Symphysiotomy and Destructive Operations
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Direct answer
Symphysiotomy is division of the pubic symphysis to enlarge the pelvis in cephalopelvic disproportion, while destructive operations are procedures on a dead fetus that reduce its size so that it can pass through an obstructed pelvis. The destructive group includes craniotomy, decapitation, cleidotomy and evisceration. These procedures are now rare because caesarean section is safer, and they are reserved for a dead fetus when caesarean section is not feasible.
What you must remember
- Symphysiotomy: division of the pubic symphysis ligaments, historically used for cephalopelvic disproportion with a living fetus, and now abandoned in most settings.
- Craniotomy: perforation and collapse of the fetal skull with a perforator and a cranioclast, used for a dead fetus with a head too large to pass.
- Decapitation: separation of the fetal head from the body, a rarely used last resort for a dead fetus in an obstructed labour.
- Cleidotomy: division of the fetal clavicle to narrow the shoulders, so that an impacted shoulder can pass through the pelvis.
- Evisceration: removal of thoracic and abdominal viscera to reduce the trunk size, used for a dead fetus in an obstructed labour.
- Indication: obstructed labour with a dead fetus, where caesarean section is not feasible or carries unacceptable maternal risk.
- Maternal hazards: injury to the bladder, urethra, cervix and birth canal, and infection and sepsis.
Choosing the operation by the obstructing part
All destructive operations share one condition, a dead fetus, and the table separates the procedures by what they reduce. The aim is to pick the least damaging option for the part that is obstructing the pelvis.
| Operation | Fetus | Purpose | Key point |
|---|---|---|---|
| Symphysiotomy | Living (historic) | Enlarge the pelvis | Pelvic instability, bladder injury |
| Craniotomy | Dead | Reduce head size | Perforate and collapse the skull |
| Cleidotomy | Dead | Reduce shoulder width | Divide the clavicle |
| Decapitation | Dead | Separate the head | Last resort |
| Evisceration | Dead | Reduce trunk size | Remove thoracic and abdominal viscera |
Exam questions usually name the obstructing part and ask for the matching operation. The rule that the fetus must be dead before any destructive step is taken is the one most often tested, and caesarean section replaces these procedures whenever it is safe to perform.
The procedures also differ in how much fetal tissue they remove, and the operator chooses the least extensive procedure that clears the obstruction.
Where the exam tries to catch you
Questions test the fetal status before any destructive operation and the modern alternative to each procedure.
- Trap: choosing craniotomy for a living fetus with a large head Correct: destructive operations are performed only on a dead fetus, and a living fetus needs caesarean section.
- Trap: treating symphysiotomy as a modern alternative to caesarean section Correct: symphysiotomy is abandoned in most settings because of pelvic instability and maternal injury.
- Trap: assuming destructive operations are routine in obstructed labour Correct: they are reserved for a dead fetus when caesarean section is not feasible, and caesarean is the default for a living fetus.
Frequently asked questions
Which destructive operation is performed for a dead fetus with a large head?
Craniotomy is the destructive operation performed for a dead fetus with a head too large to pass the pelvis. The skull is perforated and collapsed with a perforator and cranioclast. The procedure is used only when caesarean section is not feasible.
What is cleidotomy used for?
Cleidotomy is used for a dead fetus with an impacted shoulder in obstructed labour. The fetal clavicle is divided to narrow the shoulders so that they can pass through the pelvis. It is one of the destructive operations tested for shoulder obstruction.
Is symphysiotomy still performed in modern obstetric practice?
Symphysiotomy is no longer performed in most modern obstetric practice, because caesarean section is safer. It was historically used for cephalopelvic disproportion. The procedure is associated with pelvic instability and injury to the bladder or urethra.
When is evisceration indicated in obstructed labour?
Evisceration is indicated for a dead fetus in obstructed labour, most often in a transverse lie where the trunk is impacted. The thoracic and abdominal viscera are removed to reduce the trunk size. It is a last resort when caesarean section cannot be performed.
Why must the fetus be dead before a destructive operation?
The fetus must be dead before a destructive operation because these procedures injure or remove fetal tissue and would kill a living fetus. Caesarean section is chosen for a living fetus instead. This condition is one of the most frequently tested points in the topic.