pubic symphysis as a fulcrum and the head can be delivered vaginally by flexion. If the mentum is posterior, vaginal delivery is virtually impossible unless the fetus is extremely small or macerated1–3. Diagnosis is based classically upon digital examination in a woman with secondary arrest of dilatation or poor fetal head descent, although the complementary use of ultrasound has been suggested by some4–6.
Correct diagnosis is crucial and the use of ultrasound may support the clinician, allowing visual confirmation of digital findings and avoidance of inappropriate management of labor. Intrapartum ultrasound is one of the most promising adjuvant tools in assessment of labor progression7–10. We have recently reported the complementary use of intrapartum translabial ultrasound in the diagnosis of fetal head asynclitism11.
Here we have presented the use of 3D ultrasound as an adjuvant tool in the diagnosis of two cases of face presentation with anterior and posterior chin position. In both cases, a comprehensive view of the fetal head on the three spatial planes of the birth canal was made possible by volume sonography. The use of ultrasound during labor may support clinical diagnosis and assist the physician in cases of face presentation in which management is difficult and prone to serious complications.