Discussion

Most anesthesiologists feel that any anesthesia, even a local anesthesia, works more smoothly if premedication is used. This is true with the paracervical block. I use meperidine hydrochloride (Demerol®), promethazine hydrochloride (Phenergan ®) and occasionally secobarbital sodium (Seconal®). They are unnecessary after the block. The Brittain Transvaginal Needle Guide* facilitates injection. This is a stainless-steel tube with a ball on one end to prevent injury to maternal tissues and a funnel on the other end to allow easy access for the 6-inch 20-gauge needle. The needle protrudes from the guide only 7 mm. This eliminates the danger of too deep an injection and reduces the danger of hematoma formation to nil. The block is performed with the patient in bed under sterile drapes but without surgical preparation. The cervicovaginal fornix is located with the examining finger and the guide is placed at the 5 o'clock and 7 o'clock positions.

It is important to sweep the guide away from the cervix in order to get into the posterior lateral fornix. The needle is then inserted through the guide, aspiration is made and the solution injected. I use chiefly a 1 per cent solution of lidocaine hydrochloride with epinephrine 1: 1, 000, 000. This is prepared by mixing 50 ml plain 1 per cent lidocaine with 5 ml 1 per cent lidocaine with epinephrine 1: 100, 000. Epinephrine is contraindicated in the presence of diseases such as diabetes, hyperthyroidism, peripheral vascular disease, hypertension, nephritis and cardiac disease. The addition of epinephrine makes the mixture much safer than plain lidocaine hydrochloride and allows a longer duration of effect, but at the expense of uterine inertia in a certain proportion of cases, sometimes requiring use of an oxytocic agent. The usual dosage of anesthetic agent is 8 to 10 ml on each side. The maximum dosage is 50 ml-that is, 500 mg of lidocaine hydrochloride with epinephrine. Only 300 mg is allowed without epinephrine. If complete anesthesia is not obtained within two or three contractions, 5 ml is repeated on either or both sides. Sometimes there remains an unanesthetized coin area in the lower abdomen on one or both sides. This can be anesthetized by injection of 5 ml at the 10 o'clock or the 2 o'clock position. I keep one guide curved to allow easier introduction to these anterior locations. Failure is unacceptable. Repeated efforts should be made until the desired effect is achieved, but with care to stay within the limits of safe dosage. It must be emphasized that the greatest danger is overdosage.

The block is given in the accelerated phase of labor, usually at about 5 cm cervical dilatation. Using lidocaine hydrochloride with epinepbrine, the duration of anesthesia is approximately one hour and twenty minutes. The quality of uterine contractions after the block might seem poor and yet the progress in cervical dilatation be dramatic. This is because the cervix has become so soft and free of tone that even the mild contractions lead rapidly to complete dilatation. Because of atonicity, cervical lacerations are rare.

We have done over four thousand blocks using this material in private practice. There have been no serious maternal complications. An occasional patient has complained of feeling faint or apprehensive from too rapid absorption, but these complaints have been very transient. Temporary numbness of one or both legs noted by some patients, disappears as the paracervical anesthesia abates. There have been no instances of hematoma, thrombosis, infection, hypersensitivity reaction or lumbosacral plexus neuritis. The only untoward effect is fetal bradycardia, noted in 4. 7 per cent of cases. This should not be viewed with alarm; it is probably due to a vasovagal reflex, and must be distinguished from fetal distress. Infants have been delivered during the period of bradycardia in some cases and after its disappearance in others, and in none of them has fetal depression been present. On the contrary, the infants are breathing and crying before the delivery is completed. The important point, therefore, is that a careful evaluation must be made to distinguish the cases of fetal bradycardia due to fetal distress from the transient bradycardia observed following paracervical anesthesia.

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