Shoulder Presentation

Shoulder presentation is a fetus lying across the pelvic inlet with a shoulder (acromion) over the cervix, found in labour in a transverse lie. It occurs often in grand multiparas and in women with placenta previa, polyhydramnios, fibroids, a contracted pelvis or a preterm fetus. It matters because vaginal birth is impossible for a term baby, and neglected shoulder presentation causes obstructed labour, arm and cord prolapse, uterine rupture and death.

• Risk factors: grand multiparity, placenta previa, polyhydramnios, uterine fibroids or anomaly, contracted pelvis, prematurity, twin pregnancy.
• Membrane rupture with a transverse lie raises the risk of cord prolapse.
• Immediate caesarean section is the safest option.

Women have a wide abdomen with the long axis of the uterus transverse (breadth greater than length), a head felt on one side and the breech on the other, and an empty lower pole. Later, the arm or the shoulder may prolapse, and a ridge (bandl ring) forms in obstruction.

• Fundal height below dates with a wide uterus.
• Prolapsed arm or cord felt in the vagina after rupture of membranes.
• Differential diagnosis: oblique lie, breech presentation, twin pregnancy with a transverse second twin, placenta previa, uterine anomaly, uterine rupture.
• Complications: cord prolapse, arm prolapse, obstructed labour, uterine rupture, fetal death, sepsis, haemorrhage, fistula, maternal death.

The diagnosis is made by abdominal palpation and vaginal examination, and confirmed by ultrasound.

• Abdominal examination: transverse lie, no presenting part over the pelvis, head in a flank.
• Vaginal examination (only after ultrasound has excluded placenta previa): shoulder, ribs (like a gridiron), axilla, arm or cord.
• Ultrasound: lie, placenta position, fetal heart, liquor volume, uterine anomaly and fibroids.
• Cardiotocography; group and cross-match.

The principle is immediate delivery by caesarean section when the fetus is alive, and careful destructive delivery by a trained operator when the fetus is dead and obstruction has occurred.

• Supportive: admit at once; do not attempt vaginal delivery; two cannulae; Ringer's lactate 1 litre IV over 1 hour; knee chest position if the cord is prolapsed; cord replaced and bladder filling with sodium chloride 0.9 percent 500 mL when cord prolapse is present; urinary catheter; group and cross-match 2 units; senior surgeon.
• Pharmacological: cefazolin 2 g IV as a single dose before caesarean section; ampicillin 2 g IV 6-hourly plus gentamicin 5 mg/kg IV once daily plus metronidazole 500 mg IV 8-hourly for obstructed labour or fever, continued until afebrile for 48 hours; terbutaline 0.25 mg subcutaneous once for contractions while preparing for theatre; glyceryl trinitrate 400 micrograms sublingual for uterine relaxation during internal podalic version of a second twin; oxytocin 10 IU IM after birth, then 20 IU in 1 litre Ringer's lactate at 125 mL per hour for 4 hours; tranexamic acid 1 g IV over 10 minutes if bleeding exceeds 500 mL; newborn vitamin K 1 mg IM.
• Procedures: caesarean section for a live fetus, with a low vertical or classical incision if the lower segment is poorly formed; decapitation or evisceration (embryotomy) by a trained operator for a neglected shoulder with a dead fetus and a contracted uterus; internal podalic version and breech extraction under general anaesthesia for a transverse second twin only; no attempt at forceful version in a contracted uterus; bladder catheter for 7 to 14 days after neglected labour.
• Special groups: a second twin in transverse lie allows internal podalic version with relaxation (glyceryl trinitrate 400 micrograms sublingual) before breech extraction; a uterine scar with a transverse lie in labour has immediate caesarean section.
• Red flags: arm or cord prolapse, bandl ring, shock, bleeding, fetal bradycardia or absent heart, fever above 38 degrees Celsius.
• Follow-up: bladder catheter and fistula check; ferrous sulphate 200 mg oral 8-hourly for 3 months if anaemic; counselling that the next birth should be in a facility; review at 6 weeks.