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Destructive Operations on the Fetus
These are a group of operations aimed at reducing the size of the head, shoulder or trunk of a dead fetus or a fetus with a lethal anomaly in order to facilitate its passage through the birth canal. Other than cases of drainage of the hydrocephalic fetal head, these procedures have no place in modern obstetrics, particularly in regions with developed health services. However, there may be situations, for cultural and clinical reasons, or in regions with poorly developed health services, when destructive operations on the fetus may be necessary to save the life of the mother.
The incidence of destructive operations is decreasing and is below 1% in developing countries. Several authors have, however, recommended that this skill be maintained in countries where hospital facilities are limited or when caesarean section for obstructed labour may carry a higher risk of maternal death than a fetal destructive procedure. In addition, the caesarean incision may have to be of the classical type with the risk for uterine rupture in the subsequent pregnancy.
The role of these operations will depend upon the clinical circumstances and the level of obstetric services available – particularly safe caesarean section. In cases of obstructed labour with mild-to-moderate cephalopelvic disproportion and a live fetus, symphysiotomy may be chosen. If there is gross disproportion and the fetus is alive then caesarean section should be performed. Similarly, if obstructed labour is due to a transverse lie, with shoulder or compound presentation, and the fetus is alive, caesarean section will be less risky to both mother and infant than internal version and breech extraction. However, when the fetus is dead and facilities for safe caesarean section are absent or marginal, craniotomy may be considered for cases of cephalopelvic disproportion, and decapitation may be indicated for transverse lie. In addition, the social and cultural context in which the woman lives may lead her to refuse caesarean delivery under all circumstances.
General Principles
In the majority of cases with obstructed labour, the woman has been through a prolonged, painful and harrowing experience. She is likely to be exhausted, demoralized, dehydrated, in pain and have sepsis.
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Initial management should include resuscitation with intravenous crystalloids and placement of a Foley catheter to monitor and guide fluid management.
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Blood should be taken for full blood count, cross-match and coagulation screen if possible. Prolonged obstructed labour leading to atonic postpartum haemorrhage and/or trauma to the genital tract during the destructive procedure increases the risk for blood loss.
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Broad-spectrum intravenous antibiotics should be administered to reduce the risk of infection.
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After the initial resuscitation, the woman and her partner and, if appropriate, a senior relative should be involved in the discussion and plan for delivery. This includes information about the condition of the fetus. Fully informed consent in these situations is difficult but every effort must be made to obtain this to the extent feasible under the circumstances.
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The choice of anaesthesia will depend on what is available and the patient’s condition. Under these trying circumstances, general anaesthesia may have some advantages for both the patient and operator. However, spinal anaesthesia combined with sedation may be a safer option. If these are not available, local anaesthesia with pudendal block, paracervical block and intravenous sedation may be adequate. An intravenous injection of 100 mg of pethidine and 10 mg of diazepam will provide sufficient analgesia and relaxation.
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The possibility of uterine rupture should be considered before embarking upon the procedure.
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Ideally, the cervix should be fully dilated, although an experienced operator may be able to perform these procedures with a cervix of 7 cm or more dilatation. The true conjugate of the pelvic brim should be at least 8 cm.
Operative Procedures
Craniotomy
This is the most commonly performed destructive operation and is used for a neglected obstructed labour with a dead fetus in cephalic presentation. The ease and safety of this procedure depend upon the degree of pelvic contraction, the size of the fetal head and the experience of the operator. In general, if the fetal head is palpable more than three-fifths above the pelvic brim or is mobile at the pelvic brim then the procedure is difficult and dangerous. In these situations, even with a dead fetus, caesarean section is usually less hazardous for the mother.
In addition to adequate anaesthesia, it is essential to confirm that the Foley catheter is properly placed and that the bladder is empty. The ideal instrument for perforation of the fetal head is Simpson’s perforator. The depth of the two cutting blades is limited by the instrument’s shoulders beneath them. The handles are held together by a hinged crossbar and are wide apart when the cutting blades are in apposition. By pressing the handles together the cutting blades are separated. The head of the infant is steadied by the assistant using suprapubic pressure. The fingers of one hand are used to protect the maternal tissues and guide the points of the perforator to the anterior or posterior fontanelle, whichever is more accessible. The perforator should be at right angles to the surface of the skull as the instrument is pushed into the head up to the shoulders of the blades and opened as widely as possible to make a longitudinal incision on the scalp and the bone below, usually by separation of the sutures. This is followed by closing the blades and turning the perforator through 90 degrees and repeating the procedure to produce a cruciate incision in the skull ( Fig. 42.1 ).
The perforator should be opened and closed while inside the cranium, and the brain broken up in all directions. Provided the perforator is kept in the skull up to the instrument’s shoulders, and this is monitored by the fingers of the other hand, there should be no risk of trauma to the maternal soft tissues. The perforator is now withdrawn under protection of the other hand. Brain matter will usually ooze out of the incision and this evacuation can be assisted digitally.
If Simpson’s perforator is not available, sharp Mayo’s or similar scissors can be used to make a cruciate incision on the fetal scalp followed by introduction of the scissors into the fetal head via the most accessible fontanelle or suture line. The scissors are retained in the fetal skull and opened repeatedly in all directions to facilitate evacuation of the brain tissue.
Once the head has been reduced in size, delivery can be assisted by traction on the edges of the cranium by Kocher’s forceps or vulsella. If the cervix is not yet fully dilated, a bandage can be tied through the handles of these forceps and a weight applied to the end to facilitate complete cervical dilatation and delivery of the head during subsequent uterine contractions. If the degree of pelvic contraction is slight and the decompressed head is low in the pelvic cavity then ordinary obstetric forceps such as Simpson’s or Neville–Barnes may be used to effect delivery of the fetal head. In cases of face presentation the most convenient site for perforation is the palate. Instruments such as the cranioclast and cephalotribe are no longer used.
Craniotomy of the After-Coming Head
This may be required for the dead fetus with the breech delivered and an obstructed after-coming head. Once the arms of the infant have been brought down the assistant ensures that the fetal back is anterior and applies traction to the legs in a direction that facilitates access of the operator to the occipital region. Protecting the maternal tissues with the fingers of one hand, Simpson’s perforator is pushed through the skull in the neighbourhood of the posterior lateral fontanelle ( Fig. 42.2 ). In some cases of contracted pelvis, this may be difficult to reach, in which case the occipital bone is perforated in the midline. The manoeuvres to enlarge the incision and evacuate the contents of the skull are the same as with the fore-coming head. Once the size of the head has been reduced it may be delivered by the Mauriceau–Smellie–Veit manoeuvre or forceps to the after-coming head.
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