Cervical Cerclage
Case Study
A 28-year-old para 1 +3 woman presented for a cervical cerclage insertion at 16 weeks’ gestation due to previous preterm labor. She weighed 55 kg and was otherwise fit and well, with no gastroesophageal reflux disease. On examination, she had a grade 2 Mallampati view, with good mouth opening, and a thyromental distance of greater than 6.5 cm. Her surgical history included several gynecologic procedures, for which she underwent general anesthesia uneventfully, although she experienced postoperative nausea and vomiting on each occasion.
For this procedure, the patient had a general anesthetic with an IV induction using fentanyl and propofol, after which a Supreme laryngeal mask airway (LMA) was inserted. She was maintained with an oxygen, air, sevoflurane mixture and allowed to breathe spontaneously. IV acetaminophen 1 g and ondansetron 4 mg were administered intraoperatively for analgesia and antiemesis. The procedure lasted 30 minutes. On emergence from anesthesia, the LMA was removed uneventfully, and the patient was taken to the post–anesthesia care unit (PACU).
In the PACU the patient experienced cramplike abdominal pains and received a further 150 µg fentanyl intravenously and 60 mg dihydrocodeine orally. She vomited once, an hour after eating a light meal. She was discharged home 8 hours postoperatively, feeling well. Discharge was delayed due to nausea and vomiting, for which the patient was treated with a further 4-mg dose of IV ondansetron and a 50-mg dose of IV cyclizine in the PACU.
Key Points
This patient had a short procedure under general anesthesia. She experienced pain and postoperative nausea and vomiting that delayed her discharge home.
If she had received a spinal anesthetic, it is likely she would have stayed a similar length of time to allow for the block to fully recede and for her to pass urine.
In the past, passing urine and tolerating oral fluids were also required after general anesthesia before the patient could be discharged home, but this is no longer compulsory, as long as the patient and care givers have written information on where to access help should they need to.1
Discussion
Cervical cerclage is used to prevent preterm labor due to cervical insufficiency. It is characterized by shortening of the cervix or painless cervical dilatation, resulting in recurrent second-trimester pregnancy losses.2 Decisions surrounding the management of cervical cerclage should be made with senior medical involvement and should also be performed by clinicians experienced with the technique.3
Indications for cervical cerclage include3
1. History Indicated. Cervical cerclage is offered to women with three or more previous preterm births and/or second-trimester miscarriages.
2. Ultrasound Indicated. Cervical cerclage is offered to women with a history of one or more spontaneous second-trimester miscarriages who have a cervical length of less than 25 mm before 24 weeks’ gestation.
3. Rescue Cerclage. Cervical cerclage is offered to women with a dilated cervix on physical or speculum examination as a salvage measure in cases of premature cervical dilatation.
The operative procedure is generally no longer than 1 hour in duration but often requires a degree of Trendelenburg positioning, which can be uncomfortable for the patient if she is undergoing the procedure awake under spinal anesthesia.
Anesthetic Considerations
There is very little in the literature regarding the safety of one form of anesthesia over another. General anesthesia is considered safe before 18 weeks’ gestation, with no increased risk of aspiration of gastric contents. Patients who undergo a general anesthetic for cervical cerclage can often be discharged home within a few hours postoperatively. Discharge criteria would be the same as for those undergoing any day-case procedure. Patients would require verbal and written instruction on discharge, should be warned of symptoms they may experience on discharge, and should have an escort suitable to care for the patient at home.
Because of concerns about the teratogenicity of certain drugs and their unlicensed use during pregnancy, clinicians are often reluctant to use multimodal antiemetic medications. This can sometimes present a challenge for the treatment of postoperative nausea and vomiting (PONV) and may delay discharge from hospital. Analgesia is limited to IV acetaminophen and short-acting opioids (e.g., fentanyl) for day-case surgery. Postoperatively, nonsteroidal anti-inflammatory drugs should be avoided because of their teratogenic effects, and a short course of a weak opioid, such as dihydrocodeine, in combination with acetaminophen is usually sufficient.
Uterine relaxation may be required intraoperatively if the fetal membranes are protruding. Trendelenburg positioning may be sufficient in some cases to reduce the herniated membranes. Volatile anesthetic agents may help further by causing a degree of uterine relaxation. Occasionally, tocolytic drugs may be required, especially if the cerclage is being carried out under a regional anesthetic.2 In the case of an emergency rescue cerclage, it is even more important that the mother does not strain or cough (and potentially prematurely rupture the fetal membranes) during the procedure. Therefore, in these emergency cases, spinal anesthesia may be advantageous because it negates the risk of coughing on emergence from general anesthesia.
If a neuraxial anesthetic technique is chosen, a sensory block height of T10–L1 and S2–S4 is required to cover the cervical, vaginal, and perineal dermatomes.2, 4
Safety of Drugs in Pregnancy
Despite the lack of published evidence, expectant mothers are often routinely informed of the potential risks associated with cerclage.3 Risks such as iatrogenic rupture of membranes, infection, hemorrhage, and cervical stenosis4 associated with the operative procedure are routinely discussed with the mothers preoperatively. The anesthetic technique, including any potential risks and benefits of one technique over another, is rarely discussed with the patient by the obstetrician. It is usually left to the anesthetist to consider and discuss. Many anesthetists, however, will inform patients that there is a potential small risk of miscarriage, regardless of technique used, and will reassure mothers that they will avoid any known teratogenic drugs.
The first trimester is the period when the fetus is most at risk of the teratogenic effects of drugs that cross the placenta because this is when organogenesis is taking place.5 IV induction agents (e.g., thiopentone, propofol) and volatile anesthetic gases will cross the placenta because they are highly lipid soluble but will not cause any long-term effects in the undelivered fetus. Opioids such as fentanyl and morphine will cross the placenta and can cause neonatal respiratory depression but again should not have any long-term adverse effects in the unborn fetus. Local anesthetic drugs such as bupivacaine are lipid soluble and so will undergo placental transfer, but only after systemic absorption from the subarachnoid or epidural space.
Learning Points
Aspiration is not considered to be a risk before 18 weeks’ gestation in an appropriately fasted otherwise healthy parturient.
Positioning and avoidance of straining may affect the choice of anesthesia.
It is a short procedure, usually under 1 hour, and can be done as a day case.
There is a lack of evidence regarding the safety of one form of anesthesia over another (often physician or unit preference).
Use of known teratogenic drugs should be avoided.
Usually the fetus is previable, negating the need for fetal monitoring intraoperatively.
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