Chapter 168: Symphysiotomy

INTRODUCTION

Symphysiotomy is the artificial division and separation of the pubic symphysis to facilitate vaginal delivery. This is not to be confused with a pubiotomy or the severance of the pubic bone a few centimeters lateral to the symphysis for the same purpose. A symphysiotomy was first performed in the seventeenth century. It is indicated in cases of cephalopelvic disproportion and may be a lifesaving alternative to cesarean delivery.^1-5 The reported success rate of this procedure is approximately 80% when performed appropriately.⁶

The procedure requires minimal equipment and can be accomplished under local anesthesia in as little as 2 to 3 minutes.^6,7 The increased availability of cesarean sections combined with the known urologic and orthopedic complications have led to its decline and lack of acceptance in modern obstetrical practice.^8,9 However, symphysiotomies are performed regularly and successfully in developing countries where resources and trained medical professionals are often limited or unavailable.^2,3,10

Indications for a symphysiotomy include breech delivery, cephalopelvic disproportion, and relief of shoulder dystocia.^1,11,12 Each of these conditions poses significant potential risks to mother and child, even under optimal conditions. Emergency Physicians should be familiar with the indications and technique of symphysiotomy as expeditious delivery is vital in these scenarios.

ANATOMY AND PATHOPHYSIOLOGY

The pelvis is composed of four bones: the sacrum, the coccyx, and the innominate bones. Each innominate bone is made up of the fused ischium, ilium, and pubis. The innominate bones are connected at the sacrum by the sacroiliac ligaments and at the pubic symphysis by the superior and arcuate pubic ligaments.¹² Together they determine the size and shape of the pelvis. The fetus assumes positions during labor that are primarily determined by the conformation of the mother’s pelvis.¹³

The pelvis is divided into a true pelvis and a false pelvis. They are separated by the linea terminalis, an anatomic boundary formed by the pelvic brim (i.e., superior pelvic aperture). The true pelvis lies below the linea terminalis and is the more relevant portion in delivery.¹⁴ Dense ligaments hold the walls of the true pelvis together. The posterior wall is the anterior surface of the sacrum and coccyx. The lateral boundaries are formed by the inner surface of the ischial bones as well as the sacrosciatic notches and ligaments. The ischial spines can be readily palpated during the vaginal or rectal examination. They serve as important landmarks in determining to which level the presenting part has descended into the true pelvis. The true pelvis is bounded anteriorly by the pubic bones, the ascending superior rami of the ischial bones, and the obturator foramina.

The ligaments of the pubic symphysis and the sacroiliac ligaments allow mobility and contribute to the increase in pelvic diameter during pregnancy.¹³ The sacral ...