Role of Intrauterine Cornual Block in Combination With Direct Cervical Block in Outpatient Endometrial Ablation

Overview

The usual intervention to control the pain during an outpatient endometrial ablation has been to use local anaesthesia (LA) injection just in the neck of the womb (cervix). However, this alone may not be sufficient to control the pain completely. Therefore, we want to find out whether an injection of LA given deep into the muscle of the womb (myometrium), in addition to that in the cervix, has a better effect on controlling the pain during the procedure. All women attending gynaecology outpatient clinics, who have consented for an outpatient hysteroscopic procedure, will be invited to take part in the study. The study will be carried out in the outpatient hysteroscopy clinic at Birmingham Women's Hospital. As part of standard pain control method during an outpatient endometrial ablation, all women will receive an injection of LA in the cervix of the uterus to 'freeze it'. During hysteroscopy a randomly selected treatment group will receive an injection into deep muscle containing only normal saline (control group) whereas the experiment group will receive fast / long acting local anaesthesia (cornual block). Women will be asked to rate the degree of pain by placing a mark on an ungraduated 10 cm horizontal line. These scales will be given before the procedure, during LA injection, immediately after, one hour and at the time of discharge from hospital. The results will help future patients undergoing a similar procedure to have much better pain relief and allow many more to have the procedure without the side effects of a general anaesthetic and its risks. In addition to having less pain, it may reduce the number of painkillers needed as well as any stay in hospital. In future this may also allow a greater variety of procedures to be done in an outpatient setting.

Outpatient local anaesthesic (LA) hysteroscopic intrauterine therapeutic interventions such as endometrial ablation have gained wider acceptance in the last decade. However, pain experienced during these procedures can be a disincentive and is the commonest reason for the use of escalating levels of analgesia post procedure, which results in prolongation of hospital stay and recovery. Various methods of LA have been studied including intrauterine topical lignocaine or cervical block using topical lignocaine, paracervical block or intracervical block. However, a single site block individually may not be sufficient to control the pain completely due to inability of the one site block to affect the sensitivity of the whole uterus, as the uterine fundus is effectively still unanaesthetised. This may be due to the uterus receiving complex innervations from different nerve routes such as the uterovaginal plexus, the Frankenhauser nerve plexuses, parasympathetic ganglia and the thoracic nerve. Therefore, it seems logical to use a direct cervical block to block the sensation through uterovaginal plexus and use an additional deep myometrial block adjacent to each cornua to directly block the thoracic nerve supply. To date, only one small observational study has looked at the effect of such a combined block in relieving pain during outpatient hysteroscopic procedures. Therefore, we propose to undertake a double blind randomised controlled trial to address this question by comparing effectiveness of a standard direct cervical block and intrauterine cornual block (ICOB) versus a direct cervical block and a normal saline intrauterine cornual injection (control).