Obstructed labour is more likely to occur if:

• The labour has been prolonged (lasting more than 12 hours)
• The mother appears exhausted, anxious and weak
• Rupture of the fetal membranes and passing of amniotic fluid was premature (several hours before labour began)
• The mother has abnormal vital signs: fast pulse rate, above 100 beats/minute; low blood pressure; respiration rate above 30 breaths/minute; possibly also a raised temperature.

You should assess a woman with this labour history by doing a vaginal examination. Any of the following additional signs would suggest the presence of obstruction:

• Foul-smelling meconium draining from the mother's vagina.
• Concentrated urine, which may contain meconium or blood.
• Oedema (swelling due to collection of fluid in the tissues) of the vulva (female external genitalia, including the labias), especially if the woman has been pushing for a long time. Vagina feels hot and dry to your gloved examining finger because of dehydration.
• Oedema of the cervix.
• A large swelling over the fetal skull can be felt (caput, Study Session 4).
• Malpresentation or malposition of the fetus.
• Poor cervical effacement (look back at Figure 1.1 in the first study session); as the result the cervix feels like an 'empty sleeve'.
• Bandl's ring may be seen (Figure 9.2).